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Search Results: 1 - 10 of 64 matches for " Arezki Tagnit-Hamou "
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Effect of Glass Powder on Concrete Sustainability  [PDF]
Ablam Zidol, Monique Tohoue Tognonvi, Arezki Tagnit-Hamou
New Journal of Glass and Ceramics (NJGC) , 2017, DOI: 10.4236/njgc.2017.72004
Abstract: As defined by the American Concrete Institute (ACI), alternative supplementary cementitious materials (ASCMs) and local materials are very important in concrete sustainability. As an ASCM, glass powder (GP) shows excellent pozzolanic properties. This paper focuses on characterization and the effect of GP on concrete properties compared to those of Class F fly ash (FFA) and ground granulated blast furnace slag (GGBS). Concrete incorporating 0, 20 and 30% of GP and other concrete mixes containing 30% of FFA or GGBS were cast. The concrete mixes considered in this study have water to binder (w/b) mass ratio ranging from 0.35 to 0.65. The mechanical properties such as compressive strength and durability including chloride ions permeability and chloride ions diffusion are evaluated. The results show that GP develops effects on mechanical properties similar to those of FFA and performs better than GGBS and FFA in terms of permeability reduction. GP reduces dramatically chloride permeability of concrete regardless w/b ratio, favoring an improvement of the concrete durability. Because of the interesting permeability developed by concretes incorporating GP, its use as an ASCM is promising.
Reactivity of Fine Quartz in Presence of Silica Fume and Slag  [PDF]
Karima Arroudj, Abdelfetah Zenati, Mohamed Nadjib Oudjit, Abderrahim Bali, Arezki Tagnit-Hamou
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.36067
Abstract: Dune sand is a very abundant material in south of Algeria. Its high silica content gives a partial pozzolanic reactivity due to its crystalline state. This paper investigates the evolution of cement hydration based on a binary addition particularly the reactivity of dune sand finely ground in the presence of an amorphous addition: silica fume or blast furnace slag. Thus, four combinations of binary additions by substitution have been chosen. The X-ray diffraction analyses performed on cement pastes containing additions have shown the importance of the mineralogy and silica content of additions on their pozzolanic reactivity. Dune sand becomes reactive at long term, especially when associated up to 10% of amorphous addition (blast furnace slag or silica fume). It results an increasing in mechanical strength of Ultra High Performance Concrete (UHPC) and an improvement of the microstructure.
Marketing: Another Way to Establish Environmental Respect
Communications of the IBIMA , 2010,
Abstract: In addition to decrees and decisions of government policies forcing companies to lead a process of changing, which is part of sustainable development, promotion and encouragement can be developed based on marketing tools. The difficulty of convincing a company to implement its management with the recommendations of sustainable development practices lies in encouraging them to start a policy of changing. That is why it is consequent to push the company to rethink and put in place a new managing system. Awareness of companies and citizens is in the centre of our communication, the state should be the first to be aware that it is nowadays essential to protect its resources, and then must introduce legislation in this way. When legal documents requiring individuals and firms to change their behaviours are absent, is not it possible to persuade firms to pursue a policy of sustainable development through the use of practices based marketing strategies (case of Non Governmental Organisations)? How should the marketing department of these companies work to transform the expenditure incurred by the changing process in a redoubtable competitive advantage (the case of businesses)?
L’opinion de Locke sur la matière pensante .
Philippe Hamou
Methodos : Savoirs et Textes , 2004, DOI: 10.4000/methodos.123
Abstract: Dans cet article, on montre que l’hypothèse de la matière pensante introduite spéculativement dans le livre IV de l’Essai sur l’Entendement humain, n’est pas seulement l’instrument d’une critique épistémologique destinée à souligner les limitations de notre connaissance, elle est aussi révélatrice des inclinations métaphysiques réelles de Locke. S’il est impossible de s’assurer par la connaissance de la nature de la substance pensante, il est permis néanmoins d’entretenir à son égard une opinion fondée sur des arguments probables. La croyance est en effet aux yeux de Locke un champ d’exercice légitime de la rationalité, un champ qu’il sera particulièrement nécessaire de cultiver lorsque la connaissance manquera et qu’il s’agira de se déterminer sur des questions cruciales – au nombre desquelles il faut compter assurément celle de la substance et de la destination de l’ame. On examine ici les textes et les arguments qui ont conduit la plupart des interprètes de Locke à lui prêter une croyance dualiste de type cartésien, favorisant l’opinion de l’immatérialité de l’esprit humain. On montre que ces textes et ces arguments non seulement ne sont pas concluants mais peuvent même être mis au service de la thèse adverse. Que Locke ait cru en la probable matérialité de l’ame humaine est d'autant plus plausible que les arguments donnés dans la troisième lettre à Stillingfleet en faveur de la concevabilité de l'hypothèse, fonctionnent aussi tacitement comme des arguments de probabilité : l'hypothèse ne contredit pas le message scripturaire, elle permet une meilleure conception de l'analogie générale du vivant, elle est mieux conforme aux requisits ontologiques de l'existence et de l'identité. This paper aims to show that the thinking matter hypothesis, which Locke introduces in the fourth book of the Essay as mere speculation, should not only be considered as an epistemological device employed to point out the limitations of human knowledge, but also tells something important about Locke’s true metaphysical inclinations. Though it is impossible to obtain any knowledge about the true nature of thinking substances, one is nevertheless allowed to frame one’s own opinion about it. Locke always considered the making and regulating of sound belief to be legitimate aims of human reason, especially when knowledge is impossible and when the topic is of great human concern, as the nature and destination of the soul evidently is. Locke scholars generally agree that, despite the thinking matter hypothesis, the author of the Essay was some sort of a Cartesian dual
A quasistatic bilateral contact problem with friction for nonlinear elastic materials
Arezki Touzaline
Electronic Journal of Differential Equations , 2006,
Abstract: We consider a mathematical model describing the bilateral contact between a deformable body and a foundation. We use a nonlinear elastic constitutive law. The contact takes into account the effects of friction, which are modelled with the regularized friction law. We derive a variational formulation of the problem and establish the existence of a weak solution under a smallness assumption of the friction coefficient. The proof is based on arguments of compactness, lower semicontinuity and time discretization.
A Quasistatic unilateral contact problem with slip-dependent coefficient of friction for nonlinear elastic materials
Arezki Touzaline
Electronic Journal of Differential Equations , 2006,
Abstract: Existence of a weak solution under a smallness assumption of the coefficient of friction for the problem of quasistatic frictional contact between a nonlinear elastic body and a rigid foundation is established. Contact is modelled with the Signorini condition. Friction is described by a slip dependent friction coefficient and a nonlocal and regularized contact pressure. The proofs employ a time-discretization method, compactness and lower semicontinuity arguments.
Frictionless contact problem with adhesion for nonlinear elastic materials
Arezki Touzaline
Electronic Journal of Differential Equations , 2007,
Abstract: We consider a quasistatic frictionless contact problem for a nonlinear elastic body. The contact is modelled with Signorini's conditions. In this problem we take into account of the adhesion which is modelled with a surface variable, the bonding field, whose evolution is described by a first order differential equation. We derive a variational formulation of the mechanical problem and we establish an existence and uniqueness result by using arguments of time-dependent variational inequalities, differential equations and Banach fixed point. Moreover, we prove that the solution of the Signorini contact problem can be obtained as the limit of the solution of a penalized problem as the penalization parameter converges to 0.
A quasistatic frictional contact problem with adhesion for nonlinear elastic materials
Arezki Touzaline
Electronic Journal of Differential Equations , 2008,
Abstract: The aim of this paper is to study a quasistatic contact problem between a nonlinear elastic body and a foundation. The contact is adhesive and frictional and is modelled with a version of normal compliance condition and the associated Coulomb's law of dry friction. The evolution of the bonding field is described by a first order differential equation. We establish the variational formulation of the mechanical problem and prove an existence result of the weak solution if the coefficient of friction is sufficiently small by passing to the limit with respect to time. The proofs are based on arguments of time-discretization, compactness, lower semicontinuity and Banach fixed point.
Resolutions of parabolic equations in non-symmetric conical domains
Arezki Kheloufi
Electronic Journal of Differential Equations , 2012,
Abstract: This article is devoted to the analysis of a two-space dimensional linear parabolic equation, subject to Cauchy-Dirichlet boundary conditions. The problem is set in a conical type domain and the right hand side term of the equation is taken in a Lebesgue space. One of the main issues of this work is that the domain can possibly be non regular. This work is an extension of the symmetric case studied in Sadallah [13].
On size and growth of cells
Arezki Boudaoud
Physics , 2002,
Abstract: Understanding how growth induces form is a longstanding biological question. Many studies concentrated on the shapes of plant cells, fungi or bacteria. Some others have shown the importance of the mechanical properties of bacterial walls and plant tissues in pattern formation. Here I sketch a simple physical picture of cell growth. The study is focussed on isolated cells that have walls. They are modeled as thin elastic shells containing a liquid, which pressure drives the growth as generally admitted for bacteria or plant cells. Requiring mechanical equilibrium leads to estimations of typical cell sizes, in quantitative agreement with compiled data including bacteria, cochlear outer hair, fungi, yeast, root hair and giant alga cells.
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