Search results for "Isotropic"

Study of the anisotropy in turbulent superfluids

2010

In this review we are interested on the anisotropy and polarity of superfluid turbulence in helium II, a still open problem which needs more details. Though some of the results presented here have already been published in different papers, this short review aims to put the main results together and to extend them when necessary. From the mesoscopic viewpoint, an evolution equation for the vortex line density was proposed in rotating counterflow (heat flux without mass flux) by means of dimensional analysis. Then, starting from the microscopic viewpoint this evolution equation was further extended to include situations where turbulence is not homogeneously distributed. Indeed, microscopical…

A molecular dynamics study of large-scale reversible aggregation of anisotropic particles

1992

We report findings of 1000 ps molecular dynamics simulations of a bidimensional system of 4050 Lennard–Jones particles with electric dipoles, undergoing spinodal separation. This simple system is used to model the reversible aggregation of building blocks bearing specific and fixed adhesion sites at their surface. Aggregation regions so obtained resemble images of self-assembled biological structures. Statistical analyses of these regions evidence the interplay of thermodynamic instability and of interaction range between the attachment sites. They also illustrate some basic aspects of the morphogenesis of extended biomolecular/cellular structures, self-organized from initially homogeneous …

A New Approach to the Modeling of Anisotropic Media with the Transmission Line Matrix Method

2021

A reformulation of the Transmission Line Matrix (TLM) method is presented to model non-dispersive anisotropic media. Two TLM-based solutions to solve this problem can already be found in the literature, each one with an interesting feature. One can be considered a more conceptual approach, close to the TLM fundamentals, which identifies each TLM in Maxwell’s equations with a specific line. But this simplicity is achieved at the expense of an increase in the memory storage requirements of a general situation. The second existing solution is a more powerful and general formulation that avoids this increase in memory storage. However, it is based on signal processing techniques and considerabl…

Non-Linear Hysteretic Instability in Rotating Machinery

2013

<title>Photoinduced AsSeS thin film phase plates as adaptive optics mirrors for eye aberration correction</title>

2008

Amorphous chalcogenide thin films are excellent materials for holographic recordings. AsSeS thin film coating is a useful optical material for it's thickness to be easily corrected with the use of exposure to light and consecutive chemical etching. Following properties allow to treat the surface of AsSeS chalcogenide films and to use them in adaptive optics systems for correction of the optical wavefront. Hereby, we characterize AsSeS film properties to be used for correction of optical aberrations of the human eye. The thickness of the film is characterized with the method of spectrodensitometry and the surface profile depth with a Hartman- Shack waveform analyzator.

Wave propagation in anisotropic turbulent superfluids

2013

In this work, a hydrodynamical model of Superfluid Turbulence previously formulated is applied to study how the presence of a non-isotropic turbulent vortex tangle modifies the propagation of waves. Two cases are considered: wave front parallel and orthogonal to the heat flux. Using a perturbation method, the first-order corrections due to the presence of the vortex tangle to the speeds and to the amplitudes of the first and second sound are determined. It is seen that the presence of the quantized vortices couples first and second sound, and the attenuation of second sound is proportional to the line density L if the wave propagates orthogonal to the heat flux, while it is proportional to …

Complete basis set prediction of methanol isotropic nuclear magnetic shieldings and indirect nuclear spin–spin coupling constants (SSCC) using polari…

2009

Efficient B3LYP and BHandH density functionals were used to estimate methanol's nuclear magnetic isotropic shieldings and spin–spin coupling constants in the basis set limit. Polarization‐consistent pcS‐n and pcJ‐n (n = 0, 1, 2, 3 and 4), and segmented contracted XZP, where X = D, T, Q and 5, basis sets were used and the results fitted with simple mathematical formulas. The performance of the methods was assessed from comparison with experiment and higher level calculations. 1J(CH) and 3J(HH) values were determined from very diluted solutions in deuterochloroform and compared with theoretical predictions. The agreement between complete basis set (CBS) density functional theory (DFT) predict…

On Some Applications of Nonlinear Differential Equations in Image Processing: Concepts and Electronic Implementation

2011

International audience

A new invariant-based method for building biomechanical behavior laws - Application to an anisotropic hyperelastic material with two fiber families

2013

Abstract In this article, we present a general constructive and original approach that allows us to calculate the invariants associated with an anisotropic hyperelastic material made of two families of collagen fibers. This approach is based on mathematical techniques from the theory of invariants: • Definition of the material symmetry group. • Analytical calculation of a set of generators using the Noether’s theorem. • Analytical calculation of an integrity basis. • Comparison between the proposed invariants and the classical ones.

A 3D multispectral integrated acquisition system : acquisition, data coding and compression

2010

We have developed an integrated system permitting the simultaneous acquisition of the 3D shape and the spectral spectral reflectance of scanned object surfaces. We call this system a 3D multispectral scanner because it combines within a stereopair, a multispectral video camera and a structured light projector. We see several application possibilities for a such acquisition system but we want to highlight applications in the field of digital archiving and broadcasting for heritage objects. In the manuscript we first introduce the acquisition system and its necessary calibrations and treatments needed for his use. Then, once the acquisition system is functional, data that are generated are ri…