To cite this version:Mohamed Chabchoub, Sébastien Besset, Mohamed Ichchou. Structural sources identification through an inverse mid-high frequency energy method. Mechanical Systems and Signal Processing, Elsevier, 2011, 25 (8) AbstractThis paper is primarily focused on the identification of structural forces, with the objective of localizing forces injected into structures in the mid-high frequency range. An energy method, called the Simplified Energy Method (MES), has already been introduced for the purpose of predicting an energy density distribution for structural acoustic problems in the mid-high frequency range. The present paper proposes using this same energy method to solve inverse structural problems. More specifically, the injected forces are to be estimated and localized through knowledge of a set of energy densities within the structure. The 2D formulation of this inverse approach, known as Inverse MES (or IMES), is first expressed. Both the boundary and internal sources can then be detected by applying the proposed formulation. Numerical test results are processed using a 2D Kirchhoff plate, and a number of conclusions are also drawn regarding IMES capabilities. Moreover, this paper offers a numerical comparison with another energy-based method.
Background: There has been increasing evidence and support for the use of digital technology in the cognitive health field. Despite the growing use of innovative digital technology to assess cognitive function, such technology remains scarce in Arabic countries, particularly in Tunisia. Objective: To investigate the effectiveness of a digitally delivered cognitive assessment battery in differentiating varying degrees of cognitive function in older Tunisian adults. Methods: One hundred fifty-five Tunisian older adults (age: 62.24±7.52 years) were assigned to one of four groups: healthy controls (HC), at-risk (AR), mild cognitive impairment (MCI), and Alzheimer’s disease (AD). Participants completed a translated version of the Neurotrack digital cognitive battery. Results: The AD group performed significantly lower on the associative learning (p = 0.01) and associative memory assessments (p = 0.002), than the HC and AR groups. The AD group also performed worse on the inhibition measure (p = 0.008) than the HC, AR, and MCI groups. For recognition memory, the was a significant difference between all four groups (p < 0.0005), with AD having the lowest scores followed by the MCI, AR, and HC groups, respectively. There were no significant differences observed on attention, executive function and processing speed performance between the four groups (p > 0.05). Conclusion: The use of digital technology appears to be a viable solution to current cognitive assessment challenges for assessing cognitive function in a Tunisian population. These findings provide further support for the use of digital technology in cognitive assessment, particularly in understudied populations.
This article deals with the behaviour of acoustic cavities in the mid-highfrequency range. An energy method called simplified energy method (MES) has already been proposed to predict energy levels in acoustic cavities. The direct MES provides energy density repartitions from the knowledge of input power and power dissipated at the boundaries. In this article we propose that the MES can be used to solve inverse problems. More precisely, the dissipated energy at the acoustic domain boundaries are retrieved from the knowledge of energy densities. The inverse MES formulation is first defined and a simple acoustic cavity test case is analysed, displaying the efficiency of the proposed method. The nature and the quality of input data as well as other parameters will be considered.
La qualité sonore des véhicules constitue aujourd'hui un critère important de conception. Dans ce cadre, la détection de sources acoustiques est une problématique majeure. En effet, si l'analyse du bruit dans une cavité peutêtre traitée de manière classique (FEM, BEM...), les problèmes inverses posent souvent des problèmes liésà la taille des calculs effectués ou au conditionnement des matricesà inverser. Nous nous proposons ici d'étudier une méthodeénergétique simplifiée (MES) qui présente la particularité d'être avantageusement inversible. Le but de la méthode proposée est de parvenirà localiser des sources acoustiques surfaciquesà partir de mesures effectuées dans une cavité. Mots clés :Source acoustique / bruit / problème inverse / méthodeénergétique simplifiée (MES) / hautes fréquences Abstract -Inverse energy method applied to the acoustic sources detection. The sound quality of the vehicles constitutes today a significant criterion of design. Within this framework, the detection of acoustic sources is a major problem. In fact, if the noise analysis in a cavity can be treated in a traditional way (FEM, BEM...), inverse methods often generate problems related to calculation size carried out or the conditioning of the matrices to be inversed. We propose to study a simplified energy method (SEM) which has the effect of being advantageously inversed. The suggested method objective is to locate surface acoustic sources starting from measurements taken in a cavity.
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