Spelling suggestions: "subject:"3dscan"" "subject:"alscan""
41 |
Analyse des émissions électromagnétiques des circuits intégrés / Electromagnetic emissions analysis of integrated circuitsOrdas, Thomas 18 January 2010 (has links)
Dans le domaine de la sécurisation des circuits intégrés, tel que les cartes à puce, les concepteurs de circuits sont contraints à innover, inlassablement, afin de trouver de nouvelles parades aux nouvelles attaques, notamment par canaux cachés. En effet, ces attaques, comme l'analyse des émissions électromagnétiques, permettent d'extraire des informations, contenues à l'intérieur des circuits, sensées être secrètes. Partant de ce constat, dans cette thèse, nous nous sommes focalisés sur l'étude et l'analyse électromagnétique et ce afin de quantifier les possibilités de ces attaques. Ce manuscrit est organisé de la manière qui suit. Dans un premier temps, une plateforme de mesures des émissions électromagnétiques temporelles, que nous avons développées, est présentée, ainsi que des résultats qui ont été obtenus, avec celle-ci, sur différents circuits. A partir de ces résultats, une synthèse des possibilités, relatives à la menace sécuritaire que constituent les analyses électromagnétiques est proposée ainsi que, des propositions de solutions, visant à réduire le rayonnement électromagnétique des circuits intégrés. Dans un second temps, nous nous sommes intéressés aux méthodes de simulation de ces émissions électromagnétiques. Un état de l'art, des outils de simulation existants aujourd'hui, nous a permis de mettre en évidence qu'aucun d'eux ne permet d'avoir une résolution suffisamment fine en termes d'émissions électromagnétiques. Afin de combler ce manque, un flot de simulation a été développé. Pour valider ce flot, une comparaison entre les résultats de mesure et les résultats de simulation a été effectuée. / In the area of secure integrated circuits, such as smart cards, circuit designers are always looking to innovate to find new countermeasures against attacks by the various side channels that exist today. Indeed, side channels attacks such as the analysis of electromagnetic emissions permit to extract secret information contained in circuits. Based on this observation, in this thesis, we focused on the study of electromagnetic analysis to observe the analysis possibilities. This manuscript is organized as follows. Initially, we presented a measurement system for electromagnetic emissions in time domain, and the results obtained on different circuits. From these results, a summary of opportunities, relating to the security threat, posed by electromagnetic analysis, is proposed as well as solutions proposals to reduce electromagnetic radiations of integrated circuits. In a second step, we are interested in the simulation of electromagnetic emissions. A state of the art of simulation tools which exist today, has allowed us to demonstrate that none of them allowed to have a fine enough resolution in terms of electromagnetic emissions. To fill this gap, a simulation tool has been developed and to validate this flow, a comparison between measurement results and simulation results was performed.
|
42 |
A revision of the small snakes of the family Anomalepididae (Reptilia: Squamata: Serpentes), using high resolution computerized tomographySantos, Fid?lis J?nio Marra 22 March 2018 (has links)
Submitted by PPG Zoologia (zoologia-pg@pucrs.br) on 2018-05-29T13:52:52Z
No. of bitstreams: 1
Tese - Santos - Fid?lis.pdf: 21234236 bytes, checksum: 6b55c8c14033601ff328f8d7bed152b9 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2018-05-29T14:16:25Z (GMT) No. of bitstreams: 1
Tese - Santos - Fid?lis.pdf: 21234236 bytes, checksum: 6b55c8c14033601ff328f8d7bed152b9 (MD5) / Made available in DSpace on 2018-05-29T14:21:21Z (GMT). No. of bitstreams: 1
Tese - Santos - Fid?lis.pdf: 21234236 bytes, checksum: 6b55c8c14033601ff328f8d7bed152b9 (MD5)
Previous issue date: 2018-03-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / A fam?lia Anomalepididae atualmente ? constitu?da por 18 esp?cies de cobras,
conhecidas como ?cobras-cegas?, fossoriais e de distribui??o geogr?fica restrita ? regi?o
Neotropical. Praticamente, n?o h? informa??es a respeito da hist?ria de vida dos
Anomalepididae, pois s?o animais de dif?cil coleta e a manuten??o em cativeiro para
estudos com biologia ? bastante dif?cil. As informa??es dispon?veis a respeito de cobras
Anomalepididae est?o concentradas em estudos anat?micos, principalmente osteologia
do cr?nio, taxonomia e filogenia a n?vel de fam?lias dentro de Serpentes. Mas, desde a
descri??o de Anomalepididae por Taylor em 1939, n?o houve uma revis?o taxon?mica
abrangente dentro da fam?lia ou alguma infer?ncia filogen?tica com novos arranjos
taxon?micos. Em rela??o ? taxonomia do grupo, a literatura ? restrita ? descri??o de
novas esp?cies e revis?es taxon?micas de dois g?neros (Anomalepis e Liotyphlops). O
objetivo prim?rio deste estudo foi a revis?o taxon?mica da fam?lia Anomalepididae e,
para isto, foi utilizado toda a amostragem poss?vel de esp?cies e esp?cimes na aquisi??o
de dados morfol?gicos, al?m do emprego da t?cnica High-Resolution X-ray Computed
Tomography (HRXCT). O objetivo secund?rio foi inferir uma hip?tese filogen?tica para
as esp?cies dentro de Anomalepididae com base nos caracteres anat?micos obtidos do
exame de esp?cimes. Este trabalho resultou em um novo arranjo taxon?mico para
Anomalepididae, com 19 esp?cies v?lidas, descri??o de duas novas esp?cies de
Liotyphlops para o Brasil, sendo uma para o estado de Mato Grosso e outra para o
estado de Santa Catarina e a recondu??o de Liotyphlops beui para a sinon?mia de
Liotyphlops ternetzii. Al?m disto, a an?lise de parcim?nia com base em caracteres do
cr?nio e da morfologia externa recuperou Anomalepididae como um t?xon monofil?tico
dentro de Scolecophidia. / The family Anomalepididae currently consists of 18 species known as "blind
snakes", fossorial in habit and with geographical distribution restricted to the
Neotropical region. Practically, there is no information about the life history of the
Anomalepididae, because they are difficult to collect and the maintenance in captivity
for biology studies is quite difficult. The information available regarding
Anomalepididae snakes is concentrated on anatomical studies, mainly osteology of the
skull, taxonomy, and phylogeny at the level of families within Serpentes. But since the
description of Anomalepididae by Taylor in 1939, there has been no comprehensive
taxonomic review within the family or some phylogenetic inference with new
taxonomic arrangements. In relation to the taxonomy of the group, the literature is
restricted to the description of new species and taxonomic revisions of two genera
(Anomalepis and Liotyphlops). The primary objective of this study was the taxonomic
revision of the Anomalepididae and, for this, all possible sampling of species and
specimens were used in the acquisition of morphological data, besides the use of the
High-resolution X-Ray Computed Tomography (HRXCT) technique. The secondary
objective was to infer a phylogenetic hypothesis for the species within Anomalepididae
based on the anatomical characters obtained from the specimen examination. This work
resulted in a new taxonomic arrangment for Anomalepididae, with 19 valid species,
description of two new species of Liotyphlops from Brazil, being one for the state of
Mato Grosso and the other for the state of Santa Catarina, and the re-conduction of
Liotyphlops beui to the synonymy of Liotyphlops ternetzii. In addition, the parsimony
analysis based on characters from the skull and external morphology recovered
Anomalepididae as a monophyletic taxon within Scolecophidia.
|
43 |
Medida de efeitos óticos não-lineares por reflexão de luz polarizada. / Measurement of non-linear optical effects through the reflection of polarized light.Marcelo Martinelli 17 February 1998 (has links)
Apresentamos neste trabalho uma nova técnica de medida dos termos não-lineares do coeficiente de absorção (beta) e do índice de refração (n_2). Esta nova técnica, denominada Varredura Z de Reflexão Inclinada, aumenta a sensibilidade da Varredura Z de Reflexão em cerca de 30 vezes pelo emprego de um feixe polarizado com incidência inclinada sobre a amostra em estudo. Para uma polarização paralela ao plano de incidência, temos um máximo de sensibilidade nas proximidades do ângulo de Brewster para materiais transparentes, ou do ângulo de mínima reflexão em materiais absortivos. Conseguimos por este método medir variações do índice de refração da ordem de 10^{-4} em absorvedores saturáveis (Aluminato de Gadolínio - GdAlO_{3}:Cr^{+3}). Tais medidas não seriam possíveis sem o aumento obtido na sensibilidade e o uso de uma alta resolução no sistema de aquisição (melhor que 0,1% em intensidade). / We present in this work a new technique that we developed for the measurements of nonlinear coefficients of the absorption (beta) and from the refractive index (n_2). The use of a polarized beam in this new technique (Reflection Z-Scan with Inclined Incidence) increases the set-up sensibility of the conventional RZ-Scan measurement in 30 times. For parallel polarization of the beam to the incidence plane, we can see an increase in the measurement sensibility as the incident light angle approaches the Brewster angle for transparent materials, or the minimum reflection angle for an absorbing material. We have measured changes in the refractive index as small as 10^{-4} in saturable absorber (Gadolinium Aluminate - GdAlO_{3}:Cr^{+3}). Such measurements would not be possible without the development of the sensitivity enhancement achieved by this technique and a high amplitude resolution on the data acquisition system, as small as 0.1%.
|
44 |
Medida de efeitos óticos não-lineares por reflexão de luz polarizada. / Measurement of non-linear optical effects through the reflection of polarized light.Martinelli, Marcelo 17 February 1998 (has links)
Apresentamos neste trabalho uma nova técnica de medida dos termos não-lineares do coeficiente de absorção (beta) e do índice de refração (n_2). Esta nova técnica, denominada Varredura Z de Reflexão Inclinada, aumenta a sensibilidade da Varredura Z de Reflexão em cerca de 30 vezes pelo emprego de um feixe polarizado com incidência inclinada sobre a amostra em estudo. Para uma polarização paralela ao plano de incidência, temos um máximo de sensibilidade nas proximidades do ângulo de Brewster para materiais transparentes, ou do ângulo de mínima reflexão em materiais absortivos. Conseguimos por este método medir variações do índice de refração da ordem de 10^{-4} em absorvedores saturáveis (Aluminato de Gadolínio - GdAlO_{3}:Cr^{+3}). Tais medidas não seriam possíveis sem o aumento obtido na sensibilidade e o uso de uma alta resolução no sistema de aquisição (melhor que 0,1% em intensidade). / We present in this work a new technique that we developed for the measurements of nonlinear coefficients of the absorption (beta) and from the refractive index (n_2). The use of a polarized beam in this new technique (Reflection Z-Scan with Inclined Incidence) increases the set-up sensibility of the conventional RZ-Scan measurement in 30 times. For parallel polarization of the beam to the incidence plane, we can see an increase in the measurement sensibility as the incident light angle approaches the Brewster angle for transparent materials, or the minimum reflection angle for an absorbing material. We have measured changes in the refractive index as small as 10^{-4} in saturable absorber (Gadolinium Aluminate - GdAlO_{3}:Cr^{+3}). Such measurements would not be possible without the development of the sensitivity enhancement achieved by this technique and a high amplitude resolution on the data acquisition system, as small as 0.1%.
|
45 |
The improvement of defect imaging with guided waves in a pipe by SAFT algorithmYeh, Chia-Jung 13 August 2010 (has links)
The guided wave method is one of the non-destructive testing methods with the ability to inspect long length of pipeline. The presence of defects and pipe features can be indicated by analyzing the reflected echoes and the mode conversion phenomena of guided waves. To provide the profile of defects, the signals of guided wave are usually processed to form a B-scan or C-scan image. As for the characteristics of multimodes and dispersion, the C-scan image of defect shows a poor resolution both in the axial and cricumferential directions. Therefore, this study uses the synthetic aperture focusing technique (SAFT) to improve the resolution of the C-scan image. The propagation and scattering of the fundamental torsional mode T(0,1) in pipes are analyzed by the transient analysis of finite element method. Furthermore, the reflected signals are processed by SAFT to form a C-scan image with better resolution. Three types of defects including circumferential crack, axial crack and pitting were discussed in this study both by finite element method and experimental method. In the numerical study, the modification of the C-scan image of the circumferential crack showed a better consequent than the axial crack and pitting. The SAFT was also used to separate the images of two circumferential cracks with different axial location on the pipe succesfully. In the experimental study, the signals of the axisymmetric weld and non-axisymmetric defects were processed by SAFT to form the C-scan image. The results showed a nice resolution of circumferential cracks and the circumferential distribution of the weld in the modified C-scan image at the same time. The application of SAFT to guided wave on a pipe is valid to overcome the effects of guide wave multimode and dispersion characteristics, it provides a new way to defects identification.
|
46 |
Θεωρητικές επεκτάσεις και πειραματικές βελτιώσεις της τεχνικής Z-scan για μέτρηση του μη γραμμικού δείκτη διάθλασηςΤσιγαρίδας, Γεώργιος 28 November 2008 (has links)
- / -
|
47 |
Medidas de intensidade de saturação por refração não-linear transiente / Measurement of saturation intensities by transient nonlinear refractionViviane Pilla 28 June 1996 (has links)
Em sólidos dopados com Cr+3, o efeito não-linear ocorre devido à população de íons dopantes no estado metaestável, o qual possui uma polarizabilidade diferente do estado fundamental. Nestes materiais, o índice de refração não-linear n2 é proporcional a Δα/Is , onde Δα é a diferença de polarizabilidade, entre os estados, excitado (metaestável) e o fundamental, e Is a intensidade de saturação da transição. A técnica conhecida como Z-Scan é na atualidade a mais popular para medidas de n2 e foi recentemente aplicada em cristais dopados com Cr+3. Nestes materiais, o tempo de resposta do meio não-linear é dado pelo longo tempo de vida espontâneo do estado excitado τ0 (usualmente τ0 > 100 µs) tornando possível medidas da resposta transiente do sinal. Isto torna possível a normalização do sinal pela medida em t =O (quando o efeito não-linear ainda não se manifestou) com o intuito de eliminar efeitos lineares parasíticos (devido a imperfeições da superfície da amostra, não paralelismo, etc.). Neste trabalho 7 nós usamos o método de Z-Scan resolvido no tempo para determinar não apenas n2, mas também a intensidade de saturação Is. Nós introduzimos um novo método para determinação de Is, através da medida de Z-Scan transiente. Os valores de n2 e Is, podem ser usados para calcular a seção de choque da absorção no estado fundamental σ1, Δα e Δσ (a diferença de seção de choque de absorção entre o estado excitado e metaestável). , Fizemos medidas em cristais de rubi e alexandrita usando um laser de Ar modulado por um \"chopper\". No caso da alexandrita, o Cr+3 pode ocupar dois sítios que apresentam propriedades bastante diferentes. A técnica resolvida no tempo permite que se diferencie estes dois sítios, e então se determine n2, Is, τ0, Δα e Δσ para o íon de Cr+3 em cada tipo de sítio (no caso do sítio de espelho os valores de n2 e Δα são inéditos). / In Cr+3 doped solids, the nonlinearity originates from the population of dopant íon metastable excited state, which has a polarizability different from that of ground state. In these materials, the non-linear refractive index n2 is proportional to a Δα/Is, where a Δα is polarizability difference between excited and ground states and Is is the transition saturation intensity. The thecnique known as Z-Scan is nowadays the most popular one for n2 measurements and was recently applied to Cr+3 doped solids. In this material, the nonlinearity response time is given by the excited state spontaneous lifetime τ0 (usually τ0 > 100 µs) permitting transient response measurements. This allows signal normalization at t=0 (when the nonlinear effect did not appear yet) in order to eliminate parasitic linear effects (due to nonparallel sample surfaces, surface imperfections, etc.). In the present work we used a time resolved Z-Scan method to determine not only n2 but also the saturation intensity Is and these values can be used to calculate the ground state absorption cross section σ1, Δα and Δσ (where Δσ is the absorption cross section difference between excited and ground states). We introduced a new method to measure Is through transient Z-Scan measurements. We performed measurements in ruby and alexandrite using a chopped Ar+ ion laser. In the alexandrite crystal the Cr+3 ion can occupied two different sites that have very different spectroscopy properties. The time resolved technique allowed us to distinguished these two sites and then determine n2, σ0, Δα , Δσ and Is for the Cr+3 ion each kind of site(our n2, Δα and Is results for the mirror site are original contributions of these work).
|
48 |
Microusinagem de dielétricos com pulsos laser de femtossegundos / Micromachining of dieletrics with femtosecond laser pulsesLeandro Matiolli Machado 24 August 2012 (has links)
Neste trabalho foi utilizado o método de regressão do diâmetro para a medida do limiar de ablação nos materiais Suprasil, BK7, Safira e Ti:Safira por pulsos de femtossegundos. Através de medidas dos limiares de ablação para pulsos únicos e pulsos sobrepostos, quantificou-se o parâmetro de incubação para cada dielétrico. Essas medidas preliminares serviram para validação do método denominado Diagonal Scan ou D-scan. Para tanto, o método D-scan teve seu formalismo expandido o que possibilitou a quantificação da sobreposição de pulsos durante o seu uso. A simplicidade e rapidez do método D-scan permitiram que o limiar de ablação no BK7 fosse medido para diferentes larguras temporais e sobreposições. O limiar de ablação para pulsos únicos em função da largura temporal dos pulsos foi comparado com uma simulação teórica. A partir do conhecimento do parâmetro de incubação desenvolveu-se uma metodologia de usinagem em dielétricos que considera a sobreposição de pulsos durante a ablação. Isso permitiu a fabricação de microcanais para uso em microfluídica em BK7. / In this study, the diameter regression method was used to measure the ablation threshold of Suprasil, BK7, Sapphire and Ti: Sapphire by femtosecond pulses. Through measurements of the ablation thresholds for single and overlapping pulses, the incubation parameter for each dielectric was quantified. These preliminary steps were used to validate the method called Diagonal Scan or D-scan. This was made possible by expanding the D-scan formalism, which allowed the quantification of overlapping pulses during its use. The simplicity of the D-scan method allowed the ablation threshold measurement in BK7 for different temporal widths and overlaps. The ablation threshold for single pulse for different temporal width was compared with a theoretical simulation. From the knowledge of the parameter of incubation, a methodology that considers dielectric machining overlapping pulses during ablation was developed. This allowed the manufacture of microchannels on BK7 for microfluidics.
|
49 |
Le contournement de résistance par Melampsora Larici-populina l'agent de la rouille du peuplier : impact démographique et déterminisme génétique / Resistance breakdown by Melampsora larici-populina, the agent of poplar rust : demographic impact and genetic determinismPersoons, Antoine 15 December 2015 (has links)
Melampsora larici-populina est un champignon pathogène responsable de la rouille foliaire sur les peupliers, causant de graves dommages dans les plantations du monde entier. Presque toutes les résistances des peupliers déployées en France ont été contournées et l'événement majeur est survenu en 1994 avec le contournement de la résistance R7 largement déployée en populiculture. Dans le but d'identifier des gènes candidats liés à la pathogénicité, j'ai mené une étude de génomique comparative basée sur le séquençage de 15 isolats. Cette analyse a mis à jour des patrons de polymorphisme corrélés à la distribution des virulences au sein des isolats tout en révélant la nécessité d'une étude populationnelle. Pour se faire, une étude de génétique des population basée sur le génotypage de 600 isolats de M. larici-populina échantillonnés de 1992 à 2012 a été conduite. Cette analyse m'a permis de décrire l'histoire démographique des populations de M. larici-populina et de documenter l'impact majeur du contournement de la R7 sur la structure des populations. Enfin, j'ai mené une analyse de génomique des populations afin d'obtenir un scenario démographique décrivant les liens historiques entre les populations et d'identifier les régions sous sélection. Cette analyse est basée sur le séquençage en Illumina de 86 isolats répartis en quatre populations clés mises en évidence par l'analyse de la structure génétique des populations. Plus de 1 000 000 positions polymorphes ont été identifiées. Un scenario fiable a été identifié par ABC à partir duquel les enveloppes de confiance des indices de génétique des populations ont été mesurées. L'analyse du génome scan qui a été réalisée sur les 86 génomes en utilisant ces mêmes indices a révélée 20 régions génomiques contenant 14 gènes candidats potentiellement impliquées dans le contournement de la R7. / Melampsora larici-populina is a pathogenic fungus responsible of poplar leaf rust, causing severe damages in plantations worldwide. Almost all poplar resistances deployed so far in France have been overcome and a major event that occurred in 1994 with the breakdown of resistance R7 mostly used in poplar cultivation. In order to identify candidate genes linked to pathogenicity, I conducted a comparative genomics study based on the sequencing of 15 isolates. This analysis revealed polymorphism patterns correlated to the distribution of virulences among isolates while the necessity of a population genetics study. I then analyzed the genetic structure of a comprehensive collection of 600 isolates of M. larici-populina sampled from 1992 to 2012. This analysis demonstrated the major impact of the R7 breakdown on populations. Finally, I conducted a population genomics analysis to obtain a demographic scenario describing the historical links between populations and to identify genomic regions under selection. This analysis is based on the Illumina sequencing of 86 isolates in four key populations identified by the population genetic analysis. Over 1,000,000 polymorphic positions were identified. The best demographic scenario was assessed using Approximate Bayesian Computation algorithms based on coalescent simulations. Using this demographic scenario, I computed the confidence interval of several population genetic indices. This genome scan analysis was performed on the 86 genomes using this same indices and revealed 20 genomic regions containing 14 genes potentially involving in the resistance 7 breakdown
|
50 |
Caching Strategies And Design Issues In CD-ROM Based Multimedia StorageShastri, Vijnan 04 1900 (has links) (PDF)
No description available.
|
Page generated in 0.0269 seconds