pinecone/core-2020-05-10-deduplication huggingface dataset:
Fine-scale gas distribution in marine sediments assessed from deep-towed seismic data

International audienceIn the context of seismic imaging of gas/gas-hydrate systems, the fine-scale structure of subseabed gas-related reflections is assessed by taking advantage of the source signature of the deep-towed high-resolution SYSIF seismic device. We demonstrate the value of an original wavelet-based method and associated multiscale seismic attributes, applied to seismic data recently acquired on the western margin of the Arctic archipelago of Svalbard. From analysis in the wavelet domain, we recognize two types of gas-related reflections associated with submetre-scale distribution of gas. We identify a thin gas-charged layer associated with an apparent normal polarity reflection, and we detect gas patches associated with a reversepolarity bright spot with frequency-dependent elastic properties at small seismic wavelengths. The results provide valuable information on the scale of features through which gas migrates and resolve ambiguities in the interpretation of the seismic data
Morphology and sedimentary architecture of a modern volcaniclastic turbidite system: The Cilaos fan, offshore La Réunion Island

International audienceRecent oceanographic surveys revealed the existence of five volcaniclastic deep-sea fans off La Réunion Island. The Cilaos fan is a large volcaniclastic submarine fan, connected to rivers that episodically experience torrential floods through a narrow and steep shelf-slope system. New piston cores presented in this study together with echosounder profiles give new insight into the evolution of this extensive and sand-rich turbidite system. The Cilaos fan extends over 15,000 km2 on an abyssal plain and is compartmentalized by topographic highs. Located southwest of the island, the sedimentary system consists of a canyon area and a deep sea fan divided into a proximal and a distal fan. The proximal fan is characterized by its wide extent and coarse-grained turbidites. The distal fan is characterized by elongated structures and fine-grained turbidites. A detailed morphological study of the fan which includes the analysis of swath bathymetry, backscatter, echosounder, and piston core data shows that the Cilaos fan is a complex volcaniclastic deep-sea fan, highly influenced by preexisting seafloor irregularities. The canyons and the slope area show a complex and evolving sediment feeding system with a direct sediment input by the river and irregular sediment supply by submarine landslide. Three main construction stages are identified for this system: (1) an old incision phase of the channels forming wide turbidites extending over the entire distal fan; (2) a period of no or low activity characterized by a thick layer of hemipelagic mud; and (3) a local reactivation of the channel in the proximal fan. Each stage seems to be linked to a different sediment source with a progressively increasing contribution of hemipelagic sediment and mud in younger stages
A Riemann solver for single-phase and two-phase shallow flow models based on relaxation. Relations with Roe and VFRoe solvers.

International audienceWe present a Riemann solver derived by a relaxation technique for classical single-phase shallow flow equations and for a two-phase shallow flow model describing a mixture of solid granular material and fluid. Our primary interest is the numerical approximation of this two-phase solid/fluid model, whose complexity poses numerical difficulties that cannot be efficiently addressed by existing solvers. In particular, we are concerned with ensuring a robust treatment of dry bed states. The relaxation system used by the proposed solver is formulated by introducing auxiliary variables that replace the momenta in the spatial gradients of the original model systems. The resulting relaxation solver is related to Roe solver in that its Riemann solution for the flow height and relaxation variables is formally computed as Roe's Riemann solution. The relaxation solver has the advantage of a certain degree of freedom in the specification of the wave structure through the choice of the relaxation parameters. This flexibility can be exploited to handle robustly vacuum states, which is a well known difficulty of standard Roe's method, while maintaining Roe's low diffusivity. For the single-phase model positivity of flow height is rigorously preserved. For the two-phase model positivity of volume fractions in general is not ensured, and a suitable restriction on the CFL number might be needed. Nonetheless, numerical experiments suggest that the proposed two-phase flow solver efficiently models wet/dry fronts and vacuum formation for a large range of flow conditions. As a corollary of our study, we show that for single-phase shallow flow equations the relaxation solver is formally equivalent to the VFRoe solver with conservative variables of Gallouët and Masella [C. R. Acad. Sci. Paris, Série I, 323, 77-84, 1996]. The relaxation interpretation allows establishing positivity conditions for this VFRoe method
Experimental analysis of groundwater flow through a landslide slip surface using natural and artificial water chemical tracers.

International audienceArtificial and natural tracer tests combined with high accurate electronic distancemeter measurements are conducted on a small landslide with a well known slip surface geometry. Outflow yields and chemical contents are monitored for all the experiment duration and they analyzed to estimate the slip surface hydraulic parameters. The main result is that the slip surface acts as a drain for groundwater flows that evacuates interstitial pressures in the slope and brings the sliding mass to be more stable one
Quantitative structural and textural assessment of laminar pyrocarbons through Raman spectroscopy, electron diffraction and few other techniques

Xavier Bourrat : Present Address = ISTO - CNRS-Université d'OrléansInternational audienceIn pyrocarbon materials, the width of the Raman D band (FWHMD) is very sensitive to low energy structural defects (e.g., disorientations of the graphene layers). The correlation between the two parameters, FWHMD and OA (as derived from selected area electron diffraction: SAED), has allowed to differentiate various pyrocarbons unambiguously. Furthermore, the optical properties of pyrocarbons, i.e., the extinction angle, the optical phase shift and the ordinary and extraordinary reflectance, have been accurately determined at 550 nm by means of the extinction curves method. These results are completed by in-plane and out-of-plane dielectric constant measurements by angular resolved EELS. Moreover, the hybridization degree of the carbon atoms has been assessed by the same technique. About 80% of the carbon atoms of the pyrocarbons have a sp2 hybridization. The lack of pure sp2 carbon atoms, as compared to graphite, might be explained by the presence of sp3-like line defects
The male mate search: an optimal foraging issue?

5 pagesInternational audienceMale insects must find and mate females to have some descendants; male fitness therefore depends on the number of females they inseminate. Males are for this reason expected to optimize the behaviors related to mate location, orientation and copulation. Although optimization of the reproductive behavior of males has long been neglected in the literature, recent studies suggest a renewed interest for this idea. Here we discuss the parallel between male mate-finding and mating strategies in insects and optimal foraging theory (OFT), a class of models which formalize the behavior of organisms seeking and exploiting resources, generally food. We highlight the different facets of male mating systems allowing such a parallel, and claim for a unifying approach of foraging behavior. Finally, we discuss novel research perspective emerging from the application of OFT to male reproductive behavior
Heatwave classification over Europe and the Mediterranean region

International audienceA method for defining and classifying heatwave events in the Euro-Mediterranean region is presented. The definition is based on the 95th centile of the local temperature probability density function, with additional criteria for spatial and temporal extension. The heatwave events are then classified into six classes by cluster analysis. The six heatwave patterns of Europe are described and compared to the existing literature. The most catastrophic extreme heatwaves (e.g.2003 in Europe, 2010 in Russia) are shown to belong to one of these classes. It is then shown that the different classes are associated with different physical mechanisms. The effect of synoptic circulation and hydrological conditions are notably investigated. In particular, a drought appears to be a pre-requisite to heatwave occurrence in some clusters but not all. © 2012 IOP Publishing Ltd
Energyplexes for the 21st Century: Coal Gasification for Co-Producing Hydrogen, Electricity and Liquid Fuels

This paper illustrates the role that integrated energy systems, also known as 'energyplexes', could play in supplying energy demands in the long term. These systems could enable a multi-fuel, multi-product strategy with both economic and environmental benefits. they could increase the adaptability and robustness of energy-services companies in the market place, providing them with flexibility in meeting demands in different market segments while achieving lower production costs and, reducing the risks of reliance on a single feedstock. In addition, with the possibility of achieving high conversion efficiencies and low polluting emissions and facilitating carbon capture, they could deliver high-quality energy services and cost-effective way while meeting stringent environmental requirements. Their potential is highlighted here using the case of coal-fired, synthesis-gas-based gasification systems that allow co-producing hydrogen, electricity and liquid fuels, i.e. Fischer-Tropsch liquids and methanol, and could be a key building block in a clean-coal technology strategy. Co-production, also known as poly-generation, strategies may contribute to improve the economics of the system and exploit potential synergies between the constituent processes. However, the technical feasibility and economic viability of poly-generation schemes have to be examined carefully on a case-by-case basis
Improvement of product design process by knowledge value analysis

Nowadays, design activities remain the core issue for global product development. As knowledge is more and more integrated, effective analysis of knowledge value becomes very useful for the improvement of product design processes. This paper aims at proposing a framework of knowledge value analysis in the context of product design process. By theoretical analysis and case study, the paper illustrates how knowledge value can be calculated and how the results can help the improvement of product design process, such as deciding which knowledge to choose and what to do next
3-D Reconstruction of Shaded Objects from Multiple Images Under Unknown Illumination

International audienceWe propose a variational algorithm to jointly estimate the shape, albedo, and light configuration of a Lambertian scene from a collection of images taken from different vantage points. Our work can be thought of as extending classical multi-view stereo to cases where point correspondence cannot be established, or extending classical shape from shading to the case of multiple views with unknown light sources. We show that a first naive formalization of this problem yields algorithms that are numerically unstable, no matter how close the initialization is to the true geometry. We then propose a computational scheme to overcome this problem, resulting in provably stable algorithms that converge to (local) minima of the cost functional. We develop a new model that explicitly enforces positivity in the light sources with the assumption that the object is Lambertian and its albedo is piecewise constant and show that the new model significantly improves the accuracy and robustness relative to existing approaches
Maximum Stress Intensity Factor for a Circumferential Crack in a Finite-Length Thin-Walled Cylinder under Transient Radial Temperature Distribution

Transient stress intensity factor of an axisymmetric circumferential crack in a finite-length, thin-walled and edges
rotation-restrained cylinder, which is suddenly cooled inside from uniform temperature distribution was formulated. Then
the effects of various structural parameters and heat transfer conditions on the value were studied. The maximum transient
stress intensity factor in a thermal cycle showed a tendency to decrease monotonously when crack length was varied to
become longer than a specific value. Furthermore, the maximum transient stress intensity factor for an infinite cylinder
length was smaller than that for a specific length when cylinder length was varied
Small sodium clusters that melt gradually: Melting mechanisms in Na30

Producción CientíficaThe meltinglike transition of Na30 is studied by orbital-free density-functional molecular dynamics simulations. The potential energy surface of Na30 is sampled by simulated annealing and regular quenchings performed along the dynamical trajectories. Both the ground-state structure and low-energy structural excitations are found to exhibit substantial polyicosahedral ordering. The most relevant feature of the potential energy landscape for the melting problem is the existence of many different structural isomers within an energy range of 1 meV/atom, resembling that of a glassy system (yet the structures have a high symmetry). The liquid phase is accessed gradually, with some isomerizations observed at a temperature as low as 30 K, while melting can be considered complete above approximately 200 K. The different dynamical mechanisms that allow the smooth opening of phase space available to the system as a function of temperature are identified and discussed. They can be classified in two different categories: (a) those that allow the exploration of isomers similar to the ground state, involving mainly surface isomerizations and surface melting, and leaving the structure of the cluster core unchanged; and (b) those associated with a more substantial structural change, more similar to the usual solid-solid phase transition in bulk phases; the structure of the cluster core changes only in this second type of transition. Mechanism (a) results in surface melting of the corresponding isomer upon heating; at that stage, mechanism (b) acts to transfer some excess energy from the surface to the core region, so that the surface melting is transiently avoided. Even in the fully developed liquid state, there are important differences from the bulk liquid due to the presence of the surface
Nanomachining of (110)-oriented silicon by scanning probe lithography and anisotropic wet etching

[[abstract]]We have demonstrated that silicon nanostructures with high aspect ratios, having ~400 nm structural height and ~55 nm lateral dimension, may be fabricated by scanning probe lithography and aqueous KOH orientation-dependent etching on the H-passivated (110) Si wafer. The high spatial resolution of fabricated features is achieved by using the atomic force microscope based nano-oxidation process in ambient. Due to the large (110)/(111) anisotropic ratio of etch rate and the large Si/SiO2 etch selectivity at a relatively low etching temperature and an optimal KOH concentration, high-aspect-ratio gratings with (111)-oriented structural sidewalls as well as hexagonal etch pit structures determined by the terminal etch geometry can be obtained.[[fileno]]2010124010015[[department]]物理
Functional Asynchronous Networks: Factorization of Dynamics and Function

In this note we describe the theory of functional asynchronous networks and
one of the main results, the Modularization of Dynamics Theorem, which for a
large class of functional asynchronous networks gives a factorization of
dynamics in terms of constituent subnetworks. For these networks we can give a
complete description of the network function in terms of the function of the
events comprising the network and thereby answer a question originally raised
by Alon in the context of biological networks
A comparison between wolves, Canis lupus, and dogs, Canis familiaris, in showing behaviour towards humans

Both human and nonhuman primates use imperative pointing to request a desired object from another individual. Gaze alternation often accompanies such pointing gestures, and in species that have no hands this can in itself function as imperative pointing. Dogs have exceptional skills in communicating with humans. The early development of these skills is suggested to have been facilitated by domestication. Adult wolves socialized with humans can use human-provided information to find food in various situations, but it is unclear whether they would use gaze alternation to show their human partner a target location they cannot reach on their own. In our experiment, we tested wolves and dogs in a task where they could indicate an out-of-reach food location to one of two human partners. One partner reacted in a cooperative way and gave the food hidden in the indicated location to the subject whereas the other responded in a competitive way and ate the food herself. Our results suggest that wolves, as well as dogs, use ‘showing’ behaviours to indicate a food location to a human partner, and that both can adjust their communication to the cooperativeness of their human partners, showing more indicating signals in the presence of the cooperative partner than in the presence of the competitive one. We conclude that wolves and dogs, both kept in packs under the same conditions, can use humans as cooperative partners, and point imperatively in order to receive a desired out-of-reach object. It seems that intensive socialization with humans enables both wolves and dogs to communicate cooperatively about a food location with humans, most probably relying on skills that evolved to promote social coordination within their packs
Global solvability and blow up for the convective Cahn-Hilliard
  equations with concave potentials

We study initial boundary value problems for the convective Cahn-Hilliard
equation $\Dt u +\px^4u +u\px u+\px^2(|u|^pu)=0$. It is well-known that without
the convective term, the solutions of this equation may blow up in finite time
for any $p>0$. In contrast to that, we show that the presence of the convective
term $u\px u$ in the Cahn-Hilliard equation prevents blow up at least for
$0<p<\frac49$. We also show that the blowing up solutions still exist if $p$ is
large enough ($p\ge2$). The related equations like
Kolmogorov-Sivashinsky-Spiegel equation, sixth order convective Cahn-Hilliard
equation, are also considered
Robust modeling of human contact networks across different scales and proximity-sensing techniques

The problem of mapping human close-range proximity networks has been tackled using a variety of technical approaches. Wearable electronic devices, in particular, have proven to be particularly successful in a variety of settings relevant for research in social science, complex networks and infectious diseases dynamics. Each device and technology used for proximity sensing (e.g., RFIDs, Bluetooth, low-power radio or infrared communication, etc.) comes with specific biases on the close-range relations it records. Hence it is important to assess which statistical features of the empirical proximity networks are robust across different measurement techniques, and which modeling frameworks generalize well across empirical data. Here we compare time-resolved proximity networks recorded in different experimental settings and show that some important statistical features are robust across all settings considered. The observed universality calls for a simplified modeling approach. We show that one such simple model is indeed able to reproduce the main statistical distributions characterizing the empirical temporal networks
Apples and oranges: the difference between the\ud
reaction of the emerging and mature markets to\ud
crashes

We study here the behavior of the eigenvalues of the covariance matrices of returns for emerging and mature markets at times of crises. Our results appear to\ud
indicate that mature markets respond to crashes differently to emerging ones and that emerging markets take longer to recover than mature markets. In addition, the results appear to indicate that the second largest eigenvalue gives additional information on market movement and that a study of the behavior of the other eigenvalues may provide insight on crash dynamics
Influence of an ultrathin GaAs interlayer on the structural properties of InAs/InGaAsP/InP (100) quantum dots investigated by cross-sectional scanning tunneling microscopy

Cross-sectional scanning tunneling microscopy is used to study at the atomic scale how the structural properties of InAsInGaAsPInP quantum dots _QDs_ are modified when an ultrathin _0–1.5 ML_ GaAs interlayer is inserted underneath the QDs. Deposition of the GaAs interlayer suppresses the influence of the AsP exchange reaction on QD formation and leads to a planarized QD growth surface. A shape transition from quantum dashes, which are strongly dissolved during capping, to well defined QDs takes place when increasing the GaAs interlayer thickness between 0 and 1.0 ML. Moreover, the GaAs interlayer allows the control of the AsP exchange reaction, reducing the QD height for increased GaAs thicknesses above 1.0 ML, and decreases the QD composition intermixing, producing almost pure InAs QDs
On the Stability of Artificial Equilibrium Points in the Circular Restricted Three Body Problem

The article analyses the stability properties of minimum-control artificial equilibrium points in the planar circular restricted three-body problem. It is seen that when the masses of the two primaries are of different orders of magnitude, minimum-control equilibrium is obtained when the spacecraft is almost coorbiting with the second primary as long as their mutual distance is not too small. In addition, stability is found when the distance from the second primary exceeds a minimum value which is a simple function of the mass ratio of the two primaries and their separation. Lyapunov stability under non-resonant conditions is demonstrated using Arnold’s theorem. Among the most promising applications of the concept we find solar-sail-stabilized observatories coorbiting with the Earth, Mars, and Venu
Selective area growth of a- and c-plane GaN nanocolumns by molecular beam epitaxy using colloidal nanolithography

Selective area growth of a-plane GaN nanocolumns by molecular beam epitaxy was performed for the first time on a-plane GaN templates. Ti masks with 150 nm diameter nanoholes were fabricated by colloidal lithography, an easy, fast and cheap process capable to handle large areas. Even though colloidal lithography does not provide a perfect geometrical arrangement like e-beam lithography, it produces a very homogeneous mask in terms of nanohole diameter and density, and is used here for the first time for the selective area growth of GaN. Selective area growth of a-plane GaN nanocolumns is compared, in terms of anisotropic lateral and vertical growth rates, with GaN nanocolumns grown selectively on the c-plan