Christophe Martinsons - Academia.edu (original) (raw)

Papers by Christophe Martinsons

Research paper thumbnail of Assessment of the health effects of low-frequency sounds and infra-sounds from wind farms. ANSES Opinion. Collective expertise report

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Research paper thumbnail of Analyse de revetements durs par radiometrie infrarouge photothermique : estimation des proprietes thermiques par techniques inverses application a l'evaluation de l'adherence

La radiometrie infrarouge photothermique est utilisee pour analyser les proprietes thermiques de ... more La radiometrie infrarouge photothermique est utilisee pour analyser les proprietes thermiques de couches dures ceramiques sur substrat d'acier. La technique consiste a induire un echauffement periodique par une source laser modulee et a detecter le rayonnement infrarouge synchrone avec l'excitation. Pour resoudre le probleme inverse, les donnees experimentales sont d'abord calibrees precisement. Puis, la modelisation est optimisee et la procedure d'estimation de parametres est adaptee aux problemes inverses mal poses apparaissant en thermique. L'introduction de la fonction de transfert photothermique, tenant compte de la non linearite du signal avec la temperature, permet d'aboutir a un modele simple dont l'application numerique est rapide. L'analyse dimensionnelle du probleme direct fournit un ensemble minimal et complet de parametres modeles. La non satisfaction d'un critere statistique, le critere k, signale l'impossibilite d'accomplir leur identification simultanee. L'approche developpee dans ce travail consiste alors a determiner les parametres les mieux resolus par l'inversion des donnees. Ces parametres optimaux, mutuellement independants, sont recherches de maniere iterative sous la forme de combinaisons lineaires des logarithmes des parametres modeles. Apres inversion des donnees, les proprietes thermiques dimensionnelles du revetement, de l'interface et du substrat sont estimees. Les resultats experimentaux conduisent a une estimation assez precise de l'effusivite thermique des revetements et la detection de tres faibles resistances thermiques d'interface (10#-#7w#-#1m#2k). En relation avec la microstructure, l'interpretation des proprietes thermiques d'echantillons d'acier revetus de nitrure de titane tin et de nitrure de titane carbure ti(n,c) montre que la resistance thermique d'interface n'est pas correlee a l'adherence, telle qu'elle est mesuree par le test de rayure ou des essais fonctionnels. En revanche, les resultats du test de rayure sont relies a la dispersion des mesures photothermiques, provoquee par des variations d'epaisseur et de diffusivite thermique du revetement.

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Research paper thumbnail of Photobiological Safety

Springer eBooks, 2017

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Research paper thumbnail of Assessment of Personal Occupational Exposure to Radiofrequency Electromagnetic Fields in Libraries and Media Libraries, Using Calibrated On-Body Exposimeters

International Journal of Environmental Research and Public Health, Jun 13, 2019

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Research paper thumbnail of Recent progress in the measurement of the thermal properties of hard coatings

Thin Solid Films, Apr 1, 1998

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Research paper thumbnail of A fiber optic array spectrometer with parallel multichannel optical lock-in detection and its application to in situ lighting measurements

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Research paper thumbnail of A method to measure the spectral responsivity of a photometer using optical excitations with arbitrary spectral distributions

Lighting Research & Technology, Jul 16, 2021

The spectral responsivity of a photometer is usually measured using very narrow optical excitatio... more The spectral responsivity of a photometer is usually measured using very narrow optical excitations, provided by a monochromator or a tuneable laser. This article describes a technique to measure the spectral responsivity using an arbitrary number of optical excitations having any type of spectral distribution. The problem is formulated as an inverse problem which is solved using a probabilistic approach based on Bayes’ theorem. The method requires a prior knowledge of the spectral responsivity, which can be proportional to the standard photopic function, with an uncertainty level related to the spectral match index of the photometer. Using this method, the estimation can be performed from data provided by a simple experimental set-up. The numerical application provides a stable and unique solution to the inverse problem, along with the estimation uncertainties. Using a tuneable LED source, the method was applied to an illuminance measurement head, giving an estimation of its spectral responsivity from 380 to 780 nm with a step of 1 nm. The results were in good agreement with data obtained by a monochromator-based technique. Our measurement had larger uncertainties towards the red and blue limits of the spectrum as the light source provided very little light at these wavelengths.

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Research paper thumbnail of Inverse analysis for the measurement of thermal properties of hard coatings

High Temperatures-high Pressures, 1999

ABSTRACT

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Research paper thumbnail of Optimal parameterization of a mathematical model for solving parameter estimation problems

Inverse Problems in Science and Engineering, Apr 1, 2005

This article presents a method to solve parameter estimation problems by finding an optimal param... more This article presents a method to solve parameter estimation problems by finding an optimal parameterization of the mathematical model. The pi-theorem of dimensional analysis is used to establish a formulation of the model based on dimensionless products and scaling parameters, together with the rules of a parameterization change. Logarithmic parameters are introduced for the purpose of working in a linear parameter space in which a given base corresponds to a specific parameterization. The optimal parameterization is assumed to yield uncorrelated estimators. A statistical independence criterion based on the Fisher information matrix is derived for maximum-likelihood estimators. The method allows one to solve inverse problems with highly correlated model parameters by identifying well-resolved parameters, leading to a solution expressed in terms of correlation laws between physical quantities.

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Research paper thumbnail of Review of Parameters Measured to Characterize Classrooms’ Indoor Environmental Quality

Buildings

As attention to indoor environmental quality (IEQ) grows, a systematic strategy for assessing IEQ... more As attention to indoor environmental quality (IEQ) grows, a systematic strategy for assessing IEQ in schools needs to be developed. For this purpose, this paper presents a summary of parameters measured in school classrooms to characterize the quality of thermal, acoustic, and visual environments and indoor air quality (IAQ). The summary is based on a review of published literature reporting measurements in schools in Europe and North America in the past ten years. It also summarizes the measurement protocols and measured concentrations. Eighty-eight papers describing measurements in schools were identified and analyzed. No unique standardized measuring method was used in the reviewed studies and different parameters were measured. The most often measured parameters were those describing the thermal environment and IAQ. The former mainly comprised air temperature and relative humidity. The latter mainly comprised concentrations of carbon dioxide, particulate matter, radon, formaldeh...

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Research paper thumbnail of Characterization of Compact Fluorescent Lights RF Emissions in the Perspective of Human Exposure

IEICE Proceeding Series

In a context where energy is valued, the use of Compact Fluorescent Light bulbs with low energy c... more In a context where energy is valued, the use of Compact Fluorescent Light bulbs with low energy consumption (CFL) tends to generalize. However, the radio noise produced by these sources is currently the subject of many discussions, particularly about the issue of human exposure. This paper is dedicated to the characterization of the electric and magnetic fields radiated by various models of lamps. For this purpose, we have carried out tests in the immediate vicinity (near field) of these CFLs in order to identify the frequencies involved, and the EM fields produced at very short distance. These measurements were conducted insitu to study the evolution of the electro-magnetic field over several minutes.

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Research paper thumbnail of Population Exposure to Electromagnetic Fields Generated by Radio Base Stations: Evaluation of the Urban Background by Using Provisional Model and Instrumental Measurements

Radiation Protection Dosimetry, 2001

Electromagnetic radiation, which is used by broadcasting and mobile telephone systems to transmit... more Electromagnetic radiation, which is used by broadcasting and mobile telephone systems to transmit information, permeates the city environment. In order to properly evaluate population exposure to electromagnetic fields, knowledge of their intensity and spectral components is necessary. In this study the results of radiofrequency field monitoring carried out in Torino, a large town located in the north-west of Italy are shown: the variation of the electromagnetic field strength is evaluated as a function of the height from the ground, the location in the urban area and the frequency. separating the contributions of the different sources (broadcasting antennas and radio base stations for mobile phones). Furthermore, the contribution of the radio base stations is theoretically evaluated, adding the emissions off all installations situated in Torino and examining the field strength maps calculated, considering the orography, for different heights. The theoretical values are also compared with those measured in the frequency range of mobile telephony emissions.

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Research paper thumbnail of Detection of the Stroboscopic Effect Under Low Levels of the Stroboscopic Visibility Measure

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Research paper thumbnail of Detection of the stroboscopic effect by young adults varying in sensitivity

Lighting Research & Technology, Feb 12, 2020

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Research paper thumbnail of Correspondence: On the state of knowledge concerning the effects of temporal light modulation

Lighting Research & Technology, 2021

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Research paper thumbnail of Assessment of the risks to worker health posed by climate change. Opinion of the French Agency for Food, Environmental and Occupational Health and Safety - collective expert appraisal report

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Research paper thumbnail of Exposition aux champs électromagnétiques au travail

Archives Des Maladies Professionnelles Et De L Environnement, Sep 1, 2017

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Research paper thumbnail of The Usefulness of Near-Field Goniophotometry Data to Assess Illuminances and Discomfort Glare in Indoor Lighting

Leukos, Jul 21, 2021

ABSTRACT In lighting simulations, a luminaire is usually modeled using a luminous intensity distr... more ABSTRACT In lighting simulations, a luminaire is usually modeled using a luminous intensity distribution emitted by a single-point source. This so-called far-field approach is valid as long as the dimensions of the luminaire are much smaller than the distance to the calculation surface. This assumption is generally not met in standard indoor lighting and may lead to significant errors in the prediction of illuminances and discomfort glare. This work describes a practical near-field approach based on splitting the luminaire into N point sources. The errors in relation to the near field (infinite value of N) are evaluated as a function of N. This approach generates a more accurate assessment of the Unified Glare Rating in the case of luminaires with non-uniform emission.

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Research paper thumbnail of Precise measurements of Thermal Diffusivity by Photothermal Radiometry for Semi-infinite Targets using Accurately Determined Boundary Conditions

Analytical Sciences/Supplements Proceedings of 11th International Conference of Photoacoustic and Photothermal Phenomena, 2002

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Research paper thumbnail of How good is the evidence that light at night can affect human health?

Graefes Archive for Clinical and Experimental Ophthalmology, Jan 3, 2020

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Research paper thumbnail of Assessment of the health effects of low-frequency sounds and infra-sounds from wind farms. ANSES Opinion. Collective expertise report

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Analyse de revetements durs par radiometrie infrarouge photothermique : estimation des proprietes thermiques par techniques inverses application a l'evaluation de l'adherence

La radiometrie infrarouge photothermique est utilisee pour analyser les proprietes thermiques de ... more La radiometrie infrarouge photothermique est utilisee pour analyser les proprietes thermiques de couches dures ceramiques sur substrat d'acier. La technique consiste a induire un echauffement periodique par une source laser modulee et a detecter le rayonnement infrarouge synchrone avec l'excitation. Pour resoudre le probleme inverse, les donnees experimentales sont d'abord calibrees precisement. Puis, la modelisation est optimisee et la procedure d'estimation de parametres est adaptee aux problemes inverses mal poses apparaissant en thermique. L'introduction de la fonction de transfert photothermique, tenant compte de la non linearite du signal avec la temperature, permet d'aboutir a un modele simple dont l'application numerique est rapide. L'analyse dimensionnelle du probleme direct fournit un ensemble minimal et complet de parametres modeles. La non satisfaction d'un critere statistique, le critere k, signale l'impossibilite d'accomplir leur identification simultanee. L'approche developpee dans ce travail consiste alors a determiner les parametres les mieux resolus par l'inversion des donnees. Ces parametres optimaux, mutuellement independants, sont recherches de maniere iterative sous la forme de combinaisons lineaires des logarithmes des parametres modeles. Apres inversion des donnees, les proprietes thermiques dimensionnelles du revetement, de l'interface et du substrat sont estimees. Les resultats experimentaux conduisent a une estimation assez precise de l'effusivite thermique des revetements et la detection de tres faibles resistances thermiques d'interface (10#-#7w#-#1m#2k). En relation avec la microstructure, l'interpretation des proprietes thermiques d'echantillons d'acier revetus de nitrure de titane tin et de nitrure de titane carbure ti(n,c) montre que la resistance thermique d'interface n'est pas correlee a l'adherence, telle qu'elle est mesuree par le test de rayure ou des essais fonctionnels. En revanche, les resultats du test de rayure sont relies a la dispersion des mesures photothermiques, provoquee par des variations d'epaisseur et de diffusivite thermique du revetement.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Photobiological Safety

Springer eBooks, 2017

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Assessment of Personal Occupational Exposure to Radiofrequency Electromagnetic Fields in Libraries and Media Libraries, Using Calibrated On-Body Exposimeters

International Journal of Environmental Research and Public Health, Jun 13, 2019

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Recent progress in the measurement of the thermal properties of hard coatings

Thin Solid Films, Apr 1, 1998

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A fiber optic array spectrometer with parallel multichannel optical lock-in detection and its application to in situ lighting measurements

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A method to measure the spectral responsivity of a photometer using optical excitations with arbitrary spectral distributions

Lighting Research & Technology, Jul 16, 2021

The spectral responsivity of a photometer is usually measured using very narrow optical excitatio... more The spectral responsivity of a photometer is usually measured using very narrow optical excitations, provided by a monochromator or a tuneable laser. This article describes a technique to measure the spectral responsivity using an arbitrary number of optical excitations having any type of spectral distribution. The problem is formulated as an inverse problem which is solved using a probabilistic approach based on Bayes’ theorem. The method requires a prior knowledge of the spectral responsivity, which can be proportional to the standard photopic function, with an uncertainty level related to the spectral match index of the photometer. Using this method, the estimation can be performed from data provided by a simple experimental set-up. The numerical application provides a stable and unique solution to the inverse problem, along with the estimation uncertainties. Using a tuneable LED source, the method was applied to an illuminance measurement head, giving an estimation of its spectral responsivity from 380 to 780 nm with a step of 1 nm. The results were in good agreement with data obtained by a monochromator-based technique. Our measurement had larger uncertainties towards the red and blue limits of the spectrum as the light source provided very little light at these wavelengths.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Inverse analysis for the measurement of thermal properties of hard coatings

High Temperatures-high Pressures, 1999

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optimal parameterization of a mathematical model for solving parameter estimation problems

Inverse Problems in Science and Engineering, Apr 1, 2005

This article presents a method to solve parameter estimation problems by finding an optimal param... more This article presents a method to solve parameter estimation problems by finding an optimal parameterization of the mathematical model. The pi-theorem of dimensional analysis is used to establish a formulation of the model based on dimensionless products and scaling parameters, together with the rules of a parameterization change. Logarithmic parameters are introduced for the purpose of working in a linear parameter space in which a given base corresponds to a specific parameterization. The optimal parameterization is assumed to yield uncorrelated estimators. A statistical independence criterion based on the Fisher information matrix is derived for maximum-likelihood estimators. The method allows one to solve inverse problems with highly correlated model parameters by identifying well-resolved parameters, leading to a solution expressed in terms of correlation laws between physical quantities.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Review of Parameters Measured to Characterize Classrooms’ Indoor Environmental Quality

Buildings

As attention to indoor environmental quality (IEQ) grows, a systematic strategy for assessing IEQ... more As attention to indoor environmental quality (IEQ) grows, a systematic strategy for assessing IEQ in schools needs to be developed. For this purpose, this paper presents a summary of parameters measured in school classrooms to characterize the quality of thermal, acoustic, and visual environments and indoor air quality (IAQ). The summary is based on a review of published literature reporting measurements in schools in Europe and North America in the past ten years. It also summarizes the measurement protocols and measured concentrations. Eighty-eight papers describing measurements in schools were identified and analyzed. No unique standardized measuring method was used in the reviewed studies and different parameters were measured. The most often measured parameters were those describing the thermal environment and IAQ. The former mainly comprised air temperature and relative humidity. The latter mainly comprised concentrations of carbon dioxide, particulate matter, radon, formaldeh...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Characterization of Compact Fluorescent Lights RF Emissions in the Perspective of Human Exposure

IEICE Proceeding Series

In a context where energy is valued, the use of Compact Fluorescent Light bulbs with low energy c... more In a context where energy is valued, the use of Compact Fluorescent Light bulbs with low energy consumption (CFL) tends to generalize. However, the radio noise produced by these sources is currently the subject of many discussions, particularly about the issue of human exposure. This paper is dedicated to the characterization of the electric and magnetic fields radiated by various models of lamps. For this purpose, we have carried out tests in the immediate vicinity (near field) of these CFLs in order to identify the frequencies involved, and the EM fields produced at very short distance. These measurements were conducted insitu to study the evolution of the electro-magnetic field over several minutes.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Population Exposure to Electromagnetic Fields Generated by Radio Base Stations: Evaluation of the Urban Background by Using Provisional Model and Instrumental Measurements

Radiation Protection Dosimetry, 2001

Electromagnetic radiation, which is used by broadcasting and mobile telephone systems to transmit... more Electromagnetic radiation, which is used by broadcasting and mobile telephone systems to transmit information, permeates the city environment. In order to properly evaluate population exposure to electromagnetic fields, knowledge of their intensity and spectral components is necessary. In this study the results of radiofrequency field monitoring carried out in Torino, a large town located in the north-west of Italy are shown: the variation of the electromagnetic field strength is evaluated as a function of the height from the ground, the location in the urban area and the frequency. separating the contributions of the different sources (broadcasting antennas and radio base stations for mobile phones). Furthermore, the contribution of the radio base stations is theoretically evaluated, adding the emissions off all installations situated in Torino and examining the field strength maps calculated, considering the orography, for different heights. The theoretical values are also compared with those measured in the frequency range of mobile telephony emissions.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Detection of the Stroboscopic Effect Under Low Levels of the Stroboscopic Visibility Measure

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Detection of the stroboscopic effect by young adults varying in sensitivity

Lighting Research & Technology, Feb 12, 2020

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Correspondence: On the state of knowledge concerning the effects of temporal light modulation

Lighting Research & Technology, 2021

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Assessment of the risks to worker health posed by climate change. Opinion of the French Agency for Food, Environmental and Occupational Health and Safety - collective expert appraisal report

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Exposition aux champs électromagnétiques au travail

Archives Des Maladies Professionnelles Et De L Environnement, Sep 1, 2017

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Usefulness of Near-Field Goniophotometry Data to Assess Illuminances and Discomfort Glare in Indoor Lighting

Leukos, Jul 21, 2021

ABSTRACT In lighting simulations, a luminaire is usually modeled using a luminous intensity distr... more ABSTRACT In lighting simulations, a luminaire is usually modeled using a luminous intensity distribution emitted by a single-point source. This so-called far-field approach is valid as long as the dimensions of the luminaire are much smaller than the distance to the calculation surface. This assumption is generally not met in standard indoor lighting and may lead to significant errors in the prediction of illuminances and discomfort glare. This work describes a practical near-field approach based on splitting the luminaire into N point sources. The errors in relation to the near field (infinite value of N) are evaluated as a function of N. This approach generates a more accurate assessment of the Unified Glare Rating in the case of luminaires with non-uniform emission.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Precise measurements of Thermal Diffusivity by Photothermal Radiometry for Semi-infinite Targets using Accurately Determined Boundary Conditions

Analytical Sciences/Supplements Proceedings of 11th International Conference of Photoacoustic and Photothermal Phenomena, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of How good is the evidence that light at night can affect human health?

Graefes Archive for Clinical and Experimental Ophthalmology, Jan 3, 2020

Bookmarks Related papers MentionsView impact