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Juan Ma Ilker Temizer Peter Wriggers 《International Journal of Solids and Structures》2011,48(2):280-291
In this work, random homogenization analysis of heterogeneous materials is addressed in the context of elasticity, where the randomness and correlation of components’ properties are fully considered and random effective properties together with their correlation for the two-phase heterogeneous material are then sought. Based on the analytical results of homogenization in linear elasticity, when the randomness of bulk and shear moduli, the volume fraction of each constituent material and correlation among random variables are considered simultaneously, formulas of random mean values and mean square deviations of analytical bounds and estimates are derived from Random Factor Method. Results from the Random Factor Method and the Monte-Carlo Method are compared with each other through numerical examples, and impacts of randomness and correlation of random variables on the random homogenization results are inspected by two methods. Moreover, the correlation coefficients of random effective properties are obtained by the Monte-Carlo Method. The Random Factor Method is found to deliver rapid results with comparable accuracy to the Monte-Carlo approach. 相似文献
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The dynamic behavior of a two-sublattice spin-1 Ising model with a crystal-field interaction (D) in the presence of a time-varying magnetic field on a hexagonal lattice is studied by using the Glauber-type stochastic dynamics. The lattice is formed by alternate layers of spins σ=1 and S=1. For this spin arrangement, any spin at one lattice site has two nearest-neighbor spins on the same sublattice, and four on the other sublattice. The intersublattice interaction is antiferromagnetic. We employ the Glauber transition rates to construct the mean-field dynamical equations. Firstly, we study time variations of the average magnetizations in order to find the phases in the system, and the temperature dependence of the average magnetizations in a period, which is also called the dynamic magnetizations, to obtain the dynamic phase transition (DPT) points as well as to characterize the nature (continuous and discontinuous) of transitions. Then, the behavior of the total dynamic magnetization as a function of the temperature is investigated to find the types of the compensation behavior. Dynamic phase diagrams are calculated for both DPT points and dynamic compensation effect. Phase diagrams contain the paramagnetic (p) and antiferromagnetic (af) phases, the p+af and nm+p mixed phases, nm is the non-magnetic phase, and the compensation temperature or the L-type behavior that strongly depend on the interaction parameters. For D<2.835 and H0>3.8275, H0 is the magnetic field amplitude, the compensation effect does not appear in the system. 相似文献
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The dynamic behavior of a mixed spin-1 and spin-2 Ising system with a crystal-field interaction in the presence of a time-dependent oscillating external magnetic field on a hexagonal lattice is studied by using the Glauber-type stochastic dynamics. The lattice is formed by alternate layers of spins σ=1 and S=2. The Hamiltonian model includes intersublattice, intrasublattice and crystal-field interactions. The set of mean-field dynamic equations is obtained by employing the Glauber transition rates. Firstly, we study time variations of the average sublattice magnetizations in order to find the phases in the system, and the thermal behavior of the average sublattice magnetizations in a period or the dynamic sublattice magnetizations to obtain the dynamic phase transition points as well as to characterize the nature (continuous and discontinuous) of transitions. Then, the behavior of the dynamic total magnetization as a function of the temperature is investigated to find the dynamic compensation points as well as determine the type of behavior. We also present the dynamic phase diagrams for both presence and absence of the dynamic compensation temperatures in the nine different planes. According to the values of Hamiltonian parameters, besides the paramagnetic (p), antiferromagnetic (af), ferrimagnetic (i) and non-magnetic (nm) fundamental phases, eight different mixed phases and the compensation temperature or L- and N-types behavior in the Néel classification nomenclature exist in the system. 相似文献
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Ü. Parts V. V. Avilov J. H. Koivuniemi M. Krusius J. J. Ruohio V. M. H. Ruutu 《Czechoslovak Journal of Physics》1996,46(1):13-14
In superfluid3He-A singly and doubly quantized vortex lines can coexist in a rotating container. We measure with NMR techniques the radial distribution of the two vortex types in an array of vortex lines. The radial composition is found to depend on the procedure by which the array has been formed. The result shows that in superfluid3He the energy barriers separating different configurations of the vortex array are inpenetrably high for a metastable state to relax. 相似文献
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A differential pulse polarographic method has been developed for determination of the antineoplastic agents vincristine and vinblastine at ng ml level, in biological fluids such as plasma and urine. The vincristine and vinblastine are extracted from urine with Amberlite XAD-2. Linear calibration plots are obtained for both over the concentration range 0.005-5 mug ml . The relative standard deviations found were 1.7% for analysis of the pure drugs, 7.3% for urine and 8.6% for plasma. 相似文献
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Abstract— The photochemical reactions in concentrated thionine solution have been studied using continuous illumination. Thionine solution is photoreduced to leucothionine in an oxygen-free acidic medium. Electrochemical measurements of the photoreduction of thionine are reported. A possible reaction pathway for the energy transfer is proposed. It is found that polymeric forms of thionine and leucothionine are not involved in photoreduction. It is proposed that a complex must be formed prior to photochemical reduction. This complex species, having a lifetime of several seconds, is reduced to leucothionine, water being the reducing agent. Following this reduction, H2 O2 is formed and the production of H2 O2 is detected by differential pulse polarography. 相似文献
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Abstract —The photoreduction of thionine by water has been studied, using a technique applied in earlier work on photoreduction of methylene blue. It is found for thionine as for methylene blue, that a long-lived excited intermediate is formed, and that two such intermediates react to produce a single reduced molecule, thus providing adequate energy for the reaction. The mechanism proposed for methylene blue photoreduction is shown to be applicable to thionine photoreduction as well, indicating the unimportance of the amine methyl groups. Although in previous work it was suggested that H2 O was the reducing agent, none of them, however, could determine the H2 O2 formed. The formation of H2 O2 is confirmed in this work, and the kinetics of its formation are shown to be in accordance with the mechanism. 相似文献
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The title compounds Tazettine (C18H21NO5) and Corydaldine (3,4-dihydro-6,7-dimethoxy-1(2H)-isoquinolinone, C11H13NO3) have been isolated from the bulbs of Pancratium maritimum L. (Amaryllidaceae) and Corydalis solida subspecies brachyloba, respectively. The X-ray structures were solvcd for Tazettine (I) and Corydaldine (II) (λ MoKα, R = 0.0499 and 0.0418, respectively). Crystals of (I) are orthorhombic, a = 7.115(1), b =13.377(1), c = 16.878(1) Å, Z = 4, Dcale = 1.370 g. cm−3, space group P212121. Crystals of (II) are monoclinic, a =10.641(1), b = 6.636(1), c = 14.938(1) Å, β = 90.31(1)°, Z = 4, Dcalc = 1.305 g. cm−3, space group P21/a. 相似文献