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排序方式: 共有213条查询结果,搜索用时 15 毫秒
1.
Hossam A. Zaki 《Computational Optimization and Applications》1995,4(1):23-45
State-of-the-art computational results have shown that the shortest augmenting path (SAP) methods are more efficient than other primal-dual and primal-simplex based methods for solving the linear assignment problem on uniprocessor computers. There is, however, some controversy concerning their merits when compared with Bertsekas' auction algorithm on multiprocessor computers. In this study we investigate the performance of these competing methods on the Alliant FX/8. For each method, theoretical motivation, sources of parallelism and computational results are presented. 相似文献
2.
Youssef Z. Boutros Mina B. Abd-el-Malek Nagwa A. Badran Hossam S. Hassan 《Applied Mathematical Modelling》2007
The non-linear equations of motion describing the laminar, isothermal and incompressible flow in a rectangular domain bounded by two weakly permeable, moving porous walls, which enable the fluid to enter or exit during successive expansions or contractions, are considered. We apply Lie-group method for determining symmetry reductions of partial differential equations. Lie-group method starts out with a general infinitesimal group of transformations under which given partial differential equations are invariant, then, the determining equations are derived. The determining equations are a set of linear differential equations, the solution of which gives the infinitesimals of the dependent and independent variables. After the group has been determined, a solution to the given partial differential equation may be found from the invariant surface condition such that its solution leads to similarity variables that reduce the number of independent variables in the system. Effect of the permeation Reynolds number Re and the dimensionless wall dilation rate α on self-axial velocity have been studied both analytically and numerically and the results are plotted. 相似文献
3.
4.
Safaa El‐din H. Etaiw Hassan Marie Elsayed M. Shalaby Rabie S. Farag Fatma A. Elsharqawy 《应用有机金属化学》2019,33(9)
Orange prismatic crystals of the supramolecular coordination polymer (SCP) ∞3[Cu(CN)2(Me3Sn)(Pyz)], SCP 1 , were synthesized using a self‐assembly method under ambient conditions. Nanosized 1 was obtained using the same molar ratio in water by ultrasonic irradiation. SCP 1 was characterized using single‐crystal X‐ray diffraction, elemental analysis, thermal analysis and Fourier transform infrared spectroscopy. SCP 1 and its nanosized 1 particles were also examined using powder X‐ay diffraction and scanning electron microscopy. The luminescence emission of SCP 1 was studied as well as its use as a sensor for the detection of common organic solvents and metal ions. Also, the catalytic activities of nanosized 1 towards various organic dyes were investigated under ambient conditions, UV irradiation and ultrasonic irradiation. Nanosized 1 as a heterogeneous nanoparticle catalyst exhibits high catalytic activity for the degradation of eosin‐Y and acid blue dyes. The mechanism of degradation investigated using various scavenger techniques is proposed and discussed. The catalytic oxidation process is mainly caused by ?OH radicals. 相似文献
5.
Hassan Talaat Ali H. Moussa M. Shalaby El-Wallid S. Sedik M. Tag El-Din Kamal 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(3):454-460
We apply the time-dependent theory to the collinear exchange reaction F + CH4 → FCH3 + H. We have performed detailed calculations on two-dimensional potential surfaces representing the ground electronic potentials of the collinear F + CH4 → FCH3 + H reaction, at incident energies. Transmission coefficients range from zero to unity, depending upon the incident energy. Normal modes of vibrations are displayed along the reaction path. 相似文献
6.
The protection power of the cationic surfactant decylammonium acetate (DAA) in seawater has been studied to define the perfect conditions have to be found for using it as a corrosion inhibitor for copper surface. The adsorption isotherm of this surfactant on copper surface has been determined at different interval times at 30°C. The given isotherms have, in general, similar shapes exhibiting a Languimirian L-shape. The corrosion measurement has been determined according to weight loss method. The study declines that cationic DAA, in seawater, protects well the copper surface against corrosion when added with low concentrations, while high concentrations show bad inhibition efficiency. ICP spectroscopic analysis assures this result where high Cu% has been obtained in the presence of high DAA concentration. 相似文献
7.
A.M. Shalaby 《The European Physical Journal C - Particles and Fields》2007,50(4):999-1006
We investigate the effective potential of the PT symmetric (-gφ4) field theory, perturbatively as well as non-perturbatively. For the perturbative calculations, we first use normal ordering
to obtain the first order effective potential, from which the predicted vacuum condensate vanishes exponentially as G→0+, in agreement with previous calculations. For the higher orders, we employ the invariance of the bare parameters under the
change of the mass scale t to fix the transformed form totally equivalent to the original theory. The form so obtained up
to G3 is new and shows that all the 1PI amplitudes are perturbative for both the and the region. For the intermediate region, we modified the fractal self-similar resummation method to have a unique resummation
formula for all G values. This unique formula is necessary, because the effective potential is the generating functional for
all the one-particle irreducible (1PI) amplitudes that can be obtained via ∂nE/∂bn, and thus we can obtain an analytic calculation of the 1PI amplitudes. Again, the resummed form of the effective potential
is new and interpolates the effective potential between the perturbative regions. Moreover, the resummed effective potential
agrees in spirit to a previous calculation concerning bound states.
PACS 11.10.Kk; 02.30.Mv; 11.10.Lm; 11.30.Er; 11.30.Qc; 11.15.Tk 相似文献
8.
By a T
*(2, k, v)-code we mean a perfect4-deletion-correcting code of length 6 over an alphabet of size v, which is capable of correcting anycombination of up to 4 deletions and/or insertions of letters that occur in transmission of codewords. Thethird author (DCC Vol. 23, No. 1) presented a combinatorial construction for such codes and prove thata T
*(2, 6, v)-code exists for all positive integers v 3 (mod 5), with 12 possible exceptions of v. In this paper, the notion of a directedgroup divisible quasidesign is introduced and used to show that a T
*(2, 6,v)-code exists for all positive integers v 3 (mod 5), except possiblyfor v {173, 178, 203, 208}. The 12 missing cases for T
*(2,6, v)-codes with v 3 (mod 5) are also provided, thereby the existenceproblem for T
*(2, 6, v)-codes is almost complete. 相似文献
9.
The synthesis and reactions of dimethyl 3, 4- and 4, 5-diaminophthalate 7 and 9 were investigated. The condensation of these isomeric diaminophthalates and their respective nitroacetamido precursors have been shown to give rise to a variety of five, six and seven membered heterocyclic ring system. Several new tetraazanthracenes have also been prepared in this sequence. 相似文献
10.
Combustion phenomena are of high scientific and technological interest, in particular for energy generation and transportation
systems. Direct Numerical Simulations (DNS) have become an essential and well established research tool to investigate the
structure of turbulent flames, since they do not rely on any approximate turbulence models. In this work two complementary
DNS codes are employed to investigate different types of fuels and flame configurations. The code is π3 is a 3-dimensional DNS code using a low-Mach number approximation. Chemistry is described through a tabulation, using two
coordinates to enter a database constructed for example with 29 species and 141 reactions for methane combustion. It is used
here to investigate the growth of a turbulent premixed flame in a methane-air mixture (Case 1). The second code,Sider is an explicit three-dimensional DNS code solving the fully compressible reactive Navier-Stokes equations, where the chemical
processes are computed using a complete reaction scheme, taking into account accurate diffusion properties. It is used here
to compute a hydrogen/air turbulent diffusion flame (Case 2), considering 9 chemical species and 38 chemical reactions. 相似文献