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Numerical investigation of Reynolds number and scaling effects in microchannels flows

Journal of Hydrodynamics 2017年第4期29卷 647-658页

作者： S.A.Si Salah e.g.filali S.Djellouli Faculty of Mechanical and Process engineering Houari Boumedienne University

Compared with conventional channels, experiments of microchannel often exhibit some controversial findings and sometimes even opposite trends, most notably the effects of the Reynolds number and the scaled channel height on the Poiseuille number. The experimental method has still been constrained by two key facts, firstly the current ability to machine microstructures and secondly the limitation of measurement of parameters related to the Poiseuille number. As a consequence, numerical method was adopted in this study in order to analyze a flow in two-dimensional rectangular microchannels using water as working fluid. Results are obtained by the solution of the steady laminar incompressible Navier-Stokes equations using control volume finite element method（CVFeM） without pressure correction. The computation was made for channel height ranging from 50 ？m to 4.58 ？m and Reynolds number varying from 0.4 to 1 600. The effect of Reynolds number and channel heights on flow characteristics was investigated. The results showed that the Poiseuille numbers agree fairly well with the experimental measurements proving that there is no scale effect at small channel height. This scaling effect has been confirmed by two additional simulations being carried out at channel heights of 2.5 ？m and 0.5 ？m, respectively and the range of Reynolds number was extended from 0.01 up to 1 600. This study confirm that the conventional analysis approach can be employed with confidence for predicting flow behavior in microchannels when coupled with carefully matched entrance and boundary conditions in the dimensional range considered here.

关键词： Rectangular microchannel Poiseuille number control volume finite element method(CVFeM) laminar flow minichannels

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A comparative study between simplified and nonlinear dynamic methods for estimating liquefaction potential

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Journal of Rock Mechanics and geotechnical engineering 2017年第5期9卷 955-966页

作者： Kamel filali Badreddine Sbartai LMgHU Laboratory University of 20 August 1955-Skikda Skikda 21000 Algeria University of Badji Mokhtar Annaba 23000 Algeria

This paper estimated the liquefaction potential of a saturated soil deposit subjected to a horizontal seismic excitation at its base using the total stress approach.A comparative analysis between the simplified and the nonlinear dynamic methods was used to verify to what extent the simplified method could be *** order to generalise the reliability of the simplified method for any value of the maximum acceleration for the used earthquakes,a correction for the maximum acceleration less than 0.3 g was proposed based on the comparison of safety factor values determined by the dynamic method illustrated by the equivalent linear model with lumped masses and the simplified method for a given profile of soil subjected to 38 *** nonlinear behaviour of soil was represented by two hyperbolic models:Hardin and Drnevich,and *** determine the cyclic resistance ratio(CRR),the cone penetration test(CPT) based method,the standard penetration test(SPT) based method,and the shear wave velocity based method were *** safety factor was calculated as the ratio of CRR/CSR,where CSR represents the cyclic stress *** results of the proposed correction have given smaller values of the safety factor compared to the nonlinear dynamic methods for the maximum acceleration less than 0.3 *** other words,by considering this correction,the most unfavourable case is always given by the modified simplified method.

关键词： Liquefaction Soil earthquake Simplified method Nonlinear dynamic method

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A comparative study of two formal semantics of the SIgNAL language

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Frontiers of Computer Science 2013年第5期7卷 673-693页

作者： Zhibin YANg Jean-Paul BODeVeIX Mamoun filali School of Computer Science and engineering Beihang University Beijing 100191 China IRIT-CNRS Universite de Toulouse Toulouse 31062 France

SIgNAL is a part of the synchronous languages family, which are broadly used in the design of safety-critical real-time systems such as avionics, space systems, and nu- clear power plants. There exist several semantics for SIg- NAL, such as denotational semantics based on traces （called trace semantics）, denotational semantics based on tags （called tagged model semantics）, operational semantics presented by structural style through an inductive definition of the set of possible transitions, operational semantics defined by syn- chronous transition systems （STS）, etc. However, there is lit- tle research about the equivalence between these semantics. In this work, we would like to prove the equivalence be- tween the trace semantics and the tagged model semantics, to get a determined and precise semantics of the SIgNAL language. These two semantics have several different defini- tions respectively, we select appropriate ones and mechanize them in the Coq platform, the Coq expressions of the abstract syntax of SIgNAL and the two semantics domains, i.e., the trace model and the tagged model, are also given. The dis- tance between these two semantics discourages a direct proof of equivalence. Instead, we transform them to an intermediate model, which mixes the features of both the trace semantics and the tagged model semantics. Finally, we get a determined and precise semantics of SIgNAL.

关键词： synchronous language SIgNAL trace seman- tics tagged model semantics semantics equivalence Coq

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Towards a simple and safe Objective Caml compiling framework for the synchronous language SIgNAL

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Frontiers of Computer Science 2019年第4期13卷 715-734页

作者： Zhibin YANg Jean-Paul BODeVeIX Mamoun filali School of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 211106 China State Key Laboratory of Software Development environment Beijing 100191 China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing 211106 China IRIT-CNRS Universite de Toulouse Toulouse 31062 France

This paper presents a simple and safe compiler, called MinSIgNAL, from a subset of the synchronous dataflow language SIgNAL to C, as well as its existing en? hancements. The compiler follows a modular architecture, and can be seen as a sequence of source-to-source transformations applied to an intermediate representation which is named Synchronous Clocked guarded Actions (S-CgA) and translation to sequential imperative code. Objective Caml (OCaml) is used for the implementation of MinSIgNAL. As a modem functional language, OCaml is adapted to symbolic computation and so, particularly suitable for compiler design and implementation of formal analysis tools. In particular, the safety of its type checking allows to skip some verification that would be mandatory with other languages. Additionally, this work is a basis for the formal verification of the compilation of SIgNAL with a theorem prover such as Coq.

关键词： synchronous languages SIgNAL Synchronous Clocked guarded Actions (S-CgA) Objective Caml functional programming

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An SPH Framework for earthquake-Induced Liquefaction Hazard Assessment of geotechnical Structures

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Computer Modeling in engineering & Sciences 2025年第1期142卷 251-277页

作者： Sourabh Mhaski g.V.Ramana Department of Civil engineering Indian Institute of Technology DelhiNew Delhi110016India

earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures *** understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient *** present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical *** coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile ***,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are *** numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando *** agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical *** present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.

关键词： earthquake seismic liquefaction stress particle PM4Sand smoothed particle hydrodynamics(SPH)

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Stepping up after spinal cord injury:negotiating an obstacle during walking

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Neural Regeneration Research 2025年第7期20卷 1919-1929页

作者： Alain Frigon Charly g.Lecomte Department of Pharmacology-Physiology Faculty of Medicine and Health SciencesUniversitéde SherbrookeCentre de recherche du Centre Hospitalier Universitaire de SherbrookeSherbrookeQCCanada

every day walking consists of frequent voluntary modifications in the gait pattern to negotiate *** spinal cord injury,stepping over an obstacle becomes *** over an obstacle requires sensorimotor transformations in several structures of the brain,including the parietal cortex,premotor cortex,and motor *** information and planning are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain *** spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including humans,fail to voluntarily modify limb trajectory to step over an ***,in this review,we discuss the neuromechanical control of stepping over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.

关键词： biomechanics locomotion neurophysiology obstacle negotiation spinal cord injury

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Projective Hilbert modules and sequential approximations

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Science China Mathematics 2025年第1期 137-168页

作者： Lawrence g.Brown Huaxin Lin Department of Mathematics Purdue University Department of Mathematics East China Normal University Department of Mathematics University of Oregon Shanghai Institute for Mathematics and Interdisciplinary Sciences

We show that when A is a separable C*-algebra,every countably generated Hilbert A-module is projective（with bounded module maps as morphisms）.We also study the approximate extensions of bounded module *** the case where A is a σ-unital simple C*-algebra with strict comparison,and every strictly positive lower semicontinuous affine function on quasitraces can be realized as the rank of an element in the Cuntz semigroup,we show that the Cuntz semigroup is equivalent to unitarily equivalent classes of countably generated Hilbert A-modules if and only if A has stable rank one.

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Towards a verified compiler prototype for the synchronous language SIgNAL

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Frontiers of Computer Science 2016年第1期10卷 37-53页

作者： Zhibin YANg Jean-Paul BODeVeIX Mamoun filali Kai HU Yongwang ZHAO Dianfu MA College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China IRIT-CNRS Universite de Toulouse Toulouse 31062 France State Key Laboratory of Software Development environment Beihang University Beijing 100191 China

SIgNAL belongs to the synchronous languages family which are widely used in the design of safety-critical real-time systems such as avionics, space systems, and nu- clear power plants. This paper reports a compiler prototype for SIgNAL. Compared with the existing SIgNAL com- piler, we propose a new intermediate representation （named S-CgA, a variant of clocked guarded actions）, to integrate more synchronous programs into our compiler prototype in the future. The front-end of the compiler, i.e., the transla- tion from SIgNAL to S-CgA, is presented. As well, the proof of semantics preservation is mechanized in the theo- rem prover Coq. Moreover, we present the back-end of the compiler, including sequential code generation and multi- threaded code generation with time-predictable properties. With the rising importance of multi-core processors in safety- critical embedded systems or cyber-physical systems （CPS）, there is a growing need for model-driven generation of multi- threaded code and thus mapping on multi-core. We propose a time-predictable multi-core architecture model in archi- tecture analysis and design language （AADL）, and map the multi-threaded code to this model.

关键词： synchronous languages SIgNAL guarded ac-tions verified compiler Coq architecture analysis and designlanguage (AADL)

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Bioelectronic medicine in modulation of cortical spreading depolarization and beyond

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Neural Regeneration Research 2025年第2期20卷 481-482页

作者： Khaled Alok Timothy g.White Chunyan Li Department of Neurosurgery Donald and Barbara Zucker School of Medicine at Hofstra/NorthwellHempsteadNYUSA Translational Brain Research Laboratory The Feinstein Institutes for Medical ResearchManhassetNYUSA

Bioelectronic interventions,specifically trigeminal nerve st imulat ion(TNS),have attracted considerable attention in conditions where cortical spreading depolarizations(CSDs)accompanied by compromised cerebral perfusion may exacerbate neurological *** pharmacological interventions have demonstrated initial potential in addressing CSDs,a standardized treatment approach has not yet been *** objective of this perspective is to explore emerging bioelectronic methodologies for addressing CSDs,particularly emphasizing TNS,and to underscore TNS’s capacity to enhance neurovascular coupling and cerebral perfusion.

关键词： cerebral perfusion electronic

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estimation of the peak flows in the catchment area of Batna(Algeria)

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Journal of groundwater Science and engineering 2020年第1期8卷 79-86页

作者： SAMI guellouh ABDeLWAHHAB filali Med ISSAM Kalla Laboratory LRNAT University of Batna-2

The limited knowledge of the variations,both spatial and temporal,of the flow patterns at the watershed level invariably leads to poor space management,generating great and often irreversible ***,measuring peak flows appears to be not only important but even *** to the absence of hydrometric stations at the outlet of the sub-basins that are part of comprehensive prevention strategy,and were established because of the high vulnerability of the city of Batna,this study provides a transformation model of rainfall into flows in the Batna *** work aims to model the transformation of rainfall into *** estimate the Q max,two formulas were used,and Turazza's seems to be the most adequate,because it demonstrates a cumulative sub-basins flow close to the result recorded by the only hydrometric station at the outlet of Batna *** this modeling,it is possible to estimate the extreme quantiles with the return periods of 10,20,50 and 100 years for each *** purpose is to help design of hydraulic works and increase the resilience of development projects that might be exposed to floods.

关键词： Flows Floods empirical methods Rainfall Turazza

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