Search results for "Modal analysis"

Spectral interest points and texture extraction and fusion for identification, control and security

2018

Biometrics is an emerging technology that proposes new methods of control, identification and security. Biometric systems are often subject to risks. Face recognition is popular and several existing approaches use images in the visible spectrum. These traditional systems operating in the visible spectrum suffer from several limitations due to changes in lighting, poses and facial expressions. The methodology presented in this thesis is based on multispectral facial recognition using infrared and visible imaging, to improve the performance of facial recognition and to overcome the deficiencies of the visible spectrum. The multispectral images used in this study are obtained by fusion of visi…

Parameters affecting the fundamental period of infilled RC frame structures

2015

Despite the fact that the fundamental period appears to be one of the most critical parameters for the seismic design of structures according to the modal superposition method, the so far available in the literature proposals for its estimation are often conflicting with each other making their use uncertain. Furthermore, the majority of these proposals do not take into account the presence of infills walls into the structure despite the fact that infill walls increase the stiffness and mass of structure leading to significant changes in the fundamental period numerical value. Toward this end, this paper presents a detailed and in-depth analytical investigation on the parameters that affect…

A modal approach for the evaluation of the response sensitivity of structural systems subjected to non-stationary random processes

2005

A method for the evaluation of the response sensitivity of both classically and non-classically damped discrete linear structural systems under stochastic actions is presented. The proposed approach requires the following items: (a) a suitable modal expansion of the response; (b) the derivation in analytical form of the equations governing the evolution of the derivatives of the response (the so-called sensitivity equations) with respect to the parameters that define the structural model; (c) an extensive use of the Kronecker algebra for determining the analytical expressions of the sensitivity of the structural response statistics to non-stationary random input processes. Moreover, a step-…

A novel identification procedure from ambient vibration data for buildings of the cultural heritage

Ambient modal identification, also known as Operational Modal Analysis (OMA), aims to identify the modal properties of a structure based on vibration data collected when the structure is under its operating conditions, i.e., no initial excitation or known artificial excitation. This procedure for testing and/or monitoring historic buildings, is particularly attractive for civil engineers concerned with the safety of complex historic structures. However, since the external force is not recorded, the identification methods have to be more sophisticated and based on stochastic mechanics. In this context, this contribution will introduce an innovative ambient identification method based on appl…

WAVELET-BASED ESTIMATION OF MODAL PARAMETERS OF A VEHICLE INVOLVED IN A FULL-SCALE IMPACT

2012

In this paper, a wavelet-based approach is presented for estimation of vehicle modal parameters. The acceleration of a colliding vehicle is measured in its center of gravity — this crash pulse contains detailed information about vehicle behavior throughout a collision. Three types of signal analysis are elaborated here: time domain analysis (i.e. description of kinematics of a vehicle in time domain), the frequency analysis (identification of the parameters of the crash pulse in frequency domain), and the time-frequency analysis, which comprises those techniques that study a signal in both the time and frequency domains simultaneously, using Morlet wavelet properties. The frequency compone…

An analysis methodology to evaluate the contribution to electrical security given by bare buried conductors in a system of intertied earthing grids

2004

The paper presents an analysis methodology for a single-line-to-ground fault, occurring at a secondary MV/LV substation in a power network formed by a HV/MV station, feeding, through a MV tri-phase cable line, N MV/LV substations whose earth electrodes are interconnected by bare buried conductors. In the preliminary explanation of the methodology, earth buried conductors are studied in their double function of earth electrodes and connection elements between earthing grids, both in absence and in presence of other interfering conductors. Subsequently analyzed is, with a distributed parameters approach, the system constituted by an earth buried conductor and a MV tri-phase cable line. The eq…

Schweigen in Videokonferenzen: Vom Umgang mit Störungen in Online-Besprechungen

2020

This paper deals with silence in video-based discourse, which includes pauses and delays. The data of the study is provided by international video conferences in which six in-service teachers and six pre-service teachers from three countries (Italy, the Netherlands, Hungary) together with a moderator and an assistent discuss sequences of their lessons. These discussions are part of a teacher training progrmme as conceived and implemented in the Erasmus+ project LEELU (www.leelu.eu). The focus of the present study is to analyse through a multimodal approach how the above-mentioned moments of silence co-constitute the video-based interaction, and how the discourse is built up with the other m…

Viscoelasticity: an electrical point of view

2014

Time dependent hereditary properties of complex materials are well described by power-laws with real order exponent. This experimental observation and analogous electrical experiments, yield a description of these properties by using fractional-order operators. In this paper, elasto-viscous and visco-elastic behaviors of fractional order hereditary materials are firstly described by using fractional mathematical operators, based on recent work of some of the authors. Then, electrical analogous models are introduced. Viscoelastic models have elastic and viscous components which can be obtained by combining springs and dashpots: these models can be equivalently viewed as electrical circuits, …

Introduzione al volume "Interaktion im Fremdsprachenunterricht"

2017

Multimodale Analyse von Interaktion im fremdsprachlichen Klassenzimmer

2016

The article offers a contribution to the interaction research in the foreign language teaching and learning. It starts with an overview of various research approaches to the foreign language teaching and learning, from the 60s to the present days. A multimodal analysis of an excerpt of videorecorded classroom interaction is then provided. The analysis is focused on several aspects of classroom participation and teaching sequences. Some implications of the present research for teachers' training are finally provided.