Numerical study of an intrinsic component mode synthesis method

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Opto-mechanical study of an optical fiber sensor based on polarimetric effects

In this paper, we studied the structure of a sensor consisting of single-mode optical fiber, inserted between two thin steel ribbons. The measuring principle is based on the analysis of the polarization modulation under external load. The sensor, thus conceived, was mechanically and optically tackled. Improvements of the initial device based on the introduction of a second optical fiber in parallel were made to increase the sensitivity of the sensor. The transfer function of the sensor as equation shows the fringes number of polarization at the fiber end versus the applied load to the sensor can be used directly by an user, for opto-geometric characteristics fixed. In other words, the model developed in this work provides a sizing tool allowing to user to get the best compromise metrological to solve a given problem of instrumentation. Keywords: Fiber optic sensors, Polarization, Elasto-optical coupling, Mechanical modelin

On the Use of Train Braking Energy Regarding the Electrical Consumption Optimization in Railway Station

AbstractNowadays, many projects have been conducted in order to reduce CO2 emissions, with the objective of reducing energy consumption. In the context of the urban railway area, the energy consumption is huge. It is respectively split into 70% for the traction and 30% for station consumers. Many works have already been carried out on traction systems, but very few of them were oriented towards the station energy problematic. This paper describes the project led by “Efficacity” Institute which concerns the use of the braking energy to manage and optimize the railway station energy consumption.Efficacity investigates energetic concepts in order to store the braking energy of the trains with a stationary electrical saving system, and to reutilize it for the power supply of electric and thermal consumers or actuators in a railway station thanks to a microgrid. The idea is to store train braking energy in hybrid storage system (composed of batteries and super-capacitors cells) and to restate it judiciously at different moments of the day (during peak or low energy consumption hours) to various kind of station loads

Inverse method for flow reconstruction using gas tracers in building environments

Air quality monitoring as well as comfort or overall energy performance require accurate information on airflow patterns, although they are particularly difficult to assess in existing buildings. We present an innovative instrumentation system using gas tracers, based on the combined use of several highly sensitive emerging micro-gas chromatographs ($\mu$GC) as pollutant sensors and an identification method for data processing. The strategy used is based on the optimal control theory in which only the time evolution of the components of the velocity field needs to be reconstructed thanks to the use of a proper orthogonal decomposition (POD) method. We present numerical results showing evidence of the performance of the approach in the case of a unimodal flow

State-parameter identification for accurate building energy audits

Building performance simulation often fails to predict accurately the real energy performance, mostly due to great uncertainties in the input data. Errors in computed performance are particularly significant in the case of existing buildings, for which the amount of information about intrinsic characteristics is low. However, efficient energy retrofit operations make necessary an accurate understanding of the initial state of a building using a calibrated prediction model. Several works have investigated the use of identification techniques for model calibration. The present paper investigates the use of such techniques to derive an energy audit procedure suitable to be an efficient aid for retrofit. In particular, we study here the possibility to determine the unknown thermal conductivity of the envelope and the internal gains based on temperature measurements only. We show how the adjoint method can be used to solve efficiently the inverse problem, while providing a fast method for computing model's sensitivities

Study of an optimal heating duration indicator for square pulsed thermography applied to CFRP gluing quality control

International audienceDuring previous works, square pulsed thermography was used to carry out non destructive testing of bonding quality of CFRP glued on civil engineering structures during reinforcement operations [1,2]. The use of such wave form excitation was motivated by " on-site " requirements, but also by measurements duration, number of composite layers to test, depth of possible faulting areas versus temperature elevation allowed at composite level according to inner heat diffusion. Nevertheless, square pulsed excitation implies to choose an adapted heat duration. This duration is directly linked to the reliability of the parameter estimator [3]. In fact, after a certain duration the standard deviation of the estimation procedure stagnates. According to these observations, an indicator able to predict the sufficient heating time when the reliability of the parameter estimator reached an asymptotic evolution behavior was studied. Based on the absolute thermal contrast, the proposed indicator Iph is defined with the maximum thermal contrast ∆Tmax and the time delay (tph) between the heating time tc and the appearance of the maximum contrast, as shown in figure 1 (left). A typical evolution of the Iph indicator is proposed in figure 1 (right). This indicator allows to take into acount the detectability as well as the induced flaw temporal effect on the thermal contrast shape evolution. It has been observed that the maximum of Iph is connected with the sufficient heating time when the standard deviation of the estimation procedure tends to be minimized. This paper will present the establishment of this indicator for optimal square heating time and present an analysis of results obtained with numerical simulations and laboratory experiments. Figure 1 Absolute thermal contrast characteristics (left) and indicator Iph evolution with heating time duration References [1] A. Crinière, J. Dumoulin, C. Ibarra-Castanedo and X. Maldague , " Inverse model for defect characterization of externally glued CFRP on reinforced concrete structures: Comparative study of square pulsed and pulsed thermography " ,] L-D. Théroux, J. Dumoulin and X. Maldague , " Square heating applied to shearography and active infrared thermography measurements coupling: from feasibility test in laboratory to numerical study of pultruded CFRP plates glued on concrete specimen " ,Strain journal, Wiley editor, 2014. doi:10.1111/str.12086. [3] V. Feuillet, L. Ibos, M. Fois, J. Dumoulin, Y. Candau, " Defect detection and characterization in composite materials using Square Pulse Thermography coupled with Singular Value Decomposition analysis and thermal quadrupole modeling " , NDT&E International, Volume 51, Octobre 2012, pp 58–67, Elsevier, http://dx

Dynamic building performance assessment using calibrated simulation

International audienceAccurate building performance assessment is necessary for the design of efficient energy retrofit operations and to foster the development of energy performance contracts. An important barrier however is that simulation tools fail to accurately predict the actual energy consumption. We present a methodology combining thermal sensor output and inverse algorithms to determine the key parameters of a multizone thermal model. The method yields calibrated thermal models that are among the most detailed ones in the literature dealing with building thermal identification. We evaluate the accuracy of the resulting thermal model through the computation of the energy consumption and the reconstruction of the main energy flux. Our method enables one to reduce standard uncertainties in the thermal state and in the quantities of interest by more than 1 order of magnitude

The mini climatic city a dedicated space for technological innovations devoted to Sustainable City

International audienceOur cities, from megalopolis to rural commune, are systems of an extraordinary technological and human complexity. Their balance is threatened by the growing population and rarefaction of resources. Massive urbanization endanges the environment, while global climate change, through natural hazards generated (climatic, hydrological and geological), threats people and goods. Connect the city, that is to say, design and spread systems able to route, between multiple actors, a very large amount of heterogeneous information natures and analyzed for various purposes, is at the heart of the hopes to make our cities more sustainable: climate-resilient, energy efficient and actresses of the energy transition, attractive to individuals and companies, health and environment friendly. If multiple players are already aware of this need, progress is slow because, beyond the only connectivity, it is the urban intelligence that will create the sustainable city, through coordinated capabilities of Perception, Decision and Action: to measure phenomena; to analyze their impact on urban sustainability in order to define strategies for improvement; to effectively act on the cause of the phenomenon. In this very active context with a strong societal impact, the Sense-City project aims to accelerate research and innovation in the field of sustainable city, particularly in the field of micro and nanosensors. The project is centered around a "mini climatic City", a unique mobile environmental chamber in Europe of 400m 2 that can accommodate realistic models of city main components, namely buildings, infrastructures, distribution networks or basements. This R&D test place, available in draft form from January 2015 and in finalized version in 2016, will allow to validate, in realistic conditions, innovative technologies performances for the sustainable city, especially micro-and nano-sensors, at the end of their development laboratory and upstream of industrialization. R & D platform located in the heart of the Cité Descartes in Paris Est and open to both academic as industrial and communities, Sense-City participates in the positioning of the Cité Descartes as a flagship tertiary center for the city of the future. The areas of interest cover the energy performance of buildings and neighborhoods, the sanitary quality of the frame (indoor air pollution), the quality and sustainability of urban networks (transport, fluid), the quality of outdoor air, soil and water, control of waste storage areas, sustainability and infrastructure security. In the framework of this project, a first outdoor test bed was designed and built in 2014. Various sensing capacity have been implemented and first experimentations started in 2015. The project partners, IFSTTAR, ESIEE-CCIP LPICM (UMR CNRS Ecole Polytechnique), CSTB, INRIA and UPEM, controls the entire value chain for the development of innovative products for the sustainable city, nano or prototyping microsensors up to validation in real conditions, not to mention the steps of integration , packaging and deployment of the sensors or the processing steps, modeling and representation of information

Merging sensor data from multiple temperature scenarios for vibration monitoring of civil structures

The ambient temperature effect may result in limitations of vibration-based structural health monitoring (SHM) approaches for civil engineering structures. This paper addresses the issue of discriminating changes in modal parameters due to damages and changes in modal parameters due to temperature effects. A non parametric damage detection algorithm is proposed, which only assumes that several datasets are recorded on the safe structure at different and unknown temperatures, and smoothes out the temperature effect using an averaging operation

Micro−transducteur ultrasonique capacitif à membrane de nanotubes de carbone : Perspectives pour le suivi immergé de la durabilité des matériaux cimentaires

Nous présentons des éléments de la conception, la réalisation et la caractérisation d'un micro−transducteur ultrasonique capacitif haute-fréquence dont la membrane vibrante est faite de nanotubes de carbone alignés. Le dispositif est conçu spécifiquement pour l'instrumentation immergée de la microporosité des matériaux cimentaires. La modélisation élasto−acoustique du dispositif valide préliminairement son intérêt applicatif pour la métrologie de la microporosité