Academic literature on the topic 'Echelle globale'
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Journal articles on the topic "Echelle globale"
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Chambon, O., F. Poncet, J. Cottraux, L. Kiss, and D. Milani. "Echelle d’évaluation de la symptomatologie négative (SANS) échelle de déficit ou échelle de ralentissement? Une étude chez le déprimé." Psychiatry and Psychobiology 4, no. 3 (1989): 159–62. http://dx.doi.org/10.1017/s0767399x00001589.
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RésuméA l’examen des items de l’échelle de ralentissement dépressif (ERD) de Widlocher et de ceux de l’échelle d’évaluation de la symptomatologie négative d’Andreasen (SANS), il apparaît une communauté symptomatologique entre syndrome déficitaire et ralentissement dépressif, ce qui a amené les auteurs á faire l’hypothése suivante: la note globale de la SANS peut être une mesure du ralentissement dépressif. Effectuée sur une population de 33 patients diagnostiqués épisode dépressif majeur, DSM III, cette étude a permis de montrer que la note globale de la SANS était corrélée a l’intensité du syndrome dépressif et que cette corrélation se faisait préférentiellement avec la composante ralentissement du syndrome dépressif (mesuré par l’ERD et par les items de l’échelle de mélancolie de Bech et Rafaelsen). Par ailleurs, la note globale de l’ERD était plus fortement corrélée a la SANS qu’aux autres échelles de dépression utilisées dans cette étude (échelle de dépression d’Hamilton á 26 items, échelle de dépression de Montgomery-Asberg). La note globale de la SANS pourrait donc être considerée comme une mesure du ralentissement dépressif.
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Encrenaz, T., C. DeWitt, M. J. Richter, T. K. Greathouse, T. Fouchet, F. Montmessin, F. Lefèvre, et al. "New measurements of D/H on Mars using EXES aboard SOFIA." Astronomy & Astrophysics 612 (April 2018): A112. http://dx.doi.org/10.1051/0004-6361/201732367.
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The global D/H ratio on Mars is an important measurement for understanding the past history of water on Mars; locally, through condensation and sublimation processes, it is a possible tracer of the sources and sinks of water vapor on Mars. Measuring D/H as a function of longitude, latitude and season is necessary for determining the present averaged value of D/H on Mars. Following an earlier measurement in April 2014, we used the Echelon Cross Echelle Spectrograph (EXES) instrument on board the Stratospheric Observatory for Infrared Astronomy (SOFIA) facility to map D/H on Mars on two occasions, on March 24, 2016 (Ls = 127°), and January 24, 2017 (Ls = 304°), by measuring simultaneously the abundances of H2O and HDO in the 1383–1391 cm−1 range (7.2 μm). The D/H disk-integrated values are 4.0 (+0.8, −0.6) × Vienna Standard Mean Ocean Water (VSMOW) and 4.5 (+0.7, −0.6) × VSMOW, respectively, in agreement with our earlier result. The main result of this study is that there is no evidence of strong local variations in the D/H ratio nor for seasonal variations in the global D/H ratio between northern summer and southern summer.
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Wang, Yuming, Youshan Qu, Hui Zhao, and Xuewu Fan. "Construction, Spectral Modeling, Parameter Inversion-Based Calibration, and Application of an Echelle Spectrometer." Sensors 23, no. 14 (July 24, 2023): 6630. http://dx.doi.org/10.3390/s23146630.
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We have developed a compact, asymmetric three-channel echelle spectrometer with remarkable high-spectral resolution capabilities. In order to achieve the desired spectral resolution, we initially establish a theoretical spectral model based on the two-dimensional coordinates of spot positions corresponding to each wavelength. Next, we present an innovative and refined method for precisely calibrating echelle spectrometers through parameter inversion. Our analysis delves into the complexities of the nonlinear two-dimensional echelle spectrogram. We employ a variety of optimization techniques, such as grid exploration, simulated annealing, genetic algorithms, and genetic simulated annealing (GSA) algorithms, to accurately invert spectrogram parameters. Our proposed GSA algorithm synergistically integrates the strengths of global and local searches, thereby enhancing calibration accuracy. Compared to the conventional grid exploration method, GSA reduces the error function by 22.8%, convergence time by 2.16 times, and calibration accuracy by 7.05 times. Experimental validation involves calibrating a low-pressure mercury lamp, resulting in an average spectral accuracy error of 0.0257 nm after performing crucial parameter inversion. Furthermore, the echelle spectrometer undergoes a laser-induced breakdown spectroscopy experiment, demonstrating exceptional spectral resolution and sub-10 ns time-resolved capability. Overall, our research offers a comprehensive and efficient solution for constructing, modeling, calibrating, and applying echelle spectrometers, significantly enhancing calibration accuracy and efficiency. This work contributes to the advancement of spectrometry and opens up new possibilities for high-resolution spectral analysis across various research and industry domains.
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Faccani, C., F. Rabier, N. Fourrié, A. Agusti-Panareda, F. Karbou, P. Moll, J. P. Lafore, M. Nuret, F. Hdidou, and O. Bock. "The Impacts of AMMA Radiosonde Data on the French Global Assimilation and Forecast System." Weather and Forecasting 24, no. 5 (October 1, 2009): 1268–86. http://dx.doi.org/10.1175/2009waf2222237.1.
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Abstract The high vertical density soundings recorded during the 2006 African Monsoon Multidisciplinary Analysis (AMMA) campaign are assimilated into the French numerical weather prediction Action de Recherche Petite Echelle Grande Echelle (ARPEGE) four-dimensional variational data assimilation (4DVAR) system, with and without a bias correction for relative humidity. Four different experiments are carried out to assess the impacts of the added observations. The analyses and forecasts from these different scenarios are evaluated over western Africa. For the full experiment using all data together with a bias correction, the humidity analysis is in better agreement with surface observations and independent GPS observations than it was for the other experiments. AMMA data also improve the African easterly jet (AEJ) on its southeasterly side, and when they are used with an appropriate bias correction, the daily and monthly averaged precipitation results are in relatively good agreement with the satellite-based precipitation estimates. Forecast scores are computed with respect to surface observations, radiosondes, and analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF). The positive impacts of additional radiosonde observations (with a relevant bias correction) are found to propagate downstream with a positive impact over Europe at the 2–3-day forecast range.
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Pereira, Margarida Belo, and Loïk Berre. "The Use of an Ensemble Approach to Study the Background Error Covariances in a Global NWP Model." Monthly Weather Review 134, no. 9 (September 1, 2006): 2466–89. http://dx.doi.org/10.1175/mwr3189.1.
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Abstract The estimation of the background error statistics is a key issue for data assimilation. Their time average is estimated here using an analysis ensemble method. The experiments are performed with the nonstretched version of the Action de Recherche Petite Echelle Grande Echelle global model, in a perfect-model context. The global (spatially averaged) correlation functions are sharper in the ensemble method than in the so-called National Meteorological Center (NMC) method. This is shown to be closely related to the differences in the analysis step representation. The local (spatially varying) variances appear to reflect some effects of the data density and of the atmospheric variability. The resulting geographical contrasts are found to be partly different from those that are visible in the operational variances and in the NMC method. An economical estimate is also introduced to calculate and compare the local correlation length scales. This allows for the diagnosis of some existing heterogeneities and anisotropies. This information can also be useful for the modeling of heterogeneous covariances based, for example, on wavelets. The implementation of the global covariances and of the local variances, which are provided by the ensemble method, appears moreover to have a positive impact on the forecast quality.
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Sabbi, Elena, Linda J. Smith, Lynn R. Carlson, Antonella Nota, Monca Tosi, Michele Cignoni, Jay S. Gallagher, Marco Sirianni, and Margaret Meixner. "Young Star Clusters in the Small Magellanic Cloud: Impact of Local and Global Conditions on Star Formation." Proceedings of the International Astronomical Union 4, S255 (June 2008): 157–61. http://dx.doi.org/10.1017/s1743921308024745.
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AbstractWe compared deep images acquired with the Advanced Camera for Surveys on board of the Hubble Space Telescope with mid-IR Spitzer Space Telescope images and University College London Echelle Spectrograph spectra of NGC 346 and NGC 602, two of the youngest star clusters in the Small Magellanic Cloud. Our multi-wavelength approach allowed us to infer very different origins for the clusters: while NGC 346 is likely the result of the hierarchical collapse of a giant molecular cloud, NGC 602 is probably the result of the collision and consequent interaction of two H I shells of gas.
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Arbogast, Philippe, Karine Maynard, and Catherine Piriou. "About the Reliability of Manual Model PV Corrections to Improve Forecasts." Weather and Forecasting 27, no. 6 (December 1, 2012): 1554–67. http://dx.doi.org/10.1175/waf-d-11-00110.1.
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Abstract The National Weather Forecast Centre of Météo-France has developed a tool that corrects the state of the atmosphere within the Action de Recherche Petite Echelle Grande Echelle (ARPEGE) operational global model by adjusting the potential vorticity when the initial conditions and available observations disagree. Among observational datasets, geostationary satellite data are the primary source of information. Here, the representation of the coherent structures of the tropopause in the model is assessed with Meteosat ozone and water vapor images. Modifications to the initial conditions of the potential vorticity (PV) in areas where the model fails can be applied using a potential vorticity inversion, thus providing a new balanced distribution of the wind and temperature that will then be used as a new initial state. The purpose of the paper is to investigate the degrees of weakness of the present qualitative approach. To this end, PV modifications to the initial conditions are applied by different experts on the eve of the windstorm Klaus (24 January 2009) that hit southwestern France. The different initial PV fields and the subsequent forecasts show significant differences in terms of wind and mean sea level pressure, while sharing some common features. The human modification process is therefore partially reproducible and skillful since the forecast is improved most of the time.
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Encrenaz, T., T. K. Greathouse, S. Aoki, F. Daerden, M. Giuranna, F. Forget, F. Lefèvre, et al. "Ground-based infrared mapping of H2O2 on Mars near opposition." Astronomy & Astrophysics 627 (July 2019): A60. http://dx.doi.org/10.1051/0004-6361/201935300.
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We pursued our ground-based seasonal monitoring of hydrogen peroxide on Mars using thermal imaging spectroscopy, with two observations of the planet near opposition, in May 2016 (solar longitude Ls = 148.5°, diameter = 17 arcsec) and July 2018 (Ls = 209°, diameter = 23 arcsec). Data were recorded in the 1232–1242 cm−1 range (8.1 μm) with the Texas Echelon Cross Echelle Spectrograph (TEXES) mounted at the 3 m Infrared Telescope Facility (IRTF) at the Mauna Kea Observatories. As in the case of our previous analyses, maps of H2O2 were obtained using line depth ratios of weak transitions of H2O2 divided by a weak CO2 line. The H2O2 map of April 2016 shows a strong dichotomy between the northern and southern hemispheres, with a mean volume mixing ratio of 45 ppbv on the north side and less than 10 ppbv on the south side; this dichotomy was expected by the photochemical models developed in the LMD Mars Global Climate Model (LMD-MGCM) and with the recently developed Global Environmental Multiscale (GEM) model. The second measurement (July 2018) was taken in the middle of the MY 34 global dust storm. H2O2 was not detected with a disk-integrated 2σ upper limit of 10 ppbv, while both the LMD-MGCM and the LEM models predicted a value above 20 ppbv (also observed by TEXES in 2003) in the absence of dust storm. This depletion is probably the result of the high dust content in the atmosphere at the time of our observations, which led to a decrease in the water vapor column density, as observed by the PFS during the global dust storm. GCM simulations using the GEM model show that the H2O depletion leads to a drop in H2O2, due to the lack of HO2 radicals. Our result brings a new constraint on the photochemistry of H2O2 in the presence of a high dust content. In parallel, we reprocessed the whole TEXES dataset of H2O2 measurements using the latest version of the GEISA database (GEISA 2015). We recently found that there is a significant difference in the H2O2 line strengths between the 2003 and 2015 versions of GEISA. Therefore, all H2O2 volume mixing ratios up to 2014 from TEXES measurements must be reduced by a factor of 1.75. As a consequence, in four cases (Ls around 80°, 100°, 150°, and 209°) the H2O2 abundances show contradictory values between different Martian years. At Ls = 209° the cause seems to be the increased dust content associated with the global dust storm. The inter-annual variability in the three other cases remains unexplained at this time.
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Farouk, Imane, Nadia Fourrié, and Vincent Guidard. "Homogeneity criteria from AVHRR information within IASI pixels in a numerical weather prediction context." Atmospheric Measurement Techniques 12, no. 6 (June 3, 2019): 3001–17. http://dx.doi.org/10.5194/amt-12-3001-2019.
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Abstract. This article focuses on the selection of satellite infrared IASI (Infrared Atmospheric Sounding Interferometer) observations in the global numerical weather prediction (NWP) system ARPEGE (Action de Recherche Petite Echelle Grande Echelle). The observation simulation is performed with the sophisticated radiative transfer model RTTOV-CLD, which takes into account the cloud scattering and the multilayer clouds from atmospheric profiles and cloud microphysical profiles (liquid water content, ice content and cloud fraction). The aim of this work is to select homogeneous scenes by using the information of the collocated Advanced Very High Resolution Radiometer (AVHRR) pixels inside each IASI field of view and to retain the most favourable cases for the assimilation of IASI infrared radiances. Two methods to select homogeneous scenes using homogeneity criteria already proposed in the literature were adapted: the criteria derived from Martinet et al. (2013) for cloudy sky selection in the French mesoscale model AROME (Applications of Research to Operations at MEsoscale) and the criteria from Eresmaa (2014) for clear-sky selection in the global model IFS (Integrated Forecasting System). A comparison between these methods reveals considerable differences, in both the method to compute the criteria and the statistical results. From this comparison a revised method representing a kind of compromise between the different tested methods is proposed and it uses the two infrared AVHRR channels to define the homogeneity criteria in the brightness temperature space. This revised method has a positive impact on the observation minus the simulation statistics, while retaining 36 % of observations for the assimilation. It was then tested in the NWP system ARPEGE for the clear-sky assimilation. These criteria were added to the current data selection based on the McNally and Watts (2003) cloud detection scheme. It appears that the impact on analyses and forecasts is rather neutral.
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Zhang, Jing, and John E. Walsh. "Thermodynamic and Hydrological Impacts of Increasing Greenness in Northern High Latitudes." Journal of Hydrometeorology 7, no. 5 (October 1, 2006): 1147–63. http://dx.doi.org/10.1175/jhm535.1.
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Abstract Satellite remote sensing data indicate that greenness has been increasing in the northern high latitudes, apparently in response to the warming of recent decades. To identify feedbacks of this land-cover change to the atmosphere, the authors employed the atmospheric general circulation model ARPEGE-CLIMAT, an adaptation of the Action de Recherche Petite Echelle Grande Echelle model for climate studies, to conduct a set of control and sensitivity modeling experiments. In the sensitivity experiments, they increased the greenness poleward of 60°N by 20% to mimic the manifestation of vegetation changes in the real world, and by 60% and 100% to represent potential aggressive vegetation change scenarios under global warming. In view of the direct exposure of vegetation to sunlight during the warm seasons, the authors focused their study on the results from late spring to early fall. The results revealed significant thermodynamic and hydrological impacts of the increased greenness in northern high latitudes, resulting in a warmer and wetter atmosphere. Surface and lower-tropospheric air temperature showed a marked increase, with a warming of 1°–2°C during much of the year when greenness is increased by 100%. Precipitation and evaporation also showed a notable increase of 10% during the summer. Snow cover decreased throughout the year, with a maximum reduction in the spring and early summer. The above changes are attributable to the following physical mechanisms: 1) increased net surface solar radiation due to a decreased surface albedo and enhanced snow–albedo feedback as a result of increased greenness; 2) intensified vegetative transpiration by the additional plant cover; and 3) reduced atmospheric stability leading to enhanced convective activity. The results imply that increased greenness is a potentially significant contributing factor to the amplified polar effects of global warming.
Dissertations / Theses on the topic "Echelle globale"
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Guinaldo, Thibault. "Paramétrisation de la dynamique lacustre dans un modèle de surface couplé pour une application à la prévision hydrologique à l’échelle globale." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0125.
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L'hydrologie continentale s'intéresse à tous les aspects du cycle de l'eau des terres émergées et représente les flux de masse d'eau qui sont échangées. Que ce soit dans le sous-sol, au sein des lacs ou dans le brassage continu des torrents, l'eau et les processus hydrologiques associés entretiennent un lien direct avec la dynamique atmosphérique et la variabilité climatique. La représentation, à l'échelle globale, de ces processus hydrologiques s'appuie sur des techniques de modélisation qui, au CNRM, passent par un système couplé composé du modèle de surface ISBA et du modèle de routage en rivière CTRIP. Ces dernières années, les progrès réalisés sur les paramétrisations existantes et la représentation des nouveaux processus dans ISBA comme dans CTRIP ont abouti à une nette amélioration des performances de ce système pour des applications hydrologiques régionales ou globales couplées avec un modèle de climat. Dans la continuité de ces efforts, l'objectif principal de cette thèse est de développer une paramétrisation dynamique des lacs pour intégrer leur bilan de masse dans le modèle global CTRIP à 1/12°. Par ailleurs, le modèle développé, MLake, propose un diagnostic sur le marnage des lacs afin de permettre le suivi du niveau d'eau basé sur des mesures satellitaires. Bénéficiant d'un réseau de mesures dense et de forçages climatiques à haute résolution, le bassin versant du Rhône a été choisi pour évaluer localement MLake sur la période 1960-2016. Les résultats sur trois stations de jaugeages montrent une progression nette des performances de CTRIP dans la simulation des débits du Rhône aboutissant à un lissage des hydrographes qui se caractérise par un écrêtement des débits de crues et un soutien à l'étiage. Par ailleurs, la confrontation du diagnostic sur les niveaux d'eau du Léman avec des mesures locales révèle une capacité du modèle à suivre les cycle annuels et inter-annuels du marnage. Une deuxième évaluation s'est ensuite portée à l'échelle globale pour confirmer le comportement du modèle dans des conditions hydroclimatiques contrastées. Cette évaluation confirme la capacité du modèle à simuler des débits réalistes mais révèle la perturbation importante du cycle hydrologique naturel par l'anthropisation. Enfin les résultats préliminaires d'une simulation globale démontre l'intérêt d'utiliser MLake avec une amélioration systématique des scores dans les zones de grande densité lacustre. Ainsi, 45% des stations évaluées, principalement dans les régions arctiques, présentent une amélioration des scores statistiques. Enfin, cette étude engage une réflexion sur les perspectives d'améliorations du modèle, notamment la mise en place d'une bathymétrie de lac à l'échelle globale, en vue d'un couplage avec un modèle de climat et de l'utilisation des données de la future mission spatiale SWOTThe water cycle encompasses the main processes related to mass fluxes that influence the atmosphere and climate variability. More specifically, continental hydrology refers to the water transfer occurring at the land surface and sub-surface. Modelling is one of the main methods used for the representation of these processes at regional to global scales. The land surface model system used in this thesis is composed of the ISBA land surface model coupled to the river routing model TRIP that combines the CNRM’s latest developments for use in stand-alone hydrological applications or coupled to a climate model. This PhD is focused on the development and evaluation of lake mass-balance dynamics and water level diagnostics using a new non-calibrated model called MLake which has been incorporated into the 1/12° version of the CTRIP model. Simulated river flows forced by high resolution hydrometeorological forcings are evaluated for the Rhone river basin against in situ observations coming from three river gauges over the period 1960-2016. Results reveal the positive contribution of MLake in simulating Rhone discharge and in representing the lake buffer effects on peak discharge. Moreover, the evaluation of the simulated and observed water level variations show the ability of MLake to reproduce the natural seasonal and interannual cycles. Based on the same framework, a final evaluation was conducted in order to assess the value of the non-calibrated MLake model for global hydrological applications. The results confirmed the capability of the model to simulate realistic river discharges worldwide. At 45% of the river gauge stations, which are mostly located within regions of high lake density, the new model resulted in improved simulated river discharge. The results also highlighted the strong effect of anthropization on the alterations of river dynamics, and the need for a global representation of human-impacted flows in the model. This study has lead to several future perspectives, such as the incorporation of a parametrization of lake hypsometry for use at global scale. The implementation of such developments will improve the representation of vertical water dynamics and facilitate both the coupling of MLake within the CNRM earth system model framework and the future spatial mission SWOT for improved future global hydrological and water resource projections
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Soccodato, Alice. "Planktonic biodiversity hotspots in the open ocean : detection, drivers and implications at the global scale." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066549/document.
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Les patterns de biodiversité et les mécanismes qui les maintiennent ont toujours intéressé les biologistes et ont été abordés en considérant des facteurs géologiques, évolutifs et écologiques. Les processus écologiques qui déterminent la co-occurrence des espèces diffèrent en fonction de l'environnement physique de l'écosystème. De nombreuses théories ont proposé des relations entre les tendances observées dans la diversité des espèces et les caractéristiques physiques de l’environnement à grande échelle. Dans les milieux terrestres et aquatiques, l’impact de la température sur la distribution de la biodiversité compte parmi les facteurs les plus influentes et étudiés. Toutefois, de nombreux taxa marins représentent des exceptions à cette influence primaire de la température, alors qu'une fraction dominante des espèces marines est planctonique ou à larves dispersibles. La dispersion par le transport physique a certainement un impact majeur sur les patterns d'abondance des espèces dans l’environnement marin. Certains courants océaniques peuvent en effet contraindre la distribution des stades planctoniques de certaines espèces, même lorsque les paramètres démographiques et physiologiques des espèces sont insensibles aux propriétés de l'eau. Les mécanismes de transport peuvent donc influencer la distribution de la diversité à toutes les échelles, de l’individu aux populations jusqu’aux espèces. Contrairement aux écosystèmes terrestres, les écosystèmes en milieu marin sont sujets à une variabilité dont les échelles spatiales et temporelles sont dictées par les processus du transport physique turbulent. Cet aspect complique l’obtention d’informations synoptiques sur la distribution des espèces marines au niveau global et à haute résolution, alors que cette vision globale est essentielle pour pouvoir comprendre les patterns de biodiversité et les mécanismes impliqués dans leurs variations. En outre, les hotspots de biodiversité sont d’importance primaire pour les efforts de conservation. Les objectifs de cet étude sont les suivants: identifier les hotspots de biodiversité pélagique des producteurs primaires à l'échelle globale et à haute résolution; déterminer les processus physiques de l'océan qui contrôlent la dynamique spatio-temporelle des hotspots, en se focalisant sur les mécanismes de transport, de dispersion, advection et mélange; étudier l'influence de ces mécanismes de structuration de la biodiversité sur les niveaux trophiques supérieurs.Pour obtenir ces résultats, les informations sur les parcelles d’eaux aux caractéristiques biophysiques cohérentes (‘niches fluido-dynamiques’) obtenues par satellite sont utilisées pour identifier les hotspots de biodiversité microbienne comme région de forte variabilité spatiale de ces niches. Ces hotspots et le rôle du transport dans leur structuration sont étudiés par l'analyse des modèles écologiques et biophysiques de circulation globale (Modèle ECCO2-Darwin) et par l’examen de données moléculaires et morphologiques sur la structure de la communauté in-situ collectées par l'expédition Tara Oceans et Atlantic Meridional Transect. Les possibles effets ‘bottom-up’ de la diversité des producteurs primaires sur les niveaux supérieurs de la chaine trophique sont évalués par comparaison avec des modèles globaux qui intègrent des bases de données in situPatterns of biodiversity and the mechanisms that maintain them have always interested biologists and have been addressed considering geological, evolutionary and ecological factors. Ecological processes that determine the co-occurrence of species differ according to the physical environment of the ecosystem. Many theories have proposed relationships between patterns in species diversity and large-scale physical features. In terrestrial and aquatic environments, the impact of temperature on the distribution of biodiversity is among the most influent and studied factors. However, many marine taxa are exceptions in the primary influence of temperature, since a large fraction of marine species is planktonic or with dispersible larvae. In the marine environment, dispersal through physical transport has a major impact on patterns of species abundance. Some ocean currents can indeed determine the distribution of planktonic stages of some species, even when demographic and physiological features of the species are unaffected by water properties. Transport mechanisms may therefore influence the distribution of diversity at all scales, from the individual to populations and species. Contrarily to the terrestrial environment, marine ecosystems are characterized by a variability that has spatial and temporal scales defined by specific biophysical processes of turbulent transport. This aspect makes it challenging to provide synoptic information on the distribution of marine species at the global level and at high resolution, features that are essential to understand patterns of biodiversity and the mechanisms involved in their changes. Moreover, hotspots of biodiversity are of primary concerns for conservation efforts. The objectives of this study are therefore: to identify biodiversity hotspots of pelagic primary producers on a global scale and at high resolution; to determine the physical ocean processes that control the spatial and temporal dynamics of such hotspots, focusing on transport-driven mechanisms like dispersion, advection and mixing; study the role of these mechanisms in the structuring of biodiversity at higher trophic levels.To obtain these results, information on water masses with coherent biophysical characteristics ('fluid-dynamical niches') obtained by remote sensing are used to identify hotspots of microbial biodiversity as regions of strong spatial patchiness. These hotspots and the role of transport in shaping their structure are studied by analysing ecological and biophysical global circulation models (Model-ECCO2 Darwin), together with molecular and morphological data on the structure of the community, obtained using in-situ data collected during the Tara-Oceans expedition and Atlantic Meridional Transect. The possible bottom-up effects of the diversity of primary producers on the upper levels of the food chain are evaluated by comparing them with global models integrated with data collected in situ.The ecological models coupled with ocean circulation, identified as biodiversity hotspots of primary producers the most dynamic areas of the global ocean characterized by increased turbulence, mixing and the presence of vortices. These oceanographic features can improve local productivity by transporting nutrients in the photic zone and increase biodiversity by the mixing of species typical of different water masses. In addition, maps of microbial biodiversity suggest a bottom up propagation of biodiversity across the ecosystem, hotspots for primary producers being positively correlated with regions where highest number of top predator species are observed
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Gibelin, Anne-Laure. "Cycle du carbone dans un modèle de surface continentale : modélisation, validation et mise en oeuvre à l'échelle globale." Phd thesis, Université Paul Sabatier - Toulouse III, 2007. http://tel.archives-ouvertes.fr/tel-00164054.
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ISBA-A-gs est une option du modèle de surface continentale du CNRM, ISBA, qui simule les échanges de carbone entre la biosphère terrestre et l'atmosphère. Au cours de cette thèse, le modèle est utilisé pour la première fois à l'échelle globale en mode forcé. Plusieurs simulations globales sont réalisées pour évaluer la sensibilité des flux turbulents et du LAI à un doublement de CO2 et au changement climatique prévu pour la fin du XXIe siècle.Une nouvelle option du modèle, nommée ISBA-CC, est aussi développée afin de simuler de manière plus réaliste la respiration de l'écosystème, en distinguant la respiration autotrophe et la respiration hétérotrophe.
La validation de la dynamique de la végétation et des flux de carbone échangés, à la fois à l'échelle globale à l'aide de données satellitaires, et à l'échelle locale sur 26 sites de mesure du réseau FLUXNET, montre que le modèle de surface est suffisamment réaliste pour être couplé à un modèle de circulation générale, afin de simuler les interactions entre la surface continentale, l'atmosphère et le cycle du carbone.
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Soccodato, Alice. "Planktonic biodiversity hotspots in the open ocean : detection, drivers and implications at the global scale." Electronic Thesis or Diss., Paris 6, 2014. http://www.theses.fr/2014PA066549.
Full textAbstract:
Les patterns de biodiversité et les mécanismes qui les maintiennent ont toujours intéressé les biologistes et ont été abordés en considérant des facteurs géologiques, évolutifs et écologiques. Les processus écologiques qui déterminent la co-occurrence des espèces diffèrent en fonction de l'environnement physique de l'écosystème. De nombreuses théories ont proposé des relations entre les tendances observées dans la diversité des espèces et les caractéristiques physiques de l’environnement à grande échelle. Dans les milieux terrestres et aquatiques, l’impact de la température sur la distribution de la biodiversité compte parmi les facteurs les plus influentes et étudiés. Toutefois, de nombreux taxa marins représentent des exceptions à cette influence primaire de la température, alors qu'une fraction dominante des espèces marines est planctonique ou à larves dispersibles. La dispersion par le transport physique a certainement un impact majeur sur les patterns d'abondance des espèces dans l’environnement marin. Certains courants océaniques peuvent en effet contraindre la distribution des stades planctoniques de certaines espèces, même lorsque les paramètres démographiques et physiologiques des espèces sont insensibles aux propriétés de l'eau. Les mécanismes de transport peuvent donc influencer la distribution de la diversité à toutes les échelles, de l’individu aux populations jusqu’aux espèces. Contrairement aux écosystèmes terrestres, les écosystèmes en milieu marin sont sujets à une variabilité dont les échelles spatiales et temporelles sont dictées par les processus du transport physique turbulent. Cet aspect complique l’obtention d’informations synoptiques sur la distribution des espèces marines au niveau global et à haute résolution, alors que cette vision globale est essentielle pour pouvoir comprendre les patterns de biodiversité et les mécanismes impliqués dans leurs variations. En outre, les hotspots de biodiversité sont d’importance primaire pour les efforts de conservation. Les objectifs de cet étude sont les suivants: identifier les hotspots de biodiversité pélagique des producteurs primaires à l'échelle globale et à haute résolution; déterminer les processus physiques de l'océan qui contrôlent la dynamique spatio-temporelle des hotspots, en se focalisant sur les mécanismes de transport, de dispersion, advection et mélange; étudier l'influence de ces mécanismes de structuration de la biodiversité sur les niveaux trophiques supérieurs.Pour obtenir ces résultats, les informations sur les parcelles d’eaux aux caractéristiques biophysiques cohérentes (‘niches fluido-dynamiques’) obtenues par satellite sont utilisées pour identifier les hotspots de biodiversité microbienne comme région de forte variabilité spatiale de ces niches. Ces hotspots et le rôle du transport dans leur structuration sont étudiés par l'analyse des modèles écologiques et biophysiques de circulation globale (Modèle ECCO2-Darwin) et par l’examen de données moléculaires et morphologiques sur la structure de la communauté in-situ collectées par l'expédition Tara Oceans et Atlantic Meridional Transect. Les possibles effets ‘bottom-up’ de la diversité des producteurs primaires sur les niveaux supérieurs de la chaine trophique sont évalués par comparaison avec des modèles globaux qui intègrent des bases de données in situPatterns of biodiversity and the mechanisms that maintain them have always interested biologists and have been addressed considering geological, evolutionary and ecological factors. Ecological processes that determine the co-occurrence of species differ according to the physical environment of the ecosystem. Many theories have proposed relationships between patterns in species diversity and large-scale physical features. In terrestrial and aquatic environments, the impact of temperature on the distribution of biodiversity is among the most influent and studied factors. However, many marine taxa are exceptions in the primary influence of temperature, since a large fraction of marine species is planktonic or with dispersible larvae. In the marine environment, dispersal through physical transport has a major impact on patterns of species abundance. Some ocean currents can indeed determine the distribution of planktonic stages of some species, even when demographic and physiological features of the species are unaffected by water properties. Transport mechanisms may therefore influence the distribution of diversity at all scales, from the individual to populations and species. Contrarily to the terrestrial environment, marine ecosystems are characterized by a variability that has spatial and temporal scales defined by specific biophysical processes of turbulent transport. This aspect makes it challenging to provide synoptic information on the distribution of marine species at the global level and at high resolution, features that are essential to understand patterns of biodiversity and the mechanisms involved in their changes. Moreover, hotspots of biodiversity are of primary concerns for conservation efforts. The objectives of this study are therefore: to identify biodiversity hotspots of pelagic primary producers on a global scale and at high resolution; to determine the physical ocean processes that control the spatial and temporal dynamics of such hotspots, focusing on transport-driven mechanisms like dispersion, advection and mixing; study the role of these mechanisms in the structuring of biodiversity at higher trophic levels.To obtain these results, information on water masses with coherent biophysical characteristics ('fluid-dynamical niches') obtained by remote sensing are used to identify hotspots of microbial biodiversity as regions of strong spatial patchiness. These hotspots and the role of transport in shaping their structure are studied by analysing ecological and biophysical global circulation models (Model-ECCO2 Darwin), together with molecular and morphological data on the structure of the community, obtained using in-situ data collected during the Tara-Oceans expedition and Atlantic Meridional Transect. The possible bottom-up effects of the diversity of primary producers on the upper levels of the food chain are evaluated by comparing them with global models integrated with data collected in situ.The ecological models coupled with ocean circulation, identified as biodiversity hotspots of primary producers the most dynamic areas of the global ocean characterized by increased turbulence, mixing and the presence of vortices. These oceanographic features can improve local productivity by transporting nutrients in the photic zone and increase biodiversity by the mixing of species typical of different water masses. In addition, maps of microbial biodiversity suggest a bottom up propagation of biodiversity across the ecosystem, hotspots for primary producers being positively correlated with regions where highest number of top predator species are observed
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Decharme, Bertrand. "Développement et validation d'une modélisation hydrologique globale incluant les effets sous maille et la représentation des zones inondées." Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00518491.
Full textAbstract:
La modélisation hydrologique globale du CNRM repose sur le modèle de surface ISBA qui calcule un bilan hydrique sur des mailles allant typiquement de 20 à 500 km de côté et sur le modèle de routage TRIP qui permet de convertir le ruissellement quotidien en débit. A ces résolutions, la répartition sous maille des caractéristiques de la surface et des flux atmosphériques a un fort impact sur les bilans d'eau simulés. Plusieurs paramétrisations des effets sous maille originales ou préexistantes ont alors été testées avec succès en mode forcé à l'échelle régionale et globale. Néanmoins, la validation globale reste parfois problématique en raison des incertitudes liées aux précipitations, aux paramètres de surface et à la modélisation de certains processus tel la représentation des zones inondées dans TRIP. Ceci souligne donc l'intérêt des futures missions satellitaires pour mieux contraindre nos modélisations hydrologiques.
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Dufour, Florence. "Méta-analyse des effets de l’environnement sur la dynamique des stocks de thonidés." Pau, 2010. http://www.theses.fr/2010PAUU3029.
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Il est probable que le changement climatique influence la distribution spatiale et temporelle des espèces de thonidés de par son impact sur les bas niveaux trophiques. L’objet de cette thèse est donc (1) de déterminer quelles sont les principales variables environnementales définissant l’habitat des thonidés, (2) de définir les gammes de préférence, tolérance et rejet pour ces mêmes variables et (3) d’étudier, à différentes échelles, l’effet de l’environnement sur la distribution spatiale et temporelle des thonidés et poissons à rostre de l’Atlantique. Des modèles additifs généralisés (GAM) ont donc été mis en place afin de déterminer quelles sont les variables environnementales définissant le mieux l’habitat des thonidés à l’échelle mondiale. Pour chacune des espèces le meilleur modèle incluait toutes les variables environnementales considérées : température, salinité, oxygène dissous, anomalie du niveau de la mer, profondeur de la couche de mélange et concentration en chlorophylle. Les GAMs ont révélé que la plupart des espèces sont principalement liées à la température de surface, l’oxygène et l’anomalie du niveau de la mer. L’analyse des quotients a par ailleurs été utilisée pour définir les gammes de préférence et rejet des thonidés pour les différentes variables environnementales. Les espèces tropicales préfèrent des eaux plus oxygénées, plus chaudes et moins productives que les espèces tempérées. La deuxième partie de cette thèse a permis de démontrer que la migration saisonnière du germon et du thon rouge vers le Golfe de Gascogne est plus précoce dans les années 2000 de respectivement 2 et 5,6 jours par décennie que lors des années 1960 et 1980. Ce changement phénologique est corrélé avec l’évolution de la température sur les mêmes périodes. De plus, la température, notamment la latitude de l’isotherme 17 °C, a également montré une corrélation avec la latitude de capture des germons dans les eaux adjacentes au Golfe de Gascogne. Celle-ci a également évolué de 2,5° vers le nord sur les 40 dernières années. On a enfin pu montrer que le changement de régime de l’Atlantique Nord à la fin des années 1980 a eu une influence sur la migration de ces deux espèces. Finalement, une synthèse de toutes les études locales concernant les thonidés et poissons à rostre de l’Atlantique Nord et Sud a été adressée par le biais d’une méta-analyse. Le résultat général indique que la distribution latitudinale de l’ensemble des espèces ne semble pas présenter de corrélation avec la température. Cependant, la corrélation générale est positive si on ne s’intéresse qu’à l’hémisphère Nord. Les latitudes de captures des différentes espèces présentent de plus fortes corrélations avec l’oscillation Nord Atlantique et l’oscillation du Sud qu’avec la température. Ces différents résultats laissent penser qu’à l’échelle locale la température pourrait être un facteur déterminant de la distribution des espèces tandis qu’une plus grande partie des processus physiques de l’océan doivent être pris en considération pour comprendre la dynamique spatiale des thonidés à l’échelle de l’océanClimate change may affect spatial and temporal distribution of tuna species due to its impact on lower trophic levels. Hence, the aims of this thesis are (1) to determine the main environmental variables that define tuna habitat (2) to define the ranges of preference, tolerance and avoidance for these variables and (3) to study, at different scales, the effect of environment on spatiotemporal distribution of tuna and billfish of the Atlantic. Generalized additive models (GAM) were carried out to determine the environmental variables defining global tuna habitat. For each species the best model included all environmental variables considered i. E. Temperature, salinity, dissolved oxygen, sea level anomaly, mixed layer depth and chlorophyll. GAMs revealed that for most species surface temperature, dissolved oxygen and sea level anomaly were variables explaining most of CPUE deviance. Besides, the quotient analysis was used to define tuna ranges of preference, tolerance and avoidance for different environmental variables. It appeared that tropical species prefer warmer, less productive, and more oxygenated waters than temperate species. The second part of this thesis revealed that albacore and bluefin tuna seasonal movements to the Bay of Biscay appeared earlier in the 2000s than in the 1960s and 1980s, respectively. The rate of change was 2 and 5. 6 days for decade, respectively. This change was correlated with phenological changes in temperature over the same periods. Moreover, the temperature, latitude of 17 °C isotherm in particular, also showed a correlation with albacore catch latitude in adjacent waters of the Bay of Biscay. It also moved 2. 5 ° northwards over the last 40 years. Lastly, we showed that the late 1980s regime shift of the North Atlantic had an influence on the migration of these two species. Finally, a synthesis of all local studies on tuna and billfish in North and South Atlantic was addressed in a meta-analytic framework. The overall result indicates that species distribution do not correlate with temperature. However, the overall correlation was positive in the northern hemisphere. Species catch latitude showed stronger correlations with the North Atlantic Oscillation and the Southern Oscillation than with temperature. These different results suggest that temperatures could be a factor determining species local distribution whereas some ocean physical processes should be considered in order to understand tuna spatial dynamics across oceans
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Das, Shouvik. "Multi echelon supply chain design for Amazon private brands." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/126953.
Full textAbstract:
Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020
Cataloged from the official PDF of thesis.
Includes bibliographical references (page 54).
Retailers across the globe continue to grow their private label portfolio to offer customers an alternative to existing brands. Typically, retailers source private label products directly from manufacturers to remove middlemen from the value chain, thereby capturing greater value and subsequently passing it on to customers. Combined with the growth of e-commerce as the primary method for consumers to shop for products, expanding private label portfolio has made e-retailers to re-think their supply chain. Amazon began its journey in Private-Label Brands (PB) in 2009 with the launch of Amazon Basics. Since then, it has expanded its presence across multiple categories. The majority of these products are imported from Asia-Pacific region (APAC) and require sourcing larger quantities to account for long-lead time between production runs and high variability in demand to maintain competitive costs.
These factors result in PB inventory dwelling for a long period at the Amazon Robotic Fulfilment Centers (FCs), reducing the turns-ratio of expensive storage bins there, which could otherwise be utilized for storing high-velocity products. The growth of PB products raises the need to build more storage space, which is expensive in highly automated robotic FCs. Additionally, since fixed storage cost is proportional to the space occupied in FCs, high 'dwell time' translates to high storage cost. To increase utilization of FC storage bins, the Inbound Supply Chain Team plans to build a low-cost upstream storage (LCS1) to supply the FCs and store excess PB inventory there. Alternatively, Amazon can also use its third party storage center in APAC, another low-cost storage node (LCS2), after sourcing PB products from manufacturers in Asia before shipping to regional markets in US, EU, Japan etc.
This could provide an opportunity for inventory savings from risk pooling by optimizing inventory storage across various nodes in the supply chain. Using multi-echelon inventory optimization techniques, this thesis explores the tradeoffs between using low-cost storage node close to end customers in the US (LCS1) versus that close to manufacturing source in APAC (LCS2). The objective of the thesis is to find the optimal inventory placement strategy across three storage points - FCs, LCS1 in US, and LCS2 in APAC - to achieve the best-in-class customer experience (InStock availability) at minimal inventory storage cost.
by Shouvik Das.
M.B.A.
S.M.
M.B.A. Massachusetts Institute of Technology, Sloan School of Management
S.M. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
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Polak, Benjamin M. (Benjamin Michael). "Multi-echelon inventory strategies for a retail replenishment business model." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90753.
Full textAbstract:
Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2014. In conjunction with the Leaders for Global Operations Program at MIT.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. In conjunction with the Leaders for Global Operations Program at MIT.
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Cataloged from PDF version of thesis.
Includes bibliographical references (page 69).
The mission of the Always Available retail replenishment business at NIKE is to ensure consumer-essential products are in-stock at retailers at all times. To achieve this goal, NIKE has developed a forecast-driven, make-to-stock supply chain model which allows retailers to place weekly orders to an on-hand inventory position in a distribution center. The challenge facing the business is how to design an inventory strategy that achieves a high level of service to its customers while minimizing inventory holding cost. Specifically, safety stock holding cost is targeted as it accounts for the majority of on-hand inventory and can be reduced without significantly impacting the underlying supply chain architecture. This thesis outlines the application of multi-echelon inventory optimization in a retail replenishment business model. This technique is used to determine where and how much safety stock should be staged throughout the supply chain in order to minimize safety stock holding cost for a fixed service level. Provided a static supply chain network, the ideal safety stock locations and quantities which result in minimal total safety stock holding cost is determined. For this business, the optimal solution is to stage lower-cost component materials with long supplier lead times and high commonality across multiple finished goods at the manufacturer in addition to finished goods at the distribution centers. Safety stock holding cost reduction from component staging increases significantly when the distance between manufacturers and the distribution center decreases and for those factories producing a variety of finished goods made from the same component materials due to inventory pooling. Forecast accuracy drives the quantity of safety stock in the network. The removal of low volume, highly unpredictable products from the portfolio yields significant inventory holding cost savings without a detrimental impact to revenue. By deploying the optimal safety stock staging solution and by removing unpredictable products, this analysis shows that finish goods safety stock inventory would be reduced by 35% for the modeling period (calendar year 2012) while only decreasing topline revenue by 5%.
by Benjamin M. Polak.
M.B.A.
S.M.
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Giacomantonio, Robert. "Multi-echelon inventory optimization in a rapid-response supply chain." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/80995.
Full textAbstract:
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division; in conjunction with the Leaders for Global Operations Program at MIT, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 91-92).
The motivation for multi-echelon supply chain management at Nike is to more cost-effectively accommodate customer-facing lead time reduction in the rapid-response replenishment business model. Multi-echelon inventory management, as opposed to a traditional finished-goods only philosophy, provides two clear benefits to a make-to-stock supply chain: first, it increases flexibility through staging calculated work-in-process inventory buffers at critical supply chain links and allowing postponed identification of finished goods; second, inventories held as work-in- process are typically carried at lower cost than finished goods. This thesis details the completion of a project intended to improve Nike's ability to determine optimal inventory levels by balancing cost and service level tradeoffs in a multi-echelon-enabled environment. The goal is to develop an inventory modeling methodology for Nike's supply chain data architecture specifically to evaluate the hypothesis that multi-echelon inventory management will present only limited opportunity for cost reduction in offshore, long lead time make-to-stock supply chains. To directly asses the hypothesis, Llamasoft's Supply Chain Guru optimization software will be deployed to create an inventory optimization model for a specific family of apparel products sold as part of Nike's replenishment offering in North America. The modeling results confirm the hypothesis that multi-echelon inventory management offers little value to the current offshore supply chain. Sensitivity and scenario analysis is utilized to identify significant inventory drivers, areas for substantial improvement, and profitable opportunities for multi-echelon inventory management.
by Robert Giacomantonio.
S.M.
M.B.A.
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Hayden, Arnita. "The Johnson and Johnson journey deploying SmartOps for multi-echelon inventory optimization." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90786.
Full textAbstract:
Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2014. In conjunction with the Leaders for Global Operations Program at MIT.Thesis: S.M., Massachusetts Institute of Technology, Engineering Systems Division, 2014. In conjunction with the Leaders for Global Operations Program at MIT.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 53).
Multi-echelon inventory technology enables firms to significantly reduce inventory costs. It gives managers the ability to make tradeoffs based on information from the entire supply chain, which results in a more powerful supply chain strategy and stronger competitive advantage. This thesis provides a case study exploring the deployment of SmartOps multi-echelon inventory optimization technology in Johnson and Johnson's Medical Devices and Diagnostics supply chain. The basis for this thesis is an internship project that focused on implementing SmartOps in the Transfusion Medicine and Mainframe Slides businesses within Ortho Clinical Diagnostics, a group within the Medical Devices and Diagnostics sector. Through a pilot program, this internship analyzed the level of complexity involved in deploying multi-echelon inventory optimization tools such as SmartOps. In addition, this internship identified key challenges associated with data quality, especially in decentralized supply chains. The results of this study show that while IT investment decisions are challenging, senior executives should strongly consider investing in multi-echelon inventory optimization software. Recommendations for implementation include automation, people development, and forecast data centralization.
by Arnita Hayden.
M.B.A.
S.M.
Books on the topic "Echelle globale"
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Chatter: Uncovering the Echelon Surveillance Network and the Secret World of Global Eavesdropping. Random House, Incorporated, 2006.
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Chatter: Uncovering the Echelon Surveillance Network and the Secret World of Global Eavesdropping. Random House Trade Paperbacks, 2006.
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Lennon, Tiffani. Recognizing Women’s Leadership. ABC-CLIO, LLC, 2014. http://dx.doi.org/10.5040/9798216005957.
Full textAbstract:
According to recent data on women leaders across all major sectors in the United States, women are outperforming men but earning less and still hitting the glass ceiling. This book uncovers the best practices to remedy these inequities, optimize performance, and benefit both genders. In compiling and analyzing 2011–2012 data on women leaders across all major sectors in the United States, author Tiffani Lennon, JD, uncovered proof that women are outperforming men–yet salaries and positional leadership roles are disproportionate to the performance and accomplishments of women in nearly all sectors. Recognizing Women's Leadership: Strategies and Best Practices for Employing Excellence presents a comprehensive look at agencies and organizations with the smallest pay gap and the largest percentage of female positional leaders to reveal best practices and strategies that ensure gender parity and optimal business performance, including impact, revenue, and efficacy. The study examined in this book included approximately 1,500 for-profit companies, not-for-profit businesses, and other organizations and associations throughout the country to establish the number of women leaders among the top echelon in each industry. Researchers also calculated leadership performance by identifying the frequency with which women received industry distinctions and awards, were top revenue generators, and achieved best-sellers list status, among other sector-specific criteria. The ramifications of the study's findings portend the future of the United States as a global competitor and as such need to be part of the public discourse surrounding the state of the American economy.
Book chapters on the topic "Echelle globale"
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Hammler, Patric, Nicolas Riesterer, Gang Mu, and Torsten Braun. "Multi-Echelon Inventory Optimization Using Deep Reinforcement Learning." In Quantitative Models in Life Science Business, 73–93. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11814-2_5.
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AbstractIn this chapter, we provide an overview of inventory management within the pharmaceutical industry and how to model and optimize it. Inventory management is a highly relevant topic, as it causes high costs such as holding, shortage, and reordering costs. Especially the event of a stock-out can cause damage that goes beyond monetary damage in the form of lost sales. To minimize those costs is the task of an optimized reorder policy. A reorder policy is optimal when it minimizes the accumulated cost in every situation. However, finding an optimal policy is not trivial. First, the problem is highly stochastic as we need to consider variable demands and lead times. Second, the supply chain consists of several warehouses incl. the factory, global distribution warehouses, and local affiliate warehouses, whereby the reorder policy of each warehouse has an impact on the optimal reorder policy of related warehouses. In this context, we discuss the concept of multi-echelon inventory optimization and a methodology that is capable of capturing both, the stochastic behavior of the environment and how it is impacted by the reorder policy: Markov decision processes (MDPs). On this basis, we introduce the concept, its related benefits and weaknesses of a methodology named Reinforcement Learning (RL). RL is capable of finding (near-) optimal (reorder) policies for MDPs. Furthermore, some simulation-based results and current research directions are presented.
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Fadoi, Elleuch. "The “Lateral Transshipment” is a Cooperative Tool for Optimizing the Profitability of a Distribution System." In Research and Development Enterprise [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101992.
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In this chapter, we discuss a network consisting of a distribution center (or central depot) and two retailers who serve customers. D1 andD2 represent, respectively, the demands of retailer 1 and 2. We assume that the demandDi (i = 1, 2) at retailer i follows a normal distribution with mean μi and standard deviationσi (known). This analysis makes it possible to assess the effect of emergency transshipment both at the level of the Average Global Profit and of the Average Global Desservice Rate. In this chapter, we consider a centralized one-echelon supply chain with two-retailers selling products and facing stochastic demand.
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Maphanyane, Joyce Gosata. "Parallel Development of Three Major Space Technology Systems and Human Side of Information Reference Services as an Essential Complementary Method." In Advances in Environmental Engineering and Green Technologies, 362–83. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7359-3.ch025.
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The first human footprints dated more than 1.9 million years ago; the Homo erectus era, “upright man,” marks the beginning of man's socio-economic historical development. It culminated in the Bronze Age, Iron Age, Industrial Revolution, and currently the Information Age. The current era has allowed rapid global communications and networking to shape modern society. Individuals are able to transfer information freely, with instant access to knowledge that would have been difficult or impossible previously. This chapter elaborates upon GIS/remote sensing: the highest echelon in ICT. It compares and contrasts the four globally used GIS systems of GOES, the Geosynchronous Orbiting Environmental Satellite; LANDSAT; SPOT, Satellite Pour l'Observation de la Terre; and the WorldView. Their temporal resolution, spatial resolution, spectral resolution, radiometric resolution, and their DEM characteristics are reviewed. The human side of information reference services in the form of TEK is alluded to.
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Maphanyane, Joyce Gosata. "Parallel Development of Three Major Space Technology Systems and Human Side of Information Reference Services as an Essential Complementary Method." In Encyclopedia of Information Science and Technology, Fourth Edition, 3484–502. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2255-3.ch303.
Full textAbstract:
The first human footprints dated more than 1, 9 million years ago; the Homo erectus Era; ‘upright man'; marks the beginning of man socio-economic-Historical Development. It culminated to Bronze Age, Iron Age, Industrial Revolution and currently Information Age. The current Era has allowed rapid global communications and networking to shape modern society. Individuals are able to transfer information freely, with instant access to knowledge that would have been difficult/ impossible previously. This chapter elaborates upon GIS/Remote Sensing; the highest echelon in ICT world. It compares and contrasts the four globally used GIS systems of GOES: the Geosynchronous Orbiting Environmental Satellite; LANDSAT, SPOT: Satellite Pour l'Observation de la Terre and the WorldView. Their temporal resolution; spatial resolution (Figure 6 – WorldView3); spectral resolution (Figure7 Landsat8); radiometric resolution (Figure8 WorldView3) and their DEM characteristics (Figure9 SPOT DEM) are reviewed. The human side of information reference services in the form of TEK is alluded to.
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"DAILY PLANNING FOR THREE-ECHELON LOGISTICS ASSOCIATED WITH INVENTORY MANAGEMENT UNDER DEMAND DEVIATION YOSH IAKI SH IMIZU." In Global Logistics Management, 24–53. CRC Press, 2014. http://dx.doi.org/10.1201/b17845-6.
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Achour, Zyed. "Board Gender Diversity and Firm Risk." In Corporate Governance - Recent Advances and Perspectives [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100189.
Full textAbstract:
In this chapter, we address the following question: Does board gender diversity affect global risk? Drawing on agency theory, upper echelon theory, and human capital theory, we hypothesize that gender diversity on the board of directors will decrease the volatility of firm risk. Applying fixed effect estimation on a panel data of listed French companies (SBF120) for the years 2011–2018, the results show a negative link between the percentage of female directors on the board and the standard deviation of monthly stock return as firm risk proxy suggesting that the inclusion of more women on corporate boards could improve financial stability. Our findings contribute to the literature by providing empirical evidence from France occupying the first place at the European level with the most female presence on the boards of directors.1
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Shaikh, Azharuddin Sarfuddin, and Poonam Prakash Mishra. "Optimal Policies for Items With Quadratic Demand and Time-Dependent Deterioration Under Two Echelon Trade Credits." In Handbook of Research on Promoting Business Process Improvement Through Inventory Control Techniques, 32–43. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3232-3.ch002.
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In today's competitive and global business scenario there is always a race to boost demand of your product over others. This can be achieved by different means and allowing permissible delay in payments is one of them. Researchers have proposed number of inventory models with trade credit that actually help to understand effect of trade credit on total profit and overall demand. This paper proposes a two – echelon trade credit where retailer receives credit period from the manufacturer and offer it to end customers appropriately to raise demand. Proposed inventory model assumes quadratic demand and subjected to time dependent deterioration. Ordering cost is considered lot – size dependent whereas holding cost has been taken time dependent. In this model profit is maximized considering cycle time as a decision variable. Sensitivity analysis of crucial inventory parameters and numeric examples are discussed in detail. Outcome of this model can be applied to a huge range of products like readymade garments, fashion accessories, electronics, furniture and home furnishing products.
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Dinç Aydemir, Sibel. "Unseen Link Between Sustainability Reporting and Financial Reporting." In Sustainability Reporting, Ethics, and Strategic Management Strategies for Modern Organizations, 42–62. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-4637-6.ch003.
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The accounting profession has intensely witnessed compelling challenges in the 21st century. Due to increased number in stakeholders and huge informational need, the traditional model has become unsatisfactory in meeting this need and evaluating company's future performance. Apparently, companies trying to survive in globally competitive markets couldn't attain this goal by focusing merely on financial outcomes. Thus, sustainability reporting has emerged as a vital non-financial information demanded by stakeholders. However, ethical insights on credibility and accountability of this information have been documented and discussed in the literature. Tapping into behavioral finance paradigm and upper echelon approach, this chapter exerts an effort to link financial reporting/audit quality to sustainability reporting and discusses those ethical issues on these processes. Further, while drawing attention to overconfidence bias in individuals involved in reporting and assurance stages, it suggests influential role of decision-makers' personal traits on these mechanisms in a misleading way.
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Lang, Rainhart, and Irma Rybnikova. "Corporate Social Responsibility Values in Transforming Societies." In Recent Advances in the Roles of Cultural and Personal Values in Organizational Behavior, 129–51. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1013-1.ch007.
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The focus of the chapter is on corporate social values of managers as one important basis, and explanation of the functioning of CSR concepts in CEE organizations. The analysis is based on theoretical concepts explaining the relationship between the national and institutional context, corporate values of managers, and CSR activities, like “upper echelon theory,” which consider managerial action as a direct or indirect expression of the individual values of top managers. The situation in transforming societies in CEE countries can be well-described using the concept of situational strength. The empirical findings, with data from the GLOBE-CEO project from 129 firms in East Germany, Estonia, and Romania, show specific country-based combinations of corporate social values in the companies studied, with strategic orientation in East Germany, shareholder focus and a relatively strong religious orientation in Romania, and an orientation on shareholders as well as on employees and community in Estonia.
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Lang, Rainhart, and Irma Rybnikova. "Corporate Social Responsibility Values in Transforming Societies." In Research Anthology on Developing Socially Responsible Businesses, 87–110. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-5590-6.ch006.
Full textAbstract:
The focus of the chapter is on corporate social values of managers as one important basis, and explanation of the functioning of CSR concepts in CEE organizations. The analysis is based on theoretical concepts explaining the relationship between the national and institutional context, corporate values of managers, and CSR activities, like “upper echelon theory,” which consider managerial action as a direct or indirect expression of the individual values of top managers. The situation in transforming societies in CEE countries can be well-described using the concept of situational strength. The empirical findings, with data from the GLOBE-CEO project from 129 firms in East Germany, Estonia, and Romania, show specific country-based combinations of corporate social values in the companies studied, with strategic orientation in East Germany, shareholder focus and a relatively strong religious orientation in Romania, and an orientation on shareholders as well as on employees and community in Estonia.
Conference papers on the topic "Echelle globale"
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Pagano, Robert, Paul Morse, and Chris Miller. "Design overview of the atmospheric IR sounder." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.thj3.
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The AIRS instrument, scheduled for launch in 1997, is designed to provide new and more accurate data about the atmosphere, land, and oceans for application to climate studies and weather prediction. Loral Infrared and Imaging Systems, Inc. (LIRIS) is currently under contract to the Jet Propulsion Laboratory (JPL) for the concept definition of the AIRS instrument. To meet the National Weather Service's temperature measurement goal, the next generation infrared sounder must have a spectral resolving power of 1200 over the spectral range 3.4–15.4 µm.1 AIRS employs two multiple-aperture echelle-array spectrometers, each using several grating orders to obtain the desired spectral resolution. Spectral-order separation is accomplished by subdividing the telescope entrance pupil into several apertures, each with its own out-of-band rejection filter. The radiation passing through these apertures is dispersed by the echelle grating before the apertures are reimaged onto a series 2 × n arrays. The focal plane arrays are made of photovoltaic and photoconductive mercury cadmium telluride. To maximize performance all spectrometer components are cooled to 155 K, and the arrays are cooled to 60 K. Systems modeling at LIRIS and JPL indicates that the instrument will achieve the 0.2 K noise-equivalent-delta-temperature goal over most of the spectral bandpass. AIRS will provide global coverage twice per day with a continuous downlink data rate of 1.85 Mbps. The design and development phase of the AIRS program will begin in October 1990.
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Mu, Yinping, Li Huang, and Haibin Wang. "Financial hedging in a three-echelon global supply chain in presence of spot market." In 2012 9th International Conference on Service Systems and Service Management (ICSSSM 2012). IEEE, 2012. http://dx.doi.org/10.1109/icsssm.2012.6252221.
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Gu, Liudong, Yifan Zhou, and Zhisheng Zhang. "Multi-echelon Inventory Optimization of Spare Parts considering Cross-region Transshipment and Changing Demand." In 2020 Global Reliability and Prognostics and Health Management (PHM-Shanghai). IEEE, 2020. http://dx.doi.org/10.1109/phm-shanghai49105.2020.9281010.
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Verma, Monika, Saket Gupta, Prof Madhusudan Singh, Mini Sreejeth, and Narendra Kumar. "Modified Mutation based Rao-3 Algorithm for Design Optimization of Surface Inset PMSM via Multi-Echelon Strategy." In 2023 IEEE IAS Global Conference on Emerging Technologies (GlobConET). IEEE, 2023. http://dx.doi.org/10.1109/globconet56651.2023.10149950.
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Rezapour, Shabnam, Janet K. Allen, and Farrokh Mistree. "Uncertainty Propagation in a Supply Chain / Network With Uncertain Facility Performance." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34255.
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Decentralized production systems in supply chains / networks makes them more profitable and agile than traditional enterprises with centralized production systems. However, this decentralization makes supply chains / networks more vulnerable respect to uncertainties which are unavoidable. Today’s supply chains / networks producing and supplying their products to markets are characterized by uncertain demands (called demand-side uncertainty) and uncertainties associated with the performances of their constituent production facilities (called supply-side uncertainty). Supply-side uncertainty is due to the fact that there is not any perfect production system. Sparse literature of supply-side uncertainty management in supply chains / networks is only restricted to supply chains / networks with single-echelon supply processes. However most of the real case supply chains / networks have longer production processes involving suppliers of suppliers, suppliers, component manufacturers, assemblers, etc. In this paper we fill this gap of the literature by considering a supply chain/network with multi-echelon supply process including unreliable production facilities working in markets with uncertain demands. We show that in such a complex production process in addition to investigating the local effects of the uncertainties in the performances of their corresponding facilities, it is necessary to consider their global and cumulative effect on the performance of the entire supply chain/networks by following the propagation of these uncertainties in the flow of the material and product. Not only we introduce and describe the salient features of uncertainty propagation phenomenon in supply chains/networks, but also we demonstrate its quantification approach. Finally we propose mathematical models and solution approaches that can provide robust production plans for the supply chain/network that are protected against all demand and supply side uncertainties and their propagated effects. Performances of the proposed models and solution approaches are tested with test problems and a real case problem from automotive industry.
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Williams, Jack, Reza Alizadeh, Janet K. Allen, and Farrokh Mistree. "Using Network Partitioning to Design a Green Supply Chain." In ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22644.
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Abstract In supply chain network design, a retailer may determine the number and locations of facilities based on the cost of opening the facility, a customer driving to the facility, and a replenishment truck driving to the facility from a warehouse. However, this does not include the system’s greenhouse gas (GHG) emissions. Given the existential threat posed by global warming, it is pertinent to consider how the design of the system affects its GHG emissions. We model the supply chain as a network of customers and store locations, with customers driving in cars to and from stores and the retailer resupplying the stores from a central warehouse. The number and location of stores is determined while minimizing the GHG emission. Our contributions are (1) to remove the assumption of uniform demand, and instead build a model of a GSC based on population data; (2) to model the GSC as a two-echelon k-median problem. We conduct a sensitivity analysis to study the effect of a carbon tax in encouraging a greener system considering various scenarios under which emissions might increase or decrease. Specific scenarios lead to a lower overall GHG emission. For example, doubling the fuel efficiency of cars decreases emissions by 46% compared to the baseline scenario. The proposed design approach is not limited to GSC design and can be extended to many design problems, including manufacturing, material design, and healthcare.
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Hajihashemi, Sara, Reza Alizadeh, Janet K. Allen, and Farrokh Mistree. "Impact of Asset Management in a Green Supply Chain." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-70826.
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Abstract With increasing concerns about global warming caused by greenhouse gasses (GHGs), organizations have become more responsible for their operations. According to the U.S. Environmental Protection Agency (EPA), companies with a supply chain (SC) generate about 42% of GHGs in their transportation (30%) and inventory systems (12%), which makes mitigating climate change through a green supply chain (GSC) management a reasonable solution. To design a GSC, we model the SC as a customer and store network, with customers driving in cars to and from stores and the retailer resupplying the stores from a central warehouse. The number and location of stores are determined to find a low-cost and low emission configuration for the SC. The key findings are (1) SCs with more small stores generate less emission than ones with fewer large stores; (2) when minimizing the operating cost is more important than mitigating GHG emissions, fewer large stores are preferred than having more small stores; (3) a SC with two warehouses reduces the number of open stores in a large area such as Puerto Rico. Our contributions are (1) building a model of a GSC based on population data; (2) modeling a GSC in a two-echelon network which can be solved simultaneously using the k-median approach; (3) evaluating the effect of multiple warehouses on the overall GHGs emissions; (4) managing the incompleteness and inaccuracy of the data through implementing the compromise Decision Support Problem construct to identify satisficing solutions. The model mentioned earlier highlights the important parameters that impact the green GHG emissions reduction from a SC that describe in this paper. We also discuss how this approach can be employed for other design problems, including manufacturing and healthcare.
Reports on the topic "Echelle globale"
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Zhytaryuk, Marian. Агресія росії проти України і світу. Рефлексії в контексті виправдання війни д. мєдвєдєвим та в. путіним 4 листопада 2022 р. Ivan Franko National University of Lviv, March 2023. http://dx.doi.org/10.30970/vjo.2023.52-53.11744.
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In this article the author analyzes in detail the “holiday” speeches by the former president of the russian federation dmitry medvedev and the current president vladimir putin devoted to the day of national unity of russia on November 4, 2022, in which politicians justify the war, call it sacred, a struggle between Good and Evil and predict their own victory. With the help of methods of critical analysis, the refutation of historical myths, the denial, an exposure and the generalization, the falsity and cynicism of the statements made regarding the expediency and possibility of geopolitical changes are demonstrated. The civilizational war of the russian federation against the Western democratic world, which began with aggression against the disobedience of neighboring Ukraine, which chose the Western vector of development, is gaining momentum. It would seem that in the 21st century global conflicts over territories are almost impossible, it is the time for the fourth-generation of war, but we can see that russia has various means in its arsenal, including weapons of mass destruction: aerial bombs, artillery, aviation, missile attacks, nuclear blackmail, rewriting history and ordinary lies. An analysis of the kremlin leaders’ military-strategic narratives about Ukraine and the West, shows the inadequacy and detachment of moscow politicians at the highest echelon of power from reality. Their aggressive and false rhetoric based on historical manipulations and maniacal efforts to transform the world order suggests that the kremlin will not stop on its own. Someone must stop him just decisively: either Ukraine or Ukraine’s allies. Sanction policy against the russian federation, political statements and words of support for Ukraine, even assistance with military equipment and finances may not be enough, because all these are certain procedures, a waste of time, and time today is the greatest value. Key words: Ukraine, russian federation, russian aggression, dmitry medvedev, vladimir putin, geopolitics.