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991.
We investigate blow-up theory and prove sharp Sobolev asymptotics for a general class of anisotropic critical equations in
bounded domains of . 相似文献
992.
A micropolar model for axisymmetric blood flow through an axially nonsymmetreic but radially symmetric mild stenosis tapered artery is presented. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the axial shape of the stenosis can be changed easily just by varying a parameter (referred to as the shape parameter). The model is also used to study the effect of the taper angle Ф. Flow parameters such as the velocity, the resistance to flow (the resistance impedance), the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis (stenosis throat) have been computed for different values of the shape parameter n, the taper angle Ф, the coupling number N and the micropolar parameter m. It is shown that the resistance to flow decreases with increasing the shape parameter n and the micropolar parameter m while it increases with increasing the coupling number N. So, the magnitude of the resistance impedance is higher for a micropolar fluid than that for a Newtonian fluid model. Finally, the velocity profile, the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis are discussed for different values of the parameters involved on the problem. 相似文献
993.
The unsteady turbulent flow around bodies at high Reynolds number is predicted by an anisotropic eddy-viscosity model in the context of the Organised Eddy Simulation (OES). A tensorial eddy-viscosity concept is developed to reinforce turbulent stress anisotropy, that is a crucial characteristic of non-equilibrium turbulence in the near-region. The theoretical aspects of the modelling are investigated by means of a phase-averaged PIV in the flow around a circular cylinder at Reynolds number 1.4×105. A pronounced stress–strain misalignment is quantified in the near-wake region of the detached flow, that is well captured by a tensorial eddy-viscosity concept. This is achieved by modelling the turbulence stress anisotropy tensor by its projection onto the principal matrices of the strain-rate tensor. Additional transport equations for the projection coefficients are derived from a second-order moment closure scheme. The modification of the turbulence length scale yielded by OES is used in the Detached Eddy Simulation hybrid approach. The detached turbulent flows around a NACA0012 airfoil (2-D) and a circular cylinder (3-D) are studied at Reynolds numbers 105 and 1.4×105, respectively. The results compared to experimental ones emphasise the predictive capabilities of the OES approach concerning the flow physics capture for turbulent unsteady flows around bodies at high Reynolds numbers. 相似文献
994.
995.
Alaa A. Hassan Kamal M. El‐Shaieb Raafat M. Shaker Dietrich Dpp 《Heteroatom Chemistry》2005,16(1):12-19
1,4‐Disubstituted thiosemicarbazides 1b–f reacted with ethenetetracarbonitrile ( 5 ) in di‐ methylformamide with formation of 2‐substituted 5‐phenyl‐1,3,4‐thiadiazoles 2a–f and 2‐substituted 5‐phenyl‐1,3,4‐oxadiazoles 4a–f . Upon addition of 5 to 1c–e in chlorobenzene, 3‐amino‐2‐benzoyl‐4,5,5‐tri‐ cyano‐2,5‐dihydro‐1H‐pyrazole‐1‐[N‐(4‐tricyanovi‐nyl)phenyl]carbothioamide ( 12 ), 5‐benzylamino‐, and 5‐allylamino‐4‐benzoyl‐2,3‐dihydro‐[1,3,4]thiadiazol‐ 2,2‐dicarbonitrile ( 13a,b ) and 5‐amino‐1‐benzoylpyrazole‐3,4‐dicarbonitrile ( 14 ) as well as 2‐phenyl‐ 4H‐[1,3,4]‐oxadiazine‐5,6‐dicarbonitrile ( 15 ) were formed. Rationales for the role of the solvent and the conversions observed are presented. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:12–19, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20071 相似文献
996.
A. E. Rashad O. A. Heikal A. O. H. El‐Nezhawy F. M. E. Abdel‐Megeid 《Heteroatom Chemistry》2005,16(3):226-234
Several derivatives containing the thieno[2,3‐d]pyrimidine system were prepared starting from 2‐amino‐4,5‐dihydronaphtho[2,1‐b]thiophene‐1‐carbonitrile ( 1 ). In particular, the synthesis and structure characterization of 8,9‐dihydronaphtho‐ [1′,2′:4,5]thieno[3,2‐e][1,2,4]triazolo[4,3‐c]pyrimidine derivatives 13–16 and their isomerization to 8,9‐dihydronaphtho[1′,2′:4,5]thieno[3,2‐e][1,2,4]‐triazolo[1,5‐c]pyrimidine derivatives 17–20 under different suitable reaction conditions were reported and verified with X‐ray analysis. Moreover, compounds 13, 14 and 22 were tested as potential anti‐inflammatory agents and derivative 14 showed potent activity in carrageenan test. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:226–234, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20114 相似文献
997.
Ahmed M. Sh. El‐Sharief Mohamed S. A. El‐Gaby Ahmed A. Atalla Abu‐Bakr A. A. M. El‐Adasy 《Heteroatom Chemistry》2005,16(3):218-225
Cyclocondensation of cyanothioformamides ( 1 ) with arylhydrazonomalononitriles ( 2 ) afforded the novel imidazole derivatives ( 4a–e ) in good yields. Isothiocyanatoazobenzene ( 6 ) was allowed to react with potassium cyanide and gave the new cyanothioformamide ( 7 ) which was reacted with 4‐chlorophenyl isocyanate to yield imidazolidinethione ( 8 ). Compound ( 8 ) was subjected to react with hydrochloric acid, o‐phenylenediamine, 4‐methylaniline, and hydrogen sulfide and furnished compounds ( 10 ), ( 11 ), ( 12 ), and ( 15 ), respectively. Also, the reactivity of thiohydantoin ( 15 ) toward some electrophilic reagents such as N,N‐dimethylformamide‐dimethylacetal and arylidene‐malononitriles was investigated. The structure of the synthesized compounds was established by analytical and spectral data. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:218–225, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20113 相似文献
998.
The crystal structure of Sr4Mn2NiO9 has been refined on single crystal. This phase belongs to the series A1+x(A′xB1–x)O3 (x=1/3) related to the 2H-hexagonal perovskite. The structure contains transition metals in chains of oxide polyhedra (trigonal prisms and octahedra); neighboring chains are separated from each other by the Sr atoms. The sequence of the face sharing polyhedra along the chains is two octahedra + one trigonal prism. Mn occupies the octahedra and Ni is disordered in the trigonal prism with ≈80% in the pseudo square faces of the prism and ≈20% at the centre. This result has been confirmed by XANES experiments at Mn K and Ni K edges, respectively. Sr4Mn2NiO9 is antiferromagnetic with a Néel temperature at T=3 K. The Curie constant measured at high temperature is in good agreement with ≈80% of the Ni2+ ions in the spin state configuration S=0. 相似文献
999.
The reaction of 3‐benzoylcyanomethylidine‐1(H)‐indole‐2‐one ( 1 ) with a variety of active methylene compounds, thioglycolic acid, glycine, hydrazine hydrate and phenyl hydrazine led to the formation of compounds 4a‐d‐10 . 3‐Thiosemicarbazide‐1(H)‐indole‐2‐one 2 on reaction with α‐halocarbonyl compounds gave compounds 11a‐c, 12a‐c . The latter compounds on heating with phosphoryl chloride, cyclization takes place via losing water to give the angular tetracyclic compounds 13a,b and 14a‐c . Cyanoacetic hydrazone derivative 3 readily cyclized upon heating in triethyl orthoformate to give the tricyclic system, oxopyridazino indole 15 . On the other hand, the reaction of 3 with benzylidine malononitrile and benzylidene ethylcyanoactate gave the pyranyl hydrazone derivatives 16a,b . 相似文献
1000.
Mançour-Billah S. Aït Hmaïdouch L. El Hadek M. Cohen-Adad R. 《Journal of Thermal Analysis and Calorimetry》2000,62(3):781-795
A program has been written to describe solubility surfaces of the polythermal ternary phase diagram Mg(NO3)2–Al(NO3)3–H2O, using the model proposed by Cohen-Adad et al. [2]. In this work we present the calculation of the solubility surface of Mg(NO3)2×6H2O and Al(NO3)3×9H2O in the phase diagram. The calculated isothermal sections are in a good agreement with experimental determinations. Coefficients
of the fitting equation that describes the solubility field allow drawing any isothermal section. The monovariant line was
also calculated. The chosen model is well adapted to calculations of these solubility surfaces and gives very good results.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献