排序方式: 共有32条查询结果,搜索用时 15 毫秒
21.
Mohand Ameziane Hamadouche 《Comptes Rendus Mecanique》2002,330(5):305-311
The shakedown analysis of elastic perfectly plastic structures is formulated as a discrete nonlinear mathematical programming problem by means of the finite element technique. The kinematical problem is regularized through the introduction of the Norton–Hoff viscoplastic material to overcome the non-differentiability of the objective function, and can be solved numerically by the augmented Lagrangian technique. To cite this article: M.A. Hamadouche, C. R. Mecanique 330 (2002) 305–311. 相似文献
22.
23.
Mhamed Mesfioui 《Journal of multivariate analysis》2008,99(3):372-385
In this article, copulas associated to multivariate conditional distributions in an Archimedean model are characterized. It is shown that this popular class of dependence structures is closed under the operation of conditioning, but that the associated conditional copula has a different analytical form in general. It is also demonstrated that the extremal copula for conditional Archimedean distributions is no longer the Fréchet upper bound, but rather a member of the Clayton family. Properties of these conditional distributions as well as conditional versions of tail dependence indices are also considered. 相似文献
24.
Thierry Godin Mhamed Bouzidi Pierre Lallemand Abdelhak Ambari 《Comptes Rendus Mecanique》2002,330(12):837
We give numerical results on the modification of the drag force Fx exerted on a sphere positioned eccentrically and moving at very low Reynolds number, at constant velocity within and along a cylindrical tube. The numerical results computed by Lattice-Boltzmann method or by finite volume formulation are in good agreement with the experimental results obtained by Ambari et al. (J. Fluid Mech. 149 (1984) 235–253). In particular, they confirm the existence of a minimum of the force Fx away from the axis of the cylinder and a sharp increase when the sphere approaches the sidewall. To cite this article: T. Godin et al., C. R. Mecanique 330 (2002) 837–842. 相似文献
25.
Gérard Audran Chiaa Adiche Paul Brémond Douniazad El Abed Mohammed Hamadouche Didier Siri Maurice Santelli 《Tetrahedron letters》2017,58(10):945-948
Enamines derived from cyclic ketones react with arenesulfonyl azides and cyanogen azide, mainly via ring contraction, with formation of the corresponding amidines. The mechanism of this efficient rearrangement, which has not been investigated experimentally, was determined with the aid of quantum-chemical calculations. In the transition state, from the intermediate 5-amino-v-triazolines, the loss of dinitrogen and a cyclic rearrangement occurred in one-step in a quite synchronous manner with a very low transition state energy. 相似文献
26.
It is known that the sums of the components of two random vectors (X 1,X 2,…,X n ) and (Y 1,Y 2,…,Y n ) ordered in the multivariate (s 1,s 2,…,s n )-increasing convex order are ordered in the univariate (s 1+s 2+?+s n )-increasing convex order. More generally, real-valued functions of (X 1,X 2,…,X n ) and (Y 1,Y 2,…,Y n ) are ordered in the same sense as long as these functions possess some specified non-negative cross-derivatives. This note extends these results to multivariate functions. In particular, we consider vectors of partial sums (S 1,S 2,…,S n ) and (T 1,T 2,…,T n ) where S j =X 1+?+X j and T j =Y 1+?+Y j and we show that these random vectors are ordered in the multivariate (s 1,s 1+s 2,…,s 1+?+s n )-increasing convex order. The consequences of these general results for the upper orthant order and the orthant convex order are discussed. 相似文献
27.
Through the use of [PdCl(C3H5)]2/Cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of aryl bromides undergoes Heck reaction with acrolein ethylene acetal. With this acetal, the selective formation of 3-arylpropionic acids/esters was observed. The functional group tolerance on the aryl halide is remarkable; substituents such as fluoro, methyl, methoxy, acetyl, formyl, benzoyl, nitro or nitrile are tolerated. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered aryl bromides. 相似文献
28.
29.
Building on the seminal work by Shaked and Shanthikumar (Adv Appl Probab 20:427–446, 1988a; Stoch Process Appl 27:1–20, 1988b), Denuit et al. (Eng Inf Sci 13:275–291, 1999; Methodol Comput Appl Probab 2:231–254, 2000; 2001) studied the stochastic s-increasing convexity properties of standard parametric families of distributions. However, the analysis is restricted there to a single parameter. As many standard families of distributions involve several parameters, multivariate higher-order stochastic convexity properties also deserve consideration for applications. This is precisely the topic of the present paper, devoted to stochastic \((s_1,s_2,\ldots ,s_d)\)-increasing convexity of distribution families indexed by a vector \((\theta _1,\theta _2,\ldots ,\theta _d)\) of parameters. This approach accounts for possible correlation in multivariate mixture models. 相似文献
30.
El Abbari Hafsa Bentahar Sarah El Marouani Maryam Taibi Mhamed Zeriouh Abdelouahab Sebbahi Saloua Kifani-Sahban Fatima 《Journal of Thermal Analysis and Calorimetry》2019,137(5):1485-1492
Journal of Thermal Analysis and Calorimetry - In this work, the physicochemical and thermomechanical characteristics of date seeds were examined during their pyrolysis under inert atmosphere from... 相似文献