Elastic properties of cellular dissipative structure

Transition towards spatio-temporal chaos in one-dimensional interfacial patterns often involves two degrees of freedom: drift and out-of-phase oscillations of cells, respectively associated to parity breaking and vacillating-breathing secondary bifurcations. In this paper, the interaction between these two modes is investigated in the case of a single domain propagating along a circular array of liquid jets. As observed by Michalland and Rabaud for the printer's instability \cite{Rabaud92}, the velocity $V_g$ of a constant width domain is linked to the angular frequency $\omega$ of oscillations and to the spacing between columns $\lambda_0$ by the relationship $V_g = \alpha \lambda_0 \omega$. We show by a simple geometrical argument that $\alpha$ should be close to $1/ \pi$ instead of the initial value $\alpha = 1/2$ deduced from their analogy with phonons. This fact is in quantitative agreement with our data, with a slight deviation increasing with flow rate

A Flow Time Model for Melt-Cast Insensitive Explosive Process

International audienceDiphasic flows of concentrated suspensions of melt-cast insensitive explosives exhibit specific rheological properties. In order to limit the handling of pyrotechnical products presenting a risk with respect to the mechanical and thermal shocks, a lot of work has been undertaken for many years in the civil engineering sector. The objective of this study is to propose a predictive model of the flow time of a concentrated suspension through a nozzle located at the bottom of a tank. Similar to our industrial process, the suspension is made out of insensitive energetic materials and flows under gravity. Experimental results are compared to three models (Quemada, Krieger-Dougherty, and Mooney) predicting the viscosity μ of a suspension as a function of the solid volume fraction ϕ, the maximum packing density ϕm and the viscosity μ0 of the interstitial liquid. De Larrard's model is used to calculate ϕm. The value of viscosity measured for the pure liquid is close to the one predicted by the Bernoulli theorem, where liquids are considered as incompressible and inviscid. Finally, it was found that the Quemada's model gives a fair agreement between predictions and experiments

Development of a new mixing rheometer for studying rheological behaviour of concentrated energetic suspensions

International audienceThe overall objective is to present a procedure based on a Couette analogy to quantitatively analyse torque/rotor speed data and extract viscosity/shear-rate curves using a non-conventional geometry. Diphasic flows of energetic concentrated suspensions of melt-cast insensitive explosives exhibit particular rheological properties. The characterization of these complex fluids may be a challenging task when conventional rheometers are used. Placing these tense suspensions in a classic cylindrical geometry may lead to a partial destruction of the internal fluid structure. To prevent that, a "RheoXF" a mixer-type rheometer has been developed : it consists of a mixing device with quite a complex geometry rotating in a cylindrical tank

Application d'un modèle de viscosité à la coulée d'explosifs : Modélisation du temps de coulée.

14 pagesLa rhéologie des coulées d'explosifs est décrite par la dynamique des écoulements diphasiques de suspensions concentrées. Afin d'améliorer la manipulation de produits présentant par nature un risque vis-à-vis des agressions mécaniques et thermiques, des avancées issues des travaux de recherche menés depuis de nombreuses années dans le secteur du génie civil permettent de développer de nouveaux procédés pyrotechniques. L'objectif de ces travaux est de proposer un modèle prédictif des temps d'écoulement des suspensions concentrées en matériaux énergétiques dans une configuration similaire au procédé de mise en oeuvre développé en production. Les résultats expérimentaux sont comparés à trois modèles (Quémada, Krieger-Dougherty, Mooney) représentant la viscosité dynamique comme étant fonction de la fraction volumique solide , de l'empilement compact maximal et de la viscosité du fluide interstitiel . Le modèle de De Larrard est utilisé pour le calcul de . Les hypothèses d'un fluide parfait et incompressible, pour le calcul du temps de coulée du fluide interstitiel , aboutissent à la relation de Bernoulli et satisfont à l'expérience. Nous montrons que le modèle de Quémada conduit à des valeurs théoriques du temps de coulée de la suspension en bon accord avec les valeurs expérimentales

Plasmonic and Hydrodynamic Effects in Ultrafast Laser-Induced Periodic Surface Structures on Metals

International audienceWe report results on the development of laser-induced periodic surface structures produced by ultrashort laser pulses irradiating metallic surfaces. The surface topology features are discussed in terms of periodicity and amplitude contrast of the pattern formation, and in relation to the chrono-logical sequence of laser-induced events. Resonant excitation of Surface Plasmons in metallic grat-ings show that the surface wave excited during the femtosecond laser pulse can initiate the observed patterning. Metallic behavior under nonequilibrium conditions on the picosecond timescale is then investigated to correlate the amount of material experiencing solid-to-liquid transitions and the sub-sequent structure amplitude. With the derived observation, the calculation of the transient nonequi-librium thermodynamic characteristics of excited nickel is performed, allowing to define character-istic timescales of thermocapillary processes which may occur under multi-pulse irradiation

Regard comparé du régime d’imposition de la plus-value immobilière des particuliers en France et en Lituanie

This paper analyzes the Real Estate sales process from the point of view of taxation in Lithuania and in France. The authors focused on the most relevant and debatable legal issues in their opinion which impact the status of the individuals selling their dwelling located in one of these countries, and the impact on the tax regulations on the property owner‘s behavior. The first part deals with profit taxation systems and their differences in both France and Lithuania. The authors analyze the legislative regulation and implementation problems, the compliance of the regulation with the European Union provisions for the taxation purposes, submit proposals for regulatory improvement. They analyse the scope of taxation of profit gained from the sales of real estate which are made by a natural person, also the effect of the real estate sales over-taxation on Lithuanian and French residents’ behavior. It should be noted that the authors of the article provide a number of tables that visually show the tax burden impact on the state‘s economy and the real estate owner‘s behavior. It should be noted that for the analysis of profits taxation issue, one of the most important questions is whether the individual is a resident of a country where such a fee is paid. As provided by the international treaties, double taxation could be avoided, but because of the many exceptions the application of such treaties is not quite clear. It should be noted that Lithuania stands out from other European Union countries in real estate taxation because the tax system is not such an immense burden on a citizen as it is in France. It can be argued that in taxation of real estate, it is necessary to take into account the application of the principle of fairness in tax law, and the state economic goals.Straipsnyje analizuojama nekilnojamojo turto pardavimo procesas Lietuvoje ir Prancūzijoje mokestiniu aspektu. Bendraautoriai pasirinko, jų nuomone, aktualiausius ir diskutuotinus fizinio asmens teisinės padėties klausimus, parduodant savo gyvenamąjį būstą esantį vienoje iš šių šalių teritorijų, bei mokestinio režimo įtaką nekilnojamojo turto savininko elgesiui. Pirmoje straipsnio dalyje aptariamos pelno apmokestinimo sistemos, jų skirtumai ir Prancūzijoje, ir Lietuvoje. Autoriai analizuoja teisės aktų reglamentacijos ir įgyvendinimo problemas, šių valstybių reglamentavimo atitiktis Europos Sąjungos numatytiems apmokestinimo tikslams, teikia pasiūlymus dėl reglamentacijos tobulinimo. Analizuoja pelno, gauto iš nekilnojamojo turto pardavimo, kai pardavimas vykdomas fizinio asmens, apmokestinimo apimtis ir per didelio apmokestino naštos poveikį Lietuvos ir Prancūzijos rezidentų elgesiui su nekilnojamuoju turtu. Pabrėžtina, kad autoriai straipsnyje pateikia lentelių, kuriomis vizualiai įrodo apmokestinimo naštos įtaką valstybės ekonomikai, bei nekilnojamojo turto savininko elgesiui. Pažymėtina, kad analizuojant gauto pelno apmokestinimo klausimą, vienas iš svarbiausių klausimų yra ar fizinis asmuo yra rezidentas šalyje, kur mokamas toks mokestis. Tarptautinės sutartys padeda išvengti dvigubo apmokestinimo, tačiau esant daugybei išimčių, jų taikymas nėra pakankamai akivaizdus. Pažymėtina, kad Lietuva išsiskiria iš kitų Europos Sąjungos valstybių mokestiniu aspektu, kadangi mokestinė sistema nėra tokia didelė našta piliečiui, kaip tai konstatuojame Prancūzijoje. Galima teigti, kad apmokestinant nekilnojamąjį turtą, būtina atsižvelgti į teisingumo principo taikymą mokesčių teisėje, bei valstybės ekonominius tikslus

Emptying time of a tank filled up with explosive paste. Comparison between experimental measurements and predictions based on rheological characterization of the paste

International audienceOne industrial process used by Nexter Munitions to manufacture pyrotechnical materials consists in preparing an emulsion of wax in TNT (2,4,6-trinitrotoluene) and adding Aluminium and ONTA (3-nitro-1,2,4-triazole-5-one) particles. When the suspension is homogeneous, it is allowed to flow by gravity through a pipe located at the bottom of the tank and to fill up a shell body. The suspension is characterized by a solid volume fraction of 53.4%, which leads to high viscosities. In some circumstances, the emptying time is prohibitively long and the economic profitability is reduced. This study has been performed to make the emptying time lower with the constraint of unchanged volume fractions and grains mean diameter. So, we investigated the influence of the grain size distribution on the suspension viscosity. Different samples of Aluminium and ONTA have been used, with rather small differences in grain size distributions. The suspensions have been prepared in the industrial tank and the flow cast times measured. It has been observed that they differ by one order of magnitude. To avoid situations with too high emptying times, a procedure has been implemented to make prior characterization of the suspension rheology. Because of particles sedimentation and emulsion destabilisation, the classical Couette rheometer is not adapted. So, we designed and built a small size tank (113 cm3), where the suspension is continuously stirred and kept homogeneous. The measurement of the torque and rotational speed together with the use of the Couette analogy allowed us to observe an Ostwald fluid behaviour (flow consistency index k, flow behaviour index n). To gain in prediction, we established a correlation between the measured (k, n) values and the grain size distributions. We characterized each suspension by the ratio of to , where is the solid volume fraction (imposed by the commercial specifications) and is the maximum packing fraction. Because of the strong analogy between concrete and energetic paste, we chose the widely used De Larrard model to compute . A linear dependance between the ratio and the indices k and n was observed. The second step was to provide an analytical expression for the flow cast time of a power-law suspension from a tank with a given geometry. Considering the large difference between the industrial inner tank diameter and the evacuation pipe diameter, we assumed that all the pressure drop was located in the evacuation pipe. Then, extending the Hagen-Poiseuille equation to Ostwald fluid, we were able to predict the emptying time with the knowledge of k and n. Experimental and predicted emptying time are in very good agreement. This work helped the industrial manufacturer to divide the emptying time by a factor 12

Subclass Mapping: Identifying Common Subtypes in Independent Disease Data Sets

Whole genome expression profiles are widely used to discover molecular subtypes of diseases. A remaining challenge is to identify the correspondence or commonality of subtypes found in multiple, independent data sets generated on various platforms. While model-based supervised learning is often used to make these connections, the models can be biased to the training data set and thus miss inherent, relevant substructure in the test data. Here we describe an unsupervised subclass mapping method (SubMap), which reveals common subtypes between independent data sets. The subtypes within a data set can be determined by unsupervised clustering or given by predetermined phenotypes before applying SubMap. We define a measure of correspondence for subtypes and evaluate its significance building on our previous work on gene set enrichment analysis. The strength of the SubMap method is that it does not impose the structure of one data set upon another, but rather uses a bi-directional approach to highlight the common substructures in both. We show how this method can reveal the correspondence between several cancer-related data sets. Notably, it identifies common subtypes of breast cancer associated with estrogen receptor status, and a subgroup of lymphoma patients who share similar survival patterns, thus improving the accuracy of a clinical outcome predictor

Load-Balanced LU and QR Factor and Solve Routines for Scalable Processors with Scalable I/O

The concept of block-cyclic order elimination can be applied to out-of-core LU and QR matrix factorizations on distributed memory architectures equipped with a parallel I/O system. This elimination scheme provides load balanced computation in both the factor and solve phases and further optimizes the use of the network bandwidth to perform I/O operations. Stability of LU factorization is enforced by full column pivoting. Performance results are presented for the Connection Machine system CM-5.Engineering and Applied Science