La gran prioridad del ingeniero civil es brindar seguridad al ciudadano en cualquiera de las edificaciones y/o construcciones que este esta seguridad siempre debe estar ligada a obtener la infraestructura adecuada a un costo razonable. En nuestro país los proyectos de construcción, en particular las edificaciones que son nuestro caso en estudio, podrían durante un sismo, presentar diversos motivos de fallas, entre ellos, y en el que nos vamos a enfocar es en la falla producida por el contacto entre estructuras vecinas durante un movimiento sísmico. Consideramos que el rápido aumento de las edificaciones para uso residencial y la todavía existente informalidad en la construcción, han sido algunas de las razones que han generado que en el Perú existan edificaciones contiguas construidas sin una adecuada junta de separación sísmica, a pesar de que en el reglamento de construcción este indicado. Tomando en cuenta que el país se encuentra ubicado en una zona altamente sísmica, dichas edificaciones podrían ser severamente dañadas durante el evento de un movimiento sísmico. Es por tal motivo, que se busca conocer y analizar el efecto en las estructuras adyacentes de concreto armado de juntas de separación sísmicas inferiores a lo reglamentado, determinando la fuerza de impacto producida por el fenómeno de golpeo entre estructuras (pounding). Se considera que la información a obtenerse será de gran importancia, debido a la falta de investigaciones en idioma español en nuestro país sobre dicho fenómeno. Una vez determinada la fuerza de impacto entre las estructuras se esbozarán posibles soluciones que consideremos que podrían ayudar a mitigar el problema. / The main priority for a civil engineer is to provide security to citizens in any buildings and/or constructions he makes, this security always has to be linked to obtain the appropriate infrastructure at reasonable cost. In our country, construction projects specially buildings that are our case of study, could have many causes of failures during an earthquake, among them —and the one we will focus on— is the failure occurred by the contact between neighbor structures during a seismic activity. We consider the rapid increase of buildings for residential use and the yet existing informality in construction have been one of the reasons for generating constructed adjoining buildings without an appropriate seismic separation joints in Peru, in spite of the indications in the building code. Considering that the country is situated in a highly seismically unstable area, these buildings might be severely damaged during a seismic activity. For that reason, we want to discover and analyse the effect in the adjoining reinforced concrete structures of seismic separation joints below regulation, determining the impact force produced by the beating phenomenon between structures (pounding). The information that is going to be obtained is considered to be relevant, due to the lack of researches about this phenomenon in Spanish in our country. Once determined the impact force between structures, possible solutions that we consider might help attenuate the problem will be outlined. / Tesis

As the cost of land in cities increases, the need to build multistory buildings in close proximity to each other also increases. Sometimes, construction materials, other objects and any projections from a building may also decrease the spacing provided between the buildings. This leads to the problem of pounding of these closely placed buildings when responding to earthquake ground motion. The recent advent of base isolation systems and their use as an efficient earthquake force resisting mechanism has led to their increased use in civil engineering structures. At the same time, building codes that reflect best design practice are also evolving. The movement of these base isolated buildings can also result in building pounding. Since base isolation is itself a relatively new technique, pounding phenomenon in base isolated buildings have not been adequately investigated to date. This study looks at the base isolated response of a single two story building and adjacent two story building systems. Four earthquakes with increasing intensity were used in this study. It was found that it is difficult to anticipate the response of the adjacent buildings due to non- linear behavior of pounding and base isolation. The worst case for pounding was found to occur when a fixed base and base isolated buildings were adjacent to each other.

As the cost of land in cities increases, the need to build multistory buildings in close proximity to each other also increases. Sometimes, construction materials, other objects and any projections from a building may also decrease the spacing provided between the buildings. This leads to the problem of pounding of these closely placed buildings when responding to earthquake ground motion. The recent advent of base isolation systems and their use as an efficient earthquake force resisting mechanism has led to their increased use in civil engineering structures. At the same time, building codes that reflect best design practice are also evolving. The movement of these base isolated buildings can also result in building pounding. Since base isolation is itself a relatively new technique, pounding phenomenon in base isolated buildings have not been adequately investigated to date. This study looks at the base isolated response of a single two story building and adjacent two story building systems. Four earthquakes with increasing intensity were used in this study. It was found that it is difficult to anticipate the response of the adjacent buildings due to non- linear behavior of pounding and base isolation. The worst case for pounding was found to occur when a fixed base and base isolated buildings were adjacent to each other.

Polymer pipes, typically high density polyethylene (HDPE), can be pulled-into-place, avoiding traditional cut-and-cover construction, using pipe bursting and horizontal directional drilling (HDD) pipe installation techniques. Of particular interest, are the ground displacements, induced by cavity expansion, associated with these techniques and the strains that develop in existing pipes in response to these displacements. Further, the axial stress-strain response of the new HDPE pipe during and after the cyclic pulling force history required to pull the pipe into place is of interest. Surface displacements and strains in an adjacent polyvinyl chloride (PVC) pipe induced by static pipe bursting were measured during the replacement of a new unreinforced concrete pipe. For the pipe bursting geometry tested, the maximum vertical surface displacement measured at the ground surface was 6 mm, while the distribution of vertical surface displacements extended no more than 2 m on either side of the centreline. The maximum longitudinal strain measured in the PVC pipe was less than 0.1% and its vertical diameter decreased by only 0.5%, suggesting that pipe bursting did not jeopardize the long-term performance of the water pipe tested. In addition, results from identical stress relaxation and creep tests performed on whole pipe samples and coupons trimmed from a pipe wall were compared, and these demonstrated that the coupons exhibited higher modulus than the pipe samples. Therefore, isolated pipe samples, as opposed to coupons, were tested to quantify the stress-strain response of HDPE pipe during the simulated installation, strain recovery, and axial restraint stages of HDD. Axial strains were found to progressively accumulate when an HDPE pipe sample was subjected to the cyclic stress history used to simulate an HDD installation. It was shown that existing linear and nonlinear viscoelastic models can serve as predictive design tools for estimating the cyclic strain history of HDPE pipe during installation. For the specific conditions examined, the tensile axial stresses redeveloped in the pipe samples, once restrained, were not large enough to lead to long-term stress conditions conducive to slow crack growth even when the short-term performance limits were exceeded by a factor of 1.5. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-04-01 18:19:24.434

Due to its ability to deliver scalable and fault-tolerant solutions, applications based on the peer-to-peer (P2P) paradigm are used by millions of users on the internet. Recently, wireless mesh networks (WMNs) have attracted a lot of interest from both academia and industry, because of their potential to provide flexible and alternative broadband wireless internet connectivity. However, due to various reasons such as unstable wireless link characteristics and multi-hop forwarding operation, the performance of current P2P systems is rather low in WMNs. This dissertation studies the technological challenges involved while deploying P2P systems over WMNs. We study the benefits of location-awareness and resource replication to the P2P overlay while targeting efficient resource lookup in WMNs. We further propose a cross-layer information exchange between the P2P overlay and the WMN in order to reduce resource lookup delay by augmenting the overlay routing table with physical neighborhood and resource lookup history information. Aiming to achieve throughput maximization and fairness in P2P systems, we model the peer selection problem as a mathematical optimization problem by using a set of mixed integer linear equations. A study of the model reveals the relationship between peer selection, resource replication and channel assignment on the performance of P2P systems over WMNs. We extend the model by formulating the P2P download problem as chunk scheduling problem. As a novelty, we introduce constraints to model the capacity limitations of the network due to the given routing and channel assignment strategy. Based on the analysis of the model, we propose a new peer selection algorithm which incorporates network load information and multi-path routing capability. By conducting testbed experiments, we evaluate the achievable throughput in multi-channel multi-radio WMNs. We show that the adjacent channel interference (ACI) problem in multi-radio systems can be mitigated, making better use of the available spectrum. Important lessons learned are also outlined in order to design practical channel and channel bandwidth assignment algorithms in multi-channel multi-radio WMNs.

Title: Binary Signed Digit Representations of Integers in Cryptanalysis of Hash Functions Author: Jiří Vábek Department: Department of Algebra Supervisor: doc. RNDr. Jiří Tůma, DrSc., Department of Algebra Abstract: The work summarizes two main papers, A New Type of 2-block Colli- sions in MD5 and On the Number of Binary Signed Digit Representations of a Given Weight, while containing also the wider introduction to the topic of crypt- analysis of MD5 and binary signed digit representations (BSDR's). In the first paper we have implemented and applied Stevens algorithm to the newly proposed initial message differences and constructed a new type of collisions in MD5. In the second paper we have introduced and proved a new improved bound for the number of optimal BSDR's and also a new recursive bound for the number of BSDR's of a given integer with a given overweight. In addition to the results in mentioned papers, the generalized result is stated with the new bound for the number of optimal D-representations of natural numbers with D = {0, 1, 3}. Keywords: hash function, MD5, binary signed digit representation (BSDR), non- adjacent form (NAF) 1

Made available in DSpace on 2016-06-02T19:51:46Z (GMT). No. of bitstreams: 1 3387.pdf: 2954742 bytes, checksum: 792e30cc93d7f68d7c0f647b0d217541 (MD5) Previous issue date: 2010-12-03 / Financiadora de Estudos e Projetos / This work deals with a production scheduling problem that appears in the aeronautics industry, involving special structures called assembly fixtures, composed of several workstations in parallel to assemble parts of the aircrafts. Tasks should be scheduled to be performed in these workstations in order to minimize the quantity of manpower needed to do the assembly and determine the production capacity of the assembly fixture, which means minimizing the makespan (the total time needed to finish the tasks). However, in addition to the usual constraints such as due dates and precedence among tasks, there are also constraints that prevent two tasks to be performed at the same time in two adjacent workstations on the assembly fixture. The assembly and the teams who work there are in continuous improvement of assembling processes, according to the cumulative production increases and the learning curve is traversed. The learning curve was divided in four stages with specific characteristics in each. Mixed integer linear programming models are proposed to represent the production scheduling problem of each stage, based on practical cases studies of assembly fixtures scheduling in an aeronautics company. Those models are solved using a modeling language and optimization software. The solutions are analyzed and compared and based on then, it is evaluated how the learning curve affects the airplane production over time and it is shown, in the results, that there exists potential of improvement in the use of assembling resources, using production scheduling and levelling the resources. / Este trabalho aborda um problema de programação da produção que ocorre na indústria aeronáutica, envolvendo estruturas especiais de montagem chamadas gabaritos, compostas de diversos postos de trabalho em paralelo para montar partes das aeronaves. Tarefas devem ser programadas para serem executadas nestes postos de trabalho de maneira a minimizar a quantidade total de mão de obra necessária para realizar a montagem em questão e determinar a capacidade de produção do gabarito, ou seja, minimizar o makespan (tempo total para executar as tarefas). Porém, além das restrições usuais, como prazos de entrega das tarefas e precedências entre as tarefas, existem também restrições que impedem que duas tarefas possam ser executadas ao mesmo tempo em dois postos de trabalho adjacentes no gabarito. A montagem e as equipes que nela trabalham estão em melhoria contínua dos processos de montagem, conforme a produção acumulada aumenta e a curva de aprendizagem é percorrida. A curva de aprendizagem foi dividida em quatro fases com características específicas em cada uma. Propõem-se modelos de programação linear inteira mista para representar o problema de programação em cada uma das fases, com base em estudos de casos práticos de programação de gabaritos de montagem de uma empresa aeronáutica. Estes modelos são resolvidos utilizando-se uma linguagem de modelagem e um software de otimização. As soluções encontradas são analisadas e comparadas e com base nelas, avalia-se como a curva de aprendizagem afeta a produção de aviões ao longo do tempo e demonstra-se que existe potencial de melhoria no uso dos recursos de montagem, utilizando programação da produção e nivelamento dos recursos.

Em radioterapia, dependendo do tamanho do volume alvo a ser irradiado, pode ser necessário mais de um feixe de radiação (fótons ou elétrons). Isto faz com que sobreposições dos feixes, tanto na superfície (campos de radiação) quanto em profundidade (composição das penumbras) resultem em sobredosagens que podem interferir nos tratamentos e restabelecimento dos pacientes. Para se evitar a sobredosagem foram criados os gaps (espaçamento ou distanciamento entre os campos dos feixes, na superfície de entrada dos mesmos) com a finalidade de diminuir a sobredosagem e homogeneizar a dose absorvida dentro de valores aceitáveis, que não devem exceder 20% acima do valor esperado. Para feixes de elétrons não há a prática do uso de gap, como para feixes de fótons, e não há equações que possam prever a sobredosagem na adjacência desses feixes, assim como não há um estudo mais aprofundado das técnicas possíveis de serem utilizadas para se evitar a sub e/ou sobredosagem desses feixes na superfície e em profundidade. Com isto, este trabalho foi estruturado visando à obtenção da homogeneidade das doses absorvidas na região de adjacência dos feixes de elétrons, partindo do conhecimento da aplicação de gaps para feixes de fótons. Para tal, foi desenvolvido um protótipo de leitura dos dosímetros FXG e filme radiocrômico, baseado no sensor Charge-Coupled Device (CCD). Esse protótipo permitiu fazer as medidas de diversos feixes de fótons e elétrons, variando suas energias, geometrias e superfícies de entrada (plana e/ou curvas), cujas respostas puderam ser comparadas com as obtidas por simulação por Método Monte Carlo (MMC), resguardando as mesmas condições de feixes e arranjos experimentais. Dos resultados obtidos, pode-se comprovar: a eficácia do protótipo desenvolvido, o desenvolvimento de uma equação para prever a sobredosagem advinda da adjacência de feixes de elétrons a partir de dados experimentais, a reversão do uso da equação de gap específica para feixes de fótons para feixes de elétrons em superfícies planas, a equivalência dos resultados da simulação por MMC com os experimentais de gap realizados, além da adequabilidade dos filtros compensadores (em cunha) desenvolvidos para superfícies de entrada curvas. Todos esses resultados indicam a possibilidade da utilização do gap para feixes adjacentes de elétrons em superfícies planas e filtros em cunha em superfícies curvas, passíveis de serem utilizados na prática radioterápica. / Radiotherapy of extensive volumes normally is made using more than one radiation beam (photons or electrons). These beams once are divergent, in the intersection of their penumbra the isodose composition value is increased increasing the absorbed dose value in the treatment region. To overcome this effect is used the \\textit (a shift between the beam fields at the entrance surface) whose scope is to homogenize the depth absorbed dose and do not let it to exceed 20% of its expected value. Only for photons exists the practice of gap (with equations predicting gap for plane surfaces) and compensator filters (for curve surfaces). Once these ideas are non existent for electron adjacent beams and once the use of this type of radiation has increased along the years for patient irradiation, most of the times replacing the photon beams, the curiosity to obtain methods to minimize the overdose due to the electron adjacent beams was triggered and turn it the goal of this research. For this work two dosimeters were used (Fricke Xylenol Gel, FXG and Radiocromic film) and their measurements were made through a developed prototype with a Charge-Coupled Device, CCD, whose results were compared also with Monte Carlo simulations considering the same experimental conditions (irradiation geometry, beam energy, entrance surface geometry, plane and/or curve, and setup). From the results obtained one could notice that: the CCD prototype resulted in an adequate device to be used with the selected dosimeters, the gap equation for photons could be used successfully also for adjacent electron beams on plane surfaces, compensator filters (acrylic wedge filters) are adequate for curve surfaces and the Monte Carlo Simulation results shown equivalence with the experimental ones. All these results encourage the gap for electron adjacent beams on plane surfaces, as well the use of wedge filters for curve surfaces in radiotherapy practice.

Children learn their first language simply by listening to the linguistic utterances provided by their caregivers and other speakers around them. In order to extract meaning and grammatical rules from these utterances, children must track regularities in the input, which are omnipresent in language. The ability to discover and adapt to these statistical regularities in the input is termed statistical learning and has been suggested to be one of the key mechanisms underlying language acquisition. In this thesis, I investigated a special case of statistical learning, non-adjacent dependency (NAD) learning. NADs are grammatical dependencies between distant elements in an utterance, such as is and -ing in the sentence Mary is walking. I examined which factors play a role in the development of NAD learning by illuminating this process from different stand points: the first study compares NAD learning in the linguistic and the non-linguistic domain during the earliest stages of development, at 4 months of age. This study suggests that at this age, NAD learning seems to be domain-specific to language. The second study puts a spotlight on the development of NAD learning in the linguistic domain and proposes that there may be a sensitive period for linguistic NAD learning during early childhood. Finally, the third study shows that children can not only recall newly learned NADs in a test immediately following familiarization, but also recall them after a retention period, which is critical to show more long-term learning. Overall, the findings in this thesis further illuminate how NADs, as a spotlight into language acquisition, are learned, stored in memory, and recalled.

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