Nantes, France
Nantes, France
Time filter
Source Type

Boillereaux L.,LUNAM | Alamir M.,French National Center for Scientific Research | Curet S.,LUNAM | Rouaud O.,LUNAM | Bellemain P.,French National Center for Scientific Research
Innovative Food Science and Emerging Technologies | Year: 2011

The present study is dedicated to the estimation of internal temperatures within a foodstuff during microwave tempering, in the presence of unknown dielectric properties. The solution consists of a software sensor based on a model originating from the closed-form solutions of Maxwell's equations coupled with the conduction heat equation solved by finite differences. The algorithm implemented enables convergence towards acceptable dielectric property functions while the temperature field is estimated simultaneously. This approach is carried out in simulation by considering the tempering of a block of raw beef located in a rectangular wave guide in order to consider a fundamental mode with perfectly known electromagnetic conditions. Industrial Relevance: In the industrial processes, the lack of sensors constitutes a brake to the design of relevant control strategies. One well-known solution is to implement software sensors (also called observers) to estimate online the lacking data. However, such a solution requires a good knowledge of the dynamical model structure and the model parameters. The development of software sensors remains nevertheless a difficult task for non specialist in process control. CLPP presented in this submission is particularly well suited to industrial cases, because it permits to estimate with a good accuracy the lacking state variables in the presence of large uncertainties on the parameters' vector. The interest is illustrated on a microwave food tempering process, where dielectric parameters are unknown, and where the available measurements are only surface temperatures. © 2011 Elsevier Ltd. All rights reserved.

Gabrieli F.,University of Padua | Artoni R.,LUNAM | Santomaso A.,University of Padua | Cola S.,University of Padua
Physics of Fluids | Year: 2013

Small quantities of liquid in a granular material control the flow dynamics as well as the triggering and jamming phases. In order to study this problem, some experimental collapse tests conducted in a rectangular box were reproduced with a 1:1 scale numerical model using the Discrete Element Method. In simulations the effect of the capillary bridges has been investigated implementing a mid-range attractive force between particles based on the minimum energy approach. Also a bonding-debonding mechanism was incorporated in the algorithm and the volume of each sessile drop on the particle surface was considered during its motion. The influence of some variables was investigated with respect to the final slope profiles and the runout lengths: the initial liquid content, the particle size, the solid density, the liquid surface tension, and the liquid-solid contact angle. Also the crucial effect of the confinement walls on the collapse phenomenon was investigated: wet particles adhere to the lateral walls providing a higher flow resistance in comparison to the same material in dry conditions. It was observed that particles with largest path-lengths are localized near the movable wall at a middle-height of the initial column sample. Other particles at the surface moves in a rigid way especially if they were wet and with a low solid density. The "fidelity" of each particle with respect to the nearest neighbours was evaluated allowing to recognize the emergence of clusters of particles and rigid parts, to extract the failure surface and to localize where debonding mechanisms concentrate in the wet case. © 2013 AIP Publishing LLC.

Califano C.,University of Rome La Sapienza | Marquez-Martinez L.A.,CICESE | Moog C.H.,LUNAM
IEEE Transactions on Automatic Control | Year: 2011

In this note the Extended Lie bracket operator is introduced for the analysis and control of nonlinear time-delay systems (NLTDS). This tool is used to characterize the integrability conditions of a given submodule. The obtained results have two fundamental outcomes. First, they define the necessary and sufficient conditions under which a given set of nonlinear one-forms in the n-dimensional delayed variables x(t),⋯,x(t-sD) D, with D constant but unknown, are integrable, thus generalizing the well known fundamental Frobenius Theorem to delay systems. Secondly, they set the basis for the extension to this context of the geometric approach used for delay-free systems. The effectiveness of the results is shown by solving the problem of the equivalence of a NLTDS to an accessible Linear Time-Delay System (LTDS) by bicausal change of coordinates. © 2011 IEEE.

Malys L.,LUNAM | Musy M.,LUNAM | Inard C.,University of La Rochelle
Building and Environment | Year: 2014

Covering a building envelope with vegetation provides a solution capable of mitigating the urban heat island phenomenon and its impact on the energy consumption of buildings. Simulation tools to assess the efficiency of such a solution are lacking, especially for green walls. The present research aims to offer a hydrothermal model of green walls and green roofs for implementation in the urban microclimate simulation software SOLENE-Microclimate. To this end, a fast, efficient coupled heat-mass transfer model has been developed. Simulation results are compared with experimental data obtained from the LEEA Laboratory in Geneva for three green wall samples. Aside from the level of uncertainty found for the evapotranspiration calculation, these results confirm that the model accurately characterizes the temperature evolution of all three prototypes. Results also show good correlation between measured and simulated temperatures. The model is indeed able to reproduce water stress and characterize various types of living walls. © 2013 Elsevier Ltd.

Fargier Y.,Center Detudes Techniques Of Lequipement Normandie Center | Fargier Y.,Électricité de France | Lopes S.P.,LUNAM | Fauchard C.,Center Detudes Techniques Of Lequipement Normandie Center | And 2 more authors.
Journal of Applied Geophysics | Year: 2014

Levee, dike and earth embankment dam structures are difficult to assess because of their length and complexity. Managers often include geophysical investigations in the overall dike condition assessment and the DC-Electrical Resistivity Imaging (ERI) method is particularly applicable owing to its cost-effectiveness and its potential sensitivity to internal erosion. However, due to the truly 3. D nature of embankment dikes, implementing inline longitudinal tomographies along with conventional 2. D inversion is likely to yield image artefacts. 3. D effects from external causes (geometry, water reservoir) can be predicted and therefore we present a new approach based on redefining the normalisation principle to derive apparent resistivities from the measured data. The aim is to provide a set of pre-processed apparent resistivities that are not contaminated by external 3. D effects and that yield more reliable results when processed within a 2. D conventional inversion scheme. The presented approach is successfully applied to synthetic and real data sets, proving superior to the conventional 2. D approach, although data acquisition approach is the same thus keeping the same cost-effectiveness. © 2014 .

Benabes J.,LUNAM | Poirson E.,LUNAM | Bennis F.,LUNAM
Expert Systems with Applications | Year: 2013

Having a significant impact on the design of many products and industrial systems, such as the subdivision of a ship, the layout of facilities in a plant or further still the assembly of parts of a mechanism, layout design optimization is at the heart of scientific issues. The design of an optimal layout solution is a critical and complex task due to the increasing demands of designers working on varied projects. This paper proposes an integrated approach to solve layout optimization problems, from the needs expressed by the designer to the creation of an ideal solution. This generic and interactive method is based on a design process divided into four steps: the description, the formulation, the solving of the problem, and the final decision. This process is based on a multiobjective modular optimization strategy that combines a genetic algorithm with local optimization modules. The method described in this paper is interactive because the designer participates in all process's steps. For example, in the final decision step, the approach includes an interactive environment in order to let the designer choose and improve an optimal solution according to his personal judgment and expertise. The global method is applied to an industrial problem which deals with the search for an optimal layout of facilities in a shelter. © 2013 Elsevier Ltd. All rights reserved.

Letaief H.,LUNAM | Letaief H.,Higher Institute of Food Industries of Tunis | Maury C.,LUNAM | Symoneaux R.,LUNAM | Siret R.,LUNAM
Journal of the Science of Food and Agriculture | Year: 2013

Background: The evolution of the sensory and instrumental properties of grape seeds was investigated during berry development, with a focus on the effects of the harvest season and growing location. Results: The sensory and instrumental texture analyses gave a consistent description of the ripening process. Moreover, the effect of maturation on the seed sensory descriptors was clearly influenced by the harvest season, and astringency was the most appropriate sensory attribute for the assessment of grape seed ripening. Except for seed cracking, which was positively correlated with fracturability (R = 0.69) and toughness (R = 0.68) in 2006, the compression parameters were generally not correlated with the sensory textural attributes but were more likely correlated with other sensory attributes such as astringency and vegetal aroma. The compression indices showed a logarithmic behaviour pattern during grape development, and seed stiffness was shown to be the most valuable textural index for parcel discrimination and identification of the optimal grape harvesting date. Conclusion: This research showed that both seed sensory attributes and instrumental texture properties are indicators of grape ripening. However, these properties could be affected by the harvest season and growing location. As no clear correlation was found between the seed sensory attributes and instrumental texture parameters, a revision of the sensory method available in the literature could be suggested. © 2013 Society of Chemical Industry.

Joannis C.,LUNAM | Hannouche A.,University Paris Est Creteil | Chebbo G.,University Paris Est Creteil | Chebbo G.,Lebanese University
Urban Water Journal | Year: 2015

This paper presents a method for assessing the respective contributions of the variations of flow-rate and concentration of any pollution parameter to the variations of the mass discharge of the same parameter. This method uses a specially designed decomposition of variance, which gives a priority to the information provided by flow-rates, either directly, or through the correlation between flow-rates and concentrations. To demonstrate the potential interest of this method, data monitored on two catchments in the city of Paris (France) are processed according this method, with turbidity being used as a surrogate for suspended solids concentration. Results show that volumes provide a fairly good evaluation of masses at the scale of whole events. Inside any particular event, concentrations are major contributors to the variations of mass discharge, despite the correlations between flow rate and concentration which may be observed for many rain events. © 2014 Taylor & Francis.

PubMed | University of Angers, LUNAM, American University of Beirut and Lebanese University
Type: | Journal: Journal of venom research | Year: 2016

Molecular richness of snake venoms is an important source of proteins and toxins with potent effects on the cardiovascular system. The alteration of the vascular system in the victim after a venomous snake bite is usually expressed by a significant decrease in blood pressure. Therefore, exploring snake venom to extract and characterize its biomolecules is of considerable medical interest, and formed the basis of this study. We assessed the potential of the venom of

Akacem M.,University of Adrar | Cerezo V.,Lunam | Hachichi A.,Oran University of Science and Technology - Mohamed Boudiaf
Construction and Building Materials | Year: 2016

Aggregates extracted from southern Algeria exhibit weak performances regarding the resistance to shock or to polishing. Indeed, the values of Los Angeles (LA), Micro Deval (MDE) and PSV (Polished Stone Value) tests do not always fulfil national requirements to be used in road pavement wearing courses. As a consequence, asphalt concrete made with these aggregates presents low values of skid resistance and a high sensitivity to polishing. This paper presents the results of a laboratory study, which explores the effect of an addition of sand from dunes both on mechanical characteristics and skid resistance under polishing with Wehner & Schulze machine for asphalt concrete made with local Algerian aggregates. Thus, the use of 10–20% of this sand improves skid resistance by creating an artificial microtexture which generates friction forces and resist wearing. In parallel, sand from dunes entails an increase of the asphalt mix stiffness and allows reaching acceptable mechanical performances for surface pavements’ use. © 2016 Elsevier Ltd

Loading LUNAM collaborators
Loading LUNAM collaborators