Multichannel Structural Inverse Filtering

1984 ◽  
Vol 106 (1) ◽  
pp. 22-28 ◽  
Author(s):  
R. E. Powell ◽  
W. Seering
Keyword(s):  
Response Functions ◽  
Inverse Filtering ◽  
Inverse Filter ◽  
Vibration Measurements ◽  
Input Force ◽  
Multiple Input ◽  
Time Histories ◽  
Force Time ◽  
Value Decomposition ◽  
Pseudo Inverse

A technique has been implemented for predicting the multiple input force time histories acting on a machinery component through the use of multiple vibration measurements and a stored matrix of mechanical frequency response functions. A least squares pseudo-inverse of this transfer matrix is computed in the frequency domain using the singular value decomposition. This decomposition is used to condition the pseudo-inverse against potential singularities caused by uncertainties in the data. The constructed inverse filter is capable of separating multiple input force signals even when the vibration signals contain reverberated information from the inputs in overlapping frequency ranges. The technique has been successfully applied to a flat plate system with two inputs and up to four vibration measurements. Guidelines are suggested for reducing the effects of measurement inaccuracies on the force predictions.

717 A study of estimation method of input force time histories for mechanical structures

2015 ◽  
Vol 2015.53 (0) ◽  
pp. _717-1_-_717-2_
Author(s):  
Takehiro OKAYAMA ◽  
Junichi HINO ◽  
Motomichi SONOBE
Keyword(s):  
Estimation Method ◽  
Input Force ◽  
Time Histories ◽  
Force Time

Determining optimal suspension system parameters for spring fatigue life using design of experiment

2019 ◽  
Vol 20 (6) ◽  
pp. 621
Author(s):  
Yat Sheng Kong ◽  
Shahrum Abdullah ◽  
Dieter Schramm ◽  
Salvinder Singh Karam Singh
Keyword(s):  
Fatigue Life ◽  
Design Of Experiment ◽  
Model Simulation ◽  
Suspension System ◽  
System Parameters ◽  
Quarter Car Model ◽  
Suspension Parameters ◽  
Multiple Input ◽  
Time Histories ◽  
Force Time

This paper presents the optimization of spring fatigue life associated with suspension system parameters using the design of experiment approach. The effects of suspension parameters on spring fatigue life were analyzed because this process can improve spring fatigue life from a distinct perspective. A quarter car model simulation was performed to obtain the force time histories for fatigue life prediction where the suspension parameters were adjusted. Multiple input regression and interaction plots were conducted to identify the interaction between these parameters. A full factorial experiment was performed to determine the optimal suspension settings that would maximize the spring fatigue life. For the regression, a high R 2 value of 0.9078 was obtained, indicating good fitting. The established regression showed normality and homoscedasticity for consistent prediction outcome. Reducing the spring stiffness and sprung mass while enhancing the damping coefficient is therefore suggested to enhance fatigue life.

IMPROVING EXTRACTION OF IMPULSE RESPONSE FUNCTIONS USING STATIONARY WAVELET SHRINKAGE IN TERAHERTZ REFLECTION IMAGING

2010 ◽  
Vol 09 (04) ◽  
pp. 387-394 ◽  
Author(s):  
YANG CHEN ◽  
YIWEN SUN ◽  
EMMA PICKWELL-MACPHERSON
Keyword(s):  
Experimental Data ◽  
Impulse Response ◽  
Response Function ◽  
Impulse Response Function ◽  
Terahertz Imaging ◽  
Impulse Response Functions ◽  
Response Functions ◽  
Inverse Filtering ◽  
Wavelet Shrinkage ◽  
Gaussian Filtering

In terahertz imaging, deconvolution is often performed to extract the impulse response function of the sample of interest. The inverse filtering process amplifies the noise and in this paper we investigate how we can suppress the noise without over-smoothing and losing useful information. We propose a robust deconvolution process utilizing stationary wavelet shrinkage theory which shows significant improvement over other popular methods such as double Gaussian filtering. We demonstrate the success of our approach on experimental data of water and isopropanol.

scholarly journals Stochastic Single Footfall Trace Model for Pedestrian Walking Load

2019 ◽  
Vol 19 (03) ◽  
pp. 1950029 ◽  
Author(s):  
Jun Chen ◽  
Guo Ding ◽  
Stana Živanović
Keyword(s):  
Random Variables ◽  
Distribution Functions ◽  
Dynamic Force ◽  
Gait Parameters ◽  
Proposed Model ◽  
Vibration Serviceability ◽  
Reliable Model ◽  
Time Histories ◽  
Trace Model ◽  
Force Time

Developing a model for the dynamic force generated by a pedestrian’s foot on a supporting structure (single footfall trace model) is crucial to advanced numerical analysis and vibration serviceability assessment of the structure. A reliable model needs to reflect the inter-subject and intra-subject randomness of human walking. This paper introduces a stochastic single footfall trace model in the form of a Fourier series in which body weight, walking frequency, and the first eight harmonics are treated as random variables. An experiment used 73 test subjects, walking at a range of pacing frequencies, to record force time histories and the corresponding gait parameters. Two variability descriptors were used to indicate inter-subject and intra-subject randomness. Further statistical analysis identified the relationships between key parameters as well as the probability distribution functions of random variables. In the final step, an application of the proposed single footfall trace model was developed and tested. The proposed model represented the experimental data well in both time and frequency domains.

On Dynamic Fracture of Rock Under Bit Impact Loads

1982 ◽  
Vol 104 (2) ◽  
pp. 105-107 ◽  
Author(s):  
I. E. Eronini
Keyword(s):  
Rock Fracture ◽  
Laboratory Data ◽  
Essential Elements ◽  
Dynamic Force ◽  
Rock Face ◽  
Time Histories ◽  
Drop Tests ◽  
Force Time ◽  
Indiana Limestone

A characterization of the dynamic interaction between an impacting tool and rock is presented. The analysis is based on the concept of rock fracture energy and on simple representations of the amount of fracturing and energy storage in the rock during fracture propagation. The governing equations are not complicated. They contain a small number of parameters and impose minimum restrictions on the form or sophistication of the model of the impacting tool. Simulation results are shown for bit-tooth drop tests on Indiana limestone under different values of the differential pressure across the rock face and for various heights of drop. The predicted dynamic force-penetration curves, force-time, displacement-time and velocity-time histories agree well with reported Laboratory data and demonstrate that the essential elements of tooth drop loading are adequately represented by the model.

Damage Detection in Rods Using Wave Propagation and Regression Analysis

1999 ◽  
Author(s):  
K. T. Feroz ◽  
S. O. Oyadiji
Keyword(s):  
Wave Propagation ◽  
Regression Analysis ◽  
Damage Detection ◽  
Numerical Study ◽  
Time History ◽  
Ball Impact ◽  
Spherical Ball ◽  
Time Histories ◽  
Measured Strain ◽  
Force Time

Abstract The phenomena of wave propagation in rods was studied both numerically and experimentally. The finite element (FE) code ABAQUS was used for the numerical study while PZT (lead zirconium titanate) sensors and a 50 MHz transient recorder were used experimentally to monitor and to capture the propagation of stress pulses. For the study of damage detection in the rods the analyses and the experiments were repeated by introducing slots in a fixed axial location of the rod. A longitudinal wave was induced in the rod via collinear impact which was modelled in the FE analyses using the force-time history computed from the classical Hertz contact theory. In the experimental measurements this was achieved by a spherical ball impact at one plane end of the rods. It is shown that the predicted and measured strain-time histories for the defect-free rod and for the rods with defect correlate quite well. These results also show that defects can be located using the wave propagation phenomena. A regression analysis technique of the predicted and measured strain histories of the defect free rod and of the rod with defect was also performed. The results show that this technique is more efficient for smaller defects. In particular, it is shown that the area enclosed by the regression curve increases as the defect size increases.

scholarly journals Broadband over Power Lines Systems Convergence: Multiple-Input Multiple-Output Communications Analysis of Overhead and Underground Low-Voltage and Medium-Voltage BPL Networks

2013 ◽  
Vol 2013 ◽  
pp. 1-30 ◽  
Author(s):  
Athanasios G. Lazaropoulos
Keyword(s):  
Modal Analysis ◽  
Review Paper ◽  
Low Voltage ◽  
Multiple Input Multiple Output ◽  
Power Lines ◽  
Mimo Channels ◽  
Medium Voltage ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Value Decomposition

This review paper reveals the broadband potential of overhead and underground low-voltage (LV) and medium-voltage (MV) broadband over power lines (BPL) networks associated with multiple-input multiple-output (MIMO) technology. The contribution of this review paper is fourfold. First, the unified value decomposition (UVD) modal analysis is introduced. UVD modal analysis is a new technique that unifies eigenvalue decomposition (EVD) and singular value decomposition (SVD) modal analyses achieving the common handling of traditional SISO/BPL and upcoming MIMO/BPL systems. The validity of UVD modal analysis is examined by comparing its simulation results with those of other exact analytical models. Second, based on the proposed UVD modal analysis, the MIMO channels of overhead and underground LV and MV BPL networks (distribution BPL networks) are investigated with regard to their inherent characteristics. Towards that direction, an extended collection of well-validated metrics from the communications literature, such as channel attenuation, average channel gain (ACG), root-mean-square delay spread (RMS-DS), coherence bandwidth (CB), cumulative capacity, capacity complementary cumulative distribution function (CCDF), and capacity gain (GC), is first applied in overhead and underground MIMO/LV and MIMO/MV BPL channels and systems. It is found that the results of the aforementioned metrics portfolio depend drastically on the frequency, the power grid type (either overhead or underground, either LV or MV), the MIMO scheme configuration properties, the MTL configuration, the physical properties of the cables used, the end-to-end distance, and the number, the electrical length, and the terminations of the branches encountered along the end-to-end BPL signal propagation. Third, three interesting findings concerning the statistical properties of MIMO channels of distribution BPL networks are demonstrated, namely, (i) the ACG, RMS-DS, and cumulative capacity lognormal distributions; (ii) the correlation between RMS-DS and ACG; and (iii) the correlation between RMS-DS and CB. By fitting the numerical results, unified regression distributions appropriate for MIMO/BPL channels and systems are proposed. These three fundamental properties can play significant role in the evaluation of recently proposed statistical channel models for various BPL systems. Fourth, the potential of transformation of overhead and underground LV/BPL and MV/BPL distribution grids to an alternative solution to fiber-to-the-building (FTTB) technology is first revealed. By examining the capacity characteristics of various MIMO scheme configurations and by comparing these capacity results against SISO ones, a new promising urban backbone network seems to be born in a smart grid (SG) environment.

Moving Force Identification for Multi-Span Bridges by Using Acceleration Measurements

2001 ◽  
Author(s):  
F. T. K. Au ◽  
R. J. Jiang ◽  
Y. K. Cheung
Keyword(s):  
Inverse Problem ◽  
Least Squares Method ◽  
Identification Problem ◽  
Singular Value ◽  
Robust Method ◽  
Force Identification ◽  
Beam Vibration ◽  
Moving Force ◽  
Value Decomposition ◽  
Pseudo Inverse

Abstract This paper reports some initial findings in the attempt to develop a robust method to identify more than one moving force on multi-span non-uniform continuous bridges. To keep the number of unknowns in the moving force identification problem to a minimum, the modified beam vibration functions are chosen as the assumed modes of a multi-span bridge. These modified beam vibration functions satisfy the zero deflection conditions at all the intermediate supports as well as the boundary conditions at the two ends of the bridge. The least squares method is used to solve the inverse problem to get the closest approximation to the moving forces. The pseudo-inverse to obtain the solution to the inverse problem is obtained by singular value decomposition. Only acceleration measurements are used for the moving force identification. The results show that this method is applicable and robust.

Experimental Investigation of the Modal Response of a Rail Span during and after Wheel Passage

2020 ◽  
Vol 2674 (12) ◽  
pp. 15-24
Author(s):  
Korkut Kaynardag ◽  
Giuseppe Battaglia ◽  
Chi Yang ◽  
Salvatore Salamone
Keyword(s):  
Field Tests ◽  
Dynamic Responses ◽  
Modal Parameters ◽  
Moving Loads ◽  
Additional Information ◽  
Time Histories ◽  
Propagation Parameters ◽  
Displacement Force ◽  
Force Time ◽  
Comparison Of The Results

This paper examines the vibrations of a rail span (rail section between two consecutive sleepers) during and after the passage of a rail car’s wheel as well as under impact hammer excitation. In literature, the dynamic response of railway tracks under moving loads has been studied extensively. Many of these studies focus on the responses in relation to displacement/force-time histories and wave propagation parameters. These responses are investigated for the time instants when rail car wheels transverse over the rail spans of interest. In this context, an investigation of responses in relation to modal parameters during and after moving loads might provide additional information. Such information can be used to examine how the loading and additional masses induced by the moving wheels affect the dynamic responses. To this end, field tests were carried out at Transportation Technology Center Inc. (TTCI) facility in Colorado, U.S. First, to find the flexural modes of a rail span under no loading, data was collected from three accelerometers placed on the span under vertical impact hammer excitation. Next, the accelerometers were placed underneath the rail span, and data was collected while a rail car traveled over the span. The signal segments corresponding to during and after a wheel passage were analyzed for the identification of modal parameters. The comparison of the results demonstrated that the frequencies of the rail span increased as the loading induced by the wheel increased.

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