Search results for "dance"
showing 10 items of 2075 documents
An integrated structural health monitoring system based on electromechanical impedance and guided ultrasonic waves
2015
We propose a structural health monitoring (SHM) paradigm based on the simultaneous use of ultrasounds and electromechanical impedance (EMI) to monitor waveguides. Methods based on the propagation of guided ultrasonic waves (GUWs) are increasingly used in all those SHM applications that benefit from built-in transduction, moderately large inspection ranges, and high sensitivity to small flaws. Meantime, impedance-based SHM promises to adequately assess locally the structural integrity of simple waveguides and complex structures such as bolted connections. As both methods utilize piezoelectric transducers bonded or embedded to the structure of interest, this paper describes a unified SHM para…
Electromechanical impedance method for the health monitoring of bonded joints: Numerical modelling and experimental validation
2014
The electromechanical impedance (EMI) method is one of the many nondestructive evaluation approaches proposed for the health monitoring of aerospace, civil, and mechanical structures. The method consists of attaching or embedding one or more wafer-type piezoelectric transducers (PZTs) to the system of interest, the host structure, and measuring certain electrical characteristics of the transducers. As these characteristics are also related to the impedance of the host structure, they can be used to infer the mechanical properties of the monitored structure. In the study presented in this paper, we utilize the EMI to monitor the quality of adhesively bonded joints. A finite element formulati…
Simultaneous determination of carrier lifetime and electron density-of-states in P3HT:PCBM organic solar cells under illumination by impedance spectr…
2010
We report new insights into recombination kinetics in poly(3-hexylthiophene):methanofullerene (P3HT:PCBM) bulk heterojunction (BHJ) solar cells, based on simultaneous determination of the density of states (DOS), internal recombination resistance, and carrier lifetime, at different steady states, by impedance spectroscopy. A set of measurements at open circuit under illumination was performed aiming to better understand the limitations to the photovoltage, which in this class of solar cells remains far below the theoretical limit which is the difference between the LUMO level of PCBM and the HOMO of P3HT (∼1.1 eV). Recombination kinetics follows a bimolecular law, being the recombination ti…
Impedance of space-charge-limited currents in organic light-emitting diodes with double injection and strong recombination
2006
The impedance model for a one-carrier space-charge-limited (SCL) current has been applied to explain some experimental features of double carrier organic light-emitting diodes. We report the analytical model of impedance of bipolar drift transport in SCL regime in the limit of infinite recombination. In this limit the ac impedance function is identical to that of a single carrier device, with a transit time modified by the sum of mobilities for electrons and holes, μn+μp. The static capacitance C(ω→0) is a factor of ¾ lower than the geometric capacitance, as observed for single carrier devices, but it is shifted to higher frequencies. It follows that impedance measurements in the dual-carri…
Design and Development of a Labview Application for the Measurement of the Complex Impedance of a Fuel Cell in Real Time
2014
International audience; To optimize the performance of fuel cells and to deepen the knowledge of their behavior, it is necessary to make measurements in real time. To run such a measure, it is necessary to use specific software and hardware tools to instrumentation fuel cells. In this context, we presented the steps of designing and developing an application for the measurement of the complex impedance by electrochemical impedance spectroscopy method (EIS) using LabVIEW® software. The experimental results are obtained using a Ballard Nexa® PEM fuel cell, an electronic load produced in our laboratory and application developed by the LabVIEW® software.
Theoretical and experimental study of the role of cell-cell dipole interaction in dielectrophoretic devices: application to polynomial electrodes
2013
BACKGROUND: We aimed to investigate the effect of cell-cell dipole interactions in the equilibrium distributions in dielectrophoretic devices. METHODS: We used a three dimensional coupled Monte Carlo-Poisson method to theoretically study the final distribution of a system of uncharged polarizable particles suspended in a static liquid medium under the action of an oscillating non-uniform electric field generated by polynomial electrodes. The simulated distributions have been compared with experimental ones observed in the case of MDA-MB-231 cells in the same operating conditions. RESULTS: The real and simulated distributions are consistent. In both cases the cells distribution near the elec…
Dorsal root ganglia neurite outgrowth measured as a function of changes in microelectrode array resistance
2017
Current research in prosthetic device design aims to mimic natural movements using a feedback system that connects to the patient's own nerves to control the device. The first step in using neurons to control motion is to make and maintain contact between neurons and the feedback sensors. Therefore, the goal of this project was to determine if changes in electrode resistance could be detected when a neuron extended a neurite to contact a sensor. Dorsal root ganglia (DRG) were harvested from chick embryos and cultured on a collagen-coated carbon nanotube microelectrode array for two days. The DRG were seeded along one side of the array so the processes extended across the array, contacting a…
Instructional support predicts children’s task avoidance in kindergarten
2011
Abstract This study examined the role of observed classroom quality in children's task-avoidant behavior and math skills in kindergarten. To investigate this, 1268 children were tested twice on their math skills during their kindergarten year. Kindergarten teachers ( N = 137) filled in questionnaires measuring their professional experience and also rated the children on their task-avoidant versus task-focused behaviors. Trained observers used the CLASS instrument ( Pianta, La Paro, & Hamre, 2008 ) to observe 49 kindergarten teachers (out of 137) on their emotional support, classroom organization, and instructional support. The results of multilevel modeling showed that kindergarten classro…
The cross-lagged associations between classroom interactions and children’s achievement behaviors
2014
This study examined the cross-lagged associations between the quality of classroom interactions and children’s behaviors in achievement situations. The achievement behaviors in challenging test situations of 166 Finnish children from 70 classrooms were rated by trained testers in grades 1 and 2. The quality of classroom interactions in terms of emotional support, classroom organization, and instructional support were observed in 25 classrooms (out of 70) in grades 1 and 2. The results of multilevel modeling showed that classroom teachers’ low emotional support predicted children’s subsequent high passive avoidance, whereas high classroom organization and instructional support predicted chil…
Attentional biases towards emotional scenes in autism spectrum condition: An eye-tracking study.
2021
Abstract Background Different attentional processing of emotional information may underlie social impairments in Autism Spectrum Condition (ASC). It has been hypothesized that individuals with ASC show hypersensitivity to threat, which may be related to an avoidance behaviour. However, research on the attentional processing of emotional information in autism is inconclusive. Aim To examine the attentional processing biases of 27 children with ASC and 25 typically developed (TD) participants. Methods and procedures The initial orienting of attention, the attentional engagement, and the attentional maintenance to complex emotional scenes in competition (happy, neutral, threatening, sad) were …