High-resolution modelling of a coastal harbour in the presence of strong tides and significant river runoff     

Paquin  Jean-Philippe  Lu  Youyu  Taylor  Stephanne  Blanken  Hauke  Marcotte  Guillaume  Hu  Xianmin  Zhai  Li  Higginson  Simon  Nudds  Shannon  Chanut  Jérôme  Smith  Gregory C.  Bernier  Natacha  Dupont  Frédéric 《Ocean Dynamics》2020,70(3):365-385

Ocean Dynamics - In the context of Canada’s Ocean Protection Plan (OPP), improved coastal and near-shore modelling is needed to enhance marine safety and emergency response capacity in the...  相似文献   

Using Training Images to Build Model Ensembles with Structural Variability          下载免费PDF全文

Guillaume Pirot 《Ground water》2017,55(5):656-659

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Analysis of collaboration networks in OpenStreetMap through weighted social multigraph mining     

Quy Thy Truong  Cyril de Runz  Guillaume Touya 《International journal of geographical information science》2019,33(8):1651-1682

This paper aims to qualify the behaviour of contributors to OpenStreetMap (OSM), a volunteered geographic information (VGI) project, through a multigraph approach. The main purpose is to reproduce contributor’s interactions in a more comprehensive way. First, we define a multigraph that combines existing spatial collaboration networks from the literature with new graphs that illustrate collaboration based on specific aspects of the VGI modes of contribution through semantics, geometry and topology. Indeed, the ways that contributors interact with one another through editing, completion, or even consumption may provide additional information on each user’s operation mode and therefore, on the quality of the contributed data. Social collaborations drawn from indirect criteria – for example, comparisons between contributors’ activity areas – can also be contemplated under another network. Second, the resulting multigraph is analysed using data mining approaches to characterise individuals and identify behavioural groups. The implementation of a multiplex network based on an OSM data sample and an initial analysis make it possible to identify useful behaviours for data qualification. The initial results characterise some contributors as pioneers, moderators and truthful contributors, according to their special roles in the graphs. Mapping elements that include these contributors’ participation are likely to be reliable data  相似文献   

Preferred orientation distribution of shock‐induced planar microstructures in quartz and feldspar     

Lidia Pittarello  Ludovic Ferrire  Jean‐Guillaume Feignon  Gordon R. Osinski  Christian Koeberl 《Meteoritics & planetary science》2020,55(5):1082-1092

Shocked quartz and feldspar grains commonly exhibit planar microstructures, such as planar fractures, planar deformation features, and possibly microtwins, which are considered to have formed by shock metamorphism. Their orientation and frequency are typically reported to be randomly distributed across a sample. The goal of this study is to investigate whether such microstructures are completely random within a given sample, or whether their orientation might also retain information on the direction of the local shock wave propagation. For this work, we selected samples of shatter cones, which were cut normal to the striated surface and the striation direction, from three impact structures (Keurusselkä, Finland, and Charlevoix and Manicouagan, Canada). These samples show different stages of pre‐impact tectonic deformation. Additionally, we investigated several shocked granite samples, selected at different depths along the drill core recovered during the joint IODP‐ICDP Chicxulub Expedition 364 (Mexico). In this case, thin sections were cut along two orthogonal directions, one parallel and one normal to the drill core axis. All the results refer to optical microscopy and universal‐stage analyses performed on petrographic thin sections. Our results show that such shock‐related microstructures do have a preferred orientation, but also that relating their orientation with the possible shock wave propagation is quite challenging and potentially impossible. This is largely due to the lack of dedicated experiments to provide a key to interpret the observed preferred orientation and to the lack of information on postimpact orientation modifications, especially in the case of the drill core samples.  相似文献   

Where do fishmeal and fish oil products come from? An analysis of the conversion ratios in the global fishmeal industry   总被引：1，自引：0，他引：1  

Guillaume Péron  Jean François Mittaine  Bertrand Le Gallic 《Marine Policy》2010

As a result of the stagnation of commercial fishery landings, aquaculture activities are expected to increase over the next decades to match the growing demand for marine protein. Overall, it is expected that the aquaculture sector could reduce some of the fishing pressure applied to wild stocks. However, this development is likely to be limited by the availability of key aquaculture inputs, specifically fishmeal and fish oil products (FMFOP). Aquaculture provided 60 % (fish meal) and 80 % (fish oil) of the world total consumption of these products in 2007. FMFOP are generally derived from small pelagic fish species, but can also be derived from other sources. Identifying the origin of FMFOP is crucial to understanding the effects of this new pressure on marine social-ecological systems. Two factors are of particular importance in the reduction sector transforming wild fish into fishmeal or fish oil: the two “conversion ratios” (i.e. the ratio between the quantity of wild fish harvested and the resulting quantity of FMFOP, and the ratio between the quantity of FMFOP and aquaculture production), and the type of raw material used by the reduction sector. Based on trade and production databases from FAO and the International Fishmeal and Fish oil Organisation (IFFO), this paper proposes an approach to identify the origin of FMFOP. It shows that whereas different countries use different pelagic resources to produce FMFOP, other countries use non-pelagic sources, and some countries use pelagic resources for human consumption.  相似文献   

High-precision Nd/Nd measurements in terrestrial rocks: Constraints on the early differentiation of the Earth’s mantle     

Guillaume Caro  Bernard Bourdon  Stephen Moorbath 《Geochimica et cosmochimica acta》2006,70(1):164-191

We present new ultra-high precision ¹⁴²Nd/¹⁴⁴Nd measurements of early Archaean rocks using the new generation thermal ionization mass spectrometer Triton. Repeated measurements of the Ames Nd standard demonstrate that the ¹⁴²Nd/¹⁴⁴Nd ratio can be determined with external precision of 2 ppm (2σ), allowing confident resolution of anomalies as small as 5 ppm. A major analytical improvement lies in the elimination of the double normalization procedure required to correct our former measurements from a secondary mass fractionation effect. Our new results indicate that metasediments, metabasalts, and orthogneisses from the 3.6 to 3.8 Ga West Greenland craton display positive ¹⁴²Nd anomalies ranging from 8 to 15 ppm. Using a simple two-stage model with an initial ε¹⁴³Nd value of 1.9 ± 0.6 ε-units, coupled ¹⁴⁷Sm-¹⁴³Nd and ¹⁴⁶Sm-¹⁴²Nd chronometry constrains mantle differentiation to 50-200 Ma after formation of the solar system. This chronological constraint is consistent with differentiation of the Earth’s mantle during the late stage of crystallization of a magma ocean. We have developed a two-box model describing ¹⁴²Nd and ¹⁴³Nd isotopic evolution of depleted mantle during the subsequent evolution of the crust-mantle system. Our results indicate that early terrestrial protocrust had a lifetime of ca. 0.7-1 Ga in order to produce the observed Nd isotope signature of Archaean rocks. In the context of this two box mantle-crust system, we model the evolution of isotopic and chemical heterogeneity of depleted mantle as a function of the mantle stirring time. Using the dispersion of ¹⁴²Nd/¹⁴⁴Nd and ¹⁴³Nd/¹⁴⁴Nd ratios observed in early Archaean rocks, we constrain the stirring time of early Earth’s mantle to 100-250 Ma, a factor of 5 shorter than the stirring time inferred from modern oceanic basalts.  相似文献   

Regularization of the two body problem with variable mass     

Pierre Guillaume 《Celestial Mechanics and Dynamical Astronomy》1974,10(2):141-149

Using Levi Civita's regularization, we put the two body problem with variable mass (x=?Mxr ^?3) into a form which can be solved analytically on computer. Two particular cases are discussed: 1. \(\dot M\) =C ^te ; 2. \(\dot M\) ÷M ^α (α unspecified).  相似文献   

Periodic symmetric solutions of the restricted problem     

P. Guillaume 《Celestial Mechanics and Dynamical Astronomy》1973,8(2):199-206

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Mesozoic–Cenozoic multistage tectonic evolution of the Pamir: Detrital fission-track constraints from the Tajik Basin     

Lin Li  Yani Najman  Guillaume Dupont-Nivet  Mauricio Parra  Pierrick Roperch  Mustafa Kaya  Niels Meijer  Paul O'Sullivan  Gilby Jepson  Jovid Aminov 《Basin Research》2023,35(2):530-550

Knowledge of the tectonic history of the Pamir contributes to our understanding of both the evolution of collisional orogenic belts as well as factors controlling Central Asian aridification. It is, however, not easy to decipher the Mesozoic–Cenozoic tectonics of the Pamir due to extensive Neogene deformation in an orogen that remains largely understudied. This study reports detrital apatite and zircon fission-track (FT) ages from both the eastern Tajik Basin sedimentary rocks and Pamir modern river sands. These FT data, supported by vitrinite reflectance and zircon and apatite U–Pb double dating, suggest that the majority of the FT ages are unreset and record exhumation stages of the Pamir, which has served as the source terrane of the Tajik Basin since the Cretaceous. Furthermore, we combine the new data with a compilation of published detrital apatite and zircon FT data from both the Tajik Basin sedimentary rocks and Pamir modern river sands, to explore the Mesozoic–Cenozoic tectonic history of Pamir. Deconvolved FT Peak Ages document two major Mesozoic exhumation events associated with the Late Triassic–Early Jurassic Cimmerian orogeny that reflects accretion of the Pamir terranes, as well as the Early–early Late Cretaceous deformation associated with the northward subduction of the Neo-Tethys Ocean beneath Pamir. The compiled data also show significant Late Eocene–Neogene exhumation associated with the ongoing formation of the Pamir, which peaks at ca. 36, 25, 14 and 7 Ma.  相似文献   

Decadal prediction skill in the GEOS-5 forecast system     

Yoo-Geun Ham  Michele M. Rienecker  Max J. Suarez  Yury Vikhliaev  Bin Zhao  Jelena Marshak  Guillaume Vernieres  Siegfried D. Schubert 《Climate Dynamics》2014,42(1-2):1-20

A suite of decadal predictions has been conducted with the NASA Global Modeling and Assimilation Office’s (GMAO’s) GEOS-5 Atmosphere–Ocean general circulation model. The hind casts are initialized every December 1st from 1959 to 2010, following the CMIP5 experimental protocol for decadal predictions. The initial conditions are from a multi-variate ensemble optimal interpolation ocean and sea-ice reanalysis, and from GMAO’s atmospheric reanalysis, the modern-era retrospective analysis for research and applications. The mean forecast skill of a three-member-ensemble is compared to that of an experiment without initialization but also forced with observed greenhouse gases. The results show that initialization increases the forecast skill of North Atlantic sea surface temperature compared to the uninitialized runs, with the increase in skill maintained for almost a decade over the subtropical and mid-latitude Atlantic. On the other hand, the initialization reduces the skill in predicting the warming trend over some regions outside the Atlantic. The annual-mean atlantic meridional overturning circulation index, which is defined here as the maximum of the zonally-integrated overturning stream function at mid-latitude, is predictable up to a 4-year lead time, consistent with the predictable signal in upper ocean heat content over the North Atlantic. While the 6- to 9-year forecast skill measured by mean squared skill score shows 50 % improvement in the upper ocean heat content over the subtropical and mid-latitude Atlantic, prediction skill is relatively low in the subpolar gyre. This low skill is due in part to features in the spatial pattern of the dominant simulated decadal mode in upper ocean heat content over this region that differ from observations. An analysis of the large-scale temperature budget shows that this is the result of a model bias, implying that realistic simulation of the climatological fields is crucial for skillful decadal forecasts.  相似文献