Polymer bonded explosives (PBXs) are composites comprised of energetic crystals with a very high energy density surrounded by a polymer binder. The formation of hotspots within polymer bonded explosives can lead to the thermal decomposition and initiation of the energetic material. A frictional heating model is applied at the mesoscale to assess the potential for the formation of hotspots under low velocity impact loadings. Monitoring of the formation and growth of damage at the mesoscale is considered through the inclusion of a piezoresistive carbon nanotube network within the energetic binder providing embedded strain and damage sensing. A coupled multiphysics thermo-electro-mechanical peridynamics framework is developed to perform computational simulations on an energetic material microstructure subject to these low velocity impact loads. With increase in impact energy, the model predicts larger amounts of sensing and damage thereby supporting the use of carbon nanotubes to assess damage growth and subsequent formation of hotspots. The framework is also applied to assess the combined effects of thermal loading due to prescribed hotspots with inertial effects due to low velocity impact loading. It has been found that the present model is able to detect the presence of hotspot dominated regions within the energetic material through the piezoresistive sensing mechanism. The influence of prescribed hotspots on the thermo-electro-mechanical response of the energetic material under a combination of thermal and inertial loading was observed to dominate the lower velocity impact response via thermal shock damage. In contrast, the higher velocity impact energies demonstrated an inertially dominated damage response. Quantifying the piezoresistive effect derived from embedding carbon nanotubes in polymers remains a challenge since these nanocomposites exhibit significant variation in their electro-mechanical properties depending upon factors such as CNT volume fraction, CNT dispersion, CNT alignment and properties of the polymer. Of interest is electrical percolation where the electrical conductivity of the CNT/polymer nanocomposite increases through orders of magnitude with increase in CNT volume fraction. Estimates and distributions for the electrical conductivity and piezoresistive coefficients of the CNT/polymer nanocomposite are obtained and analyzed with increasing CNT volume fraction and varying barrier potential, which is a parameter that controls the extent of electron tunneling. The effect of CNT alignment is analyzed by comparing the electro-mechanical properties in the alignment direction versus the transverse direction for different orientation conditions. Estimates of piezoresistive coefficients are converted into gage factors and compared with experimental sources in literature. The methodology for this work uses automated scripts which are used in conjunction with high performance computing to generate several 5 μm ×5 μm realizations for different CNT volume fractions. These realizations are then analyzed using finite elements to obtain volume averaged effective values, which are then subsequently used to generate measures of central tendency (estimated mean) and variability (standard deviation, coefficient of variation, skewness and kurtosis) in a descriptive statistical analysis. / Doctor of Philosophy / Carbon nanotubes or CNTs belong to a class of novel materials known as nanomaterials which are materials with length scales on the order of nanometers. CNTs have been widely studied due to their unique mechanical, electrical and thermal properties in comparison to traditional materials such as metals or plastics. Often times, research and applications concerning the use of CNTs involves embedding the CNTs as a filler within a larger composite material system. In the present work, CNTs are considered to be embedded within a polymer. It is known that the electrical properties of such a CNT/polymer composite change in response to the application of a mechanical force. This change in electrical properties is caused due to the presence of CNTs and is used as a means of sensing the mechanical state of the composite, i.e. real time structural monitoring. The extent of the change in electrical properties, also known as sensing, depends upon a number of different factors such as the amount of CNTs used per unit volume of the polymer, how well dispersed or clumped together the CNTs are within the polymer and the type of polymer material used, among other factors. A statistical analysis is performed with several case studies where these factors are varied and the resulting change in the sensing response is monitored. Several important conclusions were made from the statistical analysis with some of the results providing new insights into the sensing behavior of CNT/polymer composites. For example, it was found that a key parameter known as barrier potential, which directly influences the extent of sensing achieved through a mechanism known as electrical tunneling, needs to be several orders of magnitude lower than previously reported values to accurately capture the sensing effects. Key metrics quantifying the extent of sensing from the analysis were found to be in agreement with previously reported experimental results. The significance of such a statistical study lies in the fact that CNT embedded composites are increasingly being proposed and used for sensing applications. The use of CNT embedded polymers to encase explosive crystalline grains such as HMX or RDX is one such example. These explosive grains are used in a number of different civil and military applications such as fuel rocket propellants, industry explosives, military munitions etc. The grains possess extremely high energy densities and are susceptible to undergo violent chemical reaction if a trigger is provided through thermal or mechanical means. As such, the monitoring of the structural state of these explosives is crucial for their safe handling and processing. In this work, the sensing response of a composite material comprising of explosive grains surrounded by polymer material containing CNTs is studied in response to different types of mechanical loads, ranging from mild stimuli to impact. It was found that the sensing mechanism was capable of tracking mechanical damage as well as the resulting temperature increases interior to the composite. In addition to its application to safety and preventative measures, the use of CNTs in this context also provided insight into the mechanisms related to the sudden release of energy in these explosive grains which is of significant interest since this is an active area of research as well.

Dans ce mémoire, nous proposons des protocoles cryptographiques d'échange de clef, de mise en gage, et de transfert équivoque. Un premier protocole de transfert équivoque, primitive cryptographique universelle pour le calcul multi-parties, s'inspire du protocole d'échange de clef par puzzle de Merkle, et améliore les résultats existants. Puis, nous montrons qu'il est possible de construire ces mêmes primitives cryptographiques sans l'hypothèse des fonctions à sens unique, mais avec le problème 3SUM. Ce problème simple ---dans une liste de n entiers, en trouver trois dont la somme a une certaine valeur--- a une borne inférieure conjecturée de Omega(n^2). / In this work, we propose cryptographic protocols for key exchange, bit commitment and oblivious transfer. Our oblivious transfer protocol, universal cryptographic primitive for multipartie computation, is inspired from Merkle's key exchange protocol with puzzles, and improves on existing results. Then, we show that it's possible to build those same cryptographic primitives without the hypothesis of one-way functions, but with the 3SUM problem. This simple problem ---in a list of n integers, find three that sum is a desired value--- has a conjectured lower bound of Omega(n^2).

Parallèlement à la dernière réforme française du droit des sûretés, les sûretés réelles chinoises ont été rénovées par la loi sur les droits réels promulguée à la même période. En s’appuyant sur une étude compréhensive des normes législative et réglementaire autour du sujet, cette thèse, essentiellement basée sur le droit chinois, révèle qu’en matière de sûreté réelle, le droit chinois se nuance du droit français et analyse les raisons et les effets de ces différences au-dessous des termes ou notions similaires. Après l’étude comparative, la thèse arrive à la conclusion que le droit chinois des sûretés réelles nécessite un futur regroupement en dépit de la nouvelle loi sur les droits réels. / During the same period, a reform of security law had completed in France, while the Chinese real rights law which has renovated security rights in rem was about to be promulgated in China. This thesis, based on Chinese law and drawing upon a comprehensive study of laws and administrative regulations on the subject, reveals the differences between Chinese and French law and analyze their cause and effect behind similar terms and notions. Grounded on the comparative study, the thesis draws the conclusion that the Chinese system of security rights in rem requires a further reform despite the arrival of new law.

Premier arrivé, premier servi. Que cela s’appelle un privilège ou un droit de préférence particulier, il reste inacceptable au regard des règles substantielles du droit positif français.Cette répartition des sommes saisies sacrifie, pour des raisons procédurales, une règle importante à savoir l’égalité entre les créanciers.Cette étude propose une solution intermédiaire entre le droit civil et le droit des voies d’exécution. La proposition consiste à donner à tous les créanciers, qui ont obtenu par leur vigilance des titres exécutoires avant le premier acte de saisie, la possibilité d’associer le premier saisissant dans la répartition des sommes saisies dans le cadre d’une saisie attribution.La combinaison de l’effet attributif immédiat de la saisie avec une durée de quinze jours,pendant laquelle les créanciers titulaires des titres exécutoires viennent en concours sous réserve des causes légitimes de préférences et des privilèges, aboutit à un double résultat. Le recouvrement des créances reste rapide et simple et l’égalité entre les créanciers sera respectée / Whether it is called a privilege or a private preference right, the ‘first come first served rule’remains debatable given the substantive rules of the French positive law. Primarily for procedural reasons, the norm of seizures distribution undermines a crucial principle, namely equality among creditors.This study proposes an intermediary solution between civil law and law of enforcement procedures. It advocates granting all creditors, who have obtained their enforcement orders before the first act of seizure, the possibility of associating with the first executioner the distribution of the seized money.The combined effect of immediate attribution of the seizure with duration of fifteen days,during which all creditors holding enforceable securities are subject to competition, and taking into account other legitimate preferences and privileges, leads to a double result: a simple and fast method of debt recovery without undermining the principle of equality between creditors.

Dans les Droits antérieurs à la codification de 1804, les conventions ne suffisaient pas, en principe, à constituer et à transférer les droits réels : pour atteindre ce résultat, un mode acquisitif, comme la tradition de la chose, était nécessaire. Quand ce n’était exceptionnellement pas le cas, le droit réel, qui était constitué ou transféré par la seule convention, était néanmoins constitué et transféré erga omnes. Or, à partir du code civil et des réformes législatives postérieures, il n’en va plus ainsi : le principe adopté est celui de la constitution et de la translation des droits réels sola conventione.Mais l’étude des textes législatifs et réglementaires ainsi que des opinions doctrinales du XIXe siècle révèle que le changement initié en 1804 est bien plus profond : si la convention suffit à constituer et à transférer les droits réels, ces droits ne sont constitués et transférés qu’à l’égard des parties.Ainsi, en Droit français actuel, la vente d’un bateau en transfère la propriété à l’égard du vendeur, mais non à l’égard des tiers et, en particulier, des créanciers chirographaires du vendeur ou de l’État. Tant que l’inscription de l’acte de vente n’est pas accomplie, ces tiers peuvent ignorer le transfert de la propriété causé par la vente. Dès lors, certaines questions se posent inévitablement : la vente a-t-elle réellement transféré la propriété ? Une propriété à l’égard du seul vendeur est-elle encore réellement une propriété ? De même, en Droit français actuel, une convention peut constituer une hypothèque, mais ce droit n’est pas opposable aux tiers tant que cet acte n’a pas été inscrit. Ainsi, les créanciers chirographaires du constituant peuvent ignorer le droit du créancier hypothécaire. Mais une hypothèque qui n’est pas un droit de préférence n’est-elle pas un concept absurde ? Cette thèse explique comment le législateur et la doctrine du XIXe siècle, en réduisant le mode acquisitif au titre acquisitif et en distinguant entre effet inter partes et effet extra partes, ont construit un mythe : celui des conventions constitutives et translatives de droits réels. Contrairement aux formules généralement retenues par la loi et les manuels, en Droit français actuel, les droits réels sont constitués et transférés par la convention et la tradition ou l’inscription. / The Law prior to the 1804 codification is ruled by the principle that agreements are not sufficient to establish and transfer real rights: in order to reach this result, an additional modus of acquisition, like the delivery of the thing, is required. When it is not the case, the real right, established or transferred by mere agreement, is nevertheless established and transferred erga omnes. However, since the civil code and the successive legislative reforms, the situation is no longer the same: the principle adopted is the establishment and the transference of real rights sola conventione. Nonetheless, the study of laws and regulations as well as the nineteenth century scholars’ opinions reveals that the change initiated in 1804 is much deeper: if the agreement is sufficient to establish and transfer real rights, these rights are established and transferred to the parties only. For example, in current French Law, the sale of a boat transfers its property regarding to the seller, but not towards to third parties and, in particular, not regarding to the seller’s unsecured creditors or to the State. As long as the registration of the deed of sale is not completed, these third parties may ignore the transfer of property resulting from the sale. A lot of questions can be raised: has the sale really settled a transfer of property? Is a property regarding only to the seller still really a property? Similarly, in current French Law, an agreement may establish a mortgage, but this right is not enforceable against third parties as long as this act has not been registered. Thus, the unsecured creditors of the settlor may ignore the right of the mortgagee. But does it make sense to consider a mortgage without a preference right?This thesis describes how the legislator and nineteenth century scholars, in reducing the acquisitive modus into the acquisitive titulus and in distinguishing between inter partes effect and extra partes effect, have built a myth : the one of the agreements establishing and transferring real rights. Unlike formulas generally used by law and textbooks, in current French Law, real rights are established and transferred by agreement and delivery or registration.

Dans ce mémoire, nous proposons des protocoles cryptographiques d'échange de clef, de mise en gage, et de transfert équivoque. Un premier protocole de transfert équivoque, primitive cryptographique universelle pour le calcul multi-parties, s'inspire du protocole d'échange de clef par puzzle de Merkle, et améliore les résultats existants. Puis, nous montrons qu'il est possible de construire ces mêmes primitives cryptographiques sans l'hypothèse des fonctions à sens unique, mais avec le problème 3SUM. Ce problème simple ---dans une liste de n entiers, en trouver trois dont la somme a une certaine valeur--- a une borne inférieure conjecturée de Omega(n^2). / In this work, we propose cryptographic protocols for key exchange, bit commitment and oblivious transfer. Our oblivious transfer protocol, universal cryptographic primitive for multipartie computation, is inspired from Merkle's key exchange protocol with puzzles, and improves on existing results. Then, we show that it's possible to build those same cryptographic primitives without the hypothesis of one-way functions, but with the 3SUM problem. This simple problem ---in a list of n integers, find three that sum is a desired value--- has a conjectured lower bound of Omega(n^2).

Made available in DSpace on 2016-12-08T17:19:14Z (GMT). No. of bitstreams: 1 Introducao.pdf: 448655 bytes, checksum: 598f8294a6f16ff80e9151c41d1a27f9 (MD5) Previous issue date: 2011-12-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Residual stresses in polymeric parts are a great source of uncertainties for the design of industrial components. They are originated mainly during the injection molding process. Some of the problems related to this phenomenon are reduction to the mechanic strength, cracks propagation and warpage. Many efforts are employed to minimize these residual stresses and, to achieve that, an essential step is its measuring. There are methods and devices already available to measure residual stress in metallic materials, but in the field of polymeric material, many aspects remain unexplored. In the present work, a device to measure strain gage signals was built, which was employed to determine residual stresses according to the most established techniques nowadays. Injection simulation techniques were utilized to estimate the build-up of residual stresses in polymeric test specimens under different manufacturing setups. Statistical analysis was performed to select the most favorable parameters for parts tensioning. Test specimens were fabricated in the selected process conditions. Samples weight measurements confirmed statistically that the process parameters selected have significantly altered the parts final mass. Residual stress measurements were carried out by employing the hole drilling technique in the manufactured specimens, thus being determined tensile residual stresses from 2.7 MPa by 6.2 MPa, in the layers closest to the parts surface. The typical profile for residual stress distribution, as described in literature, was observed in the experiments performed. / Tensões residuais em peças poliméricas são grande fonte de incertezas para o projeto de componentes industriais. São causadas principalmente durante o processo de injeção. Alguns dos problemas relacionados a esse fenômeno são a diminuição da resistência mecânica, surgimento de trincas e empenamento das peças. Muitos esforços são empregados na minimização dessas tensões residuais e, para isso, uma etapa indispensável é a sua medição. Existem métodos e equipamentos já disponíveis para medição de tensões residuais em materiais metálicos, porém, no campo dos materiais poliméricos ainda há muitos aspectos a serem melhor explorados. Neste trabalho foi construído um dispositivo para medição de sinais de extensiometria, o qual foi utilizado para determinação de tensões residuais segundo as técnicas mais utilizadas atualmente para metais. Técnicas de simulação de injeção foram utilizadas para estimar o surgimento de tensões residuais em corpos-de-prova poliméricos sob diversas condições de fabricação. Análise estatística foi realizada para selecionar as condições de fabricação mais propícias ao tensionamento das peças. Corpos-de-prova foram fabricados nas condições de processo selecionadas. Medições de peso das amostras confirmaram estatisticamente que os parâmetros de processo utilizados alteraram significativamente a massa final das peças. Medições de tensões residuais foram realizadas aplicando-se a técnica do furo cego nas amostras fabricadas, determinando-se tensões residuais de tração entre 2,7 MPa e 6,2 MPa, nas camadas próximas às superfície das amostras. O perfil típico de tensões residuais previsto em literatura foi observado nos experimentos realizados.

Dans cette thèse,nous étudions comment exploiter des contraintes spatio-temporelles,notamment le principe d'impossibilité de transmission supraluminique,dans le but de créer des primitives cryptographiques sûres,par exemple la vérification de position ou la "mise en gage de bit''(bit commitment). D'après le principe d'impossibilité de transmission supraluminique,aucun vecteur physique d'information ne peut voyager plus vite que la vitesse de la lumière. Ce principe entraîne une contrainte sur le temps de communication entre deux points éloignés. Ce délai dans le transfert d'information peut être utilisé comme une contrainte temporelle interdisant la communication. En cryptographie multi-agents,il est connu que l'hypothèse de non-communication entre les agents permet de réaliser de manière sécurisée de nombreuses primitives comme la "mise en gage de bit'' et l'un des buts de cette thèse est de comprendre à quel point les contraintes spatio-temporelles peuvent être exploitèes pour simuler des scénarios de non-communication. Dans la première partie de cette thèse nous étudions comment utiliser une contrainte de non-communication pour essayer de vérifier la position d'une personne.Dans la dernière partie,nous nous penchons sur deux exemples de protocoles de ``mise en gage de bit'' relativistes afin d'en étudier la sécurité contre des adversaires classiques. Pour conclure cette thèse,nous mentionnons quelques problèmes ouverts intéréssants. Ces problèmes ouverts peuvent être très utiles pour comprendre le rôle de contraintes spatio-temporelles,par exemple de l'impossibilité de transmission supraluminique,dans la conception de primitives cryptographiques parfaitement sûres. / In this thesis we have studied how to exploit relativistic constraints such as the non-superluminal signalling principle to design secure cryptographic primitives like position-verification and bit commitment. According to non-superluminal signalling principle, no physical carrier of information can travel faster than the speed of light. This put a constraint on the communication time between two distant stations. One can consider this delay in information transfer as a temporal non-communication constraint. Cryptographic primitives like bit-commitment, oblivious transfer can be implemented with perfect secrecy under such non-communication assumption between the agents. The first part of this thesis has studied how non-signalling constraints can be used for secure position verification. Here, we have discussed about a strategy which can attack any position verification scheme. In the next part of this thesis we have discussed about the nonlocal games, relevant for studying relativistic bit commitment protocols. We have established an upper bound on the classical value of such family of games. The last part of this thesis discusses about two relativistic bit commitment protocols and their security against classical adversaries. We conclude this thesis by giving a brief summary of the content of each chapter and mentioning interesting open problems. These open problems can be very useful for better understanding of the role of spacetime constraints such as non-superluminal signalling in designing perfectly secure cryptographic primitives.

Orientador: Paulo Roberto Gardel Kurka / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T16:26:05Z (GMT). No. of bitstreams: 1 Iizuka_EduardoKenji_M.pdf: 15704991 bytes, checksum: d25013321bbe7f7be9760b4235125e16 (MD5) Previous issue date: 2006 / Resumo: O trabalho apresenta os resultados obtidos na simulação numérica e medição extensométrica de peneiras vibratórias de alta capacidade. Para o estudo numérico utilizou-se o software MSC.FEA 2005 que é uma integração dos softwares MSC.Patran e MSC.Nastran, obtendo-se resultados de tensão de von Mises apresentados na forma de gráficos e tabelas. Nas medições experimentais foram empregados extensômetros do tipo roseta 45° que possibilitaram a determinação das tensões principais e consequentemente a tensão de von Mises dos pontos instrumentados. Os valores de tensão de von Mises numéricos e experimentais formam comparados resultando em uma diferença média satisfatória de 8,4% considerando-se a complexidade do equipamento analisado. Os resultados deste trabalho são importantes para os futuros projetos de peneiras vibratórias de alta capacidade, visando garantir a integridade física do equipamento / Abstract: The work presents the results of numerical simulation and strain gage measurements for high capacity vibrating screens. MSC.FEA 2005 software that is an integration of the MSC.Patran and MSC.Nastran softwares was used to get the numerical results of von Mises stress, which is presented in charts and tables formo Strain gages type rosette 45° were used on experimental measurements and allowed the determination of principal stress hence von Mises stress, in the analyzed points. Numerical and experimental values of stress were compared and resulted into an 8.4% mean difference, which is a satisfactory result considering the complexity of the equipment. The results presented in this work create an important base to future designs of high capacity vibrating screens, aiming at the physical integrity of the equipment / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Partant du constat que l’affectation en garantie de la monnaie est aujourd’hui susceptible de revêtir de multiples qualifications et d’obéir à des régimes tout aussi divers, selon que la monnaie est analysée comme un bien corporel ou incorporel et selon que les sommes affectées en garantie sont ou non confondues dans le patrimoine du créancier, cet essai propose d’adopter une conception unifiée de la monnaie susceptible de la soumettre à un régime simplifié d’affectation en garantie qui, sans faire fi de l’irréductible dualité tenant au caractère individualisé ou non des sommes d’argent, est appelé à remplacer les actuels gage de choses fongibles, nantissement de compte, nantissement de créance ou fiducie-sûreté sur créances et sommes d’argent, par un unique nantissement de monnaie. Les modalités de constitution de ce nantissement seront propres à évincer les sempiternelles querelles sur le caractère ou non translatif de propriété du « gage-espèces » puisque la confusion des sommes nanties dans le patrimoine du créancier nanti opérera un démembrement de propriété sui generis qui, s’apparentant à un quasi-usufruit à titre de garantie, ne conférera au créancier ni un simple droit de préférence, ni un droit de propriété plein et entier, ni même un droit comparable à celui d’un fiduciaire, mais un droit de disposer à titre provisoire grevant temporairement la propriété restée entre les mains du constituant. Ses conditions de constitution ainsi clarifiées, le nantissement de monnaie pourra se réaliser plus rapidement et plus efficacement par la reconstitution de la propriété démembrée entre les mains du constituant ou du créancier nanti, selon que la dette garantie aura ou non été payée, sans même qu’il soit besoin s’interroger sur le fait de savoir s’il faut recourir à l’attribution judiciaire ou conventionnelle ou à la compensation. / As the law stands, security rights in money are likely to be subject to different legal treatment, depending on whether money is regarded as a tangible asset or as an intangible asset, and depending on whether sums of money as a guarantee are assimilated with the secured creditor’s property or not. Taking this observation as its starting point, the present essay suggests adopting a unified approach of legal nature of money, that is likely to justify that money should be subject to a simplified security regime. Without ignoring that it is bound to be dual, depending on whether sums of money as a guarantee are separated from the secured creditor’s property or not, this security regime would be called upon to replace the present fungible assets, bank account and receivables pledge agreements, and also security trust on receivables and money, with a single money pledge agreement.The rules of the lodging of this money pledge agreement will be designed to eliminate the never-ending debates as to whether the “cash collateral” vests ownership of the encumbered money in the secured creditor, or not. Indeed, the assimilation of the encumbered sums of money with the secured creditor’s property will involve a sui generis division of the ownership rights that will be like an irregular usufruct by way of collateral, and that will grant the creditor neither mere preferential rights, nor ownership rights, nor any right similar to the right of a security trustee, but the right to dispose of money provisionally. This right of disposal will encumber temporarily the ownership rights that will remain in the hands of the grantor of the security.The rules of its lodging being therefore clarified, the rights granted by the money pledge agreement will be enforced more quickly and more effectively since the divided ownership of money will be reconstructed in the hands of the grantor of the security or in the hands of the secured creditor, depending on whether the secured debt will be paid or not, and without there being a need to wonder if the rights granted by the pledge have to be enforced either through judicial or contractual award of the right of ownership, or through legal, judicial or contractual compensation.