Search results for "EXPANSION"
showing 10 items of 630 documents
High-Temperature Series Analysis of the Free Energy and Susceptibility of the 2D Random-Bond Ising Model
1999
We derive high-temperature series expansions for the free energy and susceptibility of the two-dimensional random-bond Ising model with a symmetric bimodal distribution of two positive coupling strengths J_1 and J_2 and study the influence of the quenched, random bond-disorder on the critical behavior of the model. By analysing the series expansions over a wide range of coupling ratios J_2/J_1, covering the crossover from weak to strong disorder, we obtain for the susceptibility with two different methods compelling evidence for a singularity of the form $\chi \sim t^{-7/4} |\ln t|^{7/8}$, as predicted theoretically by Shalaev, Shankar, and Ludwig. For the specific heat our results are less…
Simulation of BSDEs with jumps by Wiener Chaos Expansion
2016
International audience; We present an algorithm to solve BSDEs with jumps based on Wiener Chaos Expansion and Picard's iterations. This paper extends the results given in Briand-Labart (2014) to the case of BSDEs with jumps. We get a forward scheme where the conditional expectations are easily computed thanks to chaos decomposition formulas. Concerning the error, we derive explicit bounds with respect to the number of chaos, the discretization time step and the number of Monte Carlo simulations. We also present numerical experiments. We obtain very encouraging results in terms of speed and accuracy.
Newton algorithm for Hamiltonian characterization in quantum control
2014
We propose a Newton algorithm to characterize the Hamiltonian of a quantum system interacting with a given laser field. The algorithm is based on the assumption that the evolution operator of the system is perfectly known at a fixed time. The computational scheme uses the Crank-Nicholson approximation to explicitly determine the derivatives of the propagator with respect to the Hamiltonians of the system. In order to globalize this algorithm, we use a continuation method that improves its convergence properties. This technique is applied to a two-level quantum system and to a molecular one with a double-well potential. The numerical tests show that accurate estimates of the unknown paramete…
Quantitative Prediction of Concentration Effects in Steric Exclusion Chromatography
1986
Abstract A semiempirical model, based on a previous one quantitatively describing the dependence of the elution volume, V(cA), on the concentration of injected polymer, cA, in exclusion chromatography (SEC) at dilute solutions, has been developed. In the derived equation, concentration effects are mainly governed by the Huggins' coefficient, kA, and by the quadratic coefficient in the polynomial expansion of the reduced specific viscosity, kA. Because of the incertitudes on reliable kA and kA' values, these are respectively removed from the model through she Imai's equation and the empirical correlation kA' + 0.122=kA, here obtained. Thus, A predicted elution volumes besides polymer concent…
Advances in Strain Gauge Measurement on Composite Materials
2010
Abstract: This article gives an overview on the application of strain gauge techniques to the analysis of the strains in composite materials. The orthotropic behaviour of the composite influences the performance of strain gauges that are calibrated for use on isotropic materials. The article considers therefore the typical topics of the strain gauge technology applied to composites with particular reference to the compensation of thermal output, the measurement of the coefficients of thermal expansion, the determination of the strain and stress state, the influence of the misalignment error, the reinforcement effect, the determination of the stress intensification factor, the analysis of r…
Fe-periclase reactivity at Earth's lower mantle conditions: Ab-initio geochemical modelling
2017
Intrinsic and extrinsic stability of the (Mg, Fe) O solid mixture in the Fe-Mg-Si-O system at high P, T conditions relevant to the Earth's mantle is investigated by the combination of quantum mechanical calculations (Hartree-26 Fock/DFT hybrid scheme), cluster expansion techniques and statistical thermodynamics. Iron in the (Mg, Fe) O binary mixture is assumed to be either in the low spin (LS) or in the high spin (HS) state. Un-mixing at solid state is observed only for the LS condition in the 23-42 GPa pressure range, whereas HS does not give rise to un-mixing. LS (Mg, Fe) O un-mixings are shown to be able to incorporate iron by subsolidus reactions with a reservoir of a virtual bridgmanit…
Noninvasive Flap Preconditioning by Foam-Mediated External Suction Improves the Survival of Fasciocutaneous Axial-Pattern Flaps in a Type 2 Diabetic …
2018
Background Advances in reconstructive surgery are leading to an increased number of flaps at risk for ischemic necrosis, because of either intrinsic (e.g., larger flap size) or extrinsic (e.g., diabetes) factors. Methods to preoperatively improve flap vascularity and limit postoperative ischemia are lacking. Noninvasive suction, using either a macrodeformational silicone cup interface (external volume expansion) or a microdeformational polyurethane foam interface (foam-mediated external volume expansion), has been shown to induce angiogenesis in tissues. The authors investigated whether the preoperative use of external volume expansion/foam-mediated external volume expansion improves flap s…
ASYMPTOTIC CURVES ON SURFACES IN ℝ5
2008
We study asymptotic curves on generically immersed surfaces in ℝ5. We characterize asymptotic directions via the contact of the surface with flat objects (k-planes, k = 1 - 4), give the equation of the asymptotic curves in terms of the coefficients of the second fundamental form and study their generic local configurations.
Urban Smartness: Tools and Experiences
2014
The necessary steps to build a different city that combines both sustainable development and urban quality include understanding of the events that emerge in different territories, identifying the appropriate actions, policies and finding innovative tools and procedures.
Study of High-Temperature Behaviour of ZnO by Ab Initio Molecular Dynamics Simulations and X-ray Absorption Spectroscopy
2021
Wurtzite-type zinc oxide (w-ZnO) is a widely used material with a pronounced structural anisotropy along the c axis, which affects its lattice dynamics and represents a difficulty for its accurate description using classical models of interatomic interactions. In this study, ab initio molecular dynamics (AIMD) was employed to simulate a bulk w-ZnO phase in the NpT ensemble in the high-temperature range from 300 K to 1200 K. The results of the simulations were validated by comparison with the experimental Zn K-edge extended X-ray absorption fine structure (EXAFS) spectra and known diffraction data. AIMD NpT simulations reproduced well the thermal expansion of the lattice, and the pronounced …