Adaptive control of base-isolated structures against near-field earthquakes using variable friction dampers

2011 ◽  
Vol 33 (12) ◽  
pp. 3143-3154 ◽  
Author(s):  
Osman E. Ozbulut ◽  
Maryam Bitaraf ◽  
Stefan Hurlebaus
Keyword(s):  
Adaptive Control ◽  
Near Field ◽  
Friction Dampers ◽  
Variable Friction ◽  
Isolated Structures

Developing a simplified method for analysis and design of isolated structures with the novel quintuple friction pendulum system under bidirectional near-field excitations

2021 ◽  
pp. 107754632110482
Author(s):  
Hamed Keikha ◽  
Gholamreza Ghodrati Amiri
Keyword(s):  
Nonlinear Response ◽  
Near Field ◽  
Lateral Force ◽  
History Analysis ◽  
Special Cases ◽  
Simplified Method ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
Isolated Structures ◽  
Friction Pendulum

Simplified analysis methods for seismically isolated structures proposed in recent structural codes and specifications are frequently used to reduce the computational effort and to simplify the design procedure, either directly for special cases or for checking the results of nonlinear response history analysis. Of the approximate methods, the equivalent lateral force procedure using the effective stiffness and effective damping is one of the best known. In this study, the simplified method is developed by combining the equivalent lateral force procedure with the capacity spectrum method and evaluated in terms of maximum isolator displacements and base shears for isolated structures with recently invented quintuple friction pendulum isolators , with different geometrical and frictional properties, under two different response spectra with corresponding two different sets of bidirectional near-field ground motions for stiff and soft soils site classes. In order to assess the accuracy of the simplified method, the delivered results of the ELF procedure are compared to those of nonlinear response history analysis, by modelling the quintuple friction pendulum isolator 3D element in OpenSees. Eventually, comments on the accuracy of the simplified method are given to make its applications more appropriate in practical design of base isolation systems.

Control of piezoelectric friction dampers in smart base-isolated structures using self-tuning and adaptive fuzzy proportional–derivative controllers

2016 ◽  
Vol 28 (10) ◽  
pp. 1287-1302 ◽  
Author(s):  
Abbas-Ali Zamani ◽  
Saeed Tavakoli ◽  
Sadegh Etedali
Keyword(s):  
Control Strategies ◽  
Near Field ◽  
The Self ◽  
Feedback Signal ◽  
Far Field ◽  
Friction Dampers ◽  
Adaptive Fuzzy ◽  
Self Tuning ◽  
Base Displacement ◽  
Proportional Derivative Controller

To adjust the contact force of piezoelectric friction dampers for a benchmark base-isolated structure, a self-tuning fuzzy proportional–derivative controller and an adaptive fuzzy proportional–derivative controller are developed. Considering three candidate signals, namely, the isolation displacement, isolation velocity, and roof acceleration, the best feedback signal for the self-tuning fuzzy proportional–derivative controller is selected based on the Pareto-optimal front. The performance of the self-tuning fuzzy proportional–derivative controller during both near-field and far-field earthquakes is enhanced using an adaptive fuzzy proportional–derivative controller, in which the output gain of the self-tuning fuzzy proportional–derivative controller is adaptively tuned according to the kind of entering earthquake. The control objective is to reduce the isolation system deformations without significant increase in superstructure accelerations during far-field and near-field earthquake excitations. Membership functions and fuzzy control rules are simultaneously tuned using a multi-objective cuckoo search algorithm. Considering 14 real-data earthquakes, simulation results show that the proposed controllers perform better than other reported control strategies in terms of simultaneous reduction of the maximum base displacement and superstructure accelerations. Also, they provide acceptable responses in terms of the inter-story drifts, root mean squared of base displacement, and the floor acceleration. Opposite to other reported control strategies, piezoelectric friction dampers controlled by the self-tuning fuzzy proportional–derivative controller and adaptive fuzzy proportional–derivative controller never enter the saturation area.

scholarly journals All-optical adaptive control of quantum cascade random lasers

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Schönhuber ◽  
N. Bachelard ◽  
B. Limbacher ◽  
M. A. Kainz ◽  
A. M. Andrews ◽  
...  
Keyword(s):  
Adaptive Control ◽  
Degrees Of Freedom ◽  
Near Infrared ◽  
Quantum Cascade Lasers ◽  
Near Field ◽  
Optimization Procedure ◽  
Light Sources ◽  
Light Modulator ◽  
Random Lasers ◽  
Quantum Cascade

Abstract Spectral fingerprints of molecules are mostly accessible in the terahertz (THz) and mid-infrared ranges, such that efficient molecular-detection technologies rely on broadband coherent light sources at such frequencies. If THz Quantum Cascade Lasers can achieve octave-spanning bandwidth, their tunability and wavelength selectivity are often constrained by the geometry of their cavity. Here we introduce an adaptive control scheme for the generation of THz light in Quantum Cascade Random Lasers, whose emission spectra are reshaped by applying an optical field that restructures the permittivity of the active medium. Using a spatial light modulator combined with an optimization procedure, a beam in the near infrared (NIR) is spatially patterned to transform an initially multi-mode THz random laser into a tunable single-mode source. Moreover, we show that local NIR illumination can be used to spatially sense complex near-field interactions amongst modes. Our approach provides access to new degrees of freedom that can be harnessed to create broadly-tunable sources with interesting potential for applications like self-referenced spectroscopy.

Sign in / Sign up

Export Citation Format

Share Document