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Conditions for Set Agreement with an Application to Synchronous Systems

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Journal of Computer Science & Technology 2009年第3期24卷 418-433页

作者： Francois Bonnet michel Raynal IRISA University of Rennes35042 Rennes CedexFrance

The k-set agreement problem is a generalization of the consensus problem： considering a system made up of n processes where each process proposes a value, each non-faulty process has to decide a value such that a decided value is a proposed value, and no more than k different values are decided. While this problem cannot be solved in an asynchronous system prone to t process crashes when t≥ k, it can always be solved in a synchronous system; [t/k]＋1 is then a lower bound on the number of rounds （consecutive communication steps） for the non-faulty processes to decide. The condition-based approach has been introduced in the consensus context. Its aim was to both circumvent the consensus impossibility in asynchronous systems, and allow for more efficient consensus algorithms in synchronous systems. This paper addresses the condition-based approach in the context of the k-set agreement problem. It has two main contributions. The first is the definition of a framework that allows defining conditions suited to the l-set agreement problem and the second is a generic synchronous k-set agreement algorithm based on conditions.

关键词： agreement problem condition efficiency lower bound synchronous system

Seismic vulnerability evaluation of axially loaded steel built-up laced members II:evaluations

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Earthquake Engineering and Engineering Vibration 2008年第2期7卷 125-136页

作者： Kangmin Lee michel Bruneau Department of Architectural Engineering Chungnam National University Department of Civil Structuraland Environmental EngineeringUniversity at BuffaloState University of New York

The test results described in Part 1 of this paper （Lee and Bruneau, 2008） on twelve steel built-up laced members （BLMs） subjected to quasi-static loading are analyzed to provide better knowledge on their seismic behavior. Strength capacity of the BLM specimens is correlated with the strength predicted by the AISC LRFD Specifications. Assessments of hysteretic properties such as ductility capacity, energy dissipation capacity, and strength degradation after buckling of the specimen are performed. The compressive strength of BLMs is found to be relatively well predicted by the AISC LRFD Specifications. BLMs with smaller kl/r were ductile but failed to reach the target ductility of 3.0 before starting to fracture, while those with larger kl/r could meet the ductility demand in most cases. The normalized energy dissipation ratio, EC/ET and the normalized compressive strength degradation, Cr″/Cr of BLMs typically decrease as normalized displacements δ/δb,exp increase, and the ratios for specimens with larger kl/r dropped more rapidly than for specimens with smaller kl/r; similar trends were observed for the monolithic braces. The BLMs with a smaller slenderness ratio, kl/r, and width-to-thickness ratio, b/t, experienced a larger number of inelastic cycles than those with larger ratios.

关键词： seismic vulnerability built-up compression member strength capacity ductility capacity energy dissipation strength degradation

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Ahlfors-regular curves and Carleson measures

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Science China Mathematics 2020年第6期63卷 1057-1064页

作者： Huaying Wei michel Zinsmeister Department of Mathematics and Statistics Jiangsu Normal UniversityXuzhou 21116China IDP Universite d'OrleansOrleans 45067France

We study the relation between the boundary of a simply connected domainΩbeing Ahlfors-regular and the invariance of Carleson measures under the push-forward operator induced by a conformal mapping from the unit disk△onto the domainΩ.As an application,we characterize the chord-arc curves with small norms and the asymptotically smooth curves in terms of the complex dilatation of some quasiconformal reflection with respect to the curve.

关键词： Ahlfors-regular curve Carleson measure push-forward operator chord-arc curve asymptotically smooth curve

Simulation of unconventional well tests with the finite volume method

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Petroleum Science 2012年第3期9卷 317-329页

作者： CANCELLIERE michel VERGA Francesca Politecnico di Torino DITAGTorino (TO) 10129 Italy

The finite volume method has been successfully applied in several engineering fields and has shown outstanding performance in fluid dynamics simulation. In this paper, the general framework for the simulation ofnear-wellbore systems using the finite volume method is described. The mathematical model and the numerical model developed by the authors are presented and discussed. A radial geometry in the vertical plane was implemented so as to thoroughly describe near-wellbore phenomena. The model was then used to simulate injection tests in an oil reservoir through a horizontal well and proved very powerful to correctly reproduce the transient pressure behavior. The reason for this is the robustness of the method, which is independent of the gridding options because the discretization is performed in the physical space. The model is able to describe the phenomena taking place in the reservoir even in complex situations, i.e. in the presence of heterogeneities and permeability barriers, demonstrating the flexibility of the finite volume method when simulating non-conventional tests. The results are presented in comparison with those obtained with the finite difference numerical approach and with analytical methods, if possible.

关键词： Finite volume method numerical methods horizontal well modeling injection testing gridding

Enhanced Userspace and In-Kernel Trace Filtering for Production Systems

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Journal of Computer Science & Technology 2016年第6期31卷 1161-1178页

作者： Suchakrapani Datt Sharma michel Dagenais Department of Computer and Software Engineering Ecole Polytechnique de Montrdal Montreal H3T 1J4 Canada

Trace tools like LTTng have a very low impact on the traced software as compared with traditional debuggers. However, for long runs, in resource constrained and high throughput environments, such as embedded network switching nodes and production servers, the collective tracing impact on the target software adds up considerably. The overhead is not just in terms of execution time but also in terms of the huge amount of data to be stored, processed and analyzed offiine. This paper presents a novel way of dealing with such huge trace data generation by introducing a Just-In-Time （JIT） filter based tracing system, for sieving through the flood of high frequency events, and recording only those that are relevant, when a specific condition is met. With a tiny filtering cost, the user can filter out most events and focus only on the events of interest. We show that in certain scenarios, the JIT compiled filters prove to be three times more effective than similar interpreted filters. We also show that with the increasing number of filter predicates and context variables, the benefits of JIT compilation increase with some JIT compiled filters being even three times faster than their interpreted counterparts. We further present a new architecture, using our filtering system, which can enable co-operative tracing between kernel and process tracing VMs （virtual machines） that share data efficiently. We demonstrate its use through a tracing scenario where the user can dynamically specify syscall latency through the userspace tracing VM whose effect is reflected in tracing decisions made by the kernel tracing VM. We compare the data access performance on our shared memory system and show an almost 100 times improvement over traditional data sharing for co-operative tracing.

关键词： tracing debugging filtering operating system interpreter

Some questions about landscape modelling

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Journal of Environmental Sciences 2001年第4期13卷 459-465页

作者： michel Godron LI Xiu-zhen CCAS F18410BrinonFrance Institute of Applied Ecology Chinese Academy of SciencesShenyang 110016China

The paper discusses mainly about the modelling process and related problems with examples from Chinese and French cases. Five practical problems must be solved for modelling the functioning of any landscape: ( 1) The field data are necessarily taken with a sampling procedure that implies a spatial (and often temporal) scale. (2) Every landscape modelled has to be identified, delimited and characterised before application of the hierarchical theory. (3) The functioning of a landscape involves data of multiple types (climate, soil, vegetation, fauna, buildings, communications, economy, aesthetics, etc.) which must be integrated in a holistic approach. (4) Every landscape is spatially heterogeneous, and the structure of the model must be more or less isomorphic with its heterogeneity. ( 5) The evolution of the landscape must be modelled on a rather long period of time. For all these reasons, it is necessary to build ad hoc models. Object-oriented computing languages may be useful for this purpose.

关键词： landscape modelling scale hierarchy holistic approach application

Shapes,structures,and evolution of small bodies

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Astrodynamics 2021年第4期5卷 293-329页

作者： Yun Zhang Patrick michel Universit´e Cote d’Azur Observatoire de la Cote d’AzurCNRSLaboratoire LagrangeNice06304France Department of Aerospace Engineering University of MarylandCollege ParkMD20742USA

Small bodies are among the best tracers of our Solar System’s history.A large number of space missions to small bodies(past and future)offer a unique opportunity to use these bodies as a natural laboratory to study the different processes,mechanical structures,and responses that drive the origin and evolution of small bodies,which are connected to the origin,evolution,and current architecture of the Solar *** of small bodies sent by spacecraft have revealed unexpectedly rich and complex geological *** addition to very diverse compositions,small bodies in the Solar System have highly diverse shapes and structures,which reflect both different evolutionary paths and material ***,each individual body has diverse geological features on its surface,which include craters of various sizes and depths,boulders of different sizes and morphologies,lineaments,fractures,pits,signatures of landslides,terraces,and *** a geological richness could not be detected via ground-based observations,and we are still at the beginning of understanding their significance on the low-gravity surfaces on which they *** combination of space mission data and numerical modeling allows us to enrich our understanding of the origin,evolution,and physical properties of these fascinating *** instance,starting from the shape models,bulk densities,and spin rates determined from space mission data,we can investigate the formation mechanisms that lead to the observed properties of small *** can also infer the interior and mechanical properties(e.g.,friction and cohesion)that allow a small body to be structurally stable,as well as its further potential evolution under processes such as a spin rate increase or an ***,considering the various processes that these bodies experience during their evolution,we can investigate how these processes modify their properties and,in turn,how those properties influence the outcome of these ***

关键词： small bodies internal structure collisional evolution thermal evolution rotational evolution tidal encounter

Uptake of U-and Th-series radionuclides by cereal crops in Upper Egypt

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Nuclear Science and Techniques 2009年第2期20卷 99-105页

作者： SHABAN Harb ROLF michel Center for Radiation Protection and Radioecology Hanover University(ZSR) Physics Department Faculty of ScienceSouth Valley University

The main aim of this study is to determine the activity concentrations of uranium series and thorium series radionuclide in crops cultivated in Upper *** types of cereal crops were collected from local markets and analyzed by γ-ray *** mean activity concentrations of the natural radionuclides 238U,226Ra and 232Th were 0.67,1.27 and 0.56 Bq·kg-1,*** annual effective doses from these radionuclides were estimated for different age groups.

关键词：天然放射性核素谷类作物埃及 U型吸收 226Ra 作物栽培有效剂量

Uranium,rare metals,and granulite-facies metamorphism

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Geoscience Frontiers 2014年第5期5卷 729-745页

作者： michel Cuney Pierre Barbey CNRS Georessources.UMR 7359.BP 239F-54506 Vandauvre-les-NancyFrance b CNRS.CRPC.UMR 7359.BP 20F-54501 Vandoeuvre-les-Nancy Cedex.France Universite de Lorraine.CS 25233.F-54042 Nancy.France

During granulite-facies metamorphism of metasedimentary rocks by the infiltration of carbonic fluids, the disappearance of hydrated minerals leads to the liberation of aqueous fluids. These fluids are strongly enriched in F and C1, and a series of Large-lon-Lithophile （LIL） elements and rare metals, resulting in their depletion in granulites. To sum up the fate of these elements, we focus on three domains representing different crustal levels and showing distinct behaviours with respect to these elements. The Lapland metasedimentary granulites illustrate the behaviour of the LILE and rare metals during lower crustal metamorphism. There is no change in Ba, moderate loss in Rb, and extreme depletion in Cs, Li, and Sn. F and CI contents are also very low compared to the protoliths or average upper continental crust. Biotite and amphibole breakdown leads to the incorporation of their partitioning into a fluid or a melt. The Tranomaro metasomatized marbles recrystallizing under granulite-facies conditions represent a demonstrative example of fluid transfer from granulite-facies supracrustals to traps represented by regional scale skarns. Such fluids may be at the origin of the incompatible element enrichment detected in leucosomes of migmatites from St Malo in Brittany （France） and Black Hills in South Dakota, The northern French Massif Central provides us with an example of a potential association between incompatible element enrichment of granitic melts and granulite-facies metamorphism. U- and F- enriched fine-grained granites are emplaced along a crustal scale shear zone active during the emplacement within the St Sylvestre peraluminous leucogranitic complex, We propose that during granulite-facies metamorphism dominated by carbonic waves in a deep segment of the continental crust, these shear zones control：（i） the percolation of F-, LILE-, rare metal-rich fluids liberated primarily by the breakdown of biotite; （ii） the enhancement of partial melting by F-rich flui

关键词： GranuliteCarbonic waveUraniumRare metalsPartial meltingFluorine