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91.
Alain Tressaud Jean Louis Soubeyroux Jean Michel Dance René Sabatier Paul Hagenmuller Barbara M. Wanklyn 《Solid State Communications》1981,37(6):479-484
The nature of the magnetic interactions in the chain compound Rb2FeF5 has been investigated using neutron diffraction and magnetic measurements under high applied fields. Rb2FeF5 orders antiferromagnetically at TN = 8.0 ± 0.5 K; the magnetic structure is of the AZ + GX mode and the moment of the Fe3+ ion extrapoled to 0K is 3.5 ± 0.2 μB, this low value being due to zero-point spin reduction. Within a chain the Fe3+ ions are antiferromagnetically coupled with an exchange constant of J/k = ?8.8 K. A spin-flop behavior has been observed and interpreted on the basis of the molecular field theory. The critical field was found to be HC = 65 kOe at 1.7 K. 相似文献
92.
René Michel 《Extremes》2007,10(3):83-107
The investigation of multivariate generalized Pareto distributions (GPDs) has begun only recently. For further progress with
these distributions simulation methods are an important part. We describe several methods of simulating GPDs, beginning with
an efficient method for the logistic GPD. The algorithm is based on the Shi transformation, which was already used for the
simulation of multivariate extreme value distributions (EVDs) of logistic type. In the sequel another algorithm is presented
simulating a broader class of GPDs. Due to its numerical complexity it is only practicably applicable in low dimensions. A
method is given to generate unconditional GPD random vectors from conditionally GPD distributed random vectors. A short application
of the simulation methods in the analysis of a real hydrological data set concludes the article. The simulation algorithms
are available on the author’s home page .
相似文献
93.
Fix a partial order P=(X, <). We first show that bipartite orders are sufficient to study structural properties of the lattice of maximal antichains. We show that all orders having the same lattice of maximal antichains can be reduced to one representative order (called the poset of irreducibles by Markowsky [14]). We then define the strong simplicial elimination scheme to characterize orders which have distributive lattice of maximal antichains. The notion of simplicial elimination corresponds to the decomposition process described in [14] for extremal lattices. This notion leads to simple greedy algorithms for distributivity checking, lattice recognition and jump number computation. In the last section, we give several algorithms for lattices and orders. 相似文献
94.
Ilfat Ghamlouche Teodor Gabriel Crainic Michel Gendreau 《Annals of Operations Research》2004,131(1-4):109-133
In this paper, we propose a path relinking procedure for the fixed-charge capacitated multicommodity network design problem. Cycle-based neighbourhoods are used both to move along paths between elite solutions and to generate the elite candidate set by a tabu-like local search procedure. Several variants of the method are implemented and compared. Extensive computational experiments indicate that the path relinking procedure offers excellent results. It systematically outperforms the cycle-based tabu search method in both solution quality and computational effort and offers the best current meta-heuristic for this difficult class of problems. 相似文献
95.
Michel Balazard 《Advances in Mathematics》2004,188(1):69-86
Opération fondamentale de l'arithmétique, familière depuis des millénaires, la division euclidienne n'a pas livré tous ses secrets. Ainsi, notons pour k et a entiers positifs, le reste de la division euclidienne de k par a, et imaginons un instant que, par un choix convenable d'un entier n et de réels c2,…,cn, nous sachions rendre arbitrairement petite la quantité
96.
Glasses in the binary system xAg2P2O6 − (1 − x)Ag2Te2O5 have been prepared for 0 x 1. For each composition only one glass transition temperature is observed in the temperature range of 180–220 °C. All glasses appear homogeneous considering their optical and electrical properties. Nevertheless, in SEM observations, some glass compositions appear to be heterogeneous after decoration following short nitric acid etching. For each composition, conductivity data obtained in the temperature range of 25–200 °C using impedance techniques obey an Arrhenius relationship with a composition independent pre-exponential term. Variation of the conductivity activation energy with x induces correlative variations of isothermal conductivity curves leading to an increase of the ionic conductivity of about one order of magnitude compared with linearity at 25 °C. This behaviour is discussed with respect to the thermodynamic properties of the glassy solutions. 相似文献
97.
We analyze some cases for which the Pollak–Grabert–Hänggi theory on the activated rate processes for generalized Langevin dynamics exhibits unexplained disagreements with numerical results. First we analyze carefully the PGH theory and we show that a kind of Markovian hypothesis implicitly made in the reasoning is sometimes violated. Then we propose modifications of the original theory in order to take into account the possible effects caused by this violation, and we compare the corrected results with simulations. 相似文献
98.
In this paper, we study the weak invariance of the multidimensional rank statistic when the underlying random variables are nonstationary absolutely regular. 相似文献
99.
Michel Nicolas 《原子核物理评论》2020,37(3):586-594
利用耦合道Gamow壳模型计算了17O和17F的低激发能谱以及16O(p,p)反应的低能弹性散射截面。结果表明,17O和17F中非束缚共振态能级的核子发射宽度的计算需要合理地考虑连续态耦合效应。计算得到的17O和17F的低激发能谱以及16O(p,p)反应的低能弹性散射激发函数都与实验数据吻合较好。这说明基于现实核力的计算可更好地描述16O(p,p)反应的低能弹性散射截面。 相似文献
100.
A tabu search procedure for multicommodity location/allocation with balancing requirements 总被引:2,自引:0,他引:2
Teodor G. Crainic Michel Gendreau Patrick Soriano Michel Toulouse 《Annals of Operations Research》1993,41(4):359-383
We propose a tabu search heuristic for the location/allocation problem with balancing requirements. This problem typically arises in the context of the medium term management of a fleet of containers of multiple types, where container depots have to be selected, the assignment of customers to depots has to be established for each type of container, and the interdepot container traffic has to be planned to account for differences in supplies and demands in various zones of the geographical territory served by a container shipping company. It is modeled as a mixed integer program, which combines zero-one location variables and a multicommodity network flow structure. Extensive computational results on a set of benchmark problems and comparisons with an efficient dual ascent procedure are reported. These show that tabu search is a competitive approach for this class of problems. 相似文献