Search results for "inho"
showing 10 items of 132 documents
Reduction of Convective Low-Frequency Noise in Thermal Lens Spectrometry
1990
The construction and optimization of a thermal lens spectrometer with coaxial pump/probe configuration is reported. The low-frequency noise of convective origin is studied in detail, and it is demonstrated that a horizontal slit, instead of a pinhole, can be used as a simple way of reducing the noise to a negligible level without losing sensitivity.
Ergodicity for a stochastic Hodgkin–Huxley model driven by Ornstein–Uhlenbeck type input
2013
We consider a model describing a neuron and the input it receives from its dendritic tree when this input is a random perturbation of a periodic deterministic signal, driven by an Ornstein-Uhlenbeck process. The neuron itself is modeled by a variant of the classical Hodgkin-Huxley model. Using the existence of an accessible point where the weak Hoermander condition holds and the fact that the coefficients of the system are analytic, we show that the system is non-degenerate. The existence of a Lyapunov function allows to deduce the existence of (at most a finite number of) extremal invariant measures for the process. As a consequence, the complexity of the system is drastically reduced in c…
Bayesian analysis of a Gibbs hard-core point pattern model with varying repulsion range
2014
A Bayesian solution is suggested for the modelling of spatial point patterns with inhomogeneous hard-core radius using Gaussian processes in the regularization. The key observation is that a straightforward use of the finite Gibbs hard-core process likelihood together with a log-Gaussian random field prior does not work without penalisation towards high local packing density. Instead, a nearest neighbour Gibbs process likelihood is used. This approach to hard-core inhomogeneity is an alternative to the transformation inhomogeneous hard-core modelling. The computations are based on recent Markovian approximation results for Gaussian fields. As an application, data on the nest locations of Sa…
Thermodynamic approach to vortex production and diffusion in inhomogeneous superfluid turbulence
2014
In this paper, we use a non-equilibrium thermodynamic framework to generalize a previous nonlocal model of counterflow superfluid turbulence to incorporate some new coupled terms which may be relevant in the evolution of inhomogeneous vortex tangles. The theory chooses as fundamental fields the energy density, the heat flux, and the averaged vortex line length per unit volume. The constitutive quantities are assumed to depend on the fundamental fields and on their first spatial derivatives, allowing us to describe thermal dissipation, vortex diffusion and a new contribution to vortex formation. The restrictions on the constitutive relations are deduced from the entropy principle, using the …
Scattering studies of large scale structures at the ultra small angle neutron scattering instrument S18
2002
Abstract In recent years ultra small angle neutron scattering (USANS) has developed into a powerful standard method for large scale structure investigations. The upgraded instrument S18 at the ILL's 58 MW high flux reactor is operated routinely with increasing beam time demand. The performance of the instrument and its abilities will be discussed in this paper. A peak to background ratio better than 10 5 is reached using Agamalian's tail reduction method. A q -range from 2.10 −5 up to 5.10 −2 A −1 can be covered. This allows a clear overlap with standard pinhole SANS instruments. The new way collecting scattering data logarithmically equidistant in q -space saves measuring time. This allows…
Inhomogeneous vortex tangles in counterflow superfluid turbulence: flow in convergent channels
2016
Abstract We investigate the evolution equation for the average vortex length per unit volume L of superfluid turbulence in inhomogeneous flows. Inhomogeneities in line density L andincounterflowvelocity V may contribute to vortex diffusion, vortex formation and vortex destruction. We explore two different families of contributions: those arising from asecondorder expansionofthe Vinenequationitself, andthose whichare notrelated to the original Vinen equation but must be stated by adding to it second-order terms obtained from dimensional analysis or other physical arguments.
Os testemunhos fotográficos da obra pública em Portugal
2013
As primeiras notícias sobre a descoberta da fotografia foram conhecidas em Portugal em 1839e, após essa data, os testemunhos fotográficos da obra pública portuguesa foram constantes. Os pioneiros da fotografia em Portugal foram estrangeiros residentes no Porto mas, pouco depois surgiram fotógrafos portugueses nas várias regiões do país. Estes fotógrafos, juntamente com os engenheiros, começaram a fazer o registo fotográfico das grandes obras públicas para responder aos pedidos oficiais ou de empresas, para fazer a sua difusão na imprensa periódica e em postais, assim como para contribuir para a construção da identidade da nação portuguesa. As principais obras públicas fotografadas estiveram…
Study of acoustic properties and impact behavior of porous materials homogeneous type metal foams and inhomogeneous
2015
This work is concerned with the theoretical and experimental study of the acoustical properties of macroscopically homogenous and inhomogeneous porous media as well as their mechanical response to impacts. The model of Johnson - Champoux - Allard appeared adapted for the acoustical modeling. This model, associated with a recently developed approach involving the concept of parallel transfer matrices has lead to a new approach of macroscopically inhomogeneous porous materials based on “mixtures of materials”. Furthermore, a parametric study of the absorption coefficient as a function of porosity and frequency has been proposed. The maximums of absorption as well as the envelop of the absorpt…
The inhomogeneous mechanical behaviour of Ascending Thoracic Aortic Aneurism (ATAA)
2017
Surgical management of ascending thoracic aortic aneurysms (aTAAs) relies on maximum diameter, growth rate, and presence of connective tissue disorders. The surgical decision however is often not considering that dissection and rupture do occur in patients who do not meet criteria for surgical repair [1,2]. In this study the authors aim to investigate the mechanical properties of aTAAs to be implemented in computational biomechanics models for a preclinical risk evaluation. Additionally, in some recent studies, some data about the biomechanical properties of the aTAAs have been reported [3], but without any relation to bicuspidal or tricuspidal aTAA. The aim of this study was to investigate…
1400 years of man-environment interactions and soil evolution in the Saint-Mont mountain (Remiremont, Vosges)
2021
International audience; The SolHoM(a) project aims at determining the degree of landscape anthropisation in the Fossard massif (Remiremont, Vosges, France) by estimating the impact of past human occupations on current soils. Nowadays, a forest covers this relatively inhospitable mountain (hard climate, steep slopes, acid soils ...), but some remains suggest human presence for at least 1400 years.The Saint-Mont is a variscan orogenic granitic summit (height 672m) with valuable preserved archaeological relics, located south of the Fossard. At the top was founded the monasterium Habendum (from the 7th century to the French Revolution), which potentially comes after a late-antic castrum.Further…