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11.
Emmanuel Moulay Romain Bourdais Wilfrid Perruquetti 《Nonlinear Analysis: Hybrid Systems》2007,1(4):482-490
In this paper, we study the stabilization of general nonlinear switched systems by using control Lyapunov functions. The concept of control Lyapunov function for nonlinear control systems is generalized to switched control systems. The first part of our contribution provides a necessary and sufficient condition of stabilization. The main idea is to use a common control Lyapunov function; this is achieved with the converse Lyapunov theorem dedicated to switched systems. In the second part, an explicit construction of a common control Lyapunov function is addressed with respect to a finite family of switched systems. The approach uses a family of control Lyapunov functions attached to the subsystems. 相似文献
12.
Saad Moulay Zakia Zeffouni 《高分子科学》2007,(3):297-302
PVC was subjected to a chemical modification aiming at replacing the chlorine atoms by pyridine groups via a homolytic route. Pyridine groups were peculiarly affixed to the PVC matrix via a carbon-carbon bond rather than a carbon-nitrogen one. PVC was first iodinated using the Conant-Finkelstein reaction, followed by the application of the homolytic conditions of Minisci to generate pyridinated PVC with a varying degree of substitution. The extent of substitution was not high; the reaction on 30% iodinated PVC afforded a degree of modification no greater than 3%. 相似文献
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Cycloaddition reactions are an integral and weighty part of organic chemistry in pedagogy and research as well. The wealthy literature on cycloaddition reactions from their birth up to now, unequivocally witnesses to their leading chemistry. The so-called “conventional solvents” are organic solvents that have indubitably promoted their success. Yet, the toxicity facet of these solvents impedes their use freely and with no fear. Not only is the operating chemist uncomfortable while experimenting, but also the environment is equally threatened. Working out the cycloaddition reactions and other organic ones in aqueous systems would certainly bring some relief to the chemist and to the environment as well. Unusual outcomes in terms of yield, reactivity and selectivity compared to those performed in organic solvents were commonly observed, and have overwhelmed the chemists with surprise indeed. In this review, homo Diels–Alder reactions in aqueous media include those involving the following dienophiles: maleimides, α,β-unsaturated esters, p-benzoquinones, vinyl ketones, phenyl-1-(2-pyridyl)-2-propen-1-one, α,β-unsaturated esters. A special case is the organocatalysis of Diels–Alder cycloaddition of α,β-unsaturated ketones (aldehydes). Of no less importance, some hetero Diels–Alder cycloaddition reactions in water systems are delineated. The impact of additives (salts, organic and inorganic chemicals), micellar catalysis and Lewis/Brønstëd acid catalysis on outcomes of such cycloaddition reactions is discussed. The 1,3-dipolar cycloaddition methodology applied to aqueous media has brought forth a number of heterocyclic compounds, usually with a regio- and stereoselectivity pecularity. These heterocycles include triazoles, tetrazoles, pyrazoles, isoxazoles, isoxazolidines, pyrroles and pyrrolidines. The superiority of copper(I) catalysis in the azide-alkyne cycloaddition (Huisgen cycloaddition) in water is endorsed by a number of examples. 相似文献
14.
The oxidation of n-propanol and n-butanol to their corresponding aldehydes was monitored by the pervaporation technique. Mass transfer phenomenon that occurs in the pervaporation process was confirmed by the results of inverse gas chromatography. Polydimethylsiloxane (PDMS), a hydrophobic polymer widely employed as a membrane in pervaporation technique, was evaluated as a stationary phase in this study. The retention times of the different molecules probes (n-propanol, n-butanol, propionaldehyde, and butyraldehyde), molecules involved as reactants and products in the oxidation reaction, gave an insight into the extent of the interactions between each of these molecules and the stationary phase. The infinite dilution conditions allowed to measure the infinite dilution activity coefficient, gamma(infinity), and the specific retention volume, V(g)(0), and to estimate the Flory-Huggins parameter interactions, chi(12)(infinity). The magnitudes of these parameters threw some light on the permselectivity of the membranes in the pervaporation operation. 相似文献
15.
Low molecular weight poly(acrylic acid) as a salt scaling inhibitor in oilfield operations 总被引:1,自引:0,他引:1
S. Moulay M. Boukherissa F. Abdoune F. Z. Benabdelmoumene 《Journal of the Iranian Chemical Society》2005,2(3):212-219
Poly(acrylic acid) (PAA) samples with molecular weights between 820 and 2950 were synthesized by a solution polymerization process using an initiating redox system. The obtained PAAs were then screened for their ability to inhibit salt scale formation. In this screening system, salt scale was formed by injecting pit water into the oil. The salt scale inhibition efficiency was higher for PAAs at a higher concentration and for lower molecular weight PAAs. A reduction of pH, extension of stirring time, or an increase in temperature caused the inhibition efficiency of the PAAs to drop. An optimal inhibition efficiency of 98.70% was observed using a PAA with a molecular weight of 820 at a concentration of 20 ppm, at 20 °C, while being stirred for 1 h at a pH of 6.029. 相似文献
16.
** Email: emmanuel.moulay{at}ec-lille.fr*** Email: wilfrid.perruquetti{at}ec-lille.fr In this paper, the problem of finite time stability is investigatedfor differential inclusion. Two sufficient conditions for finitetime stability, using a smooth Lyapunov function and a non-smoothone, are established. Then, the same idea is used to give twonecessary conditions. Examples are developed using the conceptof Krasovskii solutions for differential equation with discontinuousright-hand sides. 相似文献
17.
Moulay Youssef Barkatou 《Journal of Geometric Analysis》2000,10(2):219-241
In this paper a new explicit integral formula is derived for solutions of the tangential Cauchy-Riemann equations on CR q-concave
manifolds and optimal estimates in the Lipschitz norms are obtained. 相似文献
18.
3‐Methyl‐1,2,4‐benzotriazine and some of its derivatives were prepared in moderate yields (50–70%) via a reductive cyclization by a PtO2‐catalyzed hydrogenation of the corresponding 2‐nitrophenylhydrazones of the pyruvic acid. The latter compounds were obtained in yields higher than 90% by reacting 2‐nitrophenylhydrazines with sodium pyruvate salt. Three 3‐phenyl‐1,2,4‐benzotriazine compounds were also produced via a reductive cyclization by a Pt/C‐catalyzed hydrogenation of their corresponding 2‐nitrophenylhydrazono‐ethers in high yields (>70%). © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:166–172, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20200 相似文献
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20.
Siham?Difi Ismael?Saadoune Moulay?Tahar?Sougrati Rachid?Hakkou Kristina?Edstrom Pierre-Emmanuel?LippensEmail author 《Hyperfine Interactions》2016,237(1):61
The role of iron in Na 1.5Fe 0.5Ti 1.5(PO 4)3/C electrode material for Na batteries has been studied by 57Fe Mössbauer spectroscopy in operando mode. The potential profile obtained in the galvanostatic regime shows three plateaus at different voltages due to different reaction mechanisms. Two of them, at 2.2 and 0.3 V vs Na +/Na 0, have been associated to redox processes involving iron and titanium in Na 1.5Fe 0.5Ti 1.5(PO 4)3. The role of titanium was previously elucidated for NaTi 2(PO 4)3 and the effect of the substitution of Fe for Ti was investigated with 57Fe Mössbauer spectroscopy. We show that iron is an electrochemically active center at 2.2 V with the reversible Fe 3+/Fe 2+ transformation and then remains at the oxidation state Fe 2+ along the sodiation until the end of discharge at 0 V. 相似文献