Search results for "Passive control"
showing 10 items of 17 documents
Computational Fluid Dynamics Suggests Ecological Diversification among Stem-Gnathostomes.
2020
Summary The evolutionary assembly of the vertebrate bodyplan has been characterized as a long-term ecological trend toward increasingly active and predatory lifestyles, culminating in jawed vertebrates that dominate modern vertebrate biodiversity [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. This contrast is no more stark than between the earliest jawed vertebrates and their immediate relatives, the extinct jawless, dermal armor-encased osteostracans, which have conventionally been interpreted as benthic mud-grubbers with poor swimming capabilities and low maneuverability [ 9 , 10 , 11 , 12 ]. Using computational fluid dynamics, we show that osteostracan headshield morphology is compatible with a dive…
Innovative modeling of tuned liquid column damper controlled structures
2016
In this paper a different formulation for the response of structural systems controlled by Tuned Liquid Column Damper (TLCD) devices is developed, based on the mathematical tool of fractional calculus. Although the increasing use of these devices for structural vibration control, it has been demonstrated that existing model may lead to inaccurate prediction of liquid motion, thus reflecting in a possible imprecise description of the structural response. For this reason the recently proposed fractional formulation introduced to model liquid displacements in TLCD devices, is here extended to deal with TLCD controlled structures under base excitations. As demonstrated through an extensive expe…
The TLCD Passive Control: Numerical Investigations vs. Experimental Results
2012
Very recently the tuned liquid column damper (TLCD) is receiving an increasing interest from researchers concerned with vibration control, to be considered an alternative device with respect to the tuned mass damper (TMD), since the former has low cost, easy adjustment, flexible installation. However, in recent studies the authors [1] have pointed out that for TMD the analytical formulation provides results that are in good agreement with the experimental ones, while for TLCD it has been deducted that the analytical formulation needs further investigation. In fact using the classical formulation of the problem, numerical results are very different from the experimental results obtained by t…
Amplification of Interstory Drift and Velocity for the Passive Control of Structural Vibrations
2008
Mitigation of structural damage due to earthquake ground motion may be performed by inserting dampers in the structure. In order to enhance the damping effect various toggle brace configurations have been recently proposed. In this paper these equipments are analyzed in detail and compared with a new one here proposed. The analysis is performed by taking into account the inherent nonlinearities of the damper by means of stochastic analysis and validated by using time histories of recorder accelerograms and by the stochastic analysis using spectrum consistent power spectral density.
COMBINED USE OF INNOVATIVE PASSIVE CONTROL DEVICES AND CONVENTIONAL BASE ISOLATION STRATEGIES
2021
This manuscript contains the main part of my research performed in the last three years at the Department of Engineering, University of Palermo, at the Department of Basic Sciences in Engineering Sciences (Unit of Applied Mechanics), University of Innsbruck, Austria and at the company FIP Mec, Selvazzano Dentro, Padova. Within the research framework of Structural Control, this dissertation proposes novel passive control strategies to mitigate the dynamic response of base isolated structural systems. Among the several types of devices proposed in literature, Tuned Mass Dampers and Tuned Liquid Column Dampers are undoubtedly the most widely employed vibration control devices for coupling with…
Robust reliable passive control of uncertain stochastic switched time-delay systems
2014
This paper investigates the problem of robust reliable passive control for a class of uncertain stochastic switched time-delay systems with actuator failures. The multiple Lyapunov functions (MLFs) technique is exploited to derive a delay-dependent sufficient condition for the stochastic switched time-delay systems to be passive and exponentially stable under a state-based switching law. Moreover, the proposed approach is extended to investigate stochastic switched systems with structured uncertainties. Finally, two numerical examples are presented to illustrate the effectiveness of the proposed method.
Differences in intermittent postural control between normal-weight and obese children.
2016
Abstract Aim The main objective of this study was to determine differences in postural control between obese and non-obese children. Methods The study design was cross-sectional, prospective, between-subjects. Postural control variables were obtained from a group of obese children and a normal-weight control group under two different postural conditions: bipedal standing position with eyes open and bipedal standing with eyes closed. Variables were obtained for each balance condition using time domain and sway-density plot analysis of the center of pressure signals acquired by means of a force plate. Results Pairwise comparisons revealed significant differences between obese and normal-weigh…
Earthquake Excited Base-Isolated Structures Protected by Tuned Liquid Column Dampers: Design Approach and Experimental Verification
2017
Abstract In this contribution a direct approach for optimal design of a Tuned Liquid Column Damper (TLCD) device attached to the base slab of a base-isolated structure is presented, aiming at reducing the seismic displacement demand of the base-isolation subsystem. Assuming white noise base excitation, for a wide parameter range a direct optimization procedure yields design charts for optimal TLCD quantities. The performance of the base-isolated structure equipped with optimally tuned TLCD device in comparison to the simple base-isolated one is evaluated both numerically and experimentally. In a numerical study the system is subjected to the 44 records of the FEMA P-695 far-field ground mot…
Hybrid Passive Control Strategies for Reducing the Displacements at the Base of Seismic Isolated Structures
2019
In this paper, the use of hybrid passive control strategies to mitigate the seismic response of a base-isolated structure is examined. The control performance of three different types of devices used for reducing base displacements of isolated buildings is investigated. Specifically, the Tuned Mass Damper (TMD), the New Tuned Mass Damper (New TMD) and the Tuned Liquid Column Damper (TLCD), each one associated to a Base Isolated structure (BI), have been considered. The seismic induced vibration control of base-isolated structures equipped with the TMD, New TMD or the TLCD is examined and compared with that of the base-isolated system without devices, using real recorded seismic signals as e…