• Smart Structures and Systems
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• v.22 no.5
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• pp.631-641
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• 2018

This paper outlines a computational procedure for the effective merging of diverse sensor measurements, displacement and acceleration signals in particular, in order to successfully monitor and simulate the current health condition of civil structures under dynamic loadings. In particular, it investigates a Kalman Filter implementation for the Heterogeneous Data Fusion of displacement and acceleration response signals of a structural system toward dynamic identification purposes. The procedure is perspectively aimed at enhancing extensive remote displacement measurements (commonly affected by high noise), by possibly integrating them with a few standard acceleration measurements (considered instead as noise-free or corrupted by slight noise only). Within the data fusion analysis, a Kalman Filter algorithm is implemented and its effectiveness in improving noise-corrupted displacement measurements is investigated. The performance of the filter is assessed based on the RMS error between the original (noise-free, numerically-determined) displacement signal and the Kalman Filter displacement estimate, and on the structural modal parameters (natural frequencies) that can be extracted from displacement signals, refined through the combined use of displacement and acceleration recordings, through inverse analysis algorithms for output-only modal dynamics identification, based on displacements.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.3
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• pp.258-266
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• 2013

This paper presents the correlation between psychological and physiological acoustics for the automotive acceleration sound. The research purpose of this paper is to evaluate the sound quality of acceleration sound of a passenger car based EEG signal. The previous method for the objective evaluation of sound quality is to use sound metrics based on psychological acoustics. This method uses not only psychological acoustics but also physiological acoustics. For this work, the sounds of 7 premium passenger cars are recorded and evaluated subjectively by 33 people. The correlation between the subjective rating and sound metrics is calculated based on physiological acoustics. Finally the correlation between the subjective rating and the EEG signal measured on the brain is also calculated. Throughout these results the new evaluation system for the sound quality on the automotive acceleration sound of a passenger car has been developed based on bio-signal.

• Earthquakes and Structures
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• v.17 no.4
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• pp.365-372
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• 2019

Post-earthquake crisis management is a key capability for a country to be able to recover after a major seismic event. Instrumental seismic data transmitted and processed in a very short time can contribute to better management of the emergency and can give insights on the earthquake's impact on a specific area. Romania is a country with a high seismic hazard, mostly due to the Vrancea intermediate-depth earthquakes. The elastic acceleration response spectrum of a seismic motion provides important information on the level of maximum acceleration the buildings were subjected to. Based on new data analysis and knowledge advancements, the acceleration elastic response spectrum for horizontal ground components recommended by the Romanian seismic codes has been evolving over the last six decades. This study aims to propose a framework for post-earthquake warning based on code spectrum exceedances. A comprehensive background analysis was undertaken using strong motion data from previous earthquakes corroborated with observational damage, to prove the method's applicability. Moreover, a case-study for two densely populated Romanian cities (Focsani and Bucharest) is presented, using data from a $5.5M_W$ earthquake (October 28, 2018) and considering the evolution of the three generations of code-based spectral levels for the two cities. Data recorded in free-field and in buildings were analyzed and has confirmed that no structural damage occurred within the two cities. For future strong seismic events, this tool can provide useful information on the effect of the earthquake on structures in the most exposed areas.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.5
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• pp.681-688
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• 2010

During certification of freefall lifeboats, it is necessary to estimate the injury potential of the impact loads exerted on the occupants during water entry. This paper focused on the numerical simulation to predict the acceleration response during the impact of freefall lifeboats on the water using FSI(Fluid-Structure Interaction) analysis technique of LS-DYNA code. FSI problems could be conveniently simulated by the overlapping capability using Arbitrary Lagrangian Eulerian(ALE) formulation and Euler-Lagrange coupling algorithm of LS-DYNA code. Through this study, it could be found that simulation results were in relatively good agreement with experimental ones in the acceleration peak values, and that the loading conditions were very sensitive to the acceleration responses by the experimental and simulation results.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.3
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• pp.121-128
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• 2020

In this paper, the ASCE 7 equivalent static approach for seismic design of non-structural elements is critically evaluated based on the measured floor acceleration data, theory of structural dynamics, and linear/nonlinear dynamic analysis of three-dimensional building models. The analysis of this study on the up-to-date database of the instrumented buildings in California clearly reveals that the measured database does not well corroborate the magnitude and the profile of the floor acceleration as proposed by ASCE 7. The basic flaws in the equivalent static approach are illustrated using elementary structural dynamics. Based on the linear and nonlinear dynamic analyses of three-dimensional case study buildings, it is shown that the magnitude and distribution of the PFA (peak floor acceleration) can significantly be affected by the supporting structural characteristics such as fundamental period, higher modes, structural nonlinearity, and torsional irregularity. In general, the equivalent static approach yields more conservative acceleration demand as building period becomes longer, and the PFA distribution in long-period buildings tend to become constant along the building height due to the higher mode effect. Structural nonlinearity was generally shown to reduce floor acceleration because of its period-lengthening effect. Torsional floor amplification as high as 250% was observed in the building model of significant torsional irregularity, indicating the need for inclusion of the torsional amplification to the equivalent static approach when building torsion is severe. All these results lead to the conclusion that, if permitted, dynamic methods which can account for supporting structural characteristics, should be preferred for rational seismic design of non-structural elements.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.1057-1063
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• 2023

The urban railway sleeper floating track, the subject of this study, is an anti-vibration track to reduce vibration transmitted to the structure. currently, the replacement cycle of resilience pad for sleeper floating tracks is set and operated based on load. however, most previous studies were conducted on load-based structural safety aspects, such as fatigue life evaluation of sleeper anti-vibration pads and increase in track impact coefficient and track support stiffness due to increase in spring stiffness. therefore, in this study, we measure the vibration acceleration of the ballast for each analysis section and use the results of 7 million fatigue tests to calculate the spring stiffness of the resilience pad for each section. the spring stiffness of the resilience pad calculated for each section was set as the analysis data and the concrete vibration acceleration was derived analytically. the adequacy of analysis modeling was verified as the analyzed concrete bed vibration acceleration for each section was within the field-measured concrete bed vibration acceleration range. using the vibration acceleration curve according to the derived spring stiffness change, the spring stiffness of the resilience pad is estimated from the measured vibration acceleration. therefore, we would like to present a technique that can estimate the spring stiffness of resilience pad of a running track using the vibration acceleration of the measured concrete bed.

• Smart Structures and Systems
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• v.25 no.2
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• pp.255-264
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• 2020

This paper deals with a defect classification technique that considers the structural characteristics of a refrigerant compressor. First, the pressure pulsation of the refrigerant flowing in the suction pipe of a normal compressor was measured at the same time as the acceleration of the shell surface, and then the transfer function between the two signals was estimated. Next, the frequency-weighted acceleration signals of the defect classification target compressors were generated using the estimated transfer function. The estimation of the variance of the transfer function is presented to formulate the frequency-weighted acceleration signals. The estimated frequency-weighted accelerations were applied to defect classification using frequency-domain features. Experiments were performed using commercial compressors to verify the technique. The results confirmed that it is possible to perform an effective defect classification of the refrigerant compressor by the shell surface acceleration of the compressor. The proposed method could make it possible to improve the total inspection performance for compressors in a mass-production line.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1363-1370
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• 2000

Dynamic stability of a flexible spinning disk with angular acceleration is considered. To avoid the coupling between the in-plane and out-of-plane displacements, the linearized strain-displacement relations are used in the Kirchhoff plate theory. The uncoupled governing equations are derived by using Hamilton's principle with considering the angular acceleration. Numerical tests show that existence of the angular acceleration makes a spinning disk dynamically unstable.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.23-30
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• 2005

The air-jet loom represents a major step in the development of shutterless weaving due to its ability to weave a wide range of yarns at high speeds. The air-jet weaving involves inserting a pre-measured length of yarn through the wraps, which is shed by means of compressed air. The analysis of air flow characteristic of the main nozzle and acceleration tube is required for improving the loom performance. In this paper, we examined the effects of the main nozzle with different acceleration tubes as well as diameters. Also, we compared the performance of a straight-type tube with a Laval-type tube and the effect of installing a suction hole on the acceleration tube.

• Korea-Australia Rheology Journal
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• v.20 no.4
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• pp.189-196
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• 2008

The pulsatile flow of blood through a stenosed artery under the influence of external periodic body acceleration is studied. The effect of non-Newtonian nature of blood in small blood vessels has been taken into account by modeling blood as a Casson fluid. The non-linear coupled equations governing the flow are solved using perturbation analysis assuming that the Womersley frequency parameter is small which is valid for physiological situations in small blood vessels. The effect of pulsatility, stenosis, body acceleration, yield stress of the fluid and pressure gradient on the yield plane locations, velocity distribution, flow rate, shear stress and frictional resistance are investigated. It is noticed that the effect of yield stress and stenosis is to reduce flow rate and increase flow resistance. The impact of body acceleration is to enhance the flow rate and reduces resistance to flow.