443 research outputs found

    Evacuação de Edifícios – Caso de estudo de um edifício escolar

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    O objetivo deste trabalho é o levantamento dos aspetos que influenciam o tempo de evacuação num edifício escolar, desde o comportamento humano às caraterísticas físicas do edifício e às metodologias possíveis de adotar para a gestão da emergência, com vista a calcular o tempo necessário e disponível para a evacuação do referido edifício. A evacuação de edifícios em situação de incêndio tem como propósito a proteção da vida humana que é inseparável das condições de emergência as quais são afetadas por fatores de difícil determinação e que necessitam de ser definidos para estimar o tempo e as condições de evacuação.info:eu-repo/semantics/publishedVersio

    Geoarchaeological Investigations of Late Pleistocene Physical Environments and Impacts of Prehistoric Foragers on the Ecosystem in Northern Malawi and Austria

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    A growing body of research shows that not only did environmental changes play an important role in human evolution, but humans in turn have impacted ecosystems and landscape evolution since the Late Pleistocene. This thesis presents collaborative work on Late Pleistocene open-air sites in the Karonga District of northern Malawi, in which new aspects of forager behavior came to light through the reconstruction of physical environments. My work has helped recognize that late Middle Stone Age (MSA) activity and tool production occurred in locally more open riparian environments within evergreen gallery forest, surrounded by a regional vegetation dominated by miombo woodlands and savanna. Additionally, MSA hunter-gatherers exploited the confluence of river and wetland areas along the shores of Lake Malawi, which likely served as important corridors for the dispersal of biota. By comparing data from the archaeological investigations with lake core records, we were able to identify effects of anthropogenic burning on vegetation structures and sedimentation in the region as early as 80 thousand years ago. These findings not only proved it possible to uncover early impacts of human activity on the ecosystem, but also emphasize the importance of fire in the lives of early foragers. Publications contained within this dissertation: A. Wright, D.K., Thompson, J.C., Schilt, F.C., Cohen, A., Choi, J-H., Mercader, J., Nightingale, S., Miller, C.E., Mentzer, S.M., Walde, D., Welling, M., and Gomani-Chindebvu, E. “Approaches to Middle Stone Age landscape archaeology in tropical Africa”. Special issue Geoarchaeology of the Tropics of Journal of Archaeological Science 77:64-77. http://dx.doi.org/10.1016/j.jas.2016.01.014 B. Schilt, F.C., Verpoorte, A., Antl, W. “Micromorphology of an Upper Paleolithic cultural layer at Grub-Kranawetberg, Austria”. Journal of Archaeological Science: Reports 14:152-162. http://dx.doi.org/10.1016/j.jasrep.2017.05.041 C. Nightingale, S., Schilt, F.C., Thompson, J.C., Wright, D.K., Forman, S., Mercader, J., Moss, P., Clarke, S. Itambu, M., Gomani-Chindebvu, E., Welling, M. Late Middle Stone Age Behavior and Environments at Chaminade I (Karonga, Malawi). Journal of Paleolithic Archaeology 2-3:258-397. https://doi.org/10.1007/s41982-019-00035-3 D. Thompson, J.C.*, Wright, D.K.*, Ivory, S.J.*, Choi, J-H., Nightingale, S., Mackay, A., Schilt, F.C., Otárola-Castillo, E., Mercader, J., Forman, S.L., Pietsch, T., Cohen, A.S., Arrowsmith, J.R., Welling, M., Davis, J., Schiery, B., Kaliba, P., Malijani, O., Blome, M.W., O’Driscoll, C., Mentzer, S.M., Miller, C., Heo, S., Choi, J., Tembo, J., Mapemba, F., Simengwa, D., and Gomani-Chindebvu, E. “Early human impacts and ecosystem reorganization in southern-central Africa”. Science Advances 7(19): eabf9776. *equal contribution https://doi.org/10.1126/sciadv.abf9776 E. Schilt, F.C., Miller, C.M., Wright, D.K., Mentzer, S.M., Mercader, J., Moss, Choi, J.-H., Siljedal, G., Clarke, S., Mwambwiga, A., Thomas, K., Barbieri, A., Kaliba, P., Gomani-Chindebvu, E., Thompson, J.C. “Hunter-gatherer environments at the Late Pleistocene sites of Bruce and Mwanganda´s Village, northern Malawi”. Quaternary Science Reviews 292: 107638. https://www.sciencedirect.com/science/article/pii/S0277379122002694 [untranslated

    Adsorption of Alkanes on the Platinum Surface: Density Functional Theory compared to the Random Phase Approximation

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    Die Dichtefunktionaltheorie (DFT) einschließlich Dispersionkorrekturen (+D) wird mit der Random-Phase-Approximation (RPA) für die Adsorption von Alkanen auf der Pt(111)-Oberfläche verglichen. RPA wird zuerst im Hinblick auf relevante technische Parameter evaluiert und für die Methanadsorption an der Pt(111)-Oberfläche getestet. Im Vergleich zum Perdew-Burke-Ernzerhof-Funktional (PBE) mit Tkatchenkos Many-Body-Dispersionskorrektur (PBE+MBD) liefert RPA gute Ergebnisse. Auch reproduziert RPA experimentelle Adsorptionsenergien bei verschiedenen, physikalisch sinnvollen Beladungsstufen der Pt(111) Oberfläche mit Alkanmolekülen. Für Platin in der hexagonal dichtesten Kugelpackung sagt RPA richtigerweise die Methanadsorption an der hollow-tripod-Stelle voraus, während mit PBE+MBD die Adsorption an einer anderen Stelle bevorzugt wäre. Dies geht aus Schwingungsspektren hervor. Da periodisches RPA sehr rechenaufwändig ist, wird ein QM:QM Hybridansatz (QM=Quantenmechanik) angewendet, wobei periodisches PBE(+D) mithilfe von RPA Rechnungen an Clustern korrigiert wird (RPA:PBE(+D)). In einem Test verschiedener Dispersionskorrekturen schneiden RPA:PBE und RPA:PBE+MBD am besten ab. Diese Arbeit ist wegbereitend für die Anwendung des QM:QM Hybridansatzes zur Beschreibung der Adsorptionsprozesse an Metalloberflächen ‒ bei hoher Genauigkeit und deutlich verringertem Rechenaufwand. Auch Kresses low-scaling RPA Algorithmus wird getestet. Dieser Algorithmus ermöglicht, große Systeme, wie z.B. die Methan-, Ethan-, Propan- und n-Butanadsorption an Pt(111), zu untersuchen. Der Vergleich mit experimentellen Daten zeigt, dass mit RPA stets die beste Übereinstimmung erreicht wird. Dabei wird eine deutliche Verbesserung gegenüber allen untersuchten Dichte-Funktionalen erzielt. Obwohl Bindungen mit RPA etwas zu schwach vorhergesagt werden, ist es die derzeit beste Methode zur Untersuchung der Adsorption an Metalloberflächen und damit der Benchmark für diese Systeme.Density Functional Theory (DFT) including dispersion (+D) is compared against the Random Phase Approximation (RPA) for the adsorption of alkanes on the Pt(111) surface. RPA is first benchmarked with respect to technical parameters and tested for methane adsorption on Pt(111). It is found to perform well relative to the Perdew–Burke–Ernzerhof (PBE) functional augmented with the many-body dispersion scheme of Tkatchenko (PBE+MBD). It also compares well relative to experimentally derived adsorption energies at physically relevant coverages. RPA correctly assigns the adsorption of methane to the hcp (hexagonal close packed) hollow tripod site, matching vibrational spectra, whereas PBE+MBD found another site. Given the high cost of periodic RPA, a high-level: low-level QM:QM (QM = quantum mechanics) hybrid approach is applied using RPA (RPA:PBE(+D)), which has also been tested with several dispersion corrections, with RPA:PBE and RPA:PBE+MBD performing best. This extends the QM:QM hybrid approach to the study of adsorption on metal surfaces, resulting in high accuracy at significantly reduced cost. Finally we test the performance of the low-scaling RPA algorithm of Kresse and co-workers. This algorithm enables the study of larger systems and is applied to the first four n-alkanes (C1-C4) on the Pt(111) surface. Comparison against experiment indicates that RPA offers the best agreement, consistently better than any studied density functional. RPA underbinds slightly but is still found to be the best method for studying adsorption on metal surfaces and is the current benchmark for such systems

    Collaborative and Cooperative Robotics Applications using Visual Perception

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    The objective of this Thesis is to develop novel integrated strategies for collaborative and cooperative robotic applications. Commonly, industrial robots operate in structured environments and in work-cell separated from human operators. Nowadays, collaborative robots have the capacity of sharing the workspace and collaborate with humans or other robots to perform complex tasks. These robots often operate in an unstructured environment, whereby they need sensors and algorithms to get information about environment changes. Advanced vision and control techniques have been analyzed to evaluate their performance and their applicability to industrial tasks. Then, some selected techniques have been applied for the first time to an industrial context. A Peg-in-Hole task has been chosen as first case study, since it has been extensively studied but still remains challenging: it requires accuracy both in the determination of the hole poses and in the robot positioning. Two solutions have been developed and tested. Experimental results have been discussed to highlight the advantages and disadvantages of each technique. Grasping partially known objects in unstructured environments is one of the most challenging issues in robotics. It is a complex task and requires to address multiple subproblems, in order to be accomplished, including object localization and grasp pose detection. Also for this class of issues some vision techniques have been analyzed. One of these has been adapted to be used in industrial scenarios. Moreover, as a second case study, a robot-to-robot object handover task in a partially structured environment and in the absence of explicit communication between the robots has been developed and validated. Finally, the two case studies have been integrated in two real industrial setups to demonstrate the applicability of the strategies to solving industrial problems

    Identification and characterization of N-degron pathways

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    Stress-Strain Models for UHPFRC and Application in Seismic Design and Retrofit of Bridges

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    With the advent of Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC), most shortcomings of conventional concrete are mitigated, since UHPFRC has exceptional mechanical and durability properties. The behavior of the material in tension is the most important property that need be characterized with confidence for practical implementation of UHPFRC in construction. This is often extracted through reverse inverse analysis of flexural tests – existing inverse analysis methods are fraught with great uncertainty and scatter. In this thesis, several alternative characterization methods are explored and corroborated with test results, including an inverse analysis procedure that is consistent with first principles, as well as a practical, chart-based procedure for quality control by practitioners. Apart from the direct tension response, the tension stiffening property of UHPFRC when it interacts with embedded reinforcement was also studied both experimentally and through detailed finite element simulation. Parameters of the study included the volumetric ratio of fibers, casting methodology, loading protocol and the condition of the embedded reinforcement (corroded or uncorroded). Results quantify the amount of tension stiffening that UHPFC cover can provide to reinforcement. The emphasis on tensile stress and strain capacity of UHPFRC is of interest in seismic retrofitting of existing columns through jacketing. In this work a design framework was developed to design UHPFRC jackets by setting performance objectives for the retrofitted column, strain limits for the UHPFRC material in tension and compression, and by development of a constitutive relationship for the encased concrete under the influence of confinement imparted by the jacket. The study includes an illustrative example of a bridge pier confined with two alternative UHPFRC materials of different strength, indicating the effectiveness of the proposed methodology in estimating the performance limit states of the retrofitted component

    The Polytope of Optimal Approximate Designs

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    For many statistical experiments, there exists a multitude of optimal designs. If we consider models with uncorrelated observations and adopt the approach of approximate experimental design, the set of all optimal designs typically forms a multivariate polytope. In this paper, we mathematically characterize the polytope of optimal designs. In particular, we show that its vertices correspond to the so-called minimal optimum designs. Consequently, we compute the vertices for several classical multifactor regression models of the first and the second degree. To this end, we use software tools based on rational arithmetic; therefore, the computed list is accurate and complete. The polytope of optimal experimental designs, and its vertices, can be applied in several ways. For instance, it can aid in constructing cost-efficient and efficient exact designs

    Towards a data-driven military: a multi-disciplinary perspective

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    Towards a data-driven military. A multi-disciplinary perspective assesses the use of data and information on modern conflict from different scientific and methodological disciplines, aiming to generate valuable contributions to the ongoing discourse on data, the military and modern warfare. Military Systems and Technology approaches the theme empirically by researching how data can enhance the utility of military materiel and subsequently accelerate the decision-making process. War Studies take a multidisciplinary approach to the evolution of warfare, while Military Management Studies take a holistic organisational and procedural approach. Based on their scientific protocols and research methods, the three domains put forward different research questions and perspectives, providing the unique character of this book
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