We propose a real-time system to visualize multi-viewpoint visibility information for terrains, supporting flight path optimization for view coverage or vehicle exposure to ground. A volume rendered display and a haptic interface assist the user in selecting, assessing, and refining the computed flight path. We construct a three-dimensional scalar field representing the visibility of a point above the terrain, describe an efficient algorithm to compute visibility, and develop visual and haptic schemes to interact with the visibility field. Given the origin and destination, the desired flight path is computed using an efficient simulation of an articulated rope under the influence of the visibility gradient. The simulation framework also accepts user input, via the haptic interface, thereby allowing manual refinement of the flight path.

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Baigiamajame magistro darbe nagrinėjamos optimalaus artėjimo procedūros ir ICAO bei EUROCONTROL pateiktos šių procedūrų rekomendacijos. Išanalizuoti pagrindiniai šių procedūrų kūrimo principai, kuriais remiantis jos yra taikomos praktikoje. Darbe apžvelgiami oro uostai naudojantys šias procedūras. Aptariama jų praktinė nauda aplinkai, oro paslaugų teikėjams ir oro vežėjams. Analizuojami pagrindiniai skirtumai tarp Vilnuje naudotų ir dabar esamų artėjimo tūpti ir tūpimo procedūrų. / In this thesis are considered continuous descent approach and landing procedures, ICAO and EUROCONTROL recommendations. There are discussed the design principles under which they are implemented in practice. Airports that use these procedures are overviewed. The practical benefits for the environment, air service providers and carriers are discussed. Furthermore, the main differences between the nowaday and the previous type of approach are analysed.

VHF står för "Very High Frequency" och är ett frekvensband som ligger i området 30 - 300 MHz. Maritim VHF är standard för Sjöfartsverket och fungerar över hela världen. Det är ett kommunikationssystem som bidrar till ökad säkerhet och kan rädda liv på sjön. Andra vanliga kommunikationssystem som mobiltelefoni fungerar inte tillförlitligt. Idag fungerar mobiltelefoni i stora delar av skärgården och längs kusterna men när det gäller kommunikation mellan fartyg längre ut till havs är den maritima VHF-kommunikationen överlägsen. Sjöfartsverket driver för sitt eget och kunders behov ett mobilradionätverk kallat kustradionätverket. Radiotrafiken i nätet sker både på Very High Frequency (VHF) och Medium frequency (MF). VHF-systemet är ett internationellt system som bland annat används till att kommunicera till sjöss och den trafiken befinner sig i frekvensbandet 155.5 - 162.025 MHz. Inom VHF-bandet finns det 55 kanaler. Kanalerna vid kustradiostationen kallas för duplexkanaler och innebär att kustradiostationerna sänder och tar emot signaler på två olika frekvenser. Radioutbredningen hos antennen som är installerad på basstationen har riktverkan i vissa riktningar och dämpningar i andra. Detta kan ses i strålningsdiagrammet under kapitlet "Täckningsmodell" och avsnittet antennen. Andra faktorer som kan påverka radioutbredningen är förluster i basstationenssystemet, topologin hos området mellan sändare och mottagare samt väderberoende utbredningsegenskaper. Genom att hitta de tänkbara faktorer som påverkar signalutbredningen kan en täckningsmodell förutses. Det är förluster som finns i basstationen, radiolänken samt förluster vid mottagarantennen.

The Constrained Shortest Path Problem (CSPP) consists of finding the shortest path in a graph or network that satisfies one or more resource constraints. Without these constraints, the shortest path problem can be solved in polynomial time; with them, the CSPP is NP-hard and thus far no polynomial-time algorithms exist for solving it optimally. The problem arises in a number of practical situations. In the case of vehicle path planning, the vehicle may be an aircraft flying through a region with obstacles such as mountains or radar detectors, with an upper bound on the fuel consumption, the travel time or the risk of attack. The vehicle may be a submarine travelling through a region with sonar detectors, with a time or risk budget. These problems all involve a network which is a discrete model of the physical domain. Another example would be the routing of voice and data information in a communications network such as a mobile phone network, where the constraints may include maximum call delays or relay node capacities. This is a problem of current economic importance, and one for which time-sensitive solutions are not always available, especially if the networks are large. We consider the simplest form of the problem, large grid networks with a single side constraint, which have been studied in the literature. This thesis explores the application of Constraint Programming combined with Lagrange Relaxation to achieve optimal or near-optimal solutions of the CSPP. The following is a brief outline of the contribution of this thesis. Lagrange Relaxation may or may not achieve optimal or near-optimal results on its own. Often, large duality gaps are present. We make a simple modification to Dijkstra’s algorithm that does not involve any additional computational work in order to generate an estimate of path time at every node. / We then use this information to constrain the network along a bisecting meridian. The combination of Lagrange Relaxation (LR) and a heuristic for filtering along the meridian provide an aggressive method for finding near-optimal solutions in a short time. Two network problems are studied in this work. The first is a Submarine Transit Path problem in which the transit field contains four sonar detectors at known locations, each with the same detection profile. The side constraint is the total transit time, with the submarine capable of 2 speeds. For the single-speed case, the initial LR duality gap may be as high as 30%. The first hybrid method uses a single centre meridian to constrain the network based on the unused time resource, and is able to produce solutions that are generally within 1% of optimal and always below 3%. Using the computation time for the initial Lagrange Relaxation as a baseline, the average computation time for the first hybrid method is about 30% to 50% higher, and the worst case CPU times are 2 to 4 times higher. The second problem is a random valued network from the literature. Edge costs, times, and lengths are uniform, randomly generated integers in a given range. Since the values given in the literature problems do not yield problems with a high duality gap, the values are varied and from a population of approximately 100,000 problems only the worst 200 from each set are chosen for study. These problems have an initial LR duality gap as high as 40%. A second hybrid method is developed, using values for the unused time resource and the lower bound values computed by Dijkstra’s algorithm as part of the LR method. The computed values are then used to position multiple constraining meridians in order to allow LR to find better solutions. / This second hybrid method is able to produce solutions that are generally within 0.1% of optimal, with computation times that are on average 2 times the initial Lagrange Relaxation time, and in the worst case only about 5 times higher. The best method for solving the Constrained Shortest Path Problem reported in the literature thus far is the LRE-A method of Carlyle et al. (2007), which uses Lagrange Relaxation for preprocessing followed by a bounded search using aggregate constraints. We replace Lagrange Relaxation with the second hybrid method and show that optimal solutions are produced for both network problems with computation times that are between one and two orders of magnitude faster than LRE-A. In addition, these hybrid methods combined with the bounded search are up to 2 orders of magnitude faster than the commercial CPlex package using a straightforward MILP formulation of the problem. Finally, the second hybrid method is used as a preprocessing step on both network problems, prior to running CPlex. This preprocessing reduces the network size sufficiently to allow CPlex to solve all cases to optimality up to 3 orders of magnitude faster than without this preprocessing, and up to an order of magnitude faster than using Lagrange Relaxation for preprocessing. Chapter 1 provides a review of the thesis and some terminology used. Chapter 2 reviews previous approaches to the CSPP, in particular the two current best methods. Chapter 3 applies Lagrange Relaxation to the Submarine Transit Path problem with 2 speeds, to provide a baseline for comparison. The problem is reduced to a single speed, which demonstrates the large duality gap problem possible with Lagrange Relaxation, and the first hybrid method is introduced. / Chapter 4 examines a grid network problem using randomly generated edge costs and weights, and introduces the second hybrid method. Chapter 5 then applies the second hybrid method to both network problems as a preprocessing step, using both CPlex and a bounded search method from the literature to solve to optimality. The conclusion of this thesis and directions for future work are discussed in Chapter 6.

A fundamental research question in regional economic development, is why some regions are able to diversify into new products and industries, while others continue to face challenges in diversification? This doctorate research explores the different pathways to diversification. It follows the three-stage modular structure of DBA for Cranfield School of Management. This thesis consists of a systematic literature review, a single qualitative case study on UAE, and a research synthesis of published cases on Singapore, Norway and UAE. The linking document provides a summary of the three projects and consolidates findings and contributions into a path creation model that provides new understanding on the pathways to regional diversifications. This research integrates existing theoretical foundations of evolutionary economic geography, institutional economic geography, path dependence, industry relatedness, economic complexity, and path creation into a unified conceptual path creation model. It generates propositions, builds a framework and develops a matrix for path creation that integrate context, actors, factors, mechanisms and outcomes shaping regional diversification. It finds that in the context of path dependence and existing conditions of a region, economic actors undertake strategic measures to influence the institutional capabilities to accumulate knowledge and trigger indigenous creation, anchoring, branching, and clustering diversification mechanisms to create complex varieties of related and unrelated diversification outcomes. The institutional collaboration capabilities are found to be instrumental in accumulating knowledge and determining the relatedness and complexity of diversification outcomes. This research further provides a set of integrated platform strategies to guide policy-makers on setting up the pathways to regional diversification.

abstract: The critical infrastructures of the nation are a large and complex network of human, physical and cyber-physical systems. In recent times, it has become increasingly apparent that individual critical infrastructures, such as the power and communication networks, do not operate in isolation, but instead are part of a complex interdependent ecosystem where a failure involving a small set of network entities can trigger a cascading event resulting in the failure of a much larger set of entities through the failure propagation process. Recognizing the need for a deeper understanding of the interdependent relationships between such critical infrastructures, several models have been proposed and analyzed in the last few years. However, most of these models are over-simplified and fail to capture the complex interdependencies that may exist between critical infrastructures. To overcome the limitations of existing models, this dissertation presents a new model -- the Implicative Interdependency Model (IIM) that is able to capture such complex interdependency relations. As the potential for a failure cascade in critical interdependent networks poses several risks that can jeopardize the nation, this dissertation explores relevant research problems in the interdependent power and communication networks using the proposed IIM and lays the foundations for further study using this model. Apart from exploring problems in interdependent critical infrastructures, this dissertation also explores resource allocation techniques for environments enabled with cyber-physical systems. Specifically, the problem of efficient path planning for data collection using mobile cyber-physical systems is explored. Two such environments are considered: a Radio-Frequency IDentification (RFID) environment with mobile “Tags” and “Readers”, and a sensor data collection environment where both the sensors and the data mules (data collectors) are mobile. Finally, from an applied research perspective, this dissertation presents Raptor, an advanced network planning and management tool for mitigating the impact of spatially correlated, or region based faults on infrastructure networks. Raptor consolidates a wide range of studies conducted in the last few years on region based faults, and provides an interface for network planners, designers and operators to use the results of these studies for designing robust and resilient networks in the presence of spatially correlated faults. / Dissertation/Thesis / Doctoral Dissertation Computer Science 2016

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-03-29T14:52:20Z No. of bitstreams: 1 arquivo total.pdf: 5170267 bytes, checksum: 3c56a27d34ff0a642cc77e2e279ae770 (MD5) / Made available in DSpace on 2017-03-29T14:52:20Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 5170267 bytes, checksum: 3c56a27d34ff0a642cc77e2e279ae770 (MD5) Previous issue date: 2014-02-14 / This research comes from the general hypothesis that Learning Objects (LOs) enable meaningful learning. To verify this hypothesis, a Learning Object was analyzed, it was developed for experimental psycholinguistics area, in order to facilitate the understanding of the Late Closure Principle, postulated by Garden-Path Theory. The Learning Objects are designed as reusable digital tools that facilitate learning, that are available over the Internet. Through the Learning Objects It is possible to simulate and study in an interactive and non-linear way. Being a non-traditional method, it provides an interesting research about the different styles of learning and, as a digital resource, provides an understanding of the use of technology in education and learning by natives and digital immigrants. To analyze the characteristics of the LO and relate them to the profiles of the participants, two questionnaires were applied to two classes of Linguistics Theories II discipline, in Letras undergraduate course, that get in touch with the content through a lecture and later explored the elements of LO. The results of the questionnaires allowed to characterize the technical and educational quality of the resource, since the survey participants positively assessed the potential of learning, usability and content. It was concluded that the analyzed learning object is characterized as a potentially significant material and, therefore, provides a meaningful learning of the Late Closure Principle because its resources were structured based on the principles of cognitive theory of meaningful learning that reflect the way how knowledge is organized in the cognitive structure of learners. Besides that, the participants identified as natives and digital immigrants and with different learning styles, performed well in the resolution of the analyzed activities, as well as showed interest in learning through learning objects. Thinking that way, the use of learning objects for understanding linguistic content in higher education is an issue that worth further investigation and it is still a challenge, as there is a need for greater availability of these resources. / A presente pesquisa parte da hipótese geral de que Objetos de Aprendizagem (OAs) possibilitam a aprendizagem significativa. Para averiguar tal hipótese, foi analisado um Objeto de Aprendizagem desenvolvido para a área da psicolinguística experimental, com o intuito de facilitar a compreensão do princípio da aposição local (Late Closure), postulada pela Teoria do Garden-Path ou Teoria do Labirinto. Os Objetos de Aprendizagem são concebidos como ferramentas digitais reutilizáveis que facilitam a aprendizagem, sendo disponibilizadas através da Internet. Através dos Objetos de Aprendizagem é possível simular e estudar de maneira interativa e não linear. Por ser um método não tradicional, proporciona uma investigação interessante sobre os diferentes estilos de aprender e, por ser um recurso digital, fornece a compreensão sobre o uso da tecnologia na educação e a aprendizagem por nativos e imigrantes digitais. Para analisar as características do OA e relacioná-las aos perfis dos participantes, foram aplicados dois questionários com duas turmas da disciplina Teorias Linguísticas II, curso de Letras, que conheceram o conteúdo abordado através de aula expositiva e, posteriormente, exploraram os elementos do OA. Os resultados dos questionários permitiram caracterizar a qualidade técnica e pedagógica do recurso, pois os participantes da pesquisa avaliaram positivamente o potencial de aprendizagem, usabilidade e conteúdo. Concluiu-se que o objeto de aprendizagem analisado é caracterizado como um material potencialmente significativo e, por isso, possibilita uma aprendizagem significativa do princípio da aposição local, pois seus recursos foram estruturados com base nos princípios da teoria cognitiva da aprendizagem significativa que refletem o modo como os conhecimentos são organizados na estrutura cognitiva dos aprendizes. Além disso, os participantes, identificados como nativos e imigrantes digitais e com diferentes estilos de aprendizagem, apresentaram um bom desempenho na resolução das atividades analisadas, assim como expuseram interesse em aprender através de objetos de aprendizagem. Nesse sentido, o uso dos objetos de aprendizagem para compreensão de conteúdos linguísticos no ensino superior é um tema que merece maior investigação e ainda é um desafio, visto que há a necessidade de uma maior disponibilização desses recursos.

Orientador: Maurice de Koning / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-08T20:27:57Z (GMT). No. of bitstreams: 1 PomaBernaola_AdolfoMaximo_M.pdf: 3697892 bytes, checksum: a07c1ad647a61d9862283f697732410e (MD5) Previous issue date: 2007 / Resumo: Nesta dissertação abordamos o estudo de uma das limitações da simulação atomística denominada o evento raro, quem é responsável pela limitação temporal, exemplos de problemas que envolvem os eventos raros são, o enovelamento de proteínas, mudanças conformacionais de moléculas, reações químicas (em solução), difusão de sólidos e os processos de nucleação numa transição de fase de 1a ordem, entre outros. Métodos convencionais como Dinâmica Molecular (MD) ou Monte Carlo (MC) são úteis para explorar a paisagem de energia potencial de sistemas muito complexos, mas em presença de eventos raros se tornam muito ineficientes, devido à falta de estatística na amostragem do evento. Estes métodos gastam muito tempo computacional amostrando as configurações irrelevantes e não as transições de interesse. Neste sentido o método Transition Path Sampling (TPS), desenvolvido por D. Chandler e seus colaboradores, consegue explorar a paisagem de energia potencial e obter um conjunto de verdadeiras trajetórias dinâmicas que conectam os estados metaestáveis em presença de evento raros. A partir do ensemble de caminhos a constante de reação e o mecanismo de reação podem ser extraídos com muito sucesso. Neste trabalho de mestrado implementamos com muito sucesso o método TPS e realizamos uma comparação quantitativa em relação ao método MC configuracional num problema padrão da isomerização de uma molécula diatômica imersa num líquido repulsivo tipo Weeks-Chandler-Andersen (WCA). A aplicação destes métodos mostrou como o ambiente, na forma de solvente, pode afetar a cinética de um evento raro / Abstract: In this dissertation we aproach the study of one of the limitations of the atomistic simulation called the rare event, which is responsible for the temporal limitation. Examples of problems that involve the rare event are the folding protein, conformational changes in molecules, chemical reactions (in solution), solid diffusion, and the processes of nucleation in a first-order phase transition, among other. Conventional methods as Molecular Dynamics (MD) or Monte Carlo (MC) are useful to explore the potencial energy landscape of very complex systems, but in presence of rare events they become very inefficient, due to lack of statistics in the sampling of the event. These methods spend much computational time sampling the irrelevant configurations and not the transition of interest. In this sense, the Transition Path Sampling (TPS) method, developed by D. Chandler and his collaborators, can explore the potential energy landscape and get a set of true dynamical trajectories that connect the metastable states in presence of the rare events. From this ensemble of trajectories the rate constant and the mechanism of reaction can be extracted with great success. In this work we implemented the TPS method and carried out a quantitative comparison in relation to the configurational MC method in a standard problem of the isomerization of a diatomic molecule immersed in a Weeks-Chandler-Andersen (WCA) repulsive fluid. The application of these methods showed as the environment, in the form of solvent, can affect the kinetic of a rare event / Mestrado / Física Estatistica e Termodinamica / Mestre em Física

A análise de caminhos de transferência de energia (TPA na sigla em inglês para Transfer Path Analysis) corresponde a um grupo de métodos numérico/experimental para análise e solução de problemas vibro-acústicos de sistemas lineares invariantes no tempo, sendo seu principal campo de aplicação a indústria automotiva. A TPA é uma técnica que identifica as principais fontes de vibração e ruído, e os caminhos estruturais e acústicos pelos quais são transmitidas para determinados locais de interesse. Conhecendo as fontes de ruído e vibração e os caminhos de propagação é possível propor modificações eficientes em minimizar o ruído/vibração nas regiões de interesse, ou atribuir características desejáveis para tais componentes, envolvendo técnicas de controle passivo e ativo. Este trabalho apresenta um estudo numérico e experimental das técnicas de TPA, utilizando métodos diretos e inversos de determinação de forças operacionais. Estes estudos foram realizados em um mockup de um veículo, com o objetivo de determinar o caminho de maior contribuição para o ruído no interior do protótipo, e a partir deste resultado, propor um sistema de controle ativo para minimizar este ruído interno. / The Transfer Path Analysis (TPA) is a group of numerical/experimental tools for the analysis and troubleshooting of noise and vibration problems in linear time invariant vibroacoustic systems, being the automotive sector its major user. TPA consists of a numerical/experimental analysis that allows the identification of the main noise and vibration sources and the structural/acoustic transfer paths to the Target points. Based on the sources and paths, it is possible to propose modifications that efficiently minimize noise and vibration at the target positions. By means of active control it is possible to modify noise and vibration in order to change, rather than minimize noise and vibration, achieving certain design targets. This work presents a numerical and experimental study of TPA techniques, using direct and inverse operational loads determination methods. These studies were performed on a vehicle mockup, in order to determine the path of greatest contribution to the noise inside the prototype, and from this result, propose an active control system to minimize this internal noise.