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排序方式: 共有219条查询结果,搜索用时 15 毫秒
21.
In this paper, the theoretical background for the failure analysis of fibre-reinforced composites under variable repeated loads in the framework of direct methods is presented. It is based on a local shakedown analysis in a representative volume element of the composite and the use of averaging techniques to study the influence of each component (matrix, fibre and interface) on the macroscopic response of such composite. 相似文献
22.
A. Vorobev D. Lyubimov T. Lyubimova Abdelkader Mojtabi Bernard Zappoli 《Comptes Rendus Mecanique》2004,332(10):803-809
Within an averaging approach, the governing equations and effective boundary conditions describing both the average and pulsation motion of a near-critical fluid subjected to high-frequency vibrations are obtained. Vibrations induce the non-homogeneities in average temperature. Owing to these non-homogeneities, the average flows can be generated even in isothermal cavity under weightlessness. These flows are examined for 1D and 2D configurations. The direct numerical simulations fulfilled earlier confirm the averaged model, we obtain the same flow structures by essentially smaller requirements for computational time. To cite this article: A.Vorobev et al., C. R. Mecanique 332 (2004). 相似文献
23.
On the Reactivity of (−)‐(R)‐Carvone and (−)‐4aα,7α,7aβ‐Nepetalactone: Synthesis of New Heterocycles
Aziz El Mebtoul Mohamed Rouani Malika Chammache Houcine Bouidida Abdelkader Ilidrissi 《Helvetica chimica acta》2011,94(3):433-437
The 1,3‐dipolar cycloaddition of 4‐chlorobenzonitrile oxide to the unsaturated system of (?)‐(R)‐carvone occurred exclusively at C(8) to give a new isoxazoline derivative. This derivative reacts with NH2OH to yield a new heterocycle, observed for the first time. On the other hand, the addition of 4‐chlorobenzonitrile oxide to the unsaturated lactone (?)‐4aα,7α,7aβ‐nepetalactone gave, in a good yield, also a new heterocycle, again obtained for the first time. The terpenoid (?)‐(R)‐carvone and iridoid (?)‐4aα,7α,7aβ‐nepetalactone were isolated from Moroccan species Mentha viridis (L.) and Nepeta tuberosa (L.), respectively. The new heterocycles obtained were identified by combination of chromatographic and spectroscopic methods. 相似文献
24.
We consider a biharmonic problem Δ2uω = fω with Navier type boundary conditions uω = Δuω = 0, on a family of truncated sectors Ωω in ?2 of radius r, 0 < r < 1 and opening angle ω, ω ∈ (2π/3, π] when ω is close to π. The family of right-hand sides (fω)ω∈(2π/3, π] is assumed to depend smoothly on ω in L2(Ωω). The main result is that uω converges to uπ when ω → π with respect to the H2-norm. We can also show that the H2-topology is optimal for such a convergence result.
相似文献25.
François Jaeger Abdelkader Khelladi Michel Mollard 《Journal of Combinatorial Theory, Series B》1985,39(2):153-163
A cocycle (resp. cycle) cover of a graph G is a family C of cocycles (resp. cycles) of G such that each edge of G belongs to at least one member of C. The length of C is the sum of the cardinalities of its members. While it is known (see [5, 6]) that every bridgeless graph G = (V, E) has a cycle cover of length not greater than , it is shown that there exists no α < 2 such that every loopless graph G = (V, E) has a cocycle cover with length not greater than α |E|. To do this, cocycle covers of minimal length are determined for the complete graphs, thus solving a problem stated at the end of [6]. 相似文献
26.
Mostafa A. Abdelkader 《Archive for Rational Mechanics and Analysis》1984,85(1):15-20
A simple pendulum acted on by gravity and subjected to a resistance proportional to the velocity of the bob is considered. If the length of the string and the mass of the bob are held constant, the amplitude of the bob decreases gradually because of the damping. We want to keep the maximum swing of the bob constant for all time; this we achieve by varying the length of the string, the mass of the bob or both. The key to the solution of our problem is a second-order nonlinear differential equation having arbitrary nonlinearity and an arbitrary coefficient function, for which we give the exact integral. We also give an application of this differential equation to a boundary-value problem for a nonlinear generalization of a hypergeometric equation. 相似文献
27.
Abdelkader Intissar 《Journal of Mathematical Analysis and Applications》2005,305(2):669-689
The Reggeon field theory is governed by a non-self adjoint operator constructed as a polynomial in A, A*, the standard Bose annihilation and creation operators. In zero transverse dimension, this Hamiltonian acting in Bargmann space is defined by
Hλ′,μ=λ′A*2A2+μA*A+iλA*(A*+A)A, 相似文献
28.
Mostafa A. Abdelkader 《Applied Scientific Research》1965,12(1):48-56
Summary Considered here first is a circuit consisting of resistanceR, inductanceL, capacitanceK, in series with a periodically variable capacitanceC(1 + cos t), with maximum value 2C and minimum value zero (i.e. open circuit). The exact solution of the Hill-type differential equation for the charge on the condensers is shown to be expressible in terms of associated Legendre functions of general degree and order. However, considerable analytical simplification is effected by appropriate choice of the value of capacitanceK, for then the solution (likewise exact) is in terms of more elementary functions. It is found that the value of the angular frequency , in relation to the circuit parameters, influences the character of the solution, which varies considerably with . Secondly, a lossless circuit consisting of a variable inductanceM(1+cos t), shunted by a fixed inductanceL and a capacitanceC, is considered. As before, appropriate choice ofL simplifies the solution functions. Actually, the circulating charge in the variable-inductance case has the same mathematical expression as that for the current in the variable-capacitance case. 相似文献
29.
Quantitative Fourier‐transform infrared spectroscopic analysis was used for the determination of adsorption capacity of a model volatile organic compound (VOC) under dynamic conditions. The analytical method used also offers the possibility of distinguishing between reversible and irreversible adsorption as well as further detection of adsorbed VOC transformation. The obtained adsorbed amounts have been used for the determination of the heat of adsorption and the activation energy of desorption using, respectively, isosteric and temperature programmed desorption methods. The approach has been applied to explore the potential use of local clay as an adsorbent material for VOC pollutants. 相似文献
30.
Djamel Ait-Akli & Abdelkader Merakeb 《偏微分方程(英文版)》2020,33(1):64-92
In this paper we consider the Lamé system on a polygonal convex domain
with mixed boundary conditions of Dirichlet-Neumann type. An explicit L2 norm
estimate for the gradient of the solution of this problem is established. This leads to an
explicit bound of the H1 norm of this solution. Note that the obtained upper-bound is
not optimal. 相似文献