Search results for "back"

Semiactive Backstepping Control for Vibration Reduction in a Structure with Magnetorheological Damper Subject to Seismic Motions

2009

The use of magnetorheological (MR) dampers for mitigating vibrations caused by seismic motions in civil engineering structures has attracted much interest in the scientific community because of the advantages of this class of device. It is known that MR dampers can generate high damping forces with low energy requirements and low cost of production. However, the complex dynamics that characterize MR dampers make difficult the control design for achieving the vibration reduction goals in an efficient manner. In this article, a semiactive controller based on the backstepping technique is proposed. The controller was applied to a three-story building with an MR damper at its first floor subje…

Semiactive vibration control of nonlinear structures through adaptive backstepping techniques withH∞performance

2011

This article presents a new approach to the vibration mitigation problem in structures subject to seismic motions. These kinds of structures are characterised by the uncertainties of the parameters that describe their dynamics, such as stiffness and damping coefficients. Moreover, the dampers used to mitigate the vibrations caused by earthquakes are usually nonlinear devices with frictional or hysteretic dynamics. We propose an adaptive backstepping controller to account for the uncertainties and the nonlinearities. The controller is formulated in such a way that it satisfies an H∞ performance. It is designed for a 10-storey building whose base is isolated with a frictional damper (passive …

Low-Cost Alternatives for Urban Noise Nuisance Monitoring Using Wireless Sensor Networks

2015

Noise pollution caused by vehicular traffic is a common problem in urban environments that has been shown to affect people's health and children's cognition. In the last decade, several studies have been conducted to assess this noise, by measuring the equivalent noise pressure level (called L eq ) to acquire an accurate sound map using wireless networks with acoustic sensors. However, even with similar values of L eq , people can feel the noise differently according to its frequency characteristics. Thus, indexes, which can express people's feelings by subjective measures, are required. In this paper, we analyze the suitability of using the psychoacoustic metrics given by the Zwicker's mod…

daptive Backstepping Control of Nonlinear Hydraulic-Mechanical System Including Valve Dynamics

2010

Published version of an article from the journal: Modeling Identification and Control. Also available from publisher: http://dx.doi.org/10.4173/mic.2010.1.3 The main contribution of the paper is the development of an adaptive backstepping controller for a nonlinear hydraulic-mechanical system considering valve dynamics. The paper also compares the performance of two variants of an adaptive backstepping tracking controller with a simple PI controller. The results show that the backstepping controller considering valve dynamics achieves significantly better tracking performance than the PI controller, while handling uncertain parameters related to internal leakage, friction, the orifice equat…

Backcalculation of airport pavement moduli and thickness using the Lévy Ant Colony Optimization Algorithm

2016

Interpretation of NDTdata is crucial in any Airport Pavement Management System (APMS), in order to implement strategies to maintain airport pavementssince they allow to estimate their remaining life and related maintenance needs and activities. In this paper, the AntColony Optimization algorithmwasused for backcalculation of pavement moduli from surface deflection data. The algorithm’s performances are illustrated and improvement in prediction quality is demonstrated both in terms of goodness of fitness and computational effort. Moreover, it is proved that the proposed algorithm is also able to predict layer thicknesses, taking into account their variation too.

Ambizioni e insuccessi di alcune politiche di sviluppo locale per il Mezzogiorno. Patti territoriali e Programmi integrati territoriali (Pit)

2008

In 1997 a “new programming” was launched in Italy by the Department of development and cohesion policies in Rome. One of the key features of this new phase was the emphasis on “endogenous” local development, i.e. a development which is mainly based on local actors and productive specializations. The new programming strikingly failed to deliver its expected results. Some wrong expectations were fostered with regard to local political elites (§§ 1). A certain concept of local development is inherently flawed (§§ 2). The first failure was that of “territorial agreements” (patti territoriali), but there is a remarkable reluctancy to admit it (§§ 3). Another experience of “local” development who…

Corrective feedback and learner uptake in an EFL classroom

2007

Oral errors, corrective feedback and learner uptake in an EFL setting

2012

Oppilaiden kielelliset virheet ovat luonnollinen osa luokkahuonediskurssia vieraiden kielten oppitunneilla. Opettaja antaa usein korjaavaa palautetta (corrective feedback) oppilaidensa virheisiin, ja parhaassa tapauksessa palaute auttaa oppilaita oppimaan virheistään. Tutkielma pyrkii kartoittamaan erilaisia opettajien käyttämiä keinoja, kun he antavat korjaavaa palautetta oppilaiden puheessa tekemiin virheisiin. Tutkielmassa tarkastellaan myös oppilaiden tapaa reagoida palautteeseen (uptake) ja sitä, onnistuvatko oppilaat korjaamaan alkuperäiset virheensä (repair). Tutkimuksen kohteena on kaksi lukiotason luokkaa ja heidän opettajansa. Aineisto koostuu kahdeksasta englannin tunnista (yhtee…

Students' perceptions about the use of oral feedback in EFL classrooms

2016

Tämän tutkimuksen tarkoituksena oli selvittää lukiossa opiskelevien oppilaiden näkökulmia ja mielipiteitä yleisesti palautteen antoon liittyen. Pääpaino oli suullisessa palautteessa, ja tutkimus pyrki selvittämään, milloin, miten ja kuinka paljon suullista palautetta annetaan englannin kielen tunneilla lukiossa, sekä millaista suullista palautetta lukiolaiset haluaisivat saada, ja mistä kielen osa-alueista. Palautteen anto on tärkeä osa oppimista ja opettamista. Palautteen antoa luokkahuoneessa on tutkittu aiemmin, ja usein tutkimukset ovat keskittyneet esimerkiksi korjaavaan palautteeseen ja sen eri muotoihin niin oppilaan kuin opettajan kannalta, tai kirjalliseen palautteeseen. Suullista …

Efecto de la retroalimentación orientada al acierto: un caso de estudio de analítica del aprendizaje

2020

La Analítica de datos en Educación se puede definir como el área encargada de medir, recopilar y analizar conjuntos de datos obtenidos mediante el uso de entornos tecnológicos de aprendizaje o plataformas de aprendizaje asistido por computadora que permiten registrar las interacciones o trazas digitales del estudiantado. En particular, el estudio de la traza digital registrada puede contribuir positivamente en la comprensión de las estrategias seguidas por el estudiantado al resolver una tarea. En este trabajo se presenta un caso de estudio exploratorio en el que analiza el posible impacto del uso de la retroalimentación orientada al acierto mediante el uso de un entorno tecnológico con el …