Keplerian expansions in terms of Henrard's practical variables     

Sławomir Breiter  Gilles Metris 《Celestial Mechanics and Dynamical Astronomy》1994,58(3):237-244

Formulae for the Keplerian expansions in terms of Henrard's practical variables are given. Two different methods were applied: one using the Bessel functions and one based on the Lie transforms. The former involves less series products, but the latter is more flexible and universal.  相似文献   

Hydrological conditions over the western Mediterranean basin during the deposition of the cold Sapropel 6 (ca. 175 kyr BP)     

Edouard Bard  Gilles Delaygue  Frauke Rostek  Fabrizio AntonioliSergio Silenzi  Daniel P. Schrag 《Earth and Planetary Science Letters》2002,202(2):481-494

A new oxygen isotope record is reported from a stalagmite collected in the Argentarola Cave located on the Tyrrhenian coast of Italy. As shown from observations and numerical modeling of δ¹⁸O in modern precipitation, the recorded δ¹⁸O variability for this zone is dominated by the amount of precipitation (so-called ‘amount effect’). The δ¹⁸O profile measured in the stalagmite is characterized by a prominent negative excursion (ca. 2-3‰) between 180 and 170 kyr BP. This paleoclimatic feature is interpreted as being due to a relatively wet period which occurred during the penultimate glacial period, more precisely, during Marine Isotope Stage 6.5. This pluvial phase is shown to correspond chronologically to the deposition of the sapropel event 6 (S6). Although this particular sapropel event occurred during a cold phase, the δ¹⁸O excursion is similar to those corresponding to other sapropels (S4, S3 and S2). The evidence for humid conditions during S6 in the western Mediterranean basin agrees with previous studies based on deep-sea sediment cores. Taken collectively, the data suggest that during sapropel events dilution of ocean surface waters was not restricted to the output of the river Nile but was rather widespread over the entire Mediterranean Sea due to increased rainfall.  相似文献   

Datation Ar/Ar des leucogranites sous couverture du complexe plutonique de Charroux–Civray (Vienne)Ar/Ar dating of leucogranites in the sediment-covered Charroux–Civray complex (Vienne)     

Paul Alexandre  Christian Le Carlier de Veslud  Michel Cuney  Gilles Ruffet  Denis Virlogeux  Alain Cheilletz 《Comptes Rendus Geoscience》2002,334(16)

⁴⁰Ar/³⁹Ar dating on muscovites, performed on leucogranitic intrusions of Charroux–Civray plutonic complex, points out the existence of two peraluminous magmatic activities, whose equivalents are known in the Limousin: (1) garnet-bearing leucogranitic veins at ca. 340 Ma; (2) a specialised leucogranite associated with W ± Sn deposits at ca 310 Ma. However, available ⁴⁰Ar/³⁹Ar data do not allow us to provide further data concerning the age and the geometry at depth of a large leucogranitic body identified by geophysics. To cite this article: P. Alexandre et al., C. R. Geoscience 334 (2002) 1141–1148.  相似文献   

On the use of long-term observation of water level and temperature along the shore for a better understanding of the dynamics: example of Toulon area,France     

Rey  Vincent  Dufresne  Christiane  Fuda  Jean-Luc  Mallarino  Didier  Missamou  Tathy  Paugam  Caroline  Rougier  Gilles  Taupier-Letage  Isabelle 《Ocean Dynamics》2020,70(7):913-933

Ocean Dynamics - A dense network of instruments has been deployed within harbors along the Mediterranean coast, in the Toulon Metropole area, between the Hyères islands and the Sanary Bay in...  相似文献   

Total organic carbon fluxes of the Red River system (Vietnam)   总被引：1，自引：0，他引：1       下载免费PDF全文

Thi Phuong Quynh Le  Viet Nga Dao  Emma Rochelle‐Newall  Josette Garnier  XiXi Lu  Gilles Billen  Thi Thuy Duong  Cuong Tu Ho  Henri Etcheber  Thi Mai Huong Nguyen  Thi Bich Ngoc Nguyen  Bich Thuy Nguyen  Nhu Da Le  Quoc Long Pham 《地球表面变化过程与地形》2017,42(9):1329-1341

Riverine transport of organic carbon from terrestrial ecosystems to the oceans plays an important role in the global carbon cycle. The Red River is located in Southeast Asia where river discharge, sediment loads and fluxes of elements (carbon, nitrogen and phosphorus) associated with suspended solids have been dramatically altered over past decades as a result of reservoir impoundment and land use, population, and climate change. Dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations were measured monthly at four stations of the Red River system from January 2008 to December 2010. The results reveal that POC changed synchronically with total suspended solids (TSS) concentration and with the river discharge, whereas no clear trend was observed for DOC concentration. The mean value of total organic carbon (TOC = DOC + POC) flux in the delta of the Red River was 31.5 × 10¹³ ± 4.0 × 10¹³ MgC.yr^?1 (range 27.9–35.8 × 10¹³ MgC.yr^?1 which leads to a specific TOC flux of 2012 ± 255 kgC.km^?2.yr^?1 during this 2008–2010 period. About 80% of the TOC flux was transferred to the estuary during the rainy season as a consequence of the higher river water discharge. The high mean value of the POC:Chl‐a ratio (1585 ± 870 mgC.mgChl‐a^?1) and the moderate C:N ratio (7.3 ± 0.1) in the water column system suggest that organic carbon in the Red River system is mainly derived from erosion and soil leaching in the basin. The effect of two new dam impoundments in the Red River was also observable with lower TOC fluxes in 2010 compared with 2008. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Modélisation de propagation d’écoulement entre lits mineur et majeur sur les fleuves Sénégal et Niger     

Jean-Claude Bader  Gilles Belaud  Jean-Pierre Lamagat  Thibaud Ferret  Philippe Vauchel 《水文科学杂志》2017,62(3):447-466

In the Senegal River valley and Niger Inner Delta, the annual floods inundate a wide floodplain consisting of a complex network of lakes and channels, where topographic information needed by standard hydraulic models is difficult to obtain. To represent the flood propagation between mainstream and floodplain, we use a model designed for flood propagation in river mainstreams with flat bed and large overflow and without topographic data. Depending on the water level in the riverbed, the model calibrated on the levels observed at two stations gives the level in the floodplains and propagation time between stations. Several cases are tested for various types of hydraulic connections between mainstream and floodplain. The model could correctly reproduce the flood rise and fall in the floodplain, even for a lake connected by a single channel to the riverbed or in the case of a strong attenuation of the flood between very distant stations.  相似文献   

War landform mapping and classification on the Verdun battlefield (France) using airborne LiDAR and multivariate analysis     

Rémi de Matos-Machado  Jean-Pierre Toumazet  Jean-Claude Bergès  Jean-Paul Amat  Gilles Arnaud-Fassetta  François Bétard  Clélia Bilodeau  Joseph P. Hupy  Stéphanie Jacquemot 《地球表面变化过程与地形》2019,44(7):1430-1448

Acting as efficient earth-movers, soldiers can be viewed as significant geomorphological drivers of landscape change when replaced in the recent debates on Anthropocene Geomorphology. ‘Polemoforms’, generated by military activities, correspond with a set of human-made landforms of various sizes and geometries. They are particularly common on the World War One battlefield of Verdun (France) which ranks among the largest battles of attrition along the Western Front. The artillery bombardments and building of defensive positions in that battle significantly altered the landscape, resulting in thousands of shell craters, dugouts, and gun positions that have altered both the meso and microtopography. This paper proposes an innovative methodology to make an exhaustive inventory of these small-scale conflict-induced landforms (excluding linear features such as trenches) using a digital terrain model (DTM) acquired by airborne LiDAR on the whole battlefield. Morphometric analysis was conducted using Kohonen's self-organizing maps (SOMs) and hierarchical agglomerative clustering (HAC) in order to quantify and classify the high number of war landforms. This combined approach allowed for mapping more than one million landforms which can be classified into eight different shapes including shell craters and various soldier-made landforms (i.e. shelters, gun positions, etc.). Detection quality evaluation using field observations revealed the algorithm successfully classified 93% of shell craters and 74% of anthropologically constructed landforms. Finally, the iconographic database and map series produced will help archaeologists and foresters to better manage the historic site of Verdun, today covered by a large forest of ~10 000 ha. © 2019 John Wiley & Sons, Ltd.  相似文献   

Performance of the LandSoil expert-based model to map erosion and sedimentation: application to a cultivated catchment in central Belgium     

Vincent Cantreul  Nathalie Pineux  Gilles Swerts  Charles Bielders  Aurore Degré 《地球表面变化过程与地形》2020,45(6):1376-1391

Intensive agricultural practices on sensitive soils induce high erosion rates in central Belgium. Expert-rules models quantify runoff and erosion at catchment scale, avoiding over-parameterization, and can include some direct or indirect connectivity features. The aim of this article is to test the ability of an expert-based model, LandSoil, to quantify runoff and to locate erosion and sedimentation areas in a small cultivated loamy catchment in Belgium during the years 2014, 2015 and 2016. Spatialized data are important for assessing model outputs and the erosive response. Measurements of runoff and observation of spatial erosion/deposition patterns, especially around major connectivity points, permitted an assessment of the reliability of the model results. Runoff modelling gave contrasting results (good linear adjustment at the outlet of the 83 ha sub-catchment (point 1): r² of 0.96, Nash–Sutcliffe criterion of 0.95; less good at the outlet of the 3.9 ha sub-catchment (point 2): r² of 0.28, Nash–Sutcliffe criterion of –0.47). For point 2 the poor results are explained by the very few runoff events observed, a scaling effect and the small area with a single land use. Graduated rulers demonstrate that the model is able to provide a coherent pattern of erosion/deposition. The study highlights great sensitivity to the effect of land use, land allocation, landscape design and slope gradients. Grass strips induce deposition of eroded particles when slopes are gentle (< 2%). Woodland strips decrease connectivity by being in the stream but deposit thinner sediment layers. Field boundaries have a role in the transport, but not really the quantity, of sediments. This model validation in the Belgian loess context allows us to use LandSoil in other similar environments in order to estimate the effects of landscape management scenarios. © 2020 John Wiley & Sons, Ltd.  相似文献   

C and O isotope stratigraphy in shallow-marine carbonate: a tool for sequence stratigraphy (example from the Lodève region,peritethian domain)     

Youri Hamon  Gilles Merzeraud 《Swiss Journal of Geoscience》2007,100(1):71-84

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Textural evolution of polyhedral olivine experiencing rapid cooling rates     

François Faure  Pierre Schiano  Gilles Trolliard  Christian Nicollet  Bernard Soulestin 《Contributions to Mineralogy and Petrology》2007,153(4):405-416

Dynamic crystallization experiments in the CaO–MgO–Al₂O₃–SiO₂ (CMAS) system have been used to investigate the change in crystal shape when pre-existing polyhedral olivine crystals are cooled rapidly (1,639–2,182°C/h). Polyhedral olivines are crystallized initially in a first step using a slow cooling rate (2°C/h), then skeletal and dendritic overgrowths develop on the polyhedral crystals during a subsequent fast cooling event. During this second episode small dendritic olivines also nucleate within the liquid phase. Observation of the experimental sample by optical microscopy shows that the polyhedral olivine shape progressively changes to a skeletal and then to a dendritic morphology in the following sequence: polyhedral ⇒ hopper polyhedral ⇒ dendritic polyhedral. This evolutional sequence is discussed in terms of changes in the crystal growth conditions during cooling and a general relation between these olivine dynamic crystallization experiments and the integrated model of crystal growth by Sunagawa (Bull Minér 104:81–87, 1981, Morphology of crystals, Terra Scientific Publishing Company, 1987) is proposed.  相似文献