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Les études fondamentales réalisées sur les kérogènes à l'aide de diverses méthodes physico-chimiques d'analyse ont permis de mettre au point une méthode et un appareillage adaptés à l'exploration pétrolière. On expose dans cet article la mise au point de cette méthode et on montre, à l'aide des paramètres qu'elle permet d'obtenir, ses applications dans le domaine de l'exploration pétrolière - reconnaissance des différents types de roche mère et de leur potentiel pétrolier; - caractérisation de leur degré d'évolution (zone à huile - zone à gaz). On montre aussi que cette méthode convient particulièrement bien à l'estimation du rendement en huile des roches bitumineuses et à l'étude de la qualité et du rang des charbons.

The Rock-Eval 6 apparatus is the latest version of the Rock-Eval product line, commercialized since 1996 by Vinci Technologies. The present work describes the methodology developed at IFP for reliable data acquisition and endorses the quality of geochemical parameters acquired with Rock-Eval 6. Data were obtained on 147 source rocks from various sedimentary basins, of different organic matter types and maturity stages. Intrinsic correlations for two different Rock-Eval 6 apparatus were performed and the obtained data set shows an excellent consistency and good reproducibility conditions for the whole set of Rock-Eval parameters. Complete recovery of total carbon (TC) by Rock-Eval 6 was confirmed by comparison with elemental analysis. In order to check the carbon partition (mineral vs. organic) determined by Rock-Eval 6, measurements of mineral carbon (MinC) and total organic carbon (TOC) were performed by alternative techniques. TOC measured by Rock-Eval 6 was compared to that obtained either by: the Leco apparatus for bulk rocks; elemental analysis for kerogens; and calculation from the mass balance determined after destruction of mineral matrix and the carbon concentration determined by elemental analysis on recovered kerogens for bulk rocks. The results display a good correlation for the whole concentration range (0-90 wt% TOC), when comparing elemental analyses and Rock-Eval 6 for source rocks and kerogens. However, comparison of Rock-Eval 6 with Leco data leads to larger deviations while correlation factors are still good. For a subset of kerogen samples, preparative pyrolysis was performed in order to confirm the value of 83 wt% for the organic carbon of the total S2 peak for any rock with any organic type and to check the absolute value of the S2 peak by gas chromatography analysis of pyrolysis by-product. MinC measured with Rock-Eval 6 was compared to that determined by: weight loss after HCl treatment; the acidimetry technique; and calculation after TC, mass balance from kerogen isolation and organic carbon measurement on kerogen by elemental analysis. The results display a good correlation for the whole concentration range (0-12 wt% MinC), when comparing elemental analyses and Rock-Eval 6. However, comparison of Rock-Eval 6 with acidimetry data leads to larger deviations while correlation factors are still good while comparison with weight loss is poor. As a whole an excellent reliability of TOC and MinC obtained by Rock-Eval 6 was demonstrated, and consequently, it is now possible to get at once the total organic and mineral carbon mass balance for a given rock. Recommendations are proposed regarding the standard samples and analytical methods selected for calibrating the Rock-Eval 6 over a large mineral and organic carbon range. Consistency between S2 and Tmax measured by Rock-Eval 2 and Rock-Eval 6 for Types I and II bulk rocks was also checked. A good correlation was obtained for S2, even though S2 values are slightlyhigher when measured with Rock-Eval 2. It was demonstrated that this is due to carrier gas (nitrogen vs. helium) by running measurements with a Rock-Eval 6 under helium, the difference ranging from 5 to 10 relative wt% for most studied samples. For Tmax correlation, data are much more scattered and as a general trend Tmax obtained by Rock-Eval 6 are higher than Tmax obtained by Rock-Eval 2 and the difference increases with Tmax: this is due to the fact that the probe measuring the temperature in the Rock-Eval 2 is located in the oven wall, consequently Tmax determination is highly dependent on the setup and calibration of the apparatus. A special attention was given for temperature measurement in the Rock-Eval 6, where the probe is in contact with the crucible containing the sample, leading to much more reliable data.

A battery of biomarkers is often used to evaluate the effects of exposure to chemical contaminants and detect responses to environmental stress. Unfortunately, field application of biomarkers is subject to various constraints (e.g., the availability of living material) that can limit data acquisition and prevent the use of multivariate methods during statistical analysis. In these circumstances, a simple method is needed to summarize biomarker responses and simplify their interpretation in biomonitoring programs. The present study used star plots to display results for the panel of biomarkers used for each station and survey. Integrated biomarker response (IBR) was then computed as the star plot area. Star plots using IBR values instead of biomarker data make it possible to visualize between-site and/or between-survey differences for comparison with exposure conditions. This approach was applied to sites in the Baltic Sea and the Seine Estuary, English Channel. In both cases, IBR values were visually compared to polycyclic aromatic hydrocarbons (PAH) or polychlorobiphenyls (PCB) levels measured in mussel or fish tissues. The IBR, as an indicator of environmental stress, appears to be a useful tool for scientists and managers in assessing ecological risk.

Successful petroleum exploration relies on detailed analysis of the petroleum system in a given area. Identification of potential source rocks, their maturity and kinetic parameters, and their regional distribution are best accomplished by rapid screening of rock samples (cores and/or cuttings) using the Rock-Eval apparatus. The technique has been routinely used for about fifteen years and has become a standard tool for hydrocarbon exploration. This paper describes how the new functions of the latest version of Rock-Eval (Rock-Eval 6) have expanded applications of the method in petroleum geoscience. Examples of new applications are illustrated for source rock characterization, reservoir geochemistry, and environmental studies, including quantification.

Abstract La co‐réaction des oléfines cycliques avec les oléfines acycliques en présence des systèmes WOCl 4 /Al(C 2 H 5 ) 2 Cl et WOCl 4 /Sn(C 4 H 9 ) 4 conduit à une télomérisation de l'oléfine cyclique; aux extrémités des molécules de télomère sont fixés deux groupements, identiques ou différents, issus de l'oléfine acyclique par une réaction non consécutive. Ont été plus particulièrement étudiés: le cyclopentène et le cyclooctène d'une part, le pentène‐2, le pentène‐1, le butène‐2 et le propylène d'autre part. Le cyclooctadiène‐1.5 et le cyclododécatriène‐1.5.9 réagissent avec le pentène‐2, par réaction non consécutive, en tant que reste CHCH 2 CH 2 CH. La répartition des télomères obéit à une loi statistique. On propose un schéma réactionnel en accord avec les faits observés dans la réaction de disproportion des oléfines acycliques, la polymérisation des oléfines cycliques et la télomérisation des oléfines cycliques par les oléfines acycliques.

Global optimization techniques, such as dynamic programming, serve mainly to evaluate the potential fuel economy of a given powertrain configuration. Unless the future driving conditions can be predicted during real-time operation but the results obtained using this noncausal approach establish a benchmark for evaluating the optimality of realizable control strategies. Real-time controllers must be simple in order to be implementable with limited computation and memory resources. Moreover, manual tuning of control parameters should be avoided. This article has analyzed two approaches, namely, feedback controllers and ECMS. Both of these approaches can lead to system behavior that is close to optimal, with feedback controllers based on dynamic programming. Additional challenges stem from the need to apply optimal energy-management controllers to advanced HEV architectures, such as combined and plug-in HEVs, as well as to optimization problems that include performance indices in addition to fuel economy, such as pollutant emissions, driveability, and thermal comfort

Conçue pour répondre aux besoins de l'exploration pétrolière, la méthode de pyrolyse Rock-Eval est maintenant largement utilisée. Elle fournit, en effet, et d'une façon rapide, différentes informations sur le contenu organique des roches, telles que le potentiel pétrolier des séries rencontrées, la nature des kérogènes, leur état de maturation. En ce qui concerne le matériel, deux nouvelles versions ont été mises au point à l'Institut Français du Pétrole (IFP) depuis l'apparition en 1977 des premiers appareils Rock-Eval : un Rock-Eval II complètement automatisé grâce à un microprocesseur et doté, en option, d'un module de dosage du carbone organique; un Rock-Eval III (Oil Show Analyzer) qui se distingue du précédent par le fait qu'il analyse séparément le gaz et l'huile et qu'il effectue le dosage du carbone organique à la place du pic S3. En ce qui concerne l'interprétation de la méthode, l'expérience acquise tant par les applications aux bassins sédimentaires que par les études expérimentales menées en laboratoire a permis de mieux connaître les paramètres utilisés (pics S1, S2, S3, température de pyrolyse Tmax) à travers leurs variations et, de là, de mieux discerner les limites d'application de la méthode. En ce qui concerne l'application de la méthode, la représentation verticale des résultats sous forme de logs géochimiques conduit à une interprétation à la fois efficace et pratique. Des abaques et des diagrammes de référence permettent de caractériser les roches mères (potentiels pétroliers, types de matière organique, degré d'évolution, altérations. . . ) ainsi que les phénomènes de migration. L'établissement de cartes géochimiques à l'échelle du bassin devient alors possible. Enfin la méthode est sortie du domaine de l'exploration pétrolière proprement dite pour trouver des applications à l'étude des charbons, des roches bitumineuses, des sédiments récents et même aux techniques du raffinage et de la récupération secondaire des bruts.

La didactique professionnelle a pour but d’analyser le travail en vue de la formation des compétences professionnelles. Née en France dans les années 1990 au confluent d’un champ de pratiques, la formation des adultes, et de trois courants théoriques, la psychologie du développement, l’ergonomie cognitive et la didactique, elle s’appuie sur la théorie de la conceptualisation dans l’action d’inspiration piagétienne. Son hypothèse : l’activité humaine est organisée sous forme de schèmes, dont le noyau central est constitué de concepts pragmatiques. Elle cherche un équilibre entre deux perspectives : une réflexion théorique et épistémologique sur les fondements des apprentissages humains ; un souci d’opérationnaliser ses méthodes d’analyse pour les faire servir à une ingénierie de la formation. L’analyse du travail qu’elle a développée a débuté avec le travail industriel et s’est étendue aux activités de service et d’enseignement. Cette analyse du travail a un double rôle : elle est un préalable à la construction d’une formation. Elle est aussi, par sa dimension réflexive, un important instrument d’apprentissage.

Background: Pollution - unwanted waste released to air, water, and land by human activity - is the largest environmental cause of disease in the world today. It is responsible for an estimated nine million premature deaths per year, enormous economic losses, erosion of human capital, and degradation of ecosystems. Ocean pollution is an important, but insufficiently recognized and inadequately controlled component of global pollution. It poses serious threats to human health and well-being. The nature and magnitude of these impacts are only beginning to be understood. Goals: (1) Broadly examine the known and potential impacts of ocean pollution on human health. (2) Inform policy makers, government leaders, international organizations, civil society, and the global public of these threats. (3) Propose priorities for interventions to control and prevent pollution of the seas and safeguard human health. Methods: Topic-focused reviews that examine the effects of ocean pollution on human health, identify gaps in knowledge, project future trends, and offer evidence-based guidance for effective intervention. Environmental Findings: Pollution of the oceans is widespread, worsening, and in most countries poorly controlled. It is a complex mixture of toxic metals, plastics, manufactured chemicals, petroleum, urban and industrial wastes, pesticides, fertilizers, pharmaceutical chemicals, agricultural runoff, and sewage. More than 80% arises from land-based sources. It reaches the oceans through rivers, runoff, atmospheric deposition and direct discharges. It is often heaviest near the coasts and most highly concentrated along the coasts of low- and middle-income countries. Plastic is a rapidly increasing and highly visible component of ocean pollution, and an estimated 10 million metric tons of plastic waste enter the seas each year. Mercury is the metal pollutant of greatest concern in the oceans; it is released from two main sources - coal combustion and small-scale gold mining. Global spread of industrialized agriculture with increasing use of chemical fertilizer leads to extension of Harmful Algal Blooms (HABs) to previously unaffected regions. Chemical pollutants are ubiquitous and contaminate seas and marine organisms from the high Arctic to the abyssal depths. Ecosystem Findings: species. Industrial discharges, pharmaceutical wastes, pesticides, and sewage contribute to global declines in fish stocks. Human Health Findings: infections, including cholera, will increase in frequency and extend to new areas. All of the health impacts of ocean pollution fall disproportionately on vulnerable populations in the Global South - environmental injustice on a planetary scale. Conclusions: Ocean pollution is a global problem. It arises from multiple sources and crosses national boundaries. It is the consequence of reckless, shortsighted, and unsustainable exploitation of the earth's resources. It endangers marine ecosystems. It impedes the production of atmospheric oxygen. Its threats to human health are great and growing, but still incompletely understood. Its economic costs are only beginning to be counted.Ocean pollution can be prevented. Like all forms of pollution, ocean pollution can be controlled by deploying data-driven strategies based on law, policy, technology, and enforcement that target priority pollution sources. Many countries have used these tools to control air and water pollution and are now applying them to ocean pollution. Successes achieved to date demonstrate that broader control is feasible. Heavily polluted harbors have been cleaned, estuaries rejuvenated, and coral reefs restored.Prevention of ocean pollution creates many benefits. It boosts economies, increases tourism, helps restore fisheries, and improves human health and well-being. It advances the Sustainable Development Goals (SDG). These benefits will last for centuries. Recommendations: World leaders who recognize the gravity of ocean pollution, acknowledge its growing dangers, engage civil society and the global public, and take bold, evidence-based action to stop pollution at source will be critical to preventing ocean pollution and safeguarding human health.Prevention of pollution from land-based sources is key. Eliminating coal combustion and banning all uses of mercury will reduce mercury pollution. Bans on single-use plastic and better management of plastic waste reduce plastic pollution. Bans on persistent organic pollutants (POPs) have reduced pollution by PCBs and DDT. Control of industrial discharges, treatment of sewage, and reduced applications of fertilizers have mitigated coastal pollution and are reducing frequency of HABs. National, regional and international marine pollution control programs that are adequately funded and backed by strong enforcement have been shown to be effective. Robust monitoring is essential to track progress.Further interventions that hold great promise include wide-scale transition to renewable fuels; transition to a circular economy that creates little waste and focuses on equity rather than on endless growth; embracing the principles of green chemistry; and building scientific capacity in all countries.Designation of Marine Protected Areas (MPAs) will safeguard critical ecosystems, protect vulnerable fish stocks, and enhance human health and well-being. Creation of MPAs is an important manifestation of national and international commitment to protecting the health of the seas.

Conçue pour répondre aux besoins de l'exploration pétrolière, la méthode de pyrolyse Rock-Eval est maintenant largement utilisée. Elle fournit, en effet, et d'une façon rapide, différentes informations sur le contenu organique des roches, telles que le potentiel pétrolier des séries rencontrées, la nature des kérogènes, leur état de maturation. En ce qui concerne le matériel, deux nouvelles versions ont été mises au point à l'Institut Français du Pétrole (IFP) depuis l'apparition en 1977 des premiers appareils Rock-Eval : un Rock-Eval II complètement automatisé grâce à un microprocesseur et doté, en option, d'un module de dosage du carbone organique; un Rock-Eval III (Oil Show Analyzer) qui se distingue du précédent par le fait qu'il analyse séparément le gaz et l'huile et qu'il effectue le dosage du carbone organique à la place du pic S3. En ce qui concerne l'interprétation de la méthode, l'expérience acquise tant par les applications aux bassins sédimentaires que par les études expérimentales menées en laboratoire a permis de mieux connaître les paramètres utilisés (pics S1, S2, S3, température de pyrolyse Tmax) à travers leurs variations et, de là, de mieux discerner les limites d'application de la méthode. En ce qui concerne l'application de la méthode, la représentation verticale des résultats sous forme de logs géochimiques conduit à une interprétation à la fois efficace et pratique. Des abaques et des diagrammes de référence permettent de caractériser les roches mères (potentiels pétroliers, types de matière organique, degré d'évolution, altérations. . . ) ainsi que les phénomènes de migration. L'établissement de cartes géochimiques à l'échelle du bassin devient alors possible. Enfin la méthode est sortie du domaine de l'exploration pétrolière proprement dite pour trouver des applications à l'étude des charbons, des roches bitumineuses, des sédiments récents et même aux techniques du raffinage et de la récupération secondaire des bruts.

Metathesis reactions are among the most important processes in organic synthesis. The decisive breakthrough in making these reactions practical for industrial purposes, which range from the synthesis of polymers to pharmaceuticals, came with the discovery of the reaction mechanism by Yves Chauvin and the targeted development of transition-metal-based metathesis catalysts by Richard Schrock and Robert Grubbs. The winners of the Chemistry Nobel Prize in 2005 present first-hand accounts of these developments.

We assess climate impacts of global warming using ongoing observations and paleoclimate data. We use Earth's measured energy imbalance, paleoclimate data, and simple representations of the global carbon cycle and temperature to define emission reductions needed to stabilize climate and avoid potentially disastrous impacts on today's young people, future generations, and nature. A cumulative industrial-era limit of ∼500 GtC fossil fuel emissions and 100 GtC storage in the biosphere and soil would keep climate close to the Holocene range to which humanity and other species are adapted. Cumulative emissions of ∼1000 GtC, sometimes associated with 2°C global warming, would spur "slow" feedbacks and eventual warming of 3-4°C with disastrous consequences. Rapid emissions reduction is required to restore Earth's energy balance and avoid ocean heat uptake that would practically guarantee irreversible effects. Continuation of high fossil fuel emissions, given current knowledge of the consequences, would be an act of extraordinary witting intergenerational injustice. Responsible policymaking requires a rising price on carbon emissions that would preclude emissions from most remaining coal and unconventional fossil fuels and phase down emissions from conventional fossil fuels.

Phenolics have been identified and quantified in nine varieties of barley and their corresponding malts as flavan-3-ols, flavonols, phenolic acids and apolar esters. Flavan-3-ols are monomers, (+)-catechin and (−)-epicatechin, and polymers constituted mainly by units of (+)-catechin and (+)-gallocatechin. The most abundant compounds were the dimers procyanidin B3 and prodelphinidin B3. The main trimeric procyanidin was procyanidin C2. After malting, the phenolic content decreased for all varieties. Catechin monomers were the most affected. Beside polyphenols, barley and malt extracts contained other antioxidants: carotenoids (lutein and zeaxanthin) and tocopherols (α, δ and γ). The antioxidant activity was measured using three methods: capacity to react with DPPH. (ARP), inhibition of lipoxygenase activity (LoxI) and inhibition of cooxidation of β-carotene in a linoleate model system (AOP). The inhibition of cooxidation of β-carotene in a linoleate model system did not allow varieties to be discriminated. They all have high antioxidative properties. Using this assay, tocopherols were the best antioxidants. The ARP (antiradical power) was correlated positively with the amount of total flavan-3-ols (r = 0.89) and increased with the degree of polymerisation. The LoxI assay allowed discrimination of the nine varieties of barley and their corresponding malts but was not correlated with any compound, although flavan-3-ols were good inhibitors of lipoxygenase activity. © 1999 Society of Chemical Industry

ABSTRACT A procedure and apparatus have been developed for rapid source-rock characterization. Based on the paralysis of small rock samples, it makes possible the determination of :various types of source rockstheir degree of evolution (immature, oil zone, gas zone)their petroleum potential The method can be performed on cores or cuttings either in the laboratory or at a well site (especially aboard offshore drilling vessels), and in this case it can be used to detect oil shows. Generally the procedure uses ground rock, but it is also possible to operate directly with small cuttings without any prior treatment. Aboard the GLOMAR CHALLENGER (LEGS 48 and 50) the apparatus was especially used as a safety tool to reveal rapidly the presence of oil shows. INTRODUCTION In the field of petroleum exploration, one of the most important aspects is to be able to recognize the various types of source rocks in a geological series which, under the effect of increasing temperature during burial, produce petroleum compounds. As a matter of fact, the quantity and character of the hydrocarbons which have been produced depend on the character of the organic matter originally deposited in these source rocks as well as on subsequent thermal evolution, i.e. temperature and geological time. Recent research 1,, on kerosene (insoluble organic matter) from sediments sampled in various basins has shown that the physical chemical analysis of these kerosene makes it possible to classify the various types of organic matter and to estimate their oil and gas potential together with their degree of evolution. Do not fulfill the requirements of petroleum exploration which requires the analysis of a large number of sediment samples by simple, cheap and rapid methods. The basic knowledge acquired from the study of various types of kerosene has been used to develop a rapid method applied to characterize the different qualities (types) of organic matter directly on sedimentary rocks and to estimate their oil potential and their degree of evolution. This method is based on the selective detection of hydrocarbon compounds and of one of the principal oxygenated compound (C02) produced by paralysis under normalized conditions of organic matter contained in sediments. The paralysis technique has already been used by various authors (4, 5,6,7,8) for studying organic matter in sedimentary rocks. CHARACTERIZATION OF VARIOUS TYPES OF KEROGEN Elementary analysis of kerosene shows that the major atomic constituents are carbon, hydrogen and oxygen. The H/C and O/C atomic ratios utilized in a diagram of the type established by Van Reveled for coal shows that the samples corresponding to the same quality of organic deposits are situated on a curve called "evolution path". (fig. 1)

A significant extension of the field of two-phase catalysis is achieved through the use of ionic liquids such as 1. In this way substrates, complexes, and ligands that are poorly soluble or unstable in water can be employed for this industrially important variant of homogeneous catalysis.

The topotactic transformation of boehmite (AlOOH) taking place under calcination and leading to γ-alumina (γ-Al2O3) has been investigated theoretically and a step-by-step mechanism for the structural transformation is proposed. This mechanism reveals two major steps. First, the structural collapse of boehmite occurs, after hydrogen transfers and water extraction. Then, through an aluminum migration process, the γ-alumina characteristics appear. The proposed mechanism demonstrates the existence of an equilibrium structure for γ-alumina containing 25−31% of tetrahedral aluminum sites in agreement with nuclear magnetic resonance (NMR) results. Temperature effects on the thermodynamic stability of the different structures involved in the mechanism has been investigated. Theoretically simulated X-ray diffraction (XRD) patterns confirm the validity of our model structures. According to this mechanism, a coherent skeleton of γ-alumina inherited from the original AlOOH network is constructed. This skeleton can be regarded as a primary matrix providing an insight into structural properties of γ-alumina. Finally, the structures involved in this process may constitute a basis for further investigation on the series of metastable alumina phases appearing before the final conversion of AlOOH to α-alumina (α-Al2O3).

Computed microtomography is applied to a piece of Fontainebleau sandstone in order to determine the geometrical structure of the pores. The topology of the void space is then derived from the tomographic image of the volume. Permeability and conductivity are computed and found in good agreement with experimental data. Perspectives offered by this new nondestructive method with a potential resolution of the order of one micrometer or less are analyzed.

Abstract A review of theoretical equations of state for polymer liquids is presented. Characteristic parameters for six equations of state, as well as parameters for the empirical Tait equation, are given for 56 polymers where pressure–volume–temperature (PVT) data over a wide range of conditions could be found in the literature. New PVT data are presented for four polymers: poly(epichlorohydrin), poly(ϵ‐caprolactone), poly(vinyl chloride), and atactic polypropylene. All six equations of state provide adequate fits of the experimental specific volume data for the 56 polymers in the low pressure range (up to 500 bar). The modified cell model of Dee and Walsh, the Simha–Somcynsky hole theory, the Prigogine cell model, and the semiempirical model of Hartmann and Haque, were all found to provide good fits of polymer liquid PVT data over the full range of experimental pressures. The Flory–Orwoll–Vrij and the Sanchez–Lacombe lattice–fluid equations of state were both significantly less accurate over the wider pressure range. © 1993 John Wiley & Sons, Inc.

The Extended Coherent Flame Model of Colin et al. (2003) developed to model combustion in perfectly or partially mixed mixtures is adapted to also account for unmixed combustion. The ECFM model is based on a flame surface density equation which takes into account the wrinkling of the flame front surface by turbulent eddies and a conditioning averaging technique which allows precise reconstruction of local properties in fresh and burned gases even in the case of high levels of local fuel stratification. This model has been used with success in gasoline engines (Duclos et al., 1996; Duclos and Zolver, 1998; Lafossas et al., 2002; Henriot et al., 2003; Kleemann et al., 2003). In order to adapt the model to unmixed combustion for Diesel application, a description of the mixing state has been added. It is represented by three mixing zones: a pure fuel zone, a pure air plus possible residual gases zone and a mixed zone in which the ECFM combustion model is applied. A mixing model is presented which allows progressive mixing of the initially unmixed fuel and air. This new combustion model, called ECFM3Z (3-Zones Extended Coherent Flame Model), can therefore be seen as a simplified CMC (Conditional Moment Closure) type model where the mixture fraction space would be discretized by only three points. The conditioning technique is extended to the three mixing zones and allows to reconstruct, like in the ECFM model, the gas properties in the unburned and burned gases of the mixed zone. Application of the model to internal combustion engine calculations implies the necessity of auto-ignition modelling coupled to premixed and diffusion flames description. Auto-ignition is modelled following (Colin et al., 2004), while the premixed turbulent flame description is given by the ECFM. The diffusion flame is now accounted for thanks to the three zones mixing structure which represents phenomenologically the diffusion of fuel and air towards the reactive layer, that is the mixed zone. The ECFM3Z combustion model has already been presented (Béard et al., 2003) in a comparative work between Diesel experiments and corresponding calculations covering different engine operating points. Here, the model is presented in all its details and its behavior is analysed when the relative duration of injection and auto-ignition delay are varied in a direct injection Diesel engine. It is shown that the model is able to reproduce the relative importance of auto-ignition and diffusion flame on the total heat release, depending on the engine operating point considered.

The Okinawa Trough, lying to the east of China, is a back arc basin formed by extension within continental lithosphere behind the Ryukyu trench‐arc system. Middle to late Miocene uplift, associated with normal faulting of the initially adjacent Ryukyu nonvolcanic arc and the Taiwan‐Sinzi folded belt, corresponds to the first rifting phase. The timing of rifting is supported by the presence of marine sediments of corresponding age drilled in the northern Okinawa Trough. The rifting occurred after a major early Miocene change in the motion of the Philippine plate with respect to Eurasia and ceased during the Pliocene. A second rifting phase started about 2 m.y. ago, at the Plio‐Pleistocene boundary and has continued until the present time. It has proceeded to a more advanced stage in the middle and southern Okinawa Trough than it has farther north. Detailed bathymetric (Sea Beam), seismic reflection, and magnetics data collected during the POP 1 cruise of the R/V Jean Charcot reveal the principal features of the extensional processes. The back arc spreading phase started very recently in the southern and middle Okinawa Trough, as exemplified by several en échelon and, in some cases, overlapping active, central graben oriented N70°E–N80°E. Some of these depressions are intruded by volcanic ridges of fresh back arc basalt with associated large magnetic anomalies. Transform faults between these en échelon active rifts are not obvious. We suggest that the major part of the southern Okinawa Trough is underlain by a thinned continental crust and that except for the system of en échelon rifts of the southern Okinawa Trough, the back arc basin oceanic domain is limited to a width of a few tens of kilometers or less in the axial portion of the trough. The system of axial back arc volcanic ridges that occur in the rifts ends at the latitude of Okinawa Island whereas active volcanoes in the Ryukyu arc occur only north of Okinawa Island. We refer to this transition between active arc and back arc volcanism as the volcanic arc‐rift migration phenomenon (VAMP). Globally, back arc volcanism propagated from the southern Okinawa Trough to the Okinawa VAMP area. Rifting continues to occur in the northern Okinawa Trough but is not yet accompanied by associated volcanism. The Okinawa VAMP area is characterized by a series of parallel basaltic ridges oriented N75°E with associated linear magnetic anomalies characteristic of dyke intrusions. We suggest that the formation of the back arc oceanic domain took place along the axial back arc extensional zone trending N75°E and that this zone presently ends at the southern extremity of the active volcanic chain. The initial phase of formation of back arc basin oceanic crust is non‐steady state and is characterized by the lack of a developed fracture zone pattern. The termination of the VAMP area in the direction of the volcanic zone of the arc is consistent with the suggestion of Molnar and Atwater that the volcanic arc is a fundamental line of weakness which determines where initial back arc spreading occurs. Apparently, back arc extension initially occurred within the continental lithosphere located westward of the Ryukyu arc, along its whole length, but the subsequent back arc volcanism was initiated in the southernmost portion of the region and then moved northward. This migration was accompanied by the shutting down of volcanic activity along the abandoned portions of the arc. It is this transfer of volcanism that we call the VAMP process. Thus arc and back arc basin volcanism seem to be associated in such a manner that spreading tends to migrate simultaneously with a cessation in volcanic activity along the arc. This interplay of arc and back arc activity is probably linked to changes in the parameters of plate convergence. Since the plate motion in the Phillippine sea is oblique to the trench at least in the southern part of the Okinawa Trough, we suggest that the oblique resisting force applied to the edge of the overriding plate engenders the development of en échelon extensional features within and behind the arc. The motion of the Ryukyu platelet with respect to Eurasia is consequently an extensional strike‐slip motion trending roughly parallel to the Okinawa Trough.