A perturbation method for problems with two critical arguments     

Jacques Henrard  Anne Lemaitre 《Celestial Mechanics and Dynamical Astronomy》1986,39(3):213-238

We develop a semi-numerical perturbation method for problems with two critical arguments. We apply it to a truncated model of the restricted, elliptic three body problem in case of a resonance 2/1 We identify regions of the phase space where chaotic motion is expected because of the presence of homoclinic orbits. One of these regions, the largest one, sits at the entrance to the resonance zone and is associated with a 2/1 resonance between the two critical arguments. The results are compared with numerical results due to Murray (1986)  相似文献   

On the velocity of jets powering hot spots similar to those in Cygnus A     

Guy Pelletier  Jacques Roland 《Astrophysics and Space Science》1984,100(1-2):351-357

Hot spots similar to those in the radio galaxy Cygnus A can be explained by the strong shock produced by a supersonic but classical jet \(\left( {u_{jet}< c/\sqrt 3 } \right)\) . The high integrated radio luminosity (L?2×10⁴⁴ erg s^?1) and the strength of mean magnetic field (B?2×10^?4 G) suggest the hot spots are the downstream flow of a very strong shock which generates the ultrarelativistic electrons of energy ?≥20 MeV. The fully-developed subsonic turbulence amplifies the magnetic field of the jet up to 1.6×10^?4 G by the dynamo effect. If we assume that the post-shock pressure is dominated by relativistic particles, the ratio between the magnetic energy density to the energy density in relativistic particles is found to be ?2×10^?2, showing that the generally accepted hypothesis of equipartition is not valid for hot spots. The current analysis allows the determination of physical parameters inside hot spots. It is found that:

1. The velocity of the upstream flow in the frame of reference of the shock isu ₁?0.2c. Radio observations indicate that the velocity of separation of hot spots isu _sep?0.05c, so that the velocity of the jet isu _jet=u ₁+u _sep?0.25c.
2. The density of the thermal electrons inside the hot spot isn ₂?5×10^?3 e ^? cm^?3 and the mass ejected per year to power the hot spot is ?4M ₀yr^?1.
3. The relativistic electron density is less than 20% of the thermal electron density inside the hot spot and the spectrum is a power law which continues to energies as low as 30 MeV.
4. The energy density of relativistic protons is lower than the energy density of relativistic electrons unlike the situation for cosmic rays in the Galaxy.

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Mn-oxide: a major source of easily mobilisable Co and Ni under reducing conditions in New Caledonia FerralsolsLes oxydes de Mn : une source majeure de Co et Ni facilement mobilisables en conditions réductrices dans les Ferralsols de Nouvelle-Calédonie     

Cécile Quantin  Thierry Becquer  Jacques Berthelin 《Comptes Rendus Geoscience》2002,334(4):273-278

Chemical and bacterial reduction and dissolution of Fe and Mn-oxide and the concomitant solubilisation of Co and Ni were studied in a surface horizon of a New-Caledonia Ferralsol. Chemical extractions showed that Mn and Co were in a large part associated in Mn-oxides. The main part of Ni was associated with goethite, but a very small fraction was also associated with Mn-oxides. Anaerobic reducing bacterial activity was responsible for Fe solubilisation at a smaller extent than for Mn solubilisation and consequently for associated metal release. Submicroscopic investigations revealed the presence of a Mn-oxide containing Co, Ni and Al, close to a lithiophorite–asbolane mixed-layers Mn-oxide, which can be considered as a main source of easily available metals in this soil. To cite this article: C. Quantin et al., C. R. Geoscience 334 (2002) 273–278.  相似文献   

Premières mesures françaises de gravimétrie absolue dans les régions polaires Antarctique (terre Adélie) et Arctique (Spitzberg)First French measurements of absolute gravity in the Antarctic (Terre Adélie) and Arctic (Spitsbergen) polar regions     

Jacques Hinderer  Martine Amalvict  Bernard Luck 《Comptes Rendus Geoscience》2002,334(11):819-826

This study is devoted to the first French determinations of absolute gravity in the Antarctic (Dumont-d'Urville, Terre Adélie) and Arctic (Ny-Alesund, Spitsbergen) polar regions. The measurements in Dumont-d'Urville were performed in 2000 with the help of the FG5#206 absolute gravimeter belonging to the French geodetic community since beginning 1997; they show a strong noise that causes an uncertainty close to 11 μGal in the determination of the mean gravity value, which will be compared, to a new determination planned for 2005. The Ny-Alesund measurements show on the contrary a noise that, although very variable in time, leads to a gravity determination of better than 5 μGal. The comparison of our value with a previous one two years before suggests a gravity decrease of about 4 μGal which is related to the vertical uplift measured by Very Large Baseline Interferometry (VLBI) at the same site. However, the uncertainty does not allow discriminating between height-to-gravity conversion factors originating from different models. To cite this article: J. Hinderer et al., C. R. Geoscience 334 (2002) 819–826.  相似文献   

Les « Sables fauves », témoins de mouvements tectoniques dans le bassin d'Aquitaine au Miocène moyenThe ‘Sables fauves’, showing tectonic deformations in the Aquitaine Basin during Middle Miocene     

Philippe Gardère  Jacques Rey  Francis Duranthon 《Comptes Rendus Geoscience》2002,334(13):987-994

New data about the ‘Sables fauves’ clearly show two different kinds of organisations: stratigraphic superposition of Langhian and Serravallian units to the south and embankment of Serravallian sediments in Langhian deposits to the north. The result consists in two different palaeogeographic schemes. The Langhian Sea is widely extended, forming the ‘Lectoure Gulf’, whereas the Serravallian Sea is much more reduced, with valleys fillings to the north and a little gulf to the south. This involves a tectonic activity along a structure which orientation is N120°E (‘flexure de la Douze’) and a relative rising of the northern part, of about 30 m. To cite this article: P. Gardère et al., C. R. Geoscience 334 (2002) 987–994.  相似文献   

A Semi-Evolutive Partially Local Filter for Data Assimilation     

Ibrahim Hoteit  Dinh-Tuan Pham  Jacques Blum 《Marine pollution bulletin》2001,43(7-12):164-174

The singular evolutive extended Kalman (SEEK) filter has been proposed recently by Pham et al. (1997) for data assimilation into numerical oceanic models. This filter has been applied in different realistic ocean frameworks and has provided satisfactory results ( Pham et al., 1997; Verron et al., 1998). However, the SEEK filter remains expensive in real operational assimilation. To reduce cost and obtain a better representativity, we introduce the idea ‘local correction basis'. Such basis however cannot be made to evolve according to the model without destroying its locality property. Therefore we shall keep this basis fixed and we augment it by a few global basis vectors which evolve. The resulting semi-evolutive partially local filter is much less costly to implement than the SEEK filter and yet can yield better results. In the first application, validation twin experiments are conducted in a realistic setting of the OPA model over the tropical Pacific Ocean.  相似文献   

新疆北部古生代大陆增生构造   总被引：35，自引：2，他引：35  

舒良树  卢华复  印栋浩  马瑞士  夏飞  卢汉 《新疆地质》2001,19(1):59-63

古生代亚洲中部是一幅两陆夹一洋、洋中多地体的构造图案，大地构造框架与现代西南太平洋格局十分相似。中亚造山带是晚古生代复杂地体的拼贴带。新疆北部古生代存在4类成因的8个地体构造。它们以裂解陆块地层块体、海山和火山弧的形式散布在中蒙大洋中，诸地体间是一系列的小洋盆。晚古生代，这些地体开始彼此拼贴并导致强烈推覆作用。石炭纪末－二叠纪初，中蒙大洋闭合，散布其中的诸地体分别增生到塔里木大陆北缘和西伯利亚大陆南缘。北天山－准噶尔地区6条蛇绿岩带记录了诸地体间碰撞事件。  相似文献   

Biomotoring groundwater contamination: Application to a karst area in Southern France   总被引：1，自引：0，他引：1  

Florian Malard  Jacques Mathieu  Jean-Louis Reygrobellet  Michel Lafont 《Aquatic Sciences - Research Across Boundaries》1996,58(2):158-187

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Lower cretaceous basalt and sediments from the Kerguelen Plateau     

Lucien Leclaire  Yannis Bassias  Micheline Denis-Clocchiatti  Hugh Davies  Isabelle Gautier  Bernard Gensous  Pierre-Jean Giannesini  Philippe Patriat  Jacques Segoufin  Michel Tesson  Jacques Wannesson 《Geo-Marine Letters》1987,7(4):169-176

Geological samples from the southern Kerguelen Plateau include Lower Cretaceous basalt and lava breccia, probable Lower Cretaceous conglomerate and shelf limestone, Upper Cretaceous chert with dolomite, Upper Cretaceous-Eocene ooze, and Tertiary conglomerate. Neogene sediments are only a few hundred m thick, and include foraminiferal and diatomaceous ooze, and ice-rafted debris. In conjunction with seismic reflection profiles, the samples indicate Early Cretaceous near-shore volcanism, followed by erosion, sedimentation, and subsidence through Cretaceous; arching of the plateau at the end of Cretaceous; subsidence through Paleogene; widespread emergence in mid-Tertiary; and slow subsidence through Neogene.  相似文献   

Setting biological reference points for Atlantic salmon stocks: transfer of information from data-rich to sparse-data situations by Bayesian hierarchical modelling     

Prevost  Etienne; Parent  Eric; Crozier  Walter; Davidson  Ian; Dumas  Jacques; Gudbergsson  Gudni; Hindar  Kjetil; McGinnity  Phil; MacLean  Julian; Saettem  Leif M 《ICES Journal of Marine Science》2003,60(6):1177-1193

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