Effect of Density Dependent Viscosities on Multiphasic Incompressible Fluid Models

In this paper, we look at the influence of the choice of the Reynolds tensor on the derivation of some multiphasic incompressible fluid models, called Kazhikhov–Smagulov type models. We show that a compatibility condition between the viscous tensor and the diffusive term allows us to obtain similar models without assuming a small diffusive term as it was done for instance by A. Kazhikhov and Sh. Smagulov. We begin with two examples: The first one concerning pollution and the last one concerning a model of combustion at low Mach number. We give the compatibility condition that provides a class of models of the Kazhikhov–Smagulov type. We prove that these models are globally well posed without assumptions between the density and the diffusion terms.     

Model-independent dynamic constraint to improve the optical reconstruction of regional kinetic parameters

Optical dye-dilution techniques can quantify kinetic parameters in a region of tissue, but currently rely on a two-step process-spatial reconstruction of the dye concentration, repeated at every time-point, and subsequent kinetic analysis of the time-dependent change in dye concentration. Inaccuracies, in this approach, are due mainly to the ill-posed nature of the spatial reconstruction problem, which propagates into kinetic analysis and result in errors in extracted dynamic parameters. We present a hybrid kinetic deconvolution optical reconstruction algorithm, effectively combining optical reconstruction and model-independent kinetic analysis into a single inverse problem that is better posed. Kinetic parameters of multiple tissue regions can be quantified simultaneously. As proof of principle, we provide numerical experiments in reflectance-based and fluorescence molecular tomography scenarios.     

Daily doses of biologically active UV radiation retrieved from commonly available parameters

A multiple linear correlation is done between atmospheric transmissivity for four biologically active radiation daily doses (UVB, erythemal, DNA and plant damage) T, and three parameters (daily sunshine fraction σ, cosine of the daily minimum solar zenith angle μ_min and daily total ozone column Ω). T is defined as the ratio of a daily dose to its extra‐atmospheric value. The data used are spectral UV measurements (390–400 nm at 0.5 nm step) recorded along year 2000 and over 8 months of year 2001 at Briançon Station (Alps, 1300 m above sea level) that forms part of the French UV network. The coefficients obtained from year 2000 correlation permit to retrieve daily doses for year 2001 with an average error running from 3 to 9% for monthly mean values and from 2 to 4.5% for 3‐monthly mean values, depending on daily dose type. The retrieval of yearly mean value gives an error between 4 and 7.5%. Retrieving the daily dose of a given day, where σ≥ 0.2, introduces error running from 16 to 32% depending on daily dose. An attempt to retrieve the yearly mean UVB daily dose for a northern France site, from the previous coefficients, gives encouraging results.     

ChemInform Abstract: Two‐Electron Three‐Centered Bond in Side‐On (η2) Uranyl(V) Superoxo Complexes.

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