Sparse structural system identification method for nonlinear dynamic systems with hysteresis/inelastic behavior

Online updating and uncertainty quantification using nonstationary output-only measurement

A general extended Kalman filter for simultaneous estimation of system and unknown inputs

The determination of the optimal sensor placement (OSP) is a significant task that must be completed before a structural health monitoring (SHM) system is implemented on a real structure. The firefly algorithm (FA) is a recently developed nature-inspired metaheuristic algorithm for continuous optimization problems. This paper proposes a cluster-in-cluster firefly algorithm (CiCFA) for the optimum SHM sensor deployment. First, the code defining position coordinates in basic FA is replaced with a one-dimensional binary coding system, and the Euclidean distance is replaced by the Hamming distance. Then, a movement scheme for a darker firefly approaching a lighter firefly is developed. Last, a cluster-in-cluster strategy is employed to improve the convergence speed. In addition, a self-adaptive dynamic penalty function is introduced to convert the constraint imposed by the limited wireless data transmission range in the optimal wireless sensor placement (OWSP) problem to an unconstrained optimization problem....

Sensor Placement Optimization in Structural Health Monitoring Using Cluster-in-Cluster Firefly Algorithm

Most of the currently available vibration-based damage detection approaches identify structural damage in the form of decrease in structural stiffness based on extracted eigenparameters and/or their derivates, and the basic hypothesis behind them is the system should be linear and the mass distribution of the system is usually known. Different from the stiffness degradation, the hysteretic restoring force of a dynamic system provides a more informative and direct description on the initiation and development of damage in structures under dynamic loadings and can be employed to quantitatively evaluate the energy dissipation during vibration. In this study, a data-based model-free hysteretic behavior identification approach with incomplete external excitations was proposed for the identification of structural hysteretic restoring force without the prior knowledge of structural mass distribution and the numerical model of the nonlinearity of the structure. The accuracy and feasibility of the approach for both structural mass and hysteretic behavior identification was illustrated: first, via numerical simulation with a lumped-mass multi-degree-of-freedom structure incorporating nonlinear magnetorheological (MR) dampers and a consistent mass plane truss structure incorporating a pseudo-elastic shape memory alloy model to mimic the nonlinearity in dynamic systems. Second, a dynamic test on a four-story frame structure equipped with MR dampers was carried out and the corresponding dynamic response was employed to validate the reliability of the proposed approach for both structural mass and hysteretic behavior identification. The results show that the proposed approach is capable of identifying different types of structural nonlinearity, which numerical model is unknown, with incomplete inputs and unknown mass distribution. The approach provides a promising way for damage detection and monitoring in the form of hysteretic behavior and energy dissipation for engineering structures under dynamic loadings, which should be dealt with as nonlinear systems.

Data-Based Model-Free Hysteretic Restoring Force and Mass Identification for Dynamic Systems

Conference Name:3rd International Conference on Dynamics, Vibration and Control. Conference Address: Hangzhou, PEOPLES R CHINA. Time:MAY 12-14, 2010.

Identification of non-linear structural parameters under limited input and output measurements

Conference Name:International Conference on Structures and Building Materials. Conference Address: Guangzhou, PEOPLES R CHINA. Time:JAN 07-09, 2011.

Identification of Nonlinear Structural Parameters under Unmeasured Excitation

Background Children with autism spectrum disorders (ASDs) suffer from sleep disorders to a considerable degree; however, there is no safe and effective treatment available in clinical practice. The objective of the trial is to assess the clinical effectiveness of auricular plaster therapy (APT) in treating sleep disorders in children with ASD. Method This is a single-center, patient-assessor blind, randomized controlled trial. A total of 44 preschool children with sleep disorders with ASD will be included in this study. Eligible participants will be randomly assigned to either the auricular plaster group or the sham auricular plaster group in a 1:1 ratio. Participants in the different groups will receive APT or sham APT, respectively, for a total of 30 sessions over 30 days. The primary outcome includes the Children's Sleep Habits Questionnaire (CSHQ), while secondary outcomes include the Autism Behavior Checklist (ABC) and polysomnography (PSG) for total sleep time, sleep latency, awakening duration, and sleep structures. The CSHQ and ABC will be assessed at baseline, 10, 20, 30, 60, 90, and 120 days after randomization, whereas PSG will be assessed at baseline and 30 days after randomization. The follow-up period will be scheduled to be 60, 90, and 120 days after randomization. Discussion The results of this study may provide evidence of the efficacy of APT, as well as offer new alternatives for the treatment of sleep disorders in children with ASD. Trial registration CHiCTR.org.cn (ChiCTR2100048257). Registered on July 5, 2021.

Efficacy of auricular plaster therapy for sleep disorders in preschool children with autism spectrum disorders: Study protocol for a randomized controlled trial

Tao Li

Papers

Identification of non-linear structural parameters under limited input and output measurements

Identification of Nonlinear Structural Parameters under Unmeasured Excitation

Efficacy of auricular plaster therapy for sleep disorders in preschool children with autism spectrum disorders: Study protocol for a randomized controlled trial