J-L Dufresne's abstracts

J-L Dufresne's ABSTRACTS

[2002 ], [2001 ], [2000 ], [1999 ], [1998 ], [1996 ] [.... ],

Monte Carlo methods and sensitivity estimations
A. de Lataillade, S. Blanco, Y. Clergent, J.L. Dufresne, M. El Hafi and R. Fournier
J.Quant. Spectrosc. Radiat. Transfer, Vol. 75, N.5, pp.529-538, Oct 2002
Abstract : It is shown that, starting from any existing Monte Carlo algorithm for estimation of a physical quantity A, it is possible to implement a simple additional procedure that simultaneously estimates the sensitivity of A to any problem parameter. The corresponding supplementary cost is very low as no additional random sampling is required. The principle is presented on a formal basis and simple radiative transfer examples are used for illustration.
Texte in ps or pdf file. " © 2002 Published by Elsevier Science Ltd. Further reproduction or electronic distribution is not permitted."
A Net Exchange Monte Carlo approach to radiation in optically thick systems
A. de Lataillade, J.L. Dufresne, M. El Hafi, V, Eymet, R. Fournier
J.Quant. Spectrosc. Radiat. Transfer, Vol. 74, N.5, pp.563-584, Jul 2002
Abstract : A Monte Carlo approach to radiative transfer in participating media is described and tested. It solves to a large extent the well known problem of Monte Carlo simulation of optically thick absorption configurations. The approach which is based on a net-exchange formulation and on adapted optical path sampling procedures is carefully designed to insure satisfactory convergence for all types of optical thicknesses. The need for such adapted algorithms is mainly related to the problem of gaseous line spectra representation in which extremely large ranges of optical thicknesses may be simultaneously encontered. The algorithm is tested against various band average computations for simple geometries using the Malkmus statistical narrow band model.
Texte in pdf file. " © 2002 Published by Elsevier Science Ltd.Further reproduction or electronic distribution is not permitted."
Longwave Scattering Effects of Mineral Aerosols
Jean-Louis Dufresne, Catherine Gautier, Paul Ricchiazzi, Yves Fouquart
J. Atmospheric Science, Vol. 59, N.12, pp.1959-1966, 15 June 2002
Abstract : Scattering in the longwave domain has been neglected in the first generation of radiative codes and is still neglected in most current GCMs. Scattering in the longwave domain does not play any significant role for clear sky conditions but recent works have shown that it is not negligible for cloudy conditions. In this paper we highlight the importance of scattering by mineral aerosols in the longwave domain for a wide range of conditions commonly encountered during dust events. We show that neglecting scattering may lead to an underestimate of longwave aerosol forcing. This underestimate may reach 50% of the longwave forcing at the top of atmosphere and 15% at the surface for aerosol effective radius greater than a few tenths of a micron. For an aerosol optical thickness of one and for typical atmospheric conditions, the longwave forcing at the TOA increases to 8 W.m-2 when scattering effects are included. In contrast, the heating rate inside the atmosphere is only slightly affected by aerosol scattering: neglecting it leads to an underestimate by no more than 10% of the cooling caused by aerosols.
Texte in pdf or in ps file. "© 2002 American Meteorological Society. Further reproduction or electronic distribution is not permitted."
Effects of climate change due to CO2 increase on land and ocean carbon uptake.
Dufresne J-L, Friedlingstein P, Berthelot M, Bopp L, Ciais P, L. Fairhead, H. LeTreut, P. Monfray
Geophys. Res. Lett., 29(10), 10.1029/2001GL013777, 23 May 2002
Abstract : We use an ocean-atmosphere general circulation model coupled to land and ocean carbon models to simulate the evolution of climate and atmospheric CO2 from 1860 to 2100. Our model reproduces the observed global mean temperature changes and the growth rate of atmospheric CO2 for the period 1860-2000. For the future, we simulate that the climate change due to CO2 increase will reduce the land carbon uptake, leaving a larger fraction of anthropogenic CO2 in the atmosphere. By 2100, we estimate that atmospheric CO2 will be 18% higher due to the climate change impact on the carbon cycle. Such a positive feedback has also been found by [Cox et al.,2000]. However, the amplitude of our feedback is three times smaller than the one they simulated. We show that the partitioning between carbon stored in the living biomass or in the soil, and their respective sensitivity to increased CO2 and climate change largely explain this discrepancy.
Texte in pdf or in ps file. "© American Geophysical Union. Further reproduction or electronic distribution is not permitted."

Positive feedback between future climate change and the carbon cycle.
Friedlingstein P, Bopp L, Ciais P, Dufresne JL, Fairhead L, LeTreut H, Monfray P, Orr J,
Geophys. Res. Lett., Vol.28, No.8, pp. 1543-1546, Apr 2001
Abstract : Future climate change due to increased atmospheric CO2 may affect land and ocean efficiency to absorb atmospheric CO2. Here, using climate and carbon three-dimensional models forced by a 1% per year increase in atmospheric CO2, we show that there is a positive feedback between the climate system and the carbon cycle. Climate change reduces land and ocean uptake of CO2, respectively by 54% and 35% at 4 x CO2. This negative impact implies that for prescribed anthropogenic CO2 emissions, the atmospheric CO2 would be higher than the level reached if climate change does not affect the carbon cycle. We estimate the gain of this climate-carbon cycle feedback to be 10% at 2 x CO2 and 20% at 4 x CO2. This translates into a 15% higher mean temperature increase.
Texte in pdf or in ps file. "© 2001 American Geophysical Union. Further reproduction or electronic distribution is not permitted."
Potential impact of climate change on marine export production.
Bopp L, Monfray P, Aumont O, Dufresne JL, Le Treut H, Madec G, Terray L, Orr JC,
Global Biogeochemical Cycles, Vol. 15, No. 1, pp. 81-99, Mar 2001
Abstract : Future climate change will affect marine productivity, as well as other many components of Earth system. We have investigated the response of marine productivity to global warming with two different ocean biogeochemical schemes and two different atmosphere-ocean coupled general circulation models (GCM). Both coupled GCMs were used without flux correction to simulate climate response to increased greenhouse gases (+1% CO2/yr for 80 years). At 2xCO(2), increased stratification leads to both reduced nutrient supply and increased light efficiency. Both effects drive a reduction in marine export production (-6%) although regionally changes can be both negative and positive (from -15% zonal average in the tropics to +10% in the Southern Ocean). Both coupled models and both biogeochemical schemes simulate a poleward shift of marine production due mainly to a longer growing season at high latitudes. At low latitudes the effect of reduced upwelling prevails. The resulting reduction in marine productivity, and other marine resources, could become detectable in the near future, if appropriate long-term observing systems are implemented.

Les rétroactions " climat-carbone " associées aux rejets anthropiques de CO2 à l'aide du modèle couplé de l'IPSL : un possible effet amplificateur?
J-L.Dufresne,P. Friedlingstein
Lettre n.11 du Programme International Géosphère Biosphère-Programme Mondial de Recherches sur le Climat (PIGB-PMRC)
Résumé : Depuis plus d'un siècle, la concentration en CO2 atmosphérique mesurée a augmenté de 25% passant de 280 ppmv en 1860 à 360 ppmv de nos jours. Cette augmentation serait environ deux fois plus forte si tout le CO2 émis par les activités humaines restaient dans l'atmosphère ; environ la moitié de ce CO2 émis est capté par la biosphère et par l'océan. Comment réagissent ces puits à un changement climatique?
Fast temperature and true airspeed measurements with the airborne ultra sonic anemometer thermometer (AUSAT).
D. Cruette, A. Marillier, J.L. Dufresne, J.Y. Grandpeix, P. Nacass, H.Bellec,
J. Atmos. Oceanic. Technol., Vol.17, No.8, pp. 1020-1039, Aug 2000
Abstract : An airbome thermometer-anemometer with fast response and high reliability is designed and built using the well-known Sonic Anemometer Thermometer technique. The shape of this new airborne sonic sensor, without the conventional style probes, is a cylinder with its axis collinear to the aircraft's longitudinal axis. The true airspeed and the air temperature are measured in the same volume. A previous paper described a preliminary version of this sensor and presented data of flight tests obtained on board Météo-France's Cessna-206. This new paper shows an improved sensor and the results obtained on faster aircrafts such as the CNRS-INSU'S Fokker-27 and the Météo-France's Merlin-IV. First, the sensor and the principle of the measuring method are described, then data collected during several flights from 1996 to 1998 are presented. Although this new thermometer-anemometer is not completely calibrated, it provides mean data very close of those measured by conventional sensors but with a response time thirty time shorter.
Summary Report of the Project Simulation, Diagnosis and Detection of the Anthropogenic Climate Change (SIDDACLICH) ENV4-CT95-0102
Ulrich Cubasch, et al.
Project report EUR N. 19310 , E.C., Bruxelle, Jul 2000.
Abstract : Climate responses under various anthropogenic and natural forcing scenarios have been studied and intercompared with several independent models and with different experimental strategies. The model simulated patterns of temperature and precipitation responses to increases in the greenhouse gas concentration are related to the model feedbacks, and therefore differ in detail between models. Nevertheless, some broad features of the responses with a surface- and lower troposheric warming in high latitudes, marked land-sea contrast with land warming more than the ocean surface, and intensified hydrological cycle (more evaporation and rainfall, with largest increases in the Tropics), are common to all models. The models produce a 10-15% increase of winter storm track activity over the north-western Europe at the time of CO2-doubling. This increase is caused by an increasing baroclinicity over the entire north-east Atlantic with main changes occurring in the upper troposphere. In a warmer climate increases in storm intensity is due to a larger amount of water vapour in the atmosphere. The observed close relationship between the NAO index and the Atlantic storm track intensity is confirmed in the model simulations During the summer and winter season, the global mean convective rain rate decreases by about 4-5 % resulting from a strong decrease of the frequency of deep convective events. Globally, for rain rates between 5 and 40 mm/day a decrease of both frequency and the respective mean daily rain rates is found. However, for convective rain rates larger than 40 mm/day both frequency and mean daily rain rate increase indicating an increase of strong rain events. There is no agreement about the net influence of glacier mass gain in Antarctica and mass loss in Greenland on sea level change between the different simulations. Common to all stabilising experiments, in which the greenhouse gas concentration is kept constant after an initial rise to 2*CO2 or 4*CO2, is a strong warming during the years, while the greenhouse gas concentration is still increasing, followed by a weaker, but still considerable, warming during the period with fixed concentrations. This long-term adjustment is also visible in the sea-level change due to thermal expansion. The overturning circulation in the North Atlantic weakens during the first 100 years of these experiments by 15% to 20%. In these runs the intensity slowly recovers after reaching the minimum, once the greenhouse gas concentration has stabilised. In the CO2-quadrupling experiments the reduction is so strong that at the end of the runs even after the recovery the intensity is still significantly weaker than in the control simulation. Nevertheless, in the quadrupling experiments an Atlantic conveyor belt-type overturning circulation pattern is present throughout the full simulation period. This reduction is caused by thermal effects, while the relative contribution of momentum and freshwater fluxes is less than 25%. With a 2D-model it can be shown that it is impossible to simulate the 20th century climate warming without the inclusion of the greenhouse-gas releases connected to human activities, Applying an optimal detection strategy to the model experiment results one finds that while the observations are consistent with greenhouse gas and aerosol forced climate change, they disagree significantly from greenhouse gas only climate change and marginally from solar forced climate change. No significant change was found on timescales of 10 years. For trends of length 30 years only the global mean change was found to be significant. Only for trends of 50 years were significant sub-global scale changes found and even so the changes are only significant for spatial scales greater than 5,000 km. The results further suggest that the unusually strong global mean warming in the middle of this century may have been influenced by an early greenhouse gas response, and possibly also by a solar irradiance increase.

Inverse gaussian k-distributions,
Dufresne, J.L., Fournier, R., Grandpeix, J.Y. ,
J.Quant. Spectrosc. Radiat. Transfer, Vol. 61, N.4, pp. 433-441, Mar 1999
Abstract : K-distributions corresponding to Malkmus' narrow band model are inverse Gaussian distributions. Inverse Gaussian theory developments are therefore directly relevant to gas radiative transfer modeling. The present text illustrates some significant benefits that could be made from this observation : i) k-distribution formulations are simplified, ii) numerical integration procedures can be optimized for each new configuration type, iii) frequently encountered integrals can be solved analyticaly and numerical integrations can be avoided. This last point is illustrated with the compuation of infra-red cooling rates in panetary atmospheres.
Radiative transfer modeling for radiation-chemistery coupling analysis ,
A. de Guilhem de Lataille, M. El Hafi, R. Fournier, J.L. Dufresne
5th International Conference on Technologies and Combustion for a Clean Environment, Lisbon, Portugal, July 1999. Ed. Gordon and Breach, 1999
Abstract : This study is devoted to the prediction of pollutant formation inside combustion chambers. In order to control minor species emissions, considering the high sensitivity of kinetic chemistry to temperature, it is required that physical analysis include detailed description of all heat transfer processes . As far as radiation is concerned, one may state that no numerical model is available at date that meets the requirements in terms of geometrical description and accuracy. The present work discusses an alternative approach that combines an accurate Monte Carlo algorithm with a simple Taylor expansion of radiative exchanges as function of temperatures and concentrations. Accurate models can be designed on this basis that can be easily coupled to detailed kinetics models.

The influence of resolution in simulating inter-annual and inter-decadal variability in a coupled ocean-atmosphere GCM, with emphasis over the North Atlantic
C. Laurent, H Le Treut, Z.X.Li, L. Fairhead and J.L. Dufresne
Notes du p�le de modélisation de l'IPSL, N.8, 1998

Abstract : Multidecadal numerical experiments have been realized at different resolutions using the coupled ocean-atmosphere general circulation model developed at IPSL (Institut Pierre Simon Laplace) in Paris. The atmospheric LMD model and the oceanic OPA-LODYC model are coupled without any flux adjustment. The mean simulated climate is stable and differs from reality through a few well established systematic errors. The variability simulated by the model at these different resolutions is compared for various areas, and more specifically the North Atlantic. A statistical method, the Multi-channel Singular Spectrum Analysis (M-SSA), is used to detect sea surface temperature oscillations at different time scales. Oscillations over the North Atlantic display a well-known tripole feature, which seems to depend primarily on the ocean resolution. The period of the oscillation (from 8 to 12 years) seems more sensitive to the atmospheric resolution.
Simulations couplées globales des changements climatiques associés a une augmentation de la teneur atmosphérique en CO2
( Global coupled simulations of climate change due to increased atmospheric CO2 concentration )
P. Barthelet, S. Bony, P. Braconnot, A. Braun, D. Cariolle, E. Cohen-Solal, J.-L. Dufresne, P. Delecluse, M. Deque, L. Fairhead, M.-A. Filiberti, M. Forichon, J.-Y. Grandpeix, E. Guilyardi, M.-N. Houssais, M. Imbard, H. Le Treut, C. Levy, Z.X. Li, G. Madec, P. Marquet, O. Marti, S. Planton, L. Terray, O. Thual, S. Valcke
Compte Rendu Académie des Sciences Paris, Série II a, Vol.326, No.10, p.677-684, mai 1998
Abstract : Two transient CO2 experiments using two coupled general circulation models developped by the french GASTON group have been realized using the same methodology . No flux corrections at the air-sea interface were used in these experiments. The main features of the present climate are reasonably well captured by both coupled models in the control simulations, although the biases are not the same. The transient CO2 simulations show a global warming, ranging between 1.6 C and 2.0 C at the time of CO2 doubling(+70 years). These values, and the main geographical characteristics of climate change are in agreement with previous studies published by other research groups, using either flux corrected or non-flux corrected models.
Résumé : Deux expériences climatiques d'augmentation de la teneur en CO2 atmosphérique, utilisant deux modèles de circulation générale couplés océan/glace/atmosphère développés au sein du groupe GASTON, ont été réalisées selon la même méthodologie, sans correction de flux artificielle à l'interface air-mer. Les simulations de contrôle reproduisent convenablement les caractéristiques principales du climat actuel, les biais des deux modèles couplés étant cependant différents. Les simulations de scénario d'augmentation de la teneur en CO2 atmosphérique (1% par an) indiquent un réchauffement global de la température à la surface du globe compris entre 1,6°C et 2,0°C au moment du doublement de la teneur en CO2 (+70 ans). L'amplitude ainsi que la répartition géographique du réchauffement sont en accord avec les résultats d'autres groupes de recherche utilisant des modèles à flux corrigés ou non.
Radiative Net Exchange Formulation within one dimensional gas enclosures with reflective surfaces ;
Cherkaoui M., Dufresne, J.L., Fournier, R., Grandpeix, J.Y. , Lahellec, A. ;
ASME Journal of Heat Transfer, Vol.120, No.1, pp. 275-278, Febr. 1998
Abstract : The Net Exchange Formulation (NEF) was proposed in (Cherkaoui et al., 1996) as a method for accurate computation of infra red radiative exchanges within gas enclosures. The Exchange Monte Carlo Method (EMCM) was then described, and applications to one dimensional configurations with either black or reflective surfaces were given. However, equations used in the reflective case were omitted. These are derived in the present technical note.
Méthode de Monte-Carlo par Echanges pour le calcul des bilans radiatif au sein d'une cavité 2D remplie de gaz,
( The Exchange Monte-Carlo Method for radiative budget computation in a gas filled two-dimensional enclosure )
Dufresne, J.L., Fournier, R., Grandpeix, J.Y. ,
C. R. Acad. Sci. Série II-b, Vol.326, No.1, pp. 33-38, Janvier 1998
Abstract : A formulation is presented based on the reciprocity principle in which radiative budgets are expressed as sums of Net Exchange Rates between all volume and surface elements. On this basis, a Monte-Carlo Method has been developed that proved numerically very efficient compared to standard Analog Monte-Carlo Methods. It was used for computation of radiative budgets inside a two-dimensional cavity field with a participating gas. Strongly irregular grids and a wide range of optical thicknesses can be studied with this method.
Résumé : Nous présentons une formulation des processus radiatifs basée sur le principe de réciprocité des rayons lumineux, dans laquelle la grandeur physique essentielle est la puissance nette échangée entre les différentes parties du système. La méthode de Monte-Carlo développée repose directement sur cette formulation et possède des avantages numériques majeurs. Elle a été appliquée au calcul des bilans radiatifs dans une cavité bidimensionnelle remplie de gaz, avec un maillage très irrégulier et pour une large gamme d'épaisseurs optiques.

Monte Carlo simulation of radiation in gases with a narrow-band model and a Net-Exchange Formulation.
Cherkaoui M, Dufresne JL, Fournier R, Grandpeix JY, Lahellec A;
ASME Journal of Heat Transfer, Vol.118, No.2, pp. 401-407, May 1996
Abstract : The Monte Carlo method is used for simulation of radiative heat transfers in non-gray gases. The proposed procedure is based on a Net-Exchange Formulation (NEF). Such a formulation provides an efficient way of systematically fulfilling the reciprocity principle, which avoids some of the major problems usually associated with the Monte Carlo method~: numerical efficiency becomes independent of optical thickness, strongly non uniform grid sizes can be used with no increase in computation times and configurations with small temperature differences can be addressed with very good accuracy. The Exchange Monte Carlo Method (EMCM) is detailed for a one-dimensional slab with diffusely or specularly reflecting surfaces.
Raccordement des Modèles Thermodynamiques de Glace, d'Océan et d'Atmosphère
( Sea-ice/ocean/atmosphere thermodynamic coupling )
Dufresne J.L, Grandpeix J.Y.
Laboratoire de Météorologie Dynamique, Note Interne 205, juin 1996
Abstract : L'interface océan-glace de mer-atmosphère est extrêmement hétérogène. Le modèle de glace-océan du LODYC, utilisé par la comunauté "GASTON", reproduit en partie cette hétérogénéité (mailles mixtes contenant de l'océan libre et différents types de glace) alors que les modèles d'atmosphère (Arpège, LMD 5) ne la reproduisent pas ou peu (mailles homogènes ou mailles mixtes océan libre - un seul type de glace). De plus, aux hautes latitudes, une maille atmosphérique recouvre un nombre élevé de mailles océaniques.
Nous avons développé un modèle de raccordement qui répartit de fa�on différenciée les flux calculés par le modèle d'atmosphère sur les diff'erents types de surface (océan libre ou variétés de glace) en fonction de leur distribution statistique (fraction surfacique) et de leur caracteristiques individuelles (temp. de surface, albédo, etc...). Ce modèle de raccordement garantit la conservation des flux à l'interface.
Dans cette note, nous abordons tout d'abord le problème de la stabilité numérique du raccordement glace-atmosphère, puis présentons le modèle de raccordement développé.
Monte Carlo simulation of radiation in gases with a narrow-band model and a Net-Exchange Formulation : numerical results for one dimesionnal configurations;
Cherkaoui M., Dufresne J.L., Fournier R. , Grandpeix J.Y. , Lahellec A.
Laboratoire de Météorologie Dynamique, Internal Report 204, Jun 1996
Abstract : Additional numerical results to the paper of (Cherkaoui et al., 1996)
L'exposition scientifique interactive , manipuler pour comprendre ;
sous la direction d'Andre BILLET,
CNRS éditions, Paris, 1996
Abstract : Aujourd'hui, le public apprend la science et la technique par l'intermédiaire de nombreux médias ; or, ces derniers ne proposent pas de démonstrations scientifiques directes et concrètes. "Expliquer la science sans pratiquer d'expériences, c'est apprendre à nager sans eau", disait Oppenheimer, créateur de l'Exploratorium de San Francisco. Ce que prouverait le succès croissant des expositions scientifiques et techniques privilégiant la communication par l'objet interactif.
Ainsi, les manipulations, par leur dispositif, représentent en trois dimensions les phénomènes, les concepts, les procédés, les démarches de la recherche ou les techniques élaborées dans les laboratoires. Ludiques, spectaculaires, instructives, interactives, d'une consultation rapide, elles requièrent la participation des visiteurs, provoquent l'étonnement et le désir d'en savoir plus, privilégient les stratégies de découverte, divertissent.
Les différents contributeurs, par leur savoir-faire et leur pratique, clarifient la conception des "manips" et retracent les différentes étapes de leur réalisation et de leur utilisation. Pour chaque manip, schémas, graphiques, tableaux, figures illustrent les démonstrations scientifiques et rendent compte des différents projets pédagogiques. Ce "manuel" intéressera aussi bien les professionnels que les visiteurs d'expositions.

Procédure d'identification inclusive d'un système thermique. Etude de cas : caractérisation d'un capteur solaire à air en régime dynamique;
( Inclusive identification procedure for a thermal system dynamical characterization. Case study : an air solar collector wall componenet. )
Dufresne, J.L., Lahellec, A., Chounet L.M.,
Revue de Physique Appliquée, Vol.25, No.11, p. 1139-1160, Nov. 1990
Abstract. - The dynamical characterisation of a solar component - taken as a case study - introduced us to the general problem of non linear multiparametric model identification (10 parameters in our case). The elaboration of such a model has three goals : first, it has to allow the designer to understand and improve his components ; then it can be integrated in a global'system model (the building and control devices) for real performances study ; and finally, it is a guidance for the monitoring process in the purpose of fulfilling the two previous objectives (global coherence). The method and its implementation are described, and the results obtained for our case study given ; we set a particular emphasis on the embedded coherence between the monitoring stage - performed in a "Technical Center" in the context of a normalisation procedure - and the physical model parameters identification. In opposition to classical measurement operation which allow different experiments to decouple each parameter, the described method determines at once the whole set of parameters versus the whole set of available experimental data (inclusive identification). We then display a few procedure intrinsic coherence tests as well as the accuracy obtained on the determined parameters. One of the critical point of the procedure is the measurement error analysis, because of its importance not only for the resulting model accuracy, but as an essential information for a proper use of the experimental data in the identification procedure itself.
Résumé. - Une étude de cas concernant la caractérisation en régime dynamique d'un composant solaire de b�timent nous a permis d'aborder le problème général que soulève l'identification d'un modèle physique, non linéaire, à nombre élevé de paramètres libres (ici dix). Le point de vue retenu est que le modèle à construire et à déterminer a trois objectifs couplés : apporter au concepteur une compréhension suffisante du fonctionnement du composant afin de guider ses tentatives d'améliorations, autoriser son intégration dans un système plus vaste (modèle de b�timent et d'organes de commande) afin d'éprouver ses performances en situation réelle, et enfin guider le choix de séquences expérimentales pour répondre aux mieux aux deux objectifs précédents (cohérence globale). On décrit la méthode, sa mise en oeuvre, et on donne les résultats obtenus en mettant en évidence la cohérence explicite qui est établie entre la phase expérimentale - effectuée dans un contexte de normalisation par un centre technique - et la détermination proprement dite des grandeurs physiques du modèle. Contrairement aux méthodes classiques de mesure pour lesquelles on peut concevoir des expériences découplant chacun des paramètres, la procédure choisie identifie d'un coup l'ensemble des paramètres libres sur l'ensemble des données expérimentales (identification inclusive). Un accent particulier est mis sur l'analyse des erreurs de mesure dont l'importance est manifeste, non seulement pour déterminer la précision du modèle obtenu, mais également pour utiliser correctement l'ensemble de l'information expérimentale pour la phase d'identification proprement dite.
Présentation d'une procédure expérimentale pour la caractérisation d'un composant en régime dynamique : application à un mur-capteur solaire à air
(Experimental procedure for dynamic characterisation of a thermal component. Example : wall-air solar collecter model identification)
Dufresne, J.L., Chounet L.M., Picard D., Gaillard P., Noppe J.M.,
Revue Générale de Thermique, Vol.29, No.339, pp. 135-151, mars 1990
Résumé. - Presentation d' une procedure experimentale d'identification des modeles permettant de caracteriser precisement en regime dynamique des composants physiquement complexes. Application a l'etude d' un mur-capteur solaire a air. Description de l'installation experimentale
Approche thermique, économique et architecturale de la réhabilitation des grands ensembles d'habitation ;
Chounet L.M., Dufresne, J.L., Franchisseur R., Lahellec, A., Rego-Texeira A.,
Revue Générale de Thermique, Vol.28, No.335-336, p. 700-711, nov-dec 1989
Résumé. - L'evaluation d'operations de rehabilitation requiert du point de vue energetique un diagnostic initial correct et un outil de prevision suffisamment fiable. Nous presentons cet ensemble methodologique sur le suivi d'une operation prototype de renovation d'une cite OPHLM de 593 logements de la region parisienne. Nous montrons qu'un code de calcul comme CALECO-DOE2, tres repandu est tout a fait adapte a ce type d'analyse. Une analyse de credibilite de l'ensemble de la demarche est resumee. Les conclusions portent sur les apports methodologiques de notre travail et leurs limites, ainsi que sur le developpement souhaitable des outils de modelisation

Back to homepage