74 research outputs found
Multipurpose S-shaped solvable profiles of the refractive index: application to modeling of antireflection layers and quasi-crystals
A class of four-parameter solvable profiles of the electromagnetic admittance
has recently been discovered by applying the newly developed Property & Field
Darboux Transformation method (PROFIDT). These profiles are highly flexible. In
addition, the related electromagnetic-field solutions are exact, in closed-form
and involve only elementary functions. In this paper, we focus on those who are
S-shaped and we provide all the tools needed for easy implementation. These
analytical bricks can be used for high-level modeling of lightwave propagation
in photonic devices presenting a piecewise-sigmoidal refractive-index profile
such as, for example, antireflection layers, rugate filters, chirped filters
and photonic crystals. For small amplitude of the index modulation, these
elementary profiles are very close to a cosine profile. They can therefore be
considered as valuable surrogates for computing the scattering properties of
components like Bragg filters and reflectors as well. In this paper we present
an application for antireflection layers and another for 1D quasicrystals (QC).
The proposed S-shaped profiles can be easily manipulated for exploring the
optical properties of smooth QC, a class of photonic devices that adds to the
classical binary-level QC.Comment: 14 pages, 18 fi
Comment on Photothermal radiometry parametric identifiability theory for reliable and unique nondestructive coating thickness and thermophysical measurements, J. Appl. Phys. 121(9), 095101 (2017)
A recent paper [X. Guo, A. Mandelis, J. Tolev and K. Tang, J. Appl. Phys.,
121, 095101 (2017)] intends to demonstrate that from the photothermal
radiometry signal obtained on a coated opaque sample in 1D transfer, one should
be able to identify separately the following three parameters of the coating:
thermal diffusivity, thermal conductivity and thickness. In this comment, it is
shown that the three parameters are correlated in the considered experimental
arrangement, the identifiability criterion is in error and the thickness
inferred therefrom is not trustable.Comment: 3 page
Development and validation of a numerical tool for the simulation of the temperature field and infrared radiance rendering in an urban scene
International audienceWe present a numerical tool aimed at simulating infrared images of an urban environment, by solving the direct heat transfer problem, and then computing the radiance rendering at the sensor level. SOLENE (Cerma, Nantes) was coupled with two software packages developed at ONERA: SUSHI (Simulation in Urban Scene of Heat dIffusion) and MOHICANS (MOdélisation Hyperspectrale d'Images en entrée Capteur pour l'ANalyse et l'inversion du Signal) for realizing this task. SUSHI is also used for computing the surface temperatures: either a 1D model or a 2D model is used. We present the whole software chain, its validation by software and experimental analysis
Detection of Open Cracks by a Photothermal Camera
The number of methods which allows for non destructive testings of opening cracks is always increasing but, for industrial applications, the visual testings are still the most widely used especially during the processing steps and the maintenance operations. Among these visual techniques, penetrant testing is one of the most popular methods because its cost is very tow and its versatility is large. Nevertheless, sometimes, this simple technique cannot be used. A few typical cases should be mentionned : unsecured human interventions, forbidden contact with the surface specimen, possibility of false alarms when the surface roughness is important, necessity of an automatised control
Round Robin comparison II of the capabilities of various thermographic techniques in the detection of defects in carbon fibre composites
Round Robin comparison II of the capabilities of various thermographic techniques in the detection of defects in carbon fibre composites
Thermal Ellipsometry: A Tool Applied for in-Depth Resolved Characterization of Fibre Orientation in Composites
Composites with a thermoplastic resin reinforced with short fibres or platelets are commonly processed by injection molding. As far as the fibre orientation is concerned, a stratification generally appears during this operation: near the mould surfaces the fibres are oriented in the direction of the flow, whereas in the middle they are oriented perpendicularly to this direction. The flow parameters obviously determine the relative thickness of this core region and consequently the longitudinal and transverse properties of the composite material. The moulding process has therefore to be optimized so that these anisotropy variations contribute the composite to fulfil the mechanical performance specifications. The in-depth resolved characterization of the filler local orientation as well as its control are thus of prime importance.</p
Comment on “Photothermal radiometry parametric identifiability theory for reliable and unique nondestructive coating thickness and thermophysical measurements” [J. Appl. Phys. 121, 095101 (2017)]
Effusivity depth profiling from pulsed radiometry data: comparison of differenct reconstruction algorithms
Effusivity depth profiling from pulsed radiometry data: comparison of differenct reconstruction algorithms,
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