Relevant bibliographies by topics / Tracé de rayon

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
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Academic literature on the topic 'Tracé de rayon'

Author: Grafiati
Published: 4 June 2021
Last updated: 11 February 2022

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Journal articles on the topic "Tracé de rayon"

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Sabbarese, C., F. Ambrosino, and V. Roca. "ANALYSIS BY SCANNER OF TRACKS PRODUCED BY RADON ALPHA PARTICLES IN CR-39 DETECTORS." Radiation Protection Dosimetry 191, no. 2 (September 2020): 154–59. http://dx.doi.org/10.1093/rpd/ncaa140.

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Abstract The most used passive detectors for Radon measurement are the CR39s, both for the good stability of the material and for the practicality of use. But, commercial reading systems are expensive and not always fast. The aim of the present work was the development of a method for a rapid, efficient and economic evaluation of the result of the indoor Radon measurement performed with CR39 detectors. The analysis and acquisition of detector images were performed using a photo scanner and the free ImageJ software. Several groups of CR-39 detectors were exposed, developed and analysed. Calibration curve was obtained in a wide range of exposure values (200–12 000 kBq·h·m −3) to allow the procedure to be applied in all possible measurement environments. Furthermore, a statistical study was carried out on the shape and size of nuclear tracks after chemical development. The dependence of the track size on Radon exposure was effective in showing the trace saturation effect as well.
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Khasbaatar, D., and Ung Su Choi. "Fourier Transform Infrared Spectroscopy Study on Cation adsorption on Viscose Rayon Succinate." Mongolian Journal of Chemistry 12 (September 24, 2014): 136–41. http://dx.doi.org/10.5564/mjc.v12i0.189.

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Ion-exchange materials have been considered as suitable material for the recovery of heavy metals in water. A viscose rayon succinate, synthesized from viscose rayon and succinic anhydride in presence of DMSO, to remove trace bivalent metal ions such as Ag+, Cu2+, Ni2+, Pb2+, Zn2+ and Cr3+, was studied using FT-IR for the behavior of metal adsorption. Both esterification and carboxyl bonding of viscose rayon succinate were assigned essentially at 1729 and 1693cm-1, respectively. And the essential band of bonding between metal and the material was determined at 1625cm-1. The available adsorption capacity of this fiber was 6.2 mequiv/g. The adsorption of metal ions on the viscose rayon succinate follows the order of Cu2+>Cr3+>Ni2+>Pb2+>Zn2+>Ag+ with maximum adsorptions capacities 4.2, 1.42, 0.91, 0.83, 0.69 and 0.35 mmol/g, respectively.DOI: http://dx.doi.org/10.5564/mjc.v12i0.189 Mongolian Journal of Chemistry Vol.12 2011: 136-141
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McLaughlin, J. P., and B. Fitzgerald. "Models for Determining the Response of Passive Alpha Particle Detectors to Radon and Its Progeny in Cylindrical Detecting Volumes." Radiation Protection Dosimetry 56, no. 1-4 (December 1, 1994): 241–46. http://dx.doi.org/10.1093/oxfordjournals.rpd.a082462.

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Abstract Many radon detectors exist in the form of a planar disc shaped alpha particle detector mounted in one end of a small cylindrical chamber. Models have been developed to determine the sensitivity of such detectors to radon exposure. A model, adapted from the Jacobi-Porstendorfer room models, is used to determine the partitioning of short-lived radon progeny between airborne and surface deposited states within the detecting volume. This is used in conjunction with Monte Carlo simulation to obtain the radon sensitivity. The use of these models with passive alpha track detectors is highlighted although they are of general applicability to passive detectors using other alpha detecting media. Using these models it is possible to design passive detectors with dimensions such that the alpha track densities may be optimised to a chosen radon exposure range. Validation of the modelling is presented in the form of comparisons between predicted and experimentally determined sensitivities of CR-39 alpha track detectors.
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Yarmoshenko, Ilia, Georgy Malinovsky, Aleksey Vasilyev, and Aleksandra Onishchenko. "Seasonal Variation of Radon Concentrations in Russian Residential High-Rise Buildings." Atmosphere 12, no. 7 (July 20, 2021): 930. http://dx.doi.org/10.3390/atmos12070930.

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Assessment of the annual radon concentration is often required in indoor radon surveys of territories and individual dwellings for comparison with reference levels, studying factors affecting radon accumulation in dwellings, assessment of exposure in epidemiological studies, etc. The indoor radon surveys were carried out in multistorey buildings in eight Russian cities using solid state nuclear track detectors with an exposure period of three months. For these surveys, the estimation of annual indoor radon concentration was required to compare radon levels in buildings of high- and low-energy-efficiency classes located in different cities. To develop approaches to seasonal normalization in high-rise buildings, long-term one-hour radon concentration series obtained applying radon-monitors in 20 flats were analyzed. The dependency of indoor radon concentration on the indoor–outdoor temperature difference was studied taking into account the known natural, technogenic and anthropogenic factors affecting radon levels. The developed model of seasonal variations in multistorey buildings includes winter, summer, and demi-season periods, which differ both in ventilation intensity and dependency of radon concentration on the temperature difference. The developed model allows to estimate annual radon concentration taking into account the actual distribution of outdoor temperatures during the exposure of the track detectors.
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Palacios, Daniel, Lászlo Sajó-Bohus, and Elisabeth M. Yoshimura. "SSNTD Techniques in Radon Surveys for Hydrocarbon Exploration and Occurrence of Natural Gas Seeps." Solid State Phenomena 238 (August 2015): 55–89. http://dx.doi.org/10.4028/www.scientific.net/ssp.238.55.

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Leakages of hydrocarbon reservoirs often increase the radon concentration on the soil surface through distinct pathways; gas migration results in either prolific macro-seeps or micro-seeps. Soil gases, including radon, are recognized as potential tracers in geoscience. The surficial radiometric anomalies over hydrocarbon reservoirs provide the oil community with a complementary survey tool for oil exploration through the use of nuclear track methodology. The Solid State Nuclear Track Detector (SSNTD) is one of the recognized techniques to be employed advantageously in radon surveys for hydrocarbon exploration and occurrence of natural gas seeps. The nuclear track method provides information on the nature of radioactive gas sources, emanations from the soil and their transport pathways. Latent track etching conditions and their analysis are included.
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Khan, Abdul Razzaq, Muhammad Rafique, Saeed Ur Rahman, Kimberlee J. Kearfott, and Matiullah. "A review of radon measurement studies with nuclear track detectors (NTDs) in Azad Kashmir." Indoor and Built Environment 26, no. 4 (January 8, 2016): 447–55. http://dx.doi.org/10.1177/1420326x15626236.

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Inhalation of radon and its progeny are the most important component of public exposure to natural radiations. Many epidemiological studies have established the fact that radon and radon progeny are associated with increased incidence of lung cancer. Beside health concerns, radon is an important consideration in other fields, e.g. hydrological research, detection of geological fault lines, prediction of earthquake, uranium deposits and oil exploration. The importance of the subject compelled many scientists to develop methods for measurement and mitigation of radon. During last decade many studies for measurement of radon and thoron have been conducted in Azad Kashmir. In most studies, the techniques used involve the usage of solid state nuclear track detectors. Building materials, including granite, marbles, gravel aggregates, bricks, sand and soil have been characterized through radon exhalation rate studies. Several research articles have been published, reporting indoor radon measurements in dwellings and at workplaces. Though these studies have provided preliminary information about radon levels in the area, however, data obtained are still unable to convey clear information to readers. This review paper attempts to organize the radon data to provide a clearer understanding and roadmap for radon measurements in Azad Kashmir.
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Ulug, Asiye, Melek Karabulut, and Nilgün Celebi. "Radon measurements with CR-39 track detectors at specific locations in Turkey." Nuclear Technology and Radiation Protection 19, no. 1 (2004): 46–49. http://dx.doi.org/10.2298/ntrp0401046u.

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Indoor radon concentration levels at three sites in Turkey were measured using CR-39 solid state nuclear track detectors. The annual mean of radon concentration was estimated on the basis of four quarter measurements at specific locations in Turkey. The measuring sites are on the active faults. The results of radon measurements are based on 280 measurements in doors. The annual arithmetic means of radon concentrations at three sites (Isparta Egirdir, and Yalvac) were found to be 164 Bqm?3, 124 Bqm?3, and 112 Bqm?3 respectively, ranging from 78 Bqm?3 to 279 Bqm?3. The in door radon concentrations were investigated with respect to the ventilation conditions and the age of buildings. The ventilation conditions were determined to be the main factor affecting the in door radon concentrations. The in door radon concentrations in the new buildings were higher than ones found in the old buildings.
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Papachristodoulou, C. A., K. G. Ioannides, T. J. Mertzimekis, D. T. Karamanis, and K. C. Stamoulis. "Assessment of arrangements for the detection of radon emanating from soil." HNPS Proceedings 6 (February 19, 2020): 288. http://dx.doi.org/10.12681/hnps.2936.

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CR-39 solid state nuclear track detectors were used to measure radon (222Rn) concentration in the soil near ground surface. The measurements were performed in the campus of the University of Ioannina, using PVC tubes at 0.25 m intervals down to depths of 1.25 m. The track detectors were etched in 7N NaOH solutions at 80°C. The tracks were counted using a microscope - camera - computer system, developed for automatic counting. The results provide evidence for the non-diffusive transport of radon in soils. A transport length of (46.9 ± 3.2) cm was estimated for radon transport near ground surface. Also the variation of soil's radon was correlated to meteorological variations.
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Ahmed, Israa Kamil. "Measurement of radon and uranium concentration in soil samples from Babylon cement plant using nuclear track detector CR-39." Iraqi Journal of Physics (IJP) 12, no. 24 (February 18, 2019): 68–74. http://dx.doi.org/10.30723/ijp.v12i24.323.

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In this study, concentrations of radon and uranium were measured for twenty six samples of soil. The radon concentrations in soil samples measured by registrant alpha-emitting radon (222Rn) by using CR-39 track detector. The uranium concentrations in soil samples measured by using registrar fission fragments tracks in CR-39 track detector that caused by the bombardment of U with thermal neutrons from 241 Am-Be neutron source that has flux of 5 ×103n cm-2 s-1.The concentrations values were calculated by a comparison with standard samples The results show that the radon concentrations are between (91.931-30.645Bq/m3).The results show that also the uranium concentrations are in soil samples under 0.051-0.0079ppm.
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Sutej, T. "Sensitivity of a Combined Charcoal and Etched Track Technique for 222Rn." Radiation Protection Dosimetry 56, no. 1-4 (December 1, 1994): 255–58. http://dx.doi.org/10.1093/oxfordjournals.rpd.a082465.

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Abstract To describe the radon detection process of a new radon dosemeter, which is based on the simultaneous utilisation of activated charcoal and CR-39 etched track detector, a simple model was formulated. The dependence of the response of the dosemeter on exposure time, irradiation time of the detector foil, thickness of the charcoal layer, diffusion and the adsorption coefficients of radon in charcoal was calculated. The theoretical model was verified by experiments. It was found that for a short (one hour) exposure to a radon atmosphere the response can be as high as (900 tracks.cm-2.(kBq.m-3)-1.
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Dissertations / Theses on the topic "Tracé de rayon"

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Sittler, Gilles. "Conception of an augmented reality system for applications in surgery." Université Louis Pasteur (Strasbourg) (1971-2008), 2008. http://www.theses.fr/2008STR13154.

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Les systèmes de réalité augmentée ont pris une importance croissante dans de nombreux domaines. On peut citer par exemple la conception aéronautique, le domaine militaire ou encore l’instrumentalisation chirurgicale. Dans ce dernier domaine, les systèmes de réalité augmentée sont souvent utilisés à des fins de formation des chirurgiens, le fait de pouvoir superposer des éléments virtuels à la vision de l’environnement réel du chirurgien apportant un plus indéniable. Ce travail de thèse s’est articulé autour de la conception de la partie optique d’un tel système. Commençant par un travail bibliographique fourni, nous détaillons les différents types de systèmes et de domaines d’applications. Dans la seconde partie de ce manuscrit, nous présentons le cahier des charges du système que nous avons développé, dont les différentes caractéristiques ont pu être extraites de publications trouvées dans la littérature. Ces dernières nous ont permis d’établir un cheminement pour les simulations optiques qui ont été suivies, de même qu’un gabarit géométrique définissant l’encombrement du système à concevoir en tenant compte de l’application visée. Dans la troisième et dernière partie de cette étude, nous détaillons les différentes simulations optiques réalisées à l’aide du logiciel de tracé de rayons CodeV. En suivant les caractéristiques imposées par le cahier des charges, nous présentons les premières simulations utilisant uniquement des « singlets » de façon à assurer une conjugaison correcte entre pupille d’entrée et de sortie du système en n’utilisant qu’un unique point source sur l’axe. Nous détaillons ensuite les différents sous-systèmes conduisant à la simulation d’une grille complète de points sources. Concernant l’introduction de la courbure de l’axe optique de façon à intégrer le système dans le gabarit géométrique défini précédemment, nous introduisons un élément holographique en transmission et les simulations ayant été menées. Les dites simulations incluent des instructions spécialement développées pour CodeV de façon à pouvoir simuler le comportement de l’élément holographique en séparant sa surface en différentes surfaces de moindre taille et en reconstruisant cette mosaïque dans une étape ultérieure. Il est ainsi possible d’obtenir une solution idéale par zone et d’évaluer les performances de l’élément conçu. Le même travail a été mené pour l’élément holographique servant de combineur holographique et les résultats et perspectives sont présentés dans une dernière étape
Augmented reality systems are taking more and more importance in varied contexts. Aeronautic conception, military applications or conception of surgical tools are examples of possible applications of such systems. In this last field of application, augmented reality systems are mostly used for teaching purposes, using the capability of these systems to superimpose virtual elements onto the vision of the surgeon. This PhD work is articulated around the conception of the optical part of such a system. Starting with a detailed bibliographic work, we detail different type of systems and fields of application. Starting from this study, we concentrate our work on the medical applications, detailing different systems developed and present on the market. In the second part of this manuscript, we present the specifications of the system we developed, said specifications being extracted from relevant publications found in the literature. Additionally, the specifications obtained enable us to define a framework of the optical simulations that have been undergone and a geometrical framework in which the system should fit to be in accordance with the field of application aimed at. In the third and last part of this study, we detail the different simulations done using the ray tracing software CodeV. Following the specifications, we present a first approach using singlets ensuring a correct first order optics conjugation of entrance and exit pupils using a single on-axis point. Then, we detail the different steps followed for a complete grid of source points, describing the different consecutive subsystems simulated. For the introduction of the bending of the optical axis to fit the system in the geometrical framework, we introduce a transmission Holographic Optical Element and the simulations that have been undergone. These simulations include custom-made macros using CodeV programming language that had to be developed in order to split the surface of the transmission HOE in smaller areas. This mosaic of small HOEs enabled us to find an ideal solution for each of the sub-zone to simulate the behavior of the whole transmission HOE. The same procedure has been applied to the reflection HOE acting as a holographic combiner. By extracting the values of the diffraction efficiency from these simulations, we have been able to characterize the behavior of both HOEs
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Le, Pape Sébastien. "Etude expérimentale du front d'onde des lasers X : application à la focalisation : modalisation de la propagation des lasers X dans leur milieu amplificateur." Paris 6, 2002. http://www.theses.fr/2002PA066534.

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Dehghan, Kaveh. "Prise en compte d'une anisotropie réaliste dans l'imagerie sismique des zones complexes." Paris, Institut de physique du globe, 2007. http://www.theses.fr/2007GLOB0015.

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In order to respond to world energy demand in the years to come and renew reserves, it is essential to support ongoing exploration efforts by developing new methods. In this way the zones with complex geological structures are one of the main explorationzones to study. To explore these zones and reduce the risk of dry wells we need to develop high performance methods through seismic imaging which could be also used for surveying the new exploration zones and re-evaluating the potential of oil fields already exploited. Anisotropy is an omnipresent property in the sedimentary layers which is mainly originated from fine stratification, effect of mineral particles and in-situ stress conditions. For the complex geological structures, the layers dip is largely variable which can lead the principal directions of sedimentary anisotropy to vary through the layers as a function of stratification. The main goal of this work is to provide a 3D modeling software which can be used for realistic layered anisotropic media in the complex tectonics area, to study the effects of such anisotropy on seismic imaging, and proposing some solutions for taking into account the anisotropy in the treatment procedure. For defining the anisotropic media, we consider here the special case of transverse isotropy (TI) with a spatially varying symmetry axis conformed with the structure (STI). The first chapter of this thesis is consecrated to a brief introduction to seismic anisotropy. Different types of seismic anisotropy and their geologic aspects are explained. Also the way we define the STI media is presented. In the second section we present the approximate ray tracing for qP waves in inhomogeneous layered STI media. All needed equations for calculating cinematic and dynamic parameters using first-order ray tracing are given in this chapter. All the quantities required for evaluation of the Green s function are calculated to first order, except the traveltime that is calculated to second order. In this chapter the accuracy of developed algorithm is verified on simple models with respect to exact ray-tracing results, then the method is applied to simple STI models and to a realistic overthrust model to study the cinematic and dynamic effects of STI media. The two next sections are consecrated to applications of developed algorithm to AVAZ study and tomography. The third chapter includes an application of our dynamic ray tracing algorithm to AVA analysis. The relative importance of several factors affecting the amplitude versus azimuth in a realistic 3D model is analyzed and the results obtained by using our dynamic ray tracing algorithm are compared with 1D analytical solutions which are current in the industry. Then we present the first attempts to STI inversion using our ray tracing algorithm. It is explained how we can calculate the partial derivatives of traveltimes with respect to the model parameters in TI media. Then the formulation used by the 3D reflection tomography software (called Jerry) developed by KIM research consortium (IFP) is presented, and the inversion method is applied to a synthetic STI example. Finally, the main points are summarized in the fifth chapter of thesis which is consecrated to conclusions and some perspectives to this study
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Ferrand, Adrien. "Développement de modèles asymptotiques en Contrôle Non Destructif (CND) par ultrasons : Interaction des ondes élastiques avec des irrégularités géométriques et prise en compte des ondes de tête." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2014. http://tel.archives-ouvertes.fr/tel-01072253.

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L'onde de tête est l'onde de première arrivée observée au cours d'une inspection TOFD (Time Of Flight Diffraction). La technique TOFD est une méthode d'inspection très répandue en CND (Contrôle Non Destructif) par ultrasons, faisant appel à deux capteurs piézoélectriques positionnés symétriquement et en vis-à-vis, avec un écartement constant, au-dessus de la surface d'entrée de la pièce à inspecter. Une étude numérique montre que la propagation de l'onde de tête près d'une surface d'entrée irrégulière n'est plus un phénomène de propagation uniquement surfacique comme dans le cas d'une surface plane, mais fait aussi intervenir un phénomène de propagation volumique induit par des diffractions du champ ultrasonore sur les irrégularités de surface. Pour modéliser ces phénomènes, une méthode générique de tracé de rayons fondée sur le principe de Fermat généralisé est développée et détermine le parcours effectif dans une pièce de surface irrégulière de toutes les ondes ultrasonores se propageant dont l'onde de tête. L'évaluation des phénomènes de diffraction par des modèles d'amplitude suivant une approche rayons permet ensuite d'obtenir une simulation complète (temps de vol, front d'onde et amplitude) de l'onde de tête pour plusieurs types d'irrégularités surfaciques. Des validations théoriques et expérimentales de l'outil de simulation développé ont été effectuées et se sont avérées concluantes.
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Devillers, Olivier. "Méthodes d'optimisation du tracé de rayons." Phd thesis, Université Paris Sud - Paris XI, 1988. http://tel.archives-ouvertes.fr/tel-00772857.

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Le tracé de rayons est la seule technique de synthèse d'images permettant le réalisation d'effets lumineux spéculaires. Cet algorithme est très coûteux en temps de calcul. Nous nous intéressons aux diverses méthodes d'optimisation du tracé de rayons basées sur la subdivision de l'espace. Nous proposons une structure de subdivision originale : les macro-régions. Cette structure utilise un grid dans lequel les éléments de grid appartenant à des zones à faible densité d'information sont regroupées en macro-régions. Nous présentons ensuite une étude théorique et pratique du coût de dif- férentes méthodes de subdivision de l'espace : grid, octree, boîtes englobantes et la structure de macro-régions. Le coût moyen d'un rayon est étudié d'un point de vue pratique d'après les résultats d'une implantation de l'algorithme, et théorique en utilisant des résultats de géométrie stochastique. Ce coût est divisé en deux parties, on calculera tout d'abord le nombre moyen d'objets rencontrés par un rayon, puis le nombre moyen de régions rencontrées par un rayon dans les différents cas de subdivision. Cette étude fournit un certain nombre de résultats généraux permettant de mener à bien les mêmes calculs pour d'autres structures. Les résultats exposés établissent l'efficacité de la subdivision par macro- régions.
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Dauphin, Myriam. "Amélioration des simulations thermiques dans les systèmes d'éclairage automobiles." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2014. http://www.theses.fr/2014EMAC0005/document.

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Les systèmes d'éclairage automobiles sont conçus pour éclairer la route de manière optimale. Une dégradation des optiques et des matériaux plastiques peut altérer la qualité du faisceau lumineux. En phase de conception, les simulations thermiques visent à minimiser les coûts engendrés par les tests expérimentaux réalisés sur des maquettes. Avec le développement de nouvelles optiques, la méthode numérique des ordonnées discrètes, utilisée pour le calcul des transferts radiatifs, souffre d'un manque de précision en raison d'une discrétisation spatiale limitée pour les réflexions spéculaires. Une augmentation de la discrétisation pourrait mener à des temps de calculs importants. Pour palier à ce problème, la méthode de Monte Carlo a été choisie afin d'évaluer les densités de flux aux parois dans le cas des surfaces opaques, ou un terme source radiatif dans le cas des matériaux semi-Transparents. Notre algorithme est implémenté dans l'environnement de développement EDStar. Cet environnement inclut la bibliothèque de synthèses d'images PBRT permettant de reproduire les trajets optiques dans une géométrie 3D complexe. L'étude porte sur des produits d'éclairage composés de lampes, ainsi le développement d'un modèle numérique fiable requiert des paramètres pertinents en entrée de modèle. Les travaux ont donc été scindés en trois axes d'études. Le premier inclut une phase de caractérisation des propriétés thermiques d'une lampe à incandescence (25W). Différentes méthodes de mesures ont été étudiées pour déterminer la température du filament, moteur des transferts thermiques, et la température de l'enveloppe. Le second axe consiste à développer un modèle des transferts radiatifs dans le système d'éclairage. L'objectif est de localiser les zones de concentration du rayonnement et estimer leur étendue. Enfin, le troisième axe vise à coupler le calcul radiatif à des simulations thermiques dans l'outil de CFD Fluent. La CFD (Computational Fluid Dynamics) est ici nécessaire pour résoudre les problèmes convectifs couplés aux autres transferts thermiques dans un produit industriel
Automotive lighting systems are designed to illuminate the road optimally. Degradation of optical properties or plastics materials may altering the quality of lighting. In the design stage, thermal simulations are intended to minimize the costs of experimental tests performed on prototypes. With the apparition of new headlights optics, the Discrete Ordinates method (DO) is not suitable in certain cases due to a lack of accuracy when dealing with specular reflections and refractions. A raise of the spatial discretization could lead to significant time computation. To overcome this problem, we chose the Monte Carlo method in order to estimate flux densities to the walls in the case of opaque surfaces, or to estimate a radiative source term in the case of semi-Transparent media. Our algorithm is implemented in EDStar coding environment. This environment includes the PBRT synthesis images library allowing the use of raytracing techniques with our algorithm, thus reproducing optical paths of rays in a complex 3D geometry. The development of a reliable numerical model requires relevant parameters in input. This need led us to split the work into three main parts. The first axis includes a characterization phase of thermal properties of an incandescent lamp (25W) in order to model its radiative emission. Different measurements methods have been investigated to determine the temperature of the filament, which is the origine of heat transfers, and the temperature of the glass envelope. The second axis consists in obtaining a precise distribution of flux density distributions in order to locate hot spots and assess their extent. Finally, the third part of study is to couple the radiative calculation to CFD (Computational Fluid Dynamics) simulations. CFD is here necessary to solve problems with convective phenomena coupled with other heat transfers in an industrial product
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Maillot, Jean-Luc. "Pseudo-réalisme et progressivité pour le tracé de rayons." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1996. http://tel.archives-ouvertes.fr/tel-00825860.

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La résolution de l'éclairement global d'une scène par le trace de rayons implique l'élaboration de méthodes de Monté Carlo adaptées à la complexité de l'équation de rendu. Nous proposons une méthode de résolution globale et adaptative un trace de chemin spectral partant de l'il basée sur un échantillonnage d'importance permettant d'augmenter la vitesse de convergence de la résolution. Notre méthode consiste à mimer les variations de la luminance réfléchie en tenant compte de la fonction de réflectance bidirectionnelle et des caractéristiques des sources. Ce premier échantillonnage a priori est progressivement modifie par un schéma a posteriori s'adaptant à la luminance réellement réfléchie à mesure qu'elle est connue. Le deuxième aspect de nos travaux porte sur la génération des points de l'écran afin de ne calculer que ceux qui sont nécessaires à une qualité d'image donnée. Nous proposons une technique progressive basée sur une notion d'homogénéité visuelle locale de l'image. Cette homogénéité est testée à l'aide d'un procède statistique puissant utilisant l'analyse séquentielle. Notre méthode permet souvent des gains en temps de calcul très substantiels pour une bonne qualité d'image. L'ensemble de nos travaux a été inspire par la notion de réalisme. Nous montrons que le photoréalisme est insuffisant au contrôle d'une image et proposons des pistes de réflexion pour ce concept trop peu aborde en synthèse d'images
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Drouet, Florence. "Mesures 3D et d'épaisseur par imagerie sur des objets en verre creux." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS062.

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Les travaux présentés dans ce mémoire portent sur l’étude et le développement d’une méthode de mesure d’épaisseur et de reconstruction 3D d’objets en verre creux, dans le cadre d’une application de contrôle industriel sur ligne de production. Les techniques de mesure d’épaisseur de parois transparentes sont actuellement très limitées par leur faible tolérance angulaire sur l’orientation des surfaces. Elles nécessitent une rotation de l’article devant le capteur, donc une manutention contraignante. De plus, les surfaces considérées étant spéculaires, les techniques de numérisation standard ne fonctionnent pas. Nous avons développé deux méthodes basées sur l’observation des réflexions d’une source diffuse ponctuelle sur les deux surfaces de la paroi de l’objet. Une observation simple à l’aide d’une caméra implique une ambiguïté entre l’orientation et la position de chacune des deux surfaces. Notre première méthode consiste à utiliser des informations de polarisation pour lever cette ambiguïté. Des résultats expérimentaux, obtenus avec un ou plusieurs points source témoignent de la faisabilité de la mesure. La seconde méthode consiste à utiliser une seconde caméra, associée à un dispositif optique spécifique. Ceci permet de trianguler directement les points d’incidence sur les deux surfaces. De plus, la source peut être étendue verticalement, de manière à augmenter la taille de la zone inspectée. Les résultats obtenus avec cette seconde technique attestent de la possibilité d’une mise en oeuvre industrielle
The work presented in this thesis focuses on the study and development of a method for measuringthe thickness and reconstructing the 3D shape of glass containers, within the frame of an industrialon-line quality monitoring. Measuring thickness techniques of transparent objects are currently limited by their lack of toleranceregarding the surface orientation at a given reflection point. A rotation of the article in front ofthe sensor is thus required, which adds complexity to the mechanical handling of the item beingmeasured. Moreover, conventional scanning techniques do not work well on specular surfaces.We developed two methods based on the observation of the reflections by both surfaces of the wallof a given item of a diffuse, point light source. Imaging these reflections with a plain camera leavesan ambiguity between the orientation and position of each surface. Our first approach uses light polarization to remove this ambiguity. Experimental results, obtainedwith one or several point sources have demonstrated the feasibility of the measure. The second approach uses a second camera, associated with a specific optical design, whichenables a mere triangulation of the incident points on the two surfaces. Moreover, the light sourcecan be vertically extended to increase the size of the inspected area. The results obtained with thissecond technique show that industrial implementation is feasible
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Leung, Yee Yiu. "Study of factors affecting the measurements of concentrations of radon gas, thoron gas and radon progeny using solid state nuclear track detectors /." access abstract and table of contents access full-text, 2006. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?mphil-ap-b21471484a.pdf.

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Thesis (M.Phil.)--City University of Hong Kong, 2006.
"Submitted to Department of Physics and Materials Science in partial fulfillment of the requirements for the degree of Master of Philosophy" Includes bibliographical references (leaves 106-116)
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Roelens, Marc. "Un environnement pour le tracé de rayons utilisant une modélisation par arbre de construction." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1993. http://tel.archives-ouvertes.fr/tel-00828017.

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Le tracé de rayons est désormais un algorithme classique pour la visualisation en synthèse d'images. Nous nous sommes cependant efforcés de ne pas le considérer comme un simple algorithme de visualisation mais comme un algorithme plus général de simulation de transfert d'énergie au sein d'un environnement géométrique. Ce choix a conduit à la définition d'un modèle géométrique indépendant du modèle de rendu qui lui est associé. Ce modèle utilise une méthode par arbre de construction (CSG) avec deux améliorations essentielles: l'utilisation d'un graphe au lieu d'un arbre ainsi que la possibilité d'associer des propriétés à n'importe quel objet du modèle. L'algorithme de calcul d'intersection entre un rayon et un objet est spécialement adapte à ce modèle, et il utilise une technique d'accélération nouvelle, basée sur l'utilisation d'englobant appelés boites englobantes généralisées, palliant certains inconvénients des techniques classiques. L'algorithme de rendu a été rendu générique, ce qui permet de changer facilement d'implémentation de l'algorithme de rendu. Les modèles classiques (Lambert et Phong) sont présentés en détail. Enfin, nous présentons trois applications de notre environnement: l'utilisation de nouveaux systèmes de perspectives, la visualisation de densités volumiques et de primitives de lumière, ainsi qu'une version parallèle de notre algorithme.
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Books on the topic "Tracé de rayon"

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction systems (winter 1987-88): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction system (winter 1988-89): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction system (winter 1988-89): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction systems (winter 1987-88): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction systems (winter 1987-88): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction systems (winter 1987-88): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction systems (winter 1987-88): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Scott, A. G. Follow-up alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction system (winter 1988-89): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Gabriel, Stefan. Retrospective radon exposure assessment: Development of alpha track techniques and field applications. Dublin: University College Dublin, 1998.

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Scott, A. G. Follow-up annual alpha-track monitoring in 40 eastern Pennsylvania houses with indoor radon reduction systems (December 1988 - December 1989): Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1991.

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Book chapters on the topic "Tracé de rayon"

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Oladapo, Olukunle Olaonipekun, Leonard Kofitse Amekudzi, Olatunde Micheal Oni, Abraham Adewale Aremu, and Marian Amoakowaah Osei. "Climate Change Impact on Soil Moisture Variability: Health Effects of Radon Flux Density Within Ogbomoso, Nigeria." In African Handbook of Climate Change Adaptation, 437–52. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_201.

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AbstractClimate affects the quantity of soil moisture within the surface of the earth and this is obtained by affecting the amount of radon flux density escaping from the land surface. This chapter contains the evaluation of climate change conditions as it affects the variability of soil water for the purpose of estimating the health effects of radon flux density within Ogbomoso metropolis. The simulated soil moisture content around Ogbomoso was done for a period of 34 years using the hydrological model, Soil Water Assessment Tool (SWAT). The calibration and validation of the SWAT model was done using the daily observed soil moisture content. The simulated daily soil moisture within Ogbomoso showed good performance when calibrated and validated. A 20 years prediction of the daily soil moisture content was done using the SWAT model. The estimation of the radon flux density for the study area was obtained using the simulated soil temperature and soil moisture from the SWAT model. In this chapter, the UNSCEAR radon flux formula was used for the radon flux estimate. The result showed that the UNSCEAR radon flux formula performed well in estimating the radon flux density in the study area. The mean value of the radon flux density of 15.09 mBqm−2 s−1 falls below the estimated world average of 33 mBqm−2 s−1 by UNSCEAR stipulated for land surface. The results showed that Ogbomoso region is not prone to high risk of radon exposure to the public. The estimation of the radon flux density value suggested that there is no radiological health hazard such as lung cancer or any other respiratory tract diseases to the inhabitant of Ogbomoso, Nigeria.
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Yonehara, H., H. Kimura, M. Sakanoue, E. Iwata, S. Kobayashi, K. Fujimoto, T. Aoyama, and T. Sugahara. "Improving Bare-Track-Detector Measurements of Radon Concentrations." In ACS Symposium Series, 172–85. Washington, DC: American Chemical Society, 1987. http://dx.doi.org/10.1021/bk-1987-0331.ch014.

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Åkerblom, G., and H. Mellander. "Geology and Radon." In Radon Measurements by Etched Track Detectors, 21–49. WORLD SCIENTIFIC, 1997. http://dx.doi.org/10.1142/9789812830197_0002.

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Monnin, M. M., and J. L. Seidel. "Radon Measurement Techniques." In Radon Measurements by Etched Track Detectors, 51–74. WORLD SCIENTIFIC, 1997. http://dx.doi.org/10.1142/9789812830197_0003.

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Jönsson, G. "Soil Radon Surveys." In Radon Measurements by Etched Track Detectors, 179–88. WORLD SCIENTIFIC, 1997. http://dx.doi.org/10.1142/9789812830197_0009.

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Jönsson, G. "Indoor Radon Surveys." In Radon Measurements by Etched Track Detectors, 157–77. WORLD SCIENTIFIC, 1997. http://dx.doi.org/10.1142/9789812830197_0008.

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Kabata-Pendias, Alina, and Barbara Szteke. "Radon [Rn, 88]." In Trace Elements in Abiotic and Biotic Environments, 257–59. CRC Press, 2015. http://dx.doi.org/10.1201/b18198-36.

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Durrani, S. A. "Alpha-Particle Etched Track Detectors." In Radon Measurements by Etched Track Detectors, 77–101. WORLD SCIENTIFIC, 1997. http://dx.doi.org/10.1142/9789812830197_0004.

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Muirhead, C. R. "Radon-Induced Health Effects." In Radon Measurements by Etched Track Detectors, 243–57. WORLD SCIENTIFIC, 1997. http://dx.doi.org/10.1142/9789812830197_0013.

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Hakl, J., I. Hunyadi, and A. Várhegyi. "Radon Monitoring in Caves." In Radon Measurements by Etched Track Detectors, 261–83. WORLD SCIENTIFIC, 1997. http://dx.doi.org/10.1142/9789812830197_0014.

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Conference papers on the topic "Tracé de rayon"

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Singh, Lalit Mohan, K. Y. Singh, Ajay Mahur, Dinesh Kumar, and Devesh Gupta. "Measurement of radon exhalation rate using solid state nuclear track detector." In ADVANCES IN BASIC SCIENCE (ICABS 2019). AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5122505.

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Fuwei, Deng, and Guo Huiping. "Measurement of Radon Concentration in the Air of Underground Establishment with Solid State Track Detector." In 2007 8th International Conference on Electronic Measurement and Instruments. IEEE, 2007. http://dx.doi.org/10.1109/icemi.2007.4350412.

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Singh, Bhupender, Krishan Kant, Maneesha Garg, Ajit Singh, B. K. Sahoo, and B. K. Sapra. "Radiological impact of radon and thoron levels in dwellings measured using solid state nuclear track detectors." In ADVANCES IN BASIC SCIENCE (ICABS 2019). AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5122498.

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Shikha, Deep, Tejinder Pal Singh, and Mohinder Pal. "Assessment of indoor radon levels in some parts of North India, using solid state nuclear track detectors." In ADVANCES IN BASIC SCIENCE (ICABS 2019). AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5122507.

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Raja, Waleed N. "Measurement of radon concentrations in water around the northern areas of Baghdad using the CN-85 track detector." In XIAMEN-CUSTIPEN WORKSHOP ON THE EQUATION OF STATE OF DENSE NEUTRON-RICH MATTER IN THE ERA OF GRAVITATIONAL WAVE ASTRONOMY. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5116990.

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Pongpiachan, S., V. Surapipit, A. Ketratanakul, N. Wuttijak, and A. Pongnoppa. "Risk analysis by emission source strengths and wind directions of trace gases at Map Ta Phut Industrial Estate, Rayong province, Thailand." In RISK ANALYSIS 2010. Southampton, UK: WIT Press, 2010. http://dx.doi.org/10.2495/risk100291.

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Reports on the topic "Tracé de rayon"

1

Scholz, Florian. Sedimentary fluxes of trace metals, radioisotopes and greenhouse gases in the southwestern Baltic Sea Cruise No. AL543, 23.08.2020 – 28.08.2020, Kiel – Kiel - SEDITRACE. GEOMAR Helmholtz Centre for Ocean Research Kiel, November 2020. http://dx.doi.org/10.3289/cr_al543.

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R/V Alkor Cruise AL543 was planned as a six-day cruise with a program of water column and sediment sampling in Kiel Bight and the western Baltic Sea. Due to restrictions related to the Covid-19 pandemic, the original plan had to be changed and the cruise was realized as six oneday cruises with sampling in Kiel Bight exclusively. The first day was dedicated to water column and sediment sampling for radionuclide analyses at Boknis Eck and Mittelgrund in Eckernförde Bay. On the remaining five days, water column, bottom water, sediment and pore water samples were collected at eleven stations covering different types of seafloor environment (grain size, redox conditions) in western Kiel Bight. The data and samples obtained on cruise AL543 will be used to investigate (i) the sedimentary cycling of bio-essential metals (e.g., nickel, zinc, and their isotopes) as a function of variable redox conditions, (ii) the impact of submarine groundwater discharge and diffusive benthic fluxes on the distribution of radium and radon as well as greenhouse gases (methane and nitrous oxide) in the water column, and (iii) to characterize and quantify the impact of coastal erosion on sedimentary iron, phosphorus and rare earth element cycling in Kiel Bight.
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Cohen, B. S. Particle deposition in human tracheobronchial casts: A determinant of radon dose to the critical cells of the respiratory tract. Final report, May 15, 1993--May 14, 1997. Office of Scientific and Technical Information (OSTI), August 1997. http://dx.doi.org/10.2172/532691.

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Chromosome damage in respiratory tract: dosimetry and cancer [Radon Program; Microbeam instrument]. Office of Scientific and Technical Information (OSTI), April 2000. http://dx.doi.org/10.2172/765288.

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