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排序方式: 共有291条查询结果,搜索用时 46 毫秒
51.
Vassilis N. Stathopoulos Vassiliki C. Belessi Athanasios K. Ladavos 《Reaction Kinetics and Catalysis Letters》2001,72(1):49-55
The catalytic combustion of methane with stoichiometric amounts of oxygen to CO2 and H2O has been studied over samarium based high surface area perovskite type oxides SmFe1-xAlxO3 (x=0.00, 0.50 0.95) prepared via a new sol-gel method. A comparison to other lanthanum perovskites prepared by the ceramic method shows higher catalytic activity for SmFeO3 and SmFe0.5Al0.5O3 samples. 相似文献
52.
Benoit Perthame Athanasios E. Tzavaras 《Archive for Rational Mechanics and Analysis》2000,155(1):1-48
For scalar conservation laws, the kinetic formulation makes it possible to generate all the entropies from a simple kernel.
We show how this concept replaces and simplifies greatly the concept of Young measures, avoiding the difficulties encountered
when working in L
p
. The general construction of the two kinetic functions that generate the entropies of 2 × 2 strictly hyperbolic systems
is also developed here. We show that it amounts to building a “universal” entropy, i.e., one that can be truncated by a “kinetic
value” along Riemann invariants. For elastodynamics, this construction can be completed and specialized using the additional
Galilean invariance. This allows a full characterization of convex entropies. It yields a kinetic formulation consisting of
two semi-kinetic equations which, as usual, are equivalent to the infinite family of all the entropy inequalities.
Accepted May 29, 2000?Published online November 16, 2000 相似文献
53.
Athanasios Deligiannis 《manuscripta mathematica》2000,102(2):251-261
We construct for all topological space X and all n∈N a natural section e
n
X
:G
n
X→G
n
G
n
X of the Ganea projection :G
n
G
n
X→G
n
X and show that the triple (G
n
,g
n
,e
n
) is a comonad on Top
*.
Received: 6 March 2000 相似文献
54.
Zoi S. Metaxa Athanasia K. Tolkou Stefania Efstathiou Abbas Rahdar Evangelos P. Favvas Athanasios C. Mitropoulos George Z. Kyzas 《Molecules (Basel, Switzerland)》2021,26(5)
This review is an update about the addition of nanomaterials in cementitious composites in order to improve their performance. The most common used nanomaterials for cementitious materials are carbon nanotubes, nanocellulose, nanographene, graphene oxide, nanosilica and nanoTiO2. All these nanomaterials can improve the physical, mechanical, thermal and electrical properties of cementitious composites, for example increase their compressive and tensile strength, accelerate hydration, decrease porosity and enhance fire resistance. Cement based materials have a very complex nanostructure consisting of hydration products, crystals, unhydrated cement particles and nanoporosity where traditional reinforcement, which is at the macro and micro scale, is not effective. Nanomaterials can reinforce the nanoscale, which wasn’t possible heretofore, enhancing the performance of the cementitious matrix. 相似文献
55.
We consider the wave equation with a focusing cubic nonlinearity in higher odd space dimensions without symmetry restrictions on the data. We prove that there exists an open set of initial data such that the corresponding solution exists in a backward light-cone and approaches the ODE blowup profile. 相似文献
56.
Hoang Tuy Saied Ghannadan Athanasios Migdalas Peter Värbrand 《Mathematical Programming》1996,72(3):229-258
We show that the production-transportation problem involving an arbitrary fixed number of factories with concave production
cost is solvable in strongly polynomial time. The algorithm is based on a parametric approach which takes full advantage of
the specific structure of the problem: monotonicity of the objective function along certain directions, small proportion of
nonlinear variables and combinatorial properties implied by transportation constraints. 相似文献
57.
We devise Lyapunov functionals and prove uniform L1 stability for one-dimensional semilinear hyperbolic systems with quadratic nonlinear source terms. These systems encompass a class of discrete velocity models for the Boltzmann equation. The Lyapunov functional is equivalent to the L1 distance between two weak solutions and non-increasing in time. They result from computations of two point interactions in the phase space. For certain models with only transversal collisional terms there exist generalizations for three and multi-point interactions. 相似文献
58.
Hoang Tuy Saied Ghannadan Athanasios Migdalas Peter Värbrand 《Journal of Global Optimization》1995,6(2):135-151
We prove that the Minimum Concave Cost Network Flow Problem with fixed numbers of sources and nonlinear arc costs can be solved by an algorithm requiring a number of elementary operations and a number of evaluations of the nonlinear cost functions which are both bounded by polynomials inr, n, m, wherer is the number of nodes,n is the number of arcs andm the number of sinks in the network.On leave from Institute of Mathematics, P.O. Box 631, Bo Ho, Hanoi, Vietnam. 相似文献
59.
60.
Methyl esters of N-(3,5-dinitrobenzoyl)-amino acids have been used as chiral solvating agents to induce NMR spectral nonequivalence between the enantiomers of a broad array of solutes. 相似文献