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11.
Messaoud Boulbrachene 《Numerical Functional Analysis & Optimization》2013,34(9):1107-1121
In this article, we introduce a new method to analyze the convergence of the standard finite element method for variational inequalities with noncoercive operators. We derive an optimal L ∞ error estimate by combining the Bensoussan-Lions algorithm with the concept of subsolutions. 相似文献
12.
Jean-Philippe Chancelier Marouen Messaoud Agnès Sulem 《Mathematical Methods of Operations Research》2007,65(2):239-259
The aim of this paper is to solve the fixed point problems:
where
is a finite set, L is contractive and B is a nonexpansive operator and
where
and
are general control sets, the operators L
w
are contractive and operators B
z
are nonexpansive. For these two problems, we give conditions which imply existence and uniqueness of a solution and provide
a policy iteration algorithm which converges to the solution. The proofs are slightly different for the two problems since
the set of controls is finite for (1) while it is not necessary the case for problem (2). Equation (2) typically arises in
numerical analysis of quasi variational inequalities and variational inequalities associated to impulse or singular stochastic
control. 相似文献
13.
Glass formation has been investigated in the Sb2O3-ZnBr2 binary system. Vitreous samples have been obtained for batches containing 20-90 mol% Sb2O3. Chemical analysis shows that bromine concentration is smaller than expected and real compositions belong to the Sb2O3-ZnBr2-ZnO ternary system. However, the discrepancy between nominal and analyzed compositions is fair for Sb2O3 content larger than 50 mol%. Optical transmission lies between 400 nm and 7 μm and refractive index ranges from 2.0 to 2.1. Glass transition occurs around 300 °C, and crystallization exotherm does not appear in the differential scanning calorimetry scan at 10 K s−1 for samples containing 50-60 mol% Sb2O3. Thermal expansion varies between 120 and 220×10−7 K−1 as antimony content decreases. Microhardness is close to 200 kg/mm2. These glasses have low phonon energy and make potential materials for infrared transmission and active fibers. 相似文献
14.
Faouzi Guenadil Houcine Aichaoui Messaoud Liacha 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):755-757
The use of the mixture of aluminum chloride-N,N-dimethylformamide 1,2 (AlCl 3 -DMF, 11:1) reagent in the Friedl-Crafts C acylation reaction of 2(3H)-benzothiazolones was previously reported. 3 These acylations reactions were found to proceed with high regioselectivity. The precise position of acylation was uniquivocally assigned by x-ray single-crystal defraction in the case of 6-benzoyl-2(3H)-benzothiazolone. 4 The assignment of the position of acylation was extended to other compounds by the use of high-field 1 H-NMR . 3 相似文献
15.
Niobium containing aluminophosphate materials with AEL structure were prepared by the hydrothermal method. The chemical composition
of the hydrogel was: 1 DIPA: 1 Al2O3: (1-x) P2O5: x Nb2O5: 80 H2O, with x=0.025, 0.050, 0.075 and 0.100. The crystallization was carried out at temperature of 170°C for 72 h. The materials
obtained were characterized by XRF, DRX, FTIR, TG and measurements of acidity. The characterization of the catalytic active
sites were carried out in the isopropanol dehydration at temperature of 400°C, and WHSV of 1.6, 3.2, 4.8, 6.4 and 8.0 h-1 . The samples showed good catalytic activity with selectivity to propene.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
Samah Ben Atia Anis Messaoud Ridha Ben Abdennour 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2018,24(1):26-43
In this paper, an online algorithm is proposed for the identification of unknown time-varying input delay in the case of discrete non-linear systems described by decoupled multimodel. This method relies on the minimization of a performance index based on the error between the real system and the partial internal models outputs. In addition, a decoupled internal multimodel control is proposed for the compensation of discrete non-linear systems with time-varying delay. This control scheme incorporates partial internal model controls. Each partial controller is associated to a specified operating zone of the non-linear system. The switching between these controllers is ensured by a supervisor that contains a set of local predictors. A simulation example is carried out to illustrate the significance of the proposed time-varying delay identification algorithm and the proposed internal multimodel control scheme. 相似文献
17.
Salah Mecheri Messaoud Bounkhel 《Journal of Mathematical Analysis and Applications》2003,287(1):51-60
In this paper we characterize the global minimum of an arbitrary function defined on a Banach space, in terms of a new concept of derivatives adapted for our case from a recent work due to D.J. Keckic (J. Operator Theory, submitted for publication). Using these results we establish several new characterizations of the global minimum of the map defined by Fψ(X)=‖ψ(X)‖1, where is a map defined by ψ(X)=S+φ(X) and φ:B(H)→B(H) is a linear map, S∈C1, and . Further, we apply these results to characterize the operators which are orthogonal to the range of elementary operators. 相似文献
18.
Malek Ennaifer Taroub Bouzaiene Chokri Messaoud Moktar Hamdi 《Natural product research》2020,34(18):2634-2638
AbstractIn Tunisia, Pelargonium graveolens is widely consumed as a food aromatizing hydrosol. Recent studies have shown the potential of plant solvent-free extracts as food and pharmaceutical natural additives. Accordingly, in this study, we investigate the phenolic content, the volatile fractions of green P. graveolens extracts such as infusion and decoction, and we evaluate their biological activities. The total phenolic content of the infusion (27.05?mg GAE/gDM) is significantly different from that of decoction (31.2?mg GAE/gDM). The GC-MS analysis identified about twenty volatile components in both extracts. The DPPH inhibition and the β-carotene bleaching tests of the infusion and the decoction had considerable results. Besides, infusion and decoction exhibited a relatively high anti-acetyl-cholinesterase activity and a considerable antimicrobial activity against S. aureus, among three tested pathogenic bacteria. 相似文献
19.
20.
Souhir Jazzar Nadia Berrejeb Chokri Messaoud Mohamed Néjib Marzouki Issam Smaali 《Applied biochemistry and biotechnology》2016,179(7):1290-1308
This work aimed to characterize two native microalgal strains newly isolated from South Mediterranean areas and identified as Chlorella sorokiniana ES3 and Neochloris sp. AM2. The growth properties and biochemical composition of these microalgae were evaluated in different culture media (Algal, BG-11, f/2, and Conway). Among the tested media, nitrate- and phosphate-rich Algal medium provided the maximum biomass productivities (85.5 and 111.5 mg l?1 day?1 for C. sorokiniana and Neochloris sp., respectively), while the nitrate- and phosphate-deficient f/2 medium resulted in the highest lipid productivities (24.1 and 35.8 mg l?1 day?1 for C. sorokiniana and Neochloris sp., respectively). The physiological state of both microalgae was investigated under different light and temperature levels using the pulse amplitude-modulated fluorometry. The better photosynthetic efficiency of C. sorokiniana was obtained at 23 °C with a light saturation of 156 μE m?2 s?1, while that of Neochloris sp. was achieved at 15 °C with a light saturation of 151 μE m?2 s?1. The analysis of fatty acid profile and biodiesel parameters revealed that C. sorokiniana, cultivated in Algal and f/2 media, can be considered as a suitable candidate for high-quality biodiesel production. 相似文献