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1.
Colette Edelman 《Celestial Mechanics and Dynamical Astronomy》1985,37(4):351-358
Dans un système d'axes fixes le problème gravitationnel des n. corps possède quatre groupes d'invariance (rectifications). Aucun de ces groupes ne peut échanger une solution non bornée et une solution bornée.Dans le cas du problème non circulaire et non rectilinéaire des deux corps, une transformation paramétrique peut-être définie, changeant seulement l'exentricité et l'horaire. Cette transformation est de type homographique et son expression anlytique dépend des valeurs de l'exentricité par rapport à l'unité. Par conséquent, une solution hyperbolique ou parabolique peut-être changée en une solution elliptique. Les applications et l'utilité d'une telle transformation concerne les captures des comètes. Finalement, une hypothétique extension est indiquée pour le problème des n. corps.
Invariant transformation of the two-body problem associated with eccentricity
In an absolute reference frame the gravitational n-body problem possesses four groups of invariant transformations (rectifications). But no one can change an unbounded solution into a bounded solution.For the non-circular two-body problem, having non-zero angular momentum a parametric transformation may be defined changing only the eccentricity and the time. This transformation is of homographic type, and it is an analytical expression depends on the value of the eccentricity with respect to unity. Therefore an hyperbolic or parabolic solution may be changed into an elliptic solution. The application and usefulness of this transformation is concerned with the capture of comets [5].Finally, an hypothetic extension is indicated to the n-body problem.相似文献
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Hadmoko Danang Sri de Belizal Edouard Mutaqin Bachtiar Wahyu Dipayana Gilang Arya Marfai Muh Aris Lavigne Franck Sartohadi Junun Worosuprojo Suratman Starheim Colette C. A. Gomez Christopher 《Natural Hazards》2018,94(1):419-444
Following the 2010 VEI 4 eruption of Merapi volcano, more than 250 lahars were triggered during two rainy seasons from October 2010 to March 2012. This high number of post-eruption lahars mainly occurred in the Kali (valley) Putih watershed and was mostly associated with high-magnitude rainstorms. A lahar occurring on January 8, 2011, caused significant damage to homes in several communities, bridges, sabo dams, and agricultural crops. The aims of this contribution are to document the impacts of lahars on the Kali Putih watershed and specifically (1) to analyze the lahar frequency during the period of 1969–2012 on an inter-annual and intra-annual basis and to determine the link between the volume of tephra and the frequency of lahars; (2) to detail the lahar trajectory and channel evolution following the January 8th lahar; (3) to map the spatial distribution of the thickness and geomorphic effects of the lahar deposit; and (4) to determine the impacts of the lahar on the infrastructure (sabo dams and roads) and settlements in the distal area of the volcano. The Kali Putih watershed has experienced 62 lahars, which represent 22% of all lahars triggered on 17 rivers at Merapi between 2010 and 2012. The main geomorphic impacts are: (1) excessive sedimentation in valleys, settlements and agricultural areas; (2) undercutting of the river banks by as much as 50 m, accompanied by channel widening; and (3) abrupt changes in the river channel direction in the distal area (15–20 km downstream of the volcano). About 19 sabo dams were damaged, and 3 were totally destroyed. Over 307 houses were damaged, and the National Road Yogyakarta–Semarang was regularly cut (18 times during approximately 25 days). Although the sabo dams on Kali Putih were originally constructed to protect distal areas from lahar damage, they had little effect on the 2010–2012 rain-triggered lahars. The underlying design of those dams along this river is one of the main reasons for the major destruction in this sector of the volcano’s lower slope. The catch basin capacity of the sabo dam was only 1.75?×?106 m3, whereas the total volume of the 2010–2011 lahars exceeded 5?×?106 m3. In order to prepare for future lahars, the government has invested in significant mitigation measures, ranging from structural approaches (e.g., building new sabo dams and developing an early warning system) to non-structural approaches (e.g., contingency and preparedness planning and hazard education).
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Colette Chassard-Bouchaud 《Marine pollution bulletin》1983,14(4):133-136
Uranium experimental intoxications were performed on the shore crab Carcinus maenas (L.) using either food (Mytilus edulis) or water pathway contamination. Cellular level investigations performed by secondary ion emission microanalysis show that gill and hindgut epithelia, and hepatopancreas (=digestive gland) R cells are the main sites of uranium concentration. Subcellular level investigations performed by electron probe X ray microanalysis show that intra- and extracellular spherocrystals (=calcium phosphate spherules) are the main target organelles which store uranium; moreover, uranium phosphate microgranules are detected within gill cuticle. A small fraction of the metal is accumulated via food in hepatopancreas spherocrystals, relative to that accumulated from sea water in gill and hindgut spherocrystals and in gill cuticle microgranules. The spherocrystals which are extruded out of the cells and the cuticle which is shed at the ecdysis appear to play a fundamental part in uranium detoxication processes. 相似文献
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Résumé L'étude des inclusions fluides des minéraux de fin de cristallisation (principalement fluorite et barytine) du filon de Chavaniac, montre une diminution de la température et de la salinité. La fluorite a commencé à se déposer vers 140°C±10°C dans une solution renfermant 20% en poids en équivalents NaCl. La température de formation de la barytine était de 40°C au plus et les solutions diluées renfermaient parfois en émulsion des hydrocarbures liquides. On a pu établir des relations entre succession paragénétique, phases de fracturation, et les résultats précédents.
Fluid inclusion studies in end-crystallisation minerals from Chavaniac mine (mainly fluorite and baryte) show that temperature and salinity fell during crystallisation. Crystallisation of fluorite began at around 140°C±10°C, in a solution containing about 20% NaCl. The temperature of formation of baryte never exceeded 40°C and the dilute solutions sometimes contained emulsified hydrocarbons. Relations have been established between paragenetic succession, fracture phases, and the above results.相似文献
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Mathieu Bringer Michel Boër Cedric Peignot Gérard Fontan Colette Mercé 《Experimental Astronomy》2001,12(1):33-48
We have developped a new method for the scheduling ofastronomical automatic telescopes, in the framework of theautonomous TAROT instrument. The MAJORDOME software canhandle a variety of observations, constrained, periodic,etc., and produces a timeline for the night, which may bemodified at any time to take into account the specificconditions of the night. The MAJORDOME can also handletarget of opportunity observations without delay. 相似文献
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Much has been written on the apparent urban renaissance in UK cities and the new lifestyle arrangements, working time patterns, economic activities and the more general reordering of work and life that appears to accompany it. Certainly, recent decades have witnessed a range of economic, social and cultural changes in the lives of those living and working in cities and surrounding suburbs. Much of the attention in this work has focused on those groups for whom the changes have appeared most profound: the high-income earners returning to live in the city - the gentrifiers - or those who suffer multiple deprivations as a result of economic restructuring. Seemingly absent from many accounts of urban change are those places where, at first glance, the effects of change have been less pronounced: low-income, working class neighbourhoods where most people continue to get by, albeit in the context of a harsher, and less secure political economic context. In light of this apparent silence, this paper draws on interviews from Wythenshawe in South Manchester, to examine how low-income mothers cope, live and labour, in a rapidly changing city, as they perform paid work at the same time as ensuring the social reproduction of the household. 相似文献
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Claudia Rossano Simone Gambineri Lucia Fanini Virginie Durier Colette Rivault Felicita Scapini 《Estuarine, Coastal and Shelf Science》2009
The aim of the present study was to test sun orientation and rhythmic activity of two sandhopper populations from two Atlantic macro-tidal beaches. A population from Le Verger beach (orientated to 346°, Ille et Vilaine, Brittany, France) and a population from Damgan (orientated to 195°, Morbihan, Brittany, France), were tested on the beach under clear sky discriminating for landscape vision. For both populations locomotor activity rhythm was recorded in the laboratory. The two beaches differed for climatic features, tidal range and for human use. Both talitrid populations resulted very well orientated toward the shoreline, and both used solar position and landscape vision to orient. However the multiple regression analysis of orientation with climatic features showed a different use of local cues by the two populations and a slight influence of tidal regime (ebbing and rising tide), in spite of the supralittoral zonation of sandhoppers. In the laboratory they showed a well defined rhythmic behaviour as well as a bimodal rhythmicity, explained as a tidal one. These results are a new brick in the complex picture of orientation and rhythm studies on sandy beach invertebrates. 相似文献
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Colette Edelman 《Celestial Mechanics and Dynamical Astronomy》1989,47(1):15-35
Résumé Cet article concerne deux familles de transformations échangeant deux solutions du pioblème des deux corps d'excentricité différente. (Rectifications). L'une d'elle a été décrite dans [5]. Elle peut associer deux orbites non bornée, et bornée, de moment angulaire non nul, régularisant ainsi l'infini. Elle est étendue, ici, au cas non circulaire. Définie pour des solutions non rectilignes, elle ne peut régulariser les collisions. Pour cela, une autre famille de rectifications, comportant une affinité orthogonale, est considerée. Elle peut régulariser la collision, mais pas l'infini. La composition de ces deux sortes de rectifications, dont l'expression analytique dépend des valeurs des excentricités par rapport a l'unité regularise les deux singularités. Certaines de ces transformations sont liées a l'intègrale de Laplace. Dans le cas de n corps, si elles existent, elles pourraient étre associées à un invariant integral d'ordre deux, par l'intermédiaire du plan invariable de Laplace.
Regularizing rectifications of the two-body problem
This paper is concerned with several rectifications (invariant transformations) involving two solutions of the two-body problem of any eccentricity. Such a transform, which can change an unbounded orbit into a bounded orbit has been described in [5]. Each having no zero angular momentum. This may be a regularization for infinity. Here, it is extended to the circular case. As it concerns only non rectilinear solution, it is not a regularization of the collision. For that purpose, another family of rectifications is considered. By involving an orthogonal affinity these transformations may regularise the collision but not infinity. By the product of these two sorts of rectifications, whose analytical expressions depend on the values of the eccentricities with respect to unity, in the two cases the problem becomes regular. Some of these transformations seem to be associated with the Laplace integral and for the n body problem, if they exist, perhaps with an integral invariant of order two, by way of the invariable plane of Laplace.相似文献
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Uncertainty analysis and probabilistic segmentation of electrical resistivity images: the 2D inverse problem 
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下载免费PDF全文 Juan Luis Fernández‐Martínez Shan Xu Colette Sirieix Zulima Fernández‐Muniz Joëlle Riss 《Geophysical Prospecting》2017,65(Z1):112-130
In this paper, we present the uncertainty analysis of the 2D electrical tomography inverse problem using model reduction and performing the sampling via an explorative member of the Particle Swarm Optimization family, called the Regressive‐Regressive Particle Swarm Optimization. The procedure begins with a local inversion to find a good resistivity model located in the nonlinear equivalence region of the set of plausible solutions. The dimension of this geophysical model is then reduced using spectral decomposition, and the uncertainty space is explored via Particle Swarm Optimization. Using this approach, we show that it is possible to sample the uncertainty space of the electrical tomography inverse problem. We illustrate this methodology with the application to a synthetic and a real dataset coming from a karstic geological set‐up. By computing the uncertainty of the inverse solution, it is possible to perform the segmentation of the resistivity images issued from inversion. This segmentation is based on the set of equivalent models that have been sampled, and makes it possible to answer geophysical questions in a probabilistic way, performing risk analysis. 相似文献