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In this paper, we show that the results obtained in [7]: On a system of general mixed variational inequalities are incorrect. Also we suggest and analyze new approximation schemes 4.1 for solving the (SGMVID) which were introduced by M.A. Noor in [7]. [ABSTRACT FROM AUTHOR]

In this paper, we propose a primal–dual interior point method for Linear Complementarity Problem (LCP) based on a new parameterized kernel function. The investigation according to it yields the best-known iteration bound O (n log ⁡ (n) log ⁡ (n ϵ)) for large-update algorithm and thus improves the iteration bound obtained in Bai et al. (SIAM J Optim. 2004;15:101–128) for large-update algorithm. Finally, we present few numerical results to demonstrate the efficiency of the proposed algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we suggest and analyze a new approximation schemes (3) to solve the extended general variational inequalities (2), which were introduced by Muhammad Aslam Noor (see[7, 9]). Using the projection operator technique, we establish the equivalence between the extended general variational inequalities and the fixed-point problem. This equivalent formulation is used to discuss the existence of a solution of the extended general variational inequalities. Several special cases are also discussed. [ABSTRACT FROM AUTHOR]

The results of a survey made on athletes in body building in Algeries show that the age and the educational level have a big impact on the youth awareness about the effects of dietary supplements on our bodies; we made a survey in Algiers where we asked about one hundred athletes chosen randomly, we came out to the following result: the youth focus on building their bodies no matter what the harms of supplements are. This may be true even with some experienced athletes because the experience is not a determining factor, whereas the age and educational level are very necessary factors. [ABSTRACT FROM AUTHOR]

Abstract: Spatial localization of scalp EEG electrodes is a major step for dipole source localization and must be accurate, reproducible and practical. Several methods have been proposed in the last 15 years. The most widely used method is currently electromagnetic digitization. Nevertheless, this method is difficult to use in a clinical environment and has not been validated with a high number of electrodes. In this paper, we introduce a new automatic method for localizing and labeling EEG sensors using MRI. First, we design a new scalp EEG sensor. Secondly, we validate this new technique on a head phantom and then in a clinical environment with volunteers and patients. For this, we compare the reproducibility, accuracy and performance of our method with electromagnetic digitization. We demonstrate that our method provides better reproducibility with a significant difference (p <0.01). Concerning precision, both methods are equally accurate with no statistical differences. To conclude, our method offers the possibility of using MRI volume for both source localization and spatial localization of EEG sensors. Automation makes this method very reproducible and easy to handle in a routine clinical environment. [Copyright &y& Elsevier]

Abstract: The purpose of this study is to contribute to the knowledge of viscoelastic fluids flows in a contraction which are often studied numerically. A device has been conceived for an experimental study of the flow by Laser Doppler velocimetry. An isothermal flow through a rectangular duct including an abrupt contraction has been considered. We have characterized the isothermal flow for different values of Reynolds number and correlations of the axial velocity are presented. To cite this article: M. Mahfoud et al., C. R. Mecanique 336 (2008). [Copyright &y& Elsevier]

Abstract: The purpose of this paper is to develop the question of regional observability of a system described by the wave equation evolving in spatial domain . It concerns the observability of such a system only on a subregion of . Then we give definitions and characterization of this notion linked with sensors structure and we describe an important approach that estimates the state of the system on a given subregion. The study examines various kind of measurements and sensors. The obtained results are illustrated by numerical examples and simulations. [Copyright &y& Elsevier]

The existence of multiple modes of instability in Rayleigh-Bénard or Marangoni-Bénard situations has been known for many years. This existence is shown for the first time for low-Prandtl-number flows in three-dimensional cavities heated from the side. For such a situation, the study of the flow transitions has long remained a challenge, as these transitions occur in already very intense flows. The study is possible here thanks to performing numerical methods, and the ten first instability modes are determined for a wide range of aspect ratios and Prandtl number values. The most striking feature of our results is the very frequent change of leading mode when aspect ratios or Prandtl number are changed, which indicates different flow structures triggered at the transitions, either steady or oscillatory and breaking some of the symmetries of the problem. [ABSTRACT FROM AUTHOR]

Abstract: Résumé: Pour les fluides newtoniens dans des configurations simples, la définition du nombre de Reynolds ne présente aucune difficulté, par contre dans le cas d''écoulement de fluides non newtoniens dans des conduites de formes quelconques, la variation de la viscosité avec la vitesse de cisaillement nécessite une généralisation de ce nombre adimensionnel. Malheureusement plusieurs définitions différentes ont été proposées dans la littérature. Ce travail propose une méthode générale valable pour une large classe de fluides non newtoniens et pour toutes les formes de conduite. Une application est développée pour un fluide viscoélastique s''écoulant dans une conduite de forme rectangulaire. Les résultats obtenus par cette étude sont en bon accord avec les corrélations connues. For Newtonian fluids in simple configurations, the definition of the Reynolds number is quite a standard problem, but for non-Newtonian fluid flows in ducts with arbitrary shape of cross section, the dependence of the viscosity with the shear rate requires a generalization of this dimensionless number, unfortunately several different definitions have been proposed in the literature. This work proposes a general method valid for a large class of non-Newtonian fluids and for all duct shapes. Application is developed for a viscoelastic flow through a rectangular duct. Results obtained in the present investigation are in a good agreement with available correlations. [Copyright &y& Elsevier]

Abstract: The study of fluid flow in a duct requires characteristic parameters of the flow and dimensionless numbers to correlate and compare experimental results. For Newtonian fluids in simple configurations, the definition of the Reynolds number is quite standard, but for non-Newtonian fluid flows in ducts with arbitrary shape of cross section, the dependence of the apparent viscosity with the shear rate requires a generalization of this dimensionless number. This note proposes a general method valid for a large class of non-Newtonian fluids and for all duct shapes. An application is developed for a viscoelastic flow through a rectangular duct. Results obtained in the present investigation are in a good agreement with available correlations. To cite this article: M. Mahfoud et al., C. R. Mecanique 333 (2005). [Copyright &y& Elsevier]

An early and reliable diagnosis of pregnancy in cows is of considerable economic interest. It would improve the profitability of farmers by reducing the calving-calving interval and avoid any delay of fertilisation which is a cause of significant economic losses. The aim of this study is to evaluate and compare two diagnostic methods of pregnancy in cows after artificial insemination by the assay of the pregnancy-associated proteins (PAGs) and the ultrasonography. The study was carried out on 41 cows aged 3 to 6 years from the Batna region. Blood samples were collected at day (D28) post insemination. This study has shown that among the 41 cows, 25 (60.98%) were pregnant and 16 (39.02%) were not using the transrectal ultrasonography. The sensitivity and the specificity of the PAG assay were 100% and 93.75%, respectively. The specificity was 100% for the ultrasonography, and the embryonic mortalities was 2.43%. The comparative study of the two diagnostic methods of pregnancy has revealed the liability and precocity of the biochemical methods. It is necessary to sensitise inseminators and farmers to the importance of early diagnosis of pregnancy, especially by the use of PAG's assay. It is an essential component of reproduction monitoring and an excellent indicator of early abortions. [ABSTRACT FROM AUTHOR]

The transient growth due to non-normality is investigated for the Poiseuille-Rayleigh-Bénard problem of binary fluids with the Soret effect. For negative separation factors such as ψ = −0.1, it is found that a large transient growth can be obtained by the non-normal interaction of the two least-stable-modes, i.e., the upstream and downstream modes, which determine the linear critical boundary curves for small Reynolds numbers. The transient growth is so strong that the optimal energy amplification factor G( t) is up to 10 ~ 10. While for positive separation factors such as ψ = 0.1, the transient growth is weak with the order O(1) of the amplification factor, which can even be computed by the least-stable-mode. However, for both cases, the least-stable-mode can govern the long-term behavior of the amplification factor for large time. The results also show that large Reynolds numbers have stabilization effects for the maximum amplification within moderate wave number regions. Meanwhile, much small negative or large positive separation factors and large Rayleigh numbers can enlarge the maximum transient growth of the pure streamwise disturbance with the wavenumber α = 3.14. Moreover, the initial and evolutionary two-dimensional spatial patterns of the large transient growth for the pure streamwise disturbance are exhibited with a plot of the velocity vector, spanwise vorticity, temperature, and concentration field. The initial three-layer cell vorticity structure is revealed. When the amplification factor reaches the maximum G , it develops into one cell structure with large amplification for the vorticity strength. [ABSTRACT FROM AUTHOR]

The numerical simulation of blood flow in arteries using non-Newtonian viscosity model, presents two major difficulties; the first one is the choice of an appropriate constitutive equation, because no one model is universally accepted as a reflection of the true behavior of blood viscosity until now. Another difficulty lies in the numerical convergence of the complex scheme solving the highly non-linear set of equations governing the blood motion. In this paper, the pulsatile blood flow through an arterial stenosis has been numerically modeled to evaluate the flow characteristics and the wall shear stress under physiological conditions. The Navier-Stokes equations governing the fluid motion are solved using the finite element method in unsteady 2-D case. The behavior of blood is considered as the generalized power-law and Cross models, where the shear-thinning characteristics of the streaming blood are taken into account. Constants in the constitutive equations of previous models have been obtained by fitting experimental viscosity data. The numerical simulations are performed for a wide range of apparent shear rates (10 s-1-750 s-1) with good convergence of the iterative scheme. Results from the blood flow simulations indicate that non-Newtonian behavior has considerable effects on instantaneous flow patterns. However, it seems that the generalized power-law model will be slightly better for describing the non-Newtonian characteristics of blood than the Cross model. [ABSTRACT FROM AUTHOR]

Abstract: The temporal stability of a Carreau fluid flowing down an inclined porous substrate is considered. A reduced model is derived under the assumption of small permeability which decouples the flow in the liquid layer from the filtration flow in the porous medium and incorporates the effect of the porous medium by means of an effective slip condition at the liquid–solid interface. The slip coefficient in the effective slip condition is a function of the structure, permeability of the porous medium and the rheology of the fluid saturating the porous medium. The effects of shear-thinning rheology and permeability of the substrate on the stability of the film flow system are investigated. This problem gives rise to a generalized eigenvalue formulation which is solved through two approaches. The problem is solved analytically for long waves in the limiting cases of weakly and strongly non-Newtonian behaviors (power-law limit). A numerical investigation is carried out in the general case. The results are shown to agree well for the weakly non-Newtonian limit. Further, the power-law model and the Carreau model agree on a wide range of shear-thinning parameter values for a thin film over a rigid substrate. However, when considering a porous medium, this trend is not observed. The Carreau model gives valid results for the entire range of shear-thinning parameter values for a film over a rigid/porous substrate. The novelty of the present investigation lies in the inclusion of both the effects of bottom permeability and shear-thinning rheology. Both permeability and shear-thinning rheology have a destabilizing effect on the film flow system. The numerical results indicate the correlation between the effects due to shear-thinning properties and permeability. An energy balance analysis performed on the perturbation fields shows that destabilization induced by both shear-thinning and permeability is linked to the viscous shear work rate on the free surface. [Copyright &y& Elsevier]

Abstract: An acoustic Strouhal number is introduced to demonstrate that the viscosity of fluid can be ignored in the process of sound propagation and acoustic streaming is independent on the frequency of the acoustic wave. Furthermore, acoustic force based on the periodic velocity fluctuation caused by standing acoustic wave is introduced into Navier–Stokes equation in order to describe the fluid flow in the acoustic boundary layer. The numerical results show that the predicted results are consistent with the analytic solution. And the effect of the nonlinear terms cannot be ignored so the analytic solution derived by boundary-velocity condition is only an approximation for acoustic streaming. [Copyright &y& Elsevier]

Abstract: Several studies have described cranio–cerebral correlations in accordance with the 10–20 electrode placement system. These studies have made a significant contribution to human brain imaging techniques, such as near-infrared spectroscopy and trans-magnetic stimulation. With the recent development of high resolution EEG, an extension of the 10–20 system has been proposed. This new configuration, namely the 10–10 system, allows the placement of a high number (64–256) of EEG electrodes. Here, we describe the cranio–cerebral correlations with the 10–10 system. Thanks to the development of a new EEG-MRI sensor and an automated algorithm which enables the projection of electrode positions onto the cortical surface, we studied the cortical projections in 16 healthy subjects using the Talairach stereotactic system and estimated the variability of cortical projections in a statistical way. We found that the cortical projections of the 10–10 system could be estimated with a grand standard deviation of 4.6 mm in x, 7.1 mm in y and 7.8 mm in z. We demonstrated that the variability of projections is greatest in the central region and parietal lobe and least in the frontal and temporal lobes. Knowledge of cranio–cerebral correlations with the 10–10 system should enable to increase the precision of surface brain imaging and should help electrophysiological analyses, such as localization of superficial focal cortical generators. [Copyright &y& Elsevier]

Abstract: The effect of acoustic streaming (more precisely the Eckart streaming) on the linear stability of a laterally heated fluid layer confined between two horizontal infinite walls (Hadley flow) has been studied. In the considered range of Prandtl number (), three types of instabilities prevail in the absence of acoustic streaming: two-dimensional stationary instabilities for low Prandtl numbers, and three-dimensional oscillatory and then stationary instabilities for higher Prandtl numbers. When an acoustic beam of width (normalized by the layer depth) is applied, the thresholds of the two-dimensional modes, which become oscillatory, increase with the acoustic intensity (monitored through the parameter A) before strongly decreasing to reach the pure acoustic streaming instability threshold. Concerning the three-dimensional instabilities, the thresholds of the oscillatory modes increase while those of the stationary modes strongly decrease. For , these evolutions induce the crossing of the critical curves of these two modes when A is increased, so that the oscillatory modes which are dominant for small values of A are replaced by the stationary modes for larger values of A. The position of the crossing depends on the width of the acoustic beam. To cite this article: W. Dridi et al., C. R. Mecanique 337 (2009). [Copyright &y& Elsevier]

Abstract: Aim of the study: An important goal for EEG-based functional brain studies is to estimate the location of brain sources that produce the scalp-recorded signals. Such source localization requires locating precisely the position of the EEG sensors. This review describes and compares different methods that are used for localizing EEG sensors. Results: Five different methods have been described in literature. Manual methods consist in manual measurements to calculate the 3D coordinates of the sensors. Electromagnetic and ultrasound digitization permit localization by using trade devices. The photogrammetry system consists in taking pictures of the patient''s head with the sensors. The last method consists in directly localizing the EEG sensors in the MRI volume. Discussion and conclusions: The spatial localization of EEG sensors is an important step in performing source localization. This method should be accurate, fast, reproducible, and cheap. Currently, electromagnetic digitization is the most currently used method but MRI localization could be an interesting way because no additional method or device needs to be used to locate the EEG sensors. [Copyright &y& Elsevier]

Abstract: The linear stability of acoustic streaming flows induced by ultrasound waves (Eckart streaming), for both isothermal and laterally heated fluids confined between two parallel horizontal infinite walls has been studied. The basic profiles were determined analytically, and the eigenvalue problem derived for the temporal stability analysis was solved by a spectral Tau Chebyshev method. In the isothermal case, a critical acoustic parameter leading to an oscillatory instability was determined. is minimum for an acoustic beam width (normalized by the height of the fluid layer) and increases when either is decreased or increased. The other result concerns the influence of the acoustic streaming flow on the stability of the laterally heated layer (Hadley flow). For rather small beam widths, the acoustic streaming flow destabilizes the Hadley flow, but for large beam widths (), a range of acoustic parameter values was found for which the Hadley flow is stabilized (increase of the thresholds), before a sharp decrease of the thresholds for larger A. Let us underline that the stability of such flows has not been yet studied in the literature. To cite this article: W. Dridi et al., C. R. Mecanique 335 (2007). [Copyright &y& Elsevier]

This paper is concerned with the problem of controlling the production rate of a production inventory system with deteriorating items. Under reasonable conditions, we derive the closed form optimal control of a cost minimization problem and a profit maximization problem. The derived analytical solutions yield good insight on how production planning tasks can be carried out. In addition, they also provide guidelines for further study and development of numerical methods for more complex systems involving more general exogenous functions. [ABSTRACT FROM AUTHOR]

Abstract: Numerical experiments have been performed in order to investigate the convection in an enclosure of aspect ratios 5:1:1.3 subject to a horizontal temperature gradient and a longitudinal sound field. The governing equations are solved by a spectral element method. Different flow structures appear when increasing (or decreasing) the Grashof number. Without acoustic field (acoustic Froude number Fr =0), a hysteresis occurs connected to a first steady bifurcation with breaking of symmetry, but for Fr ≠0, no hysteresis is observed as this symmetry is no more effective. The further transition to oscillatory flow is found to be stabilized by the acoustic field. Depending on Fr, this transition can occur with or without the breaking of the left–right symmetry. [Copyright &y& Elsevier]

The influence of a vertical magnetic field and of surface tension on the stability of thermogravitational convection in an infinite layer subject to a horizontal temperature gradient is investigated through a linear stability analysis. Magnetic field is found to strongly stabilize the flow, as well as surface tension if thermocapillary effects contribute to increase the velocity at the upper surface of the layer. This strong stabilization is mainly connected to the modifications of the basic flow profile. A simple model based on the existence of an inflexion point in the velocity profile is proposed which qualitatively depicts these results. [ABSTRACT FROM AUTHOR]

We propose a nonsmooth dynamic system integrating production and inventory where the items may deteriorate and the demand is stock-dependent. We aim to derive the optimal production rate. In our first model, backorders are not allowed, while in the second model they are. Using optimal control, necessary optimality conditions are obtained for general forms of the cost, demand, and deterioration rates and closed form solutions are derived for specific forms of these rates. Numerical simulations are presented and sensitivity of the solutions are examined. [ABSTRACT FROM AUTHOR]

We construct in the present paper the effective growth response of trabecular bone, based on micromechanical analyses at the scale of a representative volume element consisting of individual trabeculae defining the representative unit cell (RUC). From a fundamental perspective, we adopt the physically and micromechanically motivated point of view that growth (resp. resorption) occurs as the surface remodeling of the individual trabeculae, the averaging of which leads to a net growth at the mesoscopic scale of the RUC. The effective model for the growing unit cell relies on an average kinematics which has been formulated in terms of the effective growth velocity gradient and effective elastic rate of deformation tensor, both functions of the rate of the effective density and stress applied over the RUC. The evaluation of the relation between the average rate of growth tensor and elastic growth rate versus the external stress applied to the RUC is obtained from a split of the average rate of growth tensor into its spherical and deviatoric parts, each of which being related to the corresponding applied stress quantities. The effective growth model is written for three different loading conditions as a polynomial relation between the components of the rate of growth tensor and similar components of the stress tensor under planar conditions, with a nonlinear function of the effective density as a weighting factor. The developed methodology is quite general and is applicable to any choice of the RUC morphology representative of the internal bone architecture. [ABSTRACT FROM AUTHOR]

The objective of this paper is to study the notion of regional observability of hyperbolic semilinear systems. For the state reconstruction in a given subregion, we give a first approach which combines the extension of the HUM method and the fixed point techniques. The analytical case is then explored using sectorial property of the considered dynamic operator and converted to a fixed point problem. The two approaches lead to algorithms which are successfully implemented numerically and illustrated with examples and simulations. [ABSTRACT FROM PUBLISHER]