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81.
Mohsen M. Mostafa Rafaat M. El-Shazly Tawfik H. Rakha Mohamed H. Abdel-Rahman 《Transition Metal Chemistry》2002,27(2):237-237
Other Index
Forthcoming articles 相似文献82.
83.
MostafaADIMY MostafaLAKLACH KhalilEZZINBI 《数学学报(英文版)》2004,20(5):933-942
In this work, we are concerned with a general class of abstract semilinear autonomous functional differential equations with a non-dense domain on a Banach space. Our objective is to study, using the Crandall-Liggett approach, the solutions as a semigroup of non-linear operators. 相似文献
84.
Quantifying elasticity and viscosity from measurement of shear wave speed dispersion 总被引:1,自引:0,他引:1
Chen S Fatemi M Greenleaf JF 《The Journal of the Acoustical Society of America》2004,115(6):2781-2785
The propagation speed of shear waves is related to frequency and the complex stiffness (shear elasticity and viscosity) of the medium. A method is presented to solve for shear elasticity and viscosity of a homogeneous medium by measuring shear wave speed dispersion. Harmonic radiation force, introduced by modulating the energy density of incident ultrasound, is used to generate cylindrical shear waves of various frequencies in a homogeneous medium. The speed of shear waves is measured from phase shift detected over the distance propagated. Measurements of shear wave speed at multiple frequencies are fit with the theoretical model to solve for the complex stiffness of the medium. Experiments in gelatin phantoms show promising results validated by an independent method. Practical considerations and challenges in possible medical applications are discussed. 相似文献
85.
Driss Drissi Mostafa Mbekhta 《Proceedings of the American Mathematical Society》2001,129(7):2011-2016
For a pair of linear bounded operators and on a complex Banach space , if commutes with then the orbits of under are uniformly bounded. The study of the converse implication was started in the 1970s by J. A. Deddens. In this paper, we present a new approach to this type of question using two localization theorems; one is an operator version of a theorem of tauberian type given by Katznelson-Tzafriri and the second one is on power-bounded operators by Gelfand-Hille. This improves former results of Deddens-Stampfli-Williams. 相似文献
86.
H. O. Ammar M. Ghorab D. M. Mostafa T. S. Makram R. M. Ali 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):121-134
Etodolac, being a practically insoluble candidate, exhibits certain toxic effects and a limited bioavailability. Upon chronic use, it causes gastro-intestinal injury and increases the risk of ulcer complications. The approach of this study was to improve the physicochemical properties of the drug utilizing complexation phenomenon with β-, methyl-β- and hydroxypropyl-β-cyclodextrins, which may enhance the aqueous solubility and dissolution rate of etodolac, in an effort to increase oral bioavailability. In certain instances, this approach can be used to increase drug solubility, improve organoleptic properties and maximize the gastrointestinal tolerance by reducing drug irritation after oral administration. Differential UV measurements as well as continuous variation plots revealed the formation of equimolar complex with hydroxypropyl-β-cyclodextrin and 1:2 complexes with β-cyclodextrin and its methyl derivative. Differential scanning calorimetry (DSC), X-ray and FT-IR measurements were applied to prove inclusion complex formation and characterize the complexes. These results lend support to the idea that solubilization of etodolac is mainly related to inclusion complex formation and to a lesser extent to cyclodextrin aggregates. Understanding the factors that influence the performance of etodolac, will allow us to state that molecular encapsulation of the drug and other modifications with appropriate hydroxylation or methylation of parent β-cyclodextrin is able to overcome its problems and facilitate safe and efficient delivery of the drug. 相似文献
87.
Mostafa Shazly Vikas Prakash Bradley A. Lerch 《International Journal of Solids and Structures》2009,46(6):1499-1515
In the present study, a modified split Hopkinson pressure bar (SHPB) is employed to investigate the dynamic response of ice under uniaxial compression in the range of strain rates from 60 to 1400 s?1 and at initial test temperatures of ?10 and ?30 °C. The compressive strength of ice shows positive strain-rate sensitivity over the range of strain rates employed; a slight influence of ice microstructure is observed, but it is much less than that reported previously for ice deformation under quasi-static loading conditions [Schulson, E.M., IIiescu, D., Frott, A., 2005. Characterization of ice for return-to-flight of the space shuttle. Part 1 – Hard ice. NASA CR-2005-213643-Part 1]. Specimen thickness, within the range studied, was found to have little or no effect on the peak (failure) strength of ice, while lowering the test temperature from ?10 to ?30 °C had a considerable effect, with ice behaving stronger at the lower test temperature. Moreover, unlike in the case of uniaxial quasi-static compression of ice, the effect of specimen end-constraint during the high rate compression was found to be negligible. One important result of these experiments, which may have important implications in modeling ice impacts, involves the post “peak-stress” behavior of the ice in that the ice samples do not catastrophically lose their load carrying capacity even after the attainment of peak stress during dynamic compression. This residual (tail) strength of the damaged/fragmented ice is sizable, and in some cases is larger than the quasi-static compression strength reported for ice. Moreover, this residual strength is observed to be dependent on sample thickness and the strain rate, being higher for thinner samples and at higher strain-rates during dynamic compression. 相似文献
88.
Mostafa Blidia 《Discrete Mathematics》2008,308(10):1785-1791
We examine classes of extremal graphs for the inequality γ(G)?|V|-max{d(v)+βv(G)}, where γ(G) is the domination number of graph G, d(v) is the degree of vertex v, and βv(G) is the size of a largest matching in the subgraph of G induced by the non-neighbours of v. This inequality improves on the classical upper bound |V|-maxd(v) due to Claude Berge. We give a characterization of the bipartite graphs and of the chordal graphs that achieve equality in the inequality. The characterization implies that the extremal bipartite graphs can be recognized in polynomial time, while the corresponding problem remains NP-complete for the extremal chordal graphs. 相似文献
89.
Mostafa A. Hamed 《Experimental Mechanics》1987,27(3):250-254
A basic theory of acoustical speckle and cross-correlation is described which utilizes the ubiquitous wave characteristics
in ultrasonics. A computer-based pulse-echo system has been developed. It is interfaced to a VAX11/780 computer which operates
the system and performs the data analysis. Data from three tests using specimens of steel, aluminum and Plexiglas are discussed.
On each specimen, a pulse-echo scan of a scattering surface is made over some area which represents reference configuration.
After the surface is displaced, a pulse-echo scan is made over the same area. A small region of the displaced configuration
is correlated with the reference as a measure of object motion. 相似文献
90.
Véronique Cariou Stéphane Verdun Emmanuelle Diaz El Mostafa Qannari Evelyne Vigneau 《Advances in Data Analysis and Classification》2009,3(3):227-241
Within the scope of cluster analysis of variables, the selection of the appropriate number of clusters is of paramount interest. The strategy of determination of the appropriate number of clusters adopted herein is based on a hypothesis testing approach. It consists in testing whether the variation of a partition quality criterion between two consecutive partitions is far removed from the expected variation under the null-hypothesis stipulating a lack of structure. Three hypothesis testing strategies are detailed and compared in the scope of clustering of variables: Gap, Weighted Gap and a statistic associated with CLV methodology. Finally, an illustration is presented based on data from a preference study. 相似文献