Search results for "Measurement"
showing 10 items of 2918 documents
Measurement of UV-induced absorption and scattering losses in photosensitive fibers
2018
UV-assisted fabrication of gratings using photosensitive fibers is a well-established technique, based on the UV-induced permanent modification of the refractive index of the fiber material. As a result, the absorption coefficient is also changed. Here, we exploit the thermal sensitivity of whispering gallery mode resonances of the fiber itself to measure the profile of the heating along an irradiated fiber versus the input power and for different UV radiation intensities. Our technique allows discriminating between the absorption and scattering contributions to the overall losses, by comparing the results obtained with our technique with direct transmission measurements. Different photosen…
The methane Raman spectrum from 1200 to 5500 cm(-1): A first step toward temperature diagnostic using methane as a probe molecule in combustion syste…
2005
International audience; We present a study of the spontaneous Raman spectra of (CH4)-C-12 from 1200 to 5500 cm(-1) at various temperatures. This study is of interest from a fundamental as well as from a practical point of view with regards to the temperature diagnostic in hydrocarbon combustion. The present investigation shows that the spontaneous (CH4)-C-12 Raman spectra are very sensitive to temperature and that the complexity of methane spectra is not an obstacle to use methane as a probe molecule in laser-diagnostic techniques. Our study consists in determining the polarisability parameters of methane (CH4)-C-12, unknown at the present time, from spontaneous Raman spectra recorded at pr…
Influence of Anodic and Thermal Barrier Layers on Physicochemical Behavior of Anodic TiO2 Nanotubes
2011
Electrochemical and photo-electrochemical behavior of self-organized TiO2 nanotubes formed in organic solvents have been studied by taking into account the formation of new barrier layers beneath nanotubes either due to the anodic polarization in aqueous solutions or air exposure during high temperature annealing. It has been shown that before annealing, electrochemical and photoelectrochemical answers are dominantly controlled by the physicochemical properties of the anodic barrier layer. Annealing in air at sufficiently high temperatures changes the initial amorphous structure of as-prepared nanotubes and forms a new oxide layer below them due to thermal oxidation of underneath titanium. …
Rheological characterization and release properties of inulin-based hydrogels
2012
Abstract In the present study the rheological properties of hydrogels obtained through UV irradiation of an aqueous solution of methacrylated inulin (INUMA) alone or in the presence of four different crosslinkers, have been recorded as a function of irradiation time, at two different wavelengths (320 and 365 nm) and fixed frequency and amplitude by oscillatory experiments. Each hydrogel has been analyzed by measurements of the frequency-dependency of the elastic modulus, G ′, in the linear viscoelastic region. The amount of polymeric chains giving an elastic response has been correlated to the chemical nature of the crosslinker used together with INUMA. Finally the release properties of the…
Enhanced thermoelectric properties of lightly Nb doped SrTiO3 thin films
2021
Novel thermoelectric materials developed for operation at room temperature must have similar or better performance along with being as ecofriendly as those commercially used, e.g., BiTe, in terms of their toxicity and cost. In this work, we present an in-depth study of the thermoelectric properties of epitaxial Nb-doped strontium titanate (SrTiNbO) thin films as a function of (i) doping concentration, (ii) film thickness and (iii) substrate type. The excellent crystal quality was confirmed by high resolution transmission electron microscopy and X-ray diffraction analysis. The thermoelectric properties were measured by the three-omega method (thermal conductivity) and van der Pauw method (el…
The Partial Discharge Behavior of Different Materials under DC Periodic Stress
2019
The aim of the present work is to evaluate the PDs behavior by stressing a specimen with a new type of waveform named DCP. This waveform was proposed by the authors in a previous work with the aim to overcome the main issues of PDs under DC stress. In the previous work PDs test on Kapton specimen was performed. In this paper, we propose a new DCP test on a different insulating material, such as the XLPE. The obtained patterns and the acquired data have been evaluated in order to validate the DCP approach as a new method for PDs measure under constant stress. The behavior of the XLPE material has been reported and compared with the former measures obtained for Kapton material.
Electrochemical Fabrication and Physicochemical Characterization of Metal/High-k Insulating Oxide/Polymer/Electrolyte Junctions
2014
Photoelectrochemical polymerization of poly(3,4-ethylenedioxythiophene), PEDOT, was successfully realized on anodic film grown to 50 V on magnetron sputtered Ti-6 atom % Si alloys. Scanning electron microscopy allowed us to evidence formation of compact and uniform polymer layers on the oxide surface. Photoelectrochemical and impedance measurements showed that photopolymerization allows one to grow PEDOT in its conducting state, while a strong cathodic polarization is necessary to bring the polymer in its p-type semiconducting state. Information on the optical and electrical properties of metal/oxide/polymer/electrolyte junctions proves that PEDOT has promising performance as an electrolyte…
Simultaneous measurement of temperature and strain in glass fiber/epoxy composites by embedded fiber optic sensors: I. Cure monitoring
2007
In this paper (Part I) the use of fiber optic sensors for real-time monitoring of the cure kinetics of GFRP composites is explored. The proposed sensing system allows the simultaneous measurement of both temperature and strain by monitoring the change in reflected wavelength from two coupled fiber Bragg grating (FBG) sensors that have been embedded into the composite laminate. Instrumented GFRP laminates with 12, 18 and 24 reinforcing plies, respectively, were prepared by means of the vacuum bagging technique. Samples were cured in a thermally controlled oven at 80 degrees C and 30 kPa for 240 min (isothermal stage) and then cooled down to ambient temperature by turning off the heating sour…
Finite difference analysis of the thermal behaviour of coated tools in orthogonal cutting of steels
2004
Abstract Temperature measurement and prediction have been a major focus of machining for several decades but now this problem became more important due to the wider use of advanced cutting tool coatings. Practically, there is a lack of simulation programs for prediction of the temperatures in the cutting zone when machining with differently coated cutting tools. In all literature items cited the finite difference methods (finite difference approaches) were used to find the distribution of temperature inside the uncoated tool body or along the tool–chip interface for continuous (turning) and interrupted (milling) machining processes. The algorithm applied overcomes this limit. In this study,…
A field method for measuring the thermal infrared emissivity
1993
Abstract In this work, a field method for measuring thermal infrared emissivities is proposed which is based on the box method, initially developed by Buettner and Kern (1965) for laboratory measurements. A theoretical analysis was made of the measurement carried out using the box and a correcting factor to Buettner and Kern's technique has been determined. Buettner and Kern's method has been modified to use radiative temperatures measured with a radiothermometer instead of radiance measurements. The walls of the box used and the cold lid was made of polished aluminium and the hot lid was made of black-painted anodized aluminium and it was heated in the field by solar radiation. With this m…