Time filter

Source Type


Bouzouidja R.,NIDAPLAST | Bouzouidja R.,CNRS Mechanical Energy, Theories, and Applications Laboratory | Sere G.,University of Lorraine | Sere G.,French National Institute for Agricultural Research | And 2 more authors.
Houille Blanche

There are several issues related to the development of green roofs: a better understanding and estimation of their thermic and hydric performances as well as the strong necessity to develop innovations. This study is primarily based on the monitoring of a large-scale in situ green-roof that instrumented with temperature sensors, capacitive tensiometers and dielectric sensors. This experimental device was completed by a weather station monitoring few microclimatic parameters (ambient temperature, humidity, wind speed and direction). The analysis of the results has lead to a better understanding of the seasonal behavior of the extensive green roof (EGR). Indeed, EGR contribution for thermal insulation has been estimated and reached maximum reduction of temperature of 24 °C in summer and a temperature gain of 5 C in winter. In spring, the EGR succeeded in storing almost the whole rainfall. The substrate appeared to play an important role on the coupled thermo-hydric performances of the EGR and needed further characterization. © 2013 Société Hydrotechnique de France. Source

Monchau J.-P.,University Paris Est Creteil | Marchetti M.,CETE de lEst | Ibos L.,University Paris Est Creteil | Dumoulin J.,IFSTTAR | And 2 more authors.
International Journal of Thermophysics

The knowledge of the infrared emissivity of materials used in buildings and civil engineering structures is useful for two specific approaches. First, quantitative diagnosis of buildings or civil engineering infrastructures by infrared thermography requires emissivity values in the spectral bandwidth of the camera used for measurements, in order to obtain accurate surface temperatures; for instance, emissivity in the band III domain is required when using cameras with uncooled detectors (such as micro-bolometer arrays). Second, setting up accurate thermal balances by numerical modeling requires the total emissivity value for a large wavelength domain; this is, for instance, the case for computing the road surface temperature to predict ice occurrence. Furthermore, periodical surveys of emissivity variations due to aging or soiling of surfaces could be useful in many situations such as thermal mapping of roads or building insulation diagnosis. The use of portable emissivity measurement devices is required for that purpose. A device using an indirect measurement method was previously developed in our lab; the method uses measurement of the reflectivity from a modulated IR source and requires calibration with a highly reflective surface. However, that device uses a low-frequency, thermal modulation well adapted to laboratory measurements but unfit for fast and in situ measurements. Therefore, a new, portable system which retains the principle of an indirect measurement but uses a faster-frequency, mechanical modulation more appropriate to outdoor measurements was developed. Both devices allow measurements in the broad (1μm to 40μm) and narrow (8μm to 14μm) bands. Experiments were performed on a large number of materials commonly used in buildings and civil engineering structures. The final objective of this work is to build a database of emissivity of these materials. A comparison of laboratory and on-site measurements of emissivity values obtained in both spectral bands will be presented along with an estimation and an analysis of measurement uncertainties. © Springer Science+Business Media New York 2013. Source

Schwager J.,CETE de lEst | Irles A.,CETE de lEst | Thiriat J.,CETE de lEst | Claverie R.,CETE de lEst | And 2 more authors.
Techniques - Sciences - Methodes

Thanks to their supposed benefits, green roofs are often held up as one of the preferred techniques to reach the objectives of sustainable development established by the recent French policies such as the Grenelle de l'environnement. However, there is a lack of scientific studies, which would allow to confirm and quantify these green roofs functions. The CETE de l'Est launched in 2009 a multi-disciplinary project, which aims to provide a better understanding of their impacts on water quality, building thermal isolation, urban heat island and biodiversity. Concerning rainwater purification, the state of the art shows mixed results, which can be explained by the fact that green roofs are not designed to purify waters. Eight green roofs with different materials have been built on the LRPC of Nancy thanks to seven industrial partners. This real-size experimental site will allow to establish recommendations for the construction of green roofs with optimised thermal, water purification and biodiversity-enhancement functions. The first results show that substrates and a drainage material contain significant metals amount with a low mobility. Besides, for most of the substances the amounts of metals coming from the green roofs are smaller than the amount brought by atmospheric deposits. Source

Remi S.,CETE de lEst | Ivana D.,CETE de lEst | Guillaume D.,CETE de lEst | Patrice B.,CNRS Laboratory of Optical Materials, Photonics, and Systems | And 3 more authors.
Energy Procedia

A detention pond used for the treatment of road water runoff and the flow control was tested for deicing salt storage. To that purpose, samples were collected from the pond's water (influent entering the pond and effluent exiting the pond) and sludge. NaCl and heavy metals concentrations in those samples were measured. In parallel, meteorological conditions and information about deicing salt application will be followed in order to evaluate the proportion of salt collected by the road drainage system. Na+ and CI- exchange and transfer processes in the detention pond and their influence on the heavy metals remobilisation were assessed. © 2013 The Authors. Source

Charbonnier P.,CETE de lEst | Chavant P.,CETE de lEst | Chavant P.,CNRS Computer Science and Engineering Laboratory | Foucher P.,CETE de lEst | And 5 more authors.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives

With recent developments in the field of technology and computer science, conventional methods are being supplanted by laser scanning and digital photogrammetry. These two different surveying techniques generate 3-D models of real world objects or structures. In this paper, we consider the application of terrestrial Laser scanning (TLS) and photogrammetry to the surveying of canal tunnels. The inspection of such structures requires time, safe access, specific processing and professional operators. Therefore, a French partnership proposes to develop a dedicated equipment based on image processing for visual inspection of canal tunnels. A 3D model of the vault and side walls of the tunnel is constructed from images recorded onboard a boat moving inside the tunnel. To assess the accuracy of this photogrammetric model (PM), a reference model is build using static TLS. We here address the problem comparing the resulting point clouds. Difficulties arise because of the highly differentiated acquisition processes, which result in very different point densities. We propose a new tool, designed to compare differences between pairs of point cloud or surfaces (triangulated meshes). Moreover, dealing with huge datasets requires the implementation of appropriate structures and algorithms. Several techniques are presented: point-to-point, cloud-to-cloud and cloud-to-mesh. In addition farthest point resampling, octree structure and Hausdorff distance are adopted and described. Experimental results are shown for a 475 m long canal tunnel located in France. Source

Discover hidden collaborations