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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Exploring the value of adding airflow to the VR-developer’s toolkit

Troost, Robbert January 2019 (has links)
To achieve the highest levels of immersion and presence possible in a Virtual Reality experience, all of the sensory input we receive in the real world must be simulatable in Virtual Environments (VE) as well. Foregoing the more popular audio-visual feedback, this project aims to better understand the benefits of adding tactile feedback (namely that of airflow) to the VR-developer‟s toolkit. Through user tests, involving a hairdryer to produce a strong airflow that is easily redirected and changed in temperature, feedback was collected on the user experiences and applications of airflow in a VE made to simulate a walk through river lands similar to the ones found in Sweden. While there was no singular way that the participants experienced the added sensory input, most reported the airflow as being equally important to feeling immersed as background music, and on average almost as important as other audio cues. Perhaps most importantly, rich insights were gathered that can guide further research.
202

Évolution des paysages végétaux en Languedoc durant l’Holocène : apport de la palynologie à l’étude des milieux et des agrosystèmes / Evolution of landscapes in Languedoc (France) during the Holocene : contribution of palynology to the study of environments and agrosystems.

Dolez, Ludovic 18 December 2018 (has links)
Cette thèse se propose d’étudier l’évolution des milieux et des agrosystèmes en Languedoc durant les derniers dix millénaires grâce à l’étude des paléo-végétations. Tout en réévaluant les recherches anciennes, ce travail affine la résolution temporelle des mutations paysagères enregistrées et apporte une vision à l’échelle du Languedoc occidental, par l’étude des bassins versants de l’Aude et de l’Hérault. À partir de l’analyse palynologique de carottages effectués dans des zones lagunaires proches d’Agde et de Narbonne, ce travail met en exergue la coévolution entre milieux et agrosystèmes, tant sur le temps long que sur le temps de l’Homme, en analysant les particularités et les rapprochements entre dynamiques de ces deux bassins versants comme les stratégies d’exploitation du territoire développées par l’Homme, l’utilisation de ressources végétales spécifiques ainsi que les types et zones de cultures et de pâturages, au niveau des aires littorales, mais aussi dans l’arrière-pays languedocien. / This thesis studies the evolution of environments and agricultural systems in Languedoc during the last ten millennia through the paleo-vegetation. Reassessing old research, this work refines the temporal resolution of the landscape changes and provides vision at the western Languedoc scale, by the study of Aude and Hérault rivers watershed. From the pollen analyzes of cores drilled in lagoons close to Agde and Narbonne, this work highlights the coevolution between agricultural systems and environments, both long time and Man time, analyzing particularities and dynamic connections between these two watersheds like the territorial exploitation strategies developed by humans, the use of specific plant resources and the types and areas of crops and pastures, in coastal areas and in the Languedoc hinterland.
203

Caracterização e análise de desempenho de uma rede de sensores sem fio. / Characterization and performance analisys of a wireless sensor network.

Cabrini, Fábio Henrique 27 October 2006 (has links)
As redes de sensores sem fio (RSSF) ganham maior visibilidade a cada ano, e a sua utilização é cada vez mais imprescindível no sensoriamento dos mais diversos ambientes. Estas redes podem ser instaladas em praticamente todos os tipos de ambientes, graças ao seu tamanho reduzido, sua facilidade de comunicação e seu baixo custo. Esta tecnologia permite transportar os dados através de nós que utilizam algoritmos de roteamento oferecendo resistência a falhas. O conhecimento das principais arquiteturas e dos protocolos envolvidos na comunicação, bem como do comportamento destas redes em ambientes reais, é de extrema importância para a compreensão do funcionamento da rede e dos fenômenos que afetam o seu desempenho. Este trabalho apresenta a utilização de uma RSSF baseada no dispositivo Mica2dot, desenvolvido pela Universidade de Berkeley, no monitoramento de parâmetros ambientais de uma sala limpa utilizada na construção de dispositivos semicondutores. Apresentamos a caracterização dos dispositivos e do ambiente em questão; também avaliamos dois protocolos de roteamento neste ambiente e fatores que afetam o funcionamento do sistema de rádio, como a variação do RSSI (Receive Signal Strength Indicator). Os protocolos de roteamento escolhidos para esta avaliação foram o TOSB (TinyOs Beaconing), que é o protocolo padrão do sistema operacional TinyOS, e o PROC (Proactive ROuting with Coordination), que apresenta características de pró-atividade. Os protocolos foram avaliados segundo as métricas de consumo de energia e taxa média de entrega de pacotes. / Wireless sensor networks (WSNs) are growing year after year, and its use is being more and more indispensable in sensing the most varied environments. These networks can be installed in almost all kinds of environments, thanks to its reduced size, its easiness of communication and its low cost. One of the main characteristics of this technology is the capacity of transporting data through the nodes that use router algorithms, offering a good resistance to failures. The knowledge of the main architectures and of the protocols involved in communication, as well the behavior of these networks in real environments, is of extreme importance to the understanding of the working conditions of the network and of the phenomena that affect its performance. This piece of work aims to present a study related to the use of a WSN based on the Mica2dot device developed by the University of Berkeley, in the monitoring of the environmental parameters of a clean room used to the construction of semiconductor devices. This work presents the characterization of the devices and of the environment in question, as well evaluates some factors that affect the working of the radio system and evaluates two router protocols in this environment. The chosen router protocols for this evaluation were TOSB (TinyOs Beaconing) that is the standard protocol of the operational system TinyOS, and PROC (Proactive Routing with Coordination), that presents some pro-active characteristics. The protocols were evaluated according to the measurement of the energy consumption and average rate of deliver of packages.
204

Geoquímica de ferro e elementos traço em solos de áreas úmidas impactadas pelo rejeito proveniente do acidente de Mariana - MG / Geochemistry of iron and trace elements found in soils of Wetlands impacted by the tailings from the Mariana accident - MG

Almeida, Leandro de Souza 11 August 2017 (has links)
Os ambientes estuarinos, interface entre oceano e o continente, são classificados como um dos mais importantes ecossistemas existentes, tanto pela sua localização na quanto pela sua importância para as espécies locais e outras tantas espécies dependentes desse habitat. Elementos como o Ferro e Enxofre desempenham importante papel nesses ambientes, devido principalmente às condições anóxicas impostas pela constante inundação. Tais elementos são peças-chave para diversos processos biogeoquímicos relacionados metais, e a oxidação da matéria orgânica em ambiente redutor, e os processos geoquímicos relacionados a estes elementos variam com a dinâmica de marés, a presença de organismos e plantas. Embora seja evidente a importância de estuários, ainda não existem muitas medidas efetivas que previnam as descargas de poluentes diretamente nessas áreas, como metais pesados; que podem estar presentes em grandes quantidades no esgoto urbano e industrial. Além disso, metais podem ser liberados em casos isolados, como por exemplo, no rompimento da barragem da Samarco em 2015 liberando grande quantidade de rejeitos de processamento de minérios. Nesse sentido este trabalho teve como objetivo, avaliar os efeitos da chegada do rejeito à Foz do Rio Doce no Estado do Espírito Santo, no comportamento geoquímico dos elementos Fe, Mn, Zn e Cu no ambiente estuarino. Foram coletadas amostras de solo e do rejeito depositado, ao longo do estuário do Rio Doce, nas proximidades do município de Regência (coordenadas 19º 24\' 20\" S e 40º 4\' 5\" W ), no nordeste do Estado do Espírito Santo. Em campo foram medidos os valores de pH e Eh e em laboratório determinado as frações de metais através de extrações sequenciais e a determinação do teor de MO e composição granulométrica. Também foi feito análise de DRX no rejeito, pelo método de amostra em pó seca o qual demonstra óxidos de ferro como hematita e goethita. Os resultados mostram grande variação de Eh e pH, predomínio da fração areia no solo, e teores de MO em média entre 2,67±2,31 e 6,28±3,51%. Os teores de metais como o Fe, Mn, Cu e Zn apresentaram-se consideravelmente elevados, devido principalmente, a composição do rejeito e fortemente associados às formas óxidos e pouco Fe e metais associados à fração pirítica, o que expõe o risco de biodisponibilidade de metais pela redução do Fe. / The estuarine environments, an interface between ocean and the continent lands are classified as one of the most important ecosystems existing, as much for its location as for its importance for the local species and other species dependent on that specific habitat. Elements such as iron and sulfur play an important role in these environments, mainly due to the anoxic conditions imposed by frequent flooding. These elements are key pieces for several biogeochemical processes related to metals, and the oxidation of organic matter in reducing environment, and the geochemical processes related to these elements vary with the dynamics of tides, the presence of organisms and plants. Although the importance of estuaries is evident, there are still many effective measures to prevent the discharge of pollutants directly into these areas, such as heavy metals; Which may be present in large quantities in urban and industrial sewage. Additionally, metals can be released in isolated cases, for example, in the colapse of the Samarco´s dam in 2015 releasing large amounts of ore processing tailings. Thus, the objective of this work was to evaluate the effects of the arrival of the tailings to Rio Doce river, in the state of Espírito Santo, in the meaning of geochemical behavior of the elements Fe, Mn, Zn and Cu in the estuarine environment. Soil and deposited tailings were sampled and collected along the Rio Doce estuary near the city of Regência (coordinates 19º 24 \'20 \"S and 40º 4\' 5\" W), in the northeast of the State of Espírito Santo. The values of pH and Eh were measured on field, and in laboratory were determined the fractions of metals through sequential extractions as well the determination of the content of MO and granulometric composition. XRD analysis was also carried out in the tailings by the dry powder sample method, which demonstrates iron oxides such as hematite and goethite. The results showed a great variation of Eh and pH, predominance of the sand fraction in the soil, and OM levels between 2.67 ± 2.31 and 6.28 ± 3.51%. The metals, such as Fe, Mn, Cu and Zn, were considerably elevated, mainly due to the composition of the waste and strongly associated with the oxides and low Fe and metals associated with the pyritic fraction, which exposes the risk of bioavailability of Metals by the reduction of Fe.
205

Semi-Supervised Hybrid Windowing Ensembles for Learning from Evolving Streams

Floyd, Sean Louis Alan 03 June 2019 (has links)
In this thesis, learning refers to the intelligent computational extraction of knowledge from data. Supervised learning tasks require data to be annotated with labels, whereas for unsupervised learning, data is not labelled. Semi-supervised learning deals with data sets that are partially labelled. A major issue with supervised and semi-supervised learning of data streams is late-arriving or missing class labels. Assuming that correctly labelled data will always be available and timely is often unfeasible, and, as such, supervised methods are not directly applicable in the real world. Therefore, real-world problems usually require the use of semi-supervised or unsupervised learning techniques. For instance, when considering a spam detection task, it is not reasonable to assume that all spam will be identified (correctly labelled) prior to learning. Additionally, in semi-supervised learning, "the instances having the highest [predictive] confidence are not necessarily the most useful ones" [41]. We investigate how self-training performs without its selective heuristic in a streaming setting. This leads us to our contributions. We extend an existing concept drift detector to operate without any labelled data, by using a sliding window of our ensemble's prediction confidence, instead of a boolean indicating whether the ensemble's predictions are correct. We also extend selective self-training, a semi-supervised learning method, by using all predictions, and not only those with high predictive confidence. Finally, we introduce a novel windowing type for ensembles, as sliding windows are very time consuming and regular tumbling windows are not a suitable replacement. Our windowing technique can be considered a hybrid of the two: we train each sub-classifier in the ensemble with tumbling windows, but delay training in such a way that only one sub-classifier can update its model per iteration. We found, through statistical significance tests, that our framework is (roughly 160 times) faster than current state of the art techniques, and achieves comparable predictive accuracy. That being said, more research is needed to further reduce the quantity of labelled data used for training, while also increasing its predictive accuracy.
206

Foam Fighting: Technology and Culture

Unknown Date (has links)
Foam fighting is a form of Live Action Role Playing (LARP) that focuses on mock combat and recreational battle, with role-playing aspects taking a less prominent role. It is sometimes referred to as a “poor man’s martial art”.While there does not appear to be any clear documentation concerning the origins, research on foam fighting suggests the sport began in Maryland in the 1970’s and slowly spread throughout the United States. This research will illustrate how the sport of foam fighting demands a level of critical thinking that takes both the participant and audience beyond the sight of a swinging stick. I plan to show how this sport provides an outlet for high levels of creativity, social interaction and strategic planning skills. It is a hobby that has had a great impact on the daily lives of many of its participants and continues to grow and evolve. / Includes bibliography. / Thesis (M.F.A.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection
207

Stochastic processes in random environment

Ortgiese, Marcel January 2009 (has links)
We are interested in two probabilistic models of a process interacting with a random environment. Firstly, we consider the model of directed polymers in random environment. In this case, a polymer, represented as the path of a simple random walk on a lattice, interacts with an environment given by a collection of time-dependent random variables associated to the vertices. Under certain conditions, the system undergoes a phase transition from an entropy-dominated regime at high temperatures, to a localised regime at low temperatures. Our main result shows that at high temperatures, even though a central limit theorem holds, we can identify a set of paths constituting a vanishing fraction of all paths that supports the free energy. We compare the situation to a mean-field model defined on a regular tree, where we can also describe the situation at the critical temperature. Secondly, we consider the parabolic Anderson model, which is the Cauchy problem for the heat equation with a random potential. Our setting is continuous in time and discrete in space, and we focus on time-constant, independent and identically distributed potentials with polynomial tails at infinity. We are concerned with the long-term temporal dynamics of this system. Our main result is that the periods, in which the profile of the solutions remains nearly constant, are increasing linearly over time, a phenomenon known as ageing. We describe this phenomenon in the weak sense, by looking at the asymptotic probability of a change in a given time window, and in the strong sense, by identifying the almost sure upper envelope for the process of the time remaining until the next change of profile. We also prove functional scaling limit theorems for profile and growth rate of the solution of the parabolic Anderson model.
208

An Initial Exploration of a Multi-Sensory Design Space: Tactile Support for Walking in Immersive Virtual Environments

Feng, Mi 27 January 2016 (has links)
Multi-sensory feedback can potentially improve user experience and performance in virtual environments. As it is complicated to study the effect of multi-sensory feedback as a single factor, we created a design space with these diverse cues, categorizing them into an appropriate granularity based on their origin and use cases. To examine the effects of tactile cues during non-fatiguing walking in immersive virtual environments, we selected certain tactile cues from the design space, movement wind, directional wind and footstep vibration, and another cue, footstep sounds, and investigated their influence and interaction with each other in more detail. We developed a virtual reality system with non-fatiguing walking interaction and low-latency, multi-sensory feedback, and then used it to conduct two successive experiments measuring user experience and performance through a triangle-completion task. We noticed some effects due to the addition of footstep vibration on task performance, and saw significant improvement due to the added tactile cues in reported user experience.
209

Presentation of visual artworks in interactive virtual environments towards user engagement

Maleshkova, Jeni January 2018 (has links)
This thesis explores the role of interactivity in interfaces for visual artwork display, and the promotion of user engagement. In contrast to most previous work, which has been based on digitally recreating the physical properties of traditional exhibition spaces, this research explores the advantages that interactive digital displays offer to user engagement by investigating different methods and techniques for presenting images of visual artworks in a virtual environment. Throughout this research, various interactive virtual presentation designs, including four interactivity modes, have been developed and tested in lab, field and online studies; data gathering and analysis have used both qualitative and quantitative methods. Further, event parameters have been introduced, the aid of which has allowed the separate phases of user engagement to be examined. The experiments on a broader scale in the final stage of this research are targeted towards demonstrating the potential of the proposed approach and will foster the application of advanced technologies for presentation of visual artworks. This thesis makes a number of contributions in the fields of digital art presentation and methods for measuring user engagement and its different phases. The conceptual framework for describing user engagement is generalised and ex- tended by additional elements. The relation between four designed interactivity modes and the extended phases of user engagement has been investigated, analysed and examined through the application of a mixed-methods approach that combines qualitative and quantitative techniques. Finally, the findings from this thesis about the design interactivity modes and evaluation of user engagement can be adopted by and applied in further research.
210

Rethinking urban lighting : geographies of artificial lighting in everyday life

Ebbensgaard, Casper Laing January 2017 (has links)
In this thesis I study the role of artificial lighting in the everyday urban life of older residents living in the London Borough of Newham. Newham's light infrastructure is currently undergoing change as the borough's entire 19,000 street lamps are being re-placed with Light Emitting Diodes and as a range of regeneration projects provide public spaces designed with new lighting. By increasing visibility and encouraging everyday activity into the evening, the Council claims that the changes in public light-ing will provide 'eyes on the streets' and encourage 'eyes from the windows' of build-ings, contributing to increasing 'natural surveillance'. The Council's avowal of every-day practices in streets and in homes, has made me question how lighting affects the way older residents move through streets and carry out domestic practices as dark-ness falls. The study explores how light planning, lighting design and everyday, rou-tine practices in the public realm and inside homes co-produce the urban, lit environ-ment. Two major contributions of the thesis lie in the (post)phenomenological ap-proach I develop to study everyday experiences of urban lighting, and the methodo-logical framework I employ to research such practices, which combines mobile and visual methods. I have conducted 11 in-depth interviews with nine different planners and designers, 12 walk-along interviews with 22 residents between 58 and 79 years old, and a collaborative photography project with 14 residents between 68 and 96 years old. As I show how older residents experiences different lighting technologies, layers of light, and different lit spaces in their neighbourhoods, I discuss how urban lighting makes them see, feel and carry out routine practices in particular ways. Based on my findings, I argue that urban lighting shapes what, and how, people see, but how people see depends on how they negotiate changes in lighting. In a range of examples where residents mould the urban, lit environment or respond to lighting in different ways, I show how they play and active part in co-producing ways of seeing. I argue it is crucial that light planners and lighting designers recognise such co-constitutive role of everyday practices in order to ensure better lighting for our future cities.

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