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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.
71

Draft-N 2.0 : En jämförande studie av täckningsgrad och bandbredd i trådlösa nätverk av typ hot-spot med IEEE 802.11A/G respektive IEEE 802.11N Draft 2.0

Mölleborg, Gabriel, Henriksson, Joel January 2008 (has links)
Rapporten är en jämförande studie av täckningsgrad och bandbredd i trådlösa nätverk av typ hot-spot med IEEE 802.11A/G respektive IEEE 802.11N Draft 2.0. Studien är gjord i tre olika scenarion på Kvarnholmen i Kalmar under april och maj månad 2008.
72

The Our Florida Reefs Coastal Use Survey: An Online Survey to Support Stakeholder Management Recommendations for Southeast Florida

Costaregni, Amanda Rose 11 December 2015 (has links)
Coral reefs are an important resource world-wide. Unfortunately, coral reef conditions are declining in many areas due to both global and local stressors. The objective of this study was to survey stakeholders in southeast Florida to better understand reef use in the region. Stakeholders spatially identified where and how often they conducted their activities. These data were compiled and analyzed in GIS to determine spatial use patterns. Both location and intensity of use were analyzed to determine which areas may be under greater stress from recreational activities. It was found that reef use was not evenly distributed in the region but clustered around inlets and piers. Reef use differed between user groups (i.e. SCUBA divers, fishers) and demographics. It was also found that use in the Broward-Miami Coral Reef Ecosystem Region was spread out over a wider spatial scale than the use in the regions north and south.. These data are important as they have the potential to inform the recommendations being made to improve coral reef management in southeast Florida. The study can provide a better understanding of human-environmental relationships and the trade-offs involved so that recommendations can better decrease user conflicts, maximize economic productivity, and preserve the environment.
73

Effects of Multimodal Police and Community Development Interventions on Violent Crime in a Target Area of Youngstown, Ohio

Simon, Jason E. January 2019 (has links)
No description available.
74

Wildlife-vehicle collisions : An evaluation of the mitigation effect by ecoducts and fauna bridges in Sweden

Rietz, Anna January 2023 (has links)
The occurrence of wildlife vehicle collisions (WVCs) is an increasing problem in Sweden with a calculated increase of 45 percent from 2015 to 2022. The highest measured number of WVCs occurred in 2021 with over 67,000 reported incidents, where only the payment for the search of wounded animals were approximately 60 million Swedish crowns. The Swedish transport agency works actively with the problem by constructing several types of wildlife passages to mitigate the increasing problem, inter alia, ecoducts and fauna bridges.   The aim of this study was to evaluate the mitigation effect of wildlife passages, in this case ecoducts and fauna bridges. In addition, were also the spatial extent of the mitigation effect together with the relationship between mitigation effect and the annual daily traffic (ADT) evaluated.   The evaluation of mitigation effect was conducted by the usage of several types of geographical information systems (GIS) tools in the software ArcGIS Pro. A selection of seven passages was made, based on several requirements and each passage was assigned a study area with an area of 100 square kilometers. The mitigation effect was initially determined by conducting an Emerging hot spot analysis, categorizing the result into showing trend of decrease or showing no trend of decrease. The spatial extent of the mitigating effect was evaluated through the Emerging hot spot results while the relation between ADT and WVCs was evaluated in an overlay analysis.   Two of the passages were concluded as to having a mitigating effect, three passages were concluded as to showing no mitigating effect and two passages were excluded from further evaluation due to high uncertainty in the results. At the passages with stated mitigating effect were the spatial extent of effect shown in the whole study area. The result showed no evident correlation between ADT and mitigating effects which led to further reflections on the degree of influence that ADT has on the occurrence of WVCs.
75

DESIGN AND FABRICATION OF SMART SERS SUBSTRATES FOR FORENSIC SCIENCE APPLICATIONS

Maria Vitoria Simas (16510902) 30 August 2023 (has links)
<p>This thesis highlights the use and significance of surface enhanced Raman spectroscopy (SERS) for forensic applications. Two unique SERS substrates are developed for successful (1) forensic toxicological drug detection in human patient plasma and (2) trace explosive detection.  </p>
76

Diverzita, ekologie a metodika průzkumu lišejníků pralesovitých porostů ve střední Evropě / Diversity, ecology and methods of the research of lichens in old-growth forests in Central Europe

Malíček, Jiří January 2016 (has links)
1 Abstract Forests are the native Central European vegetation, which have dominated in the landscape for the last c. 10,000 years. Stands with an oak and hornbeam dominance occupied lower elevations before human colonization, beech and silver fir-beech forests middle elevations and spruce stands at higher elevations. Only a few remnants of forests, which can be regarded as primeval or with a minimal impact of forest management, have survived in densely populated Central Europe. Examples of the most preserved primeval forests are Rothwald (Austria), Białowieża (Poland, Belorussia), Stužica/Stuzhytsia (Slovakia, Ukraine) and Boubín (Czech Republic). Although these sites are small and isolated, they are local diversity centers for many organisms, mainly for fungi, lichens and bryophytes, refugia for numerous endangered species and some of them have their last localities there. Epiphytic and epixylic lichens are an ideal model group for studies about forests because they sensitively indicate management, continuity, heterogeneity and age of a woodland. Therefore they could help us to answer many important questions about the conservation of natural forests. This thesis comprises several different points of view on lichens in Central European forests and its aim is to join these heterogeneous fields into one...
77

Conformal Thermal Models for Optimal Loading and Elapsed Life Estimation of Power Transformers

Pradhan, Manoj Kumar 08 1900 (has links)
Power and Generator Transformers are important and expensive elements of a power system. Inadvertent failure of Power Transformers would cause long interruption in power supply with consequent loss of reliability and revenue to the supply utilities. The mineral oil impregnated paper, OIP, is an insulation of choice in large power transformers in view of its excellent dielectric and other properties, besides being relatively inexpensive. During the normal working regime of the transformer, the insulation thereof is subjected to various stresses, the more important among them are, electrical, thermal, mechanical and chemical. Each of these stresses, appearing singly, or in combination, would lead to a time variant deterioration in the properties of insulation, called Ageing. This normal and inevitable process of degradation in the several essential properties of the insulation is irreversible, is a non-Markov physico-chemical reaction kinetic process. The speed or the rapidity of insulation deterioration is a very strong function of the magnitude of the stresses and the duration over which they acted. This is further compounded, if the stresses are in synergy. During the processes of ageing, some, or all the vital properties undergo subtle changes, more often, not in step with the duration of time over which the damage has been accumulated. Often, these changes are non monotonic, thus presenting a random or a chaotic picture and understanding the processes leading to eventual failure becomes difficult. But, there is some order in this chaos, in that, the time average of the changes over short intervals of time, seems to indicate some degree of predictability. The status of insulation at any given point in time is assessed by measuring such of those properties as are sensitive to the amount of ageing and comparing it with earlier measurements. This procedure, called the Diagnostic or nondestructive Testing, has been in vogue for some time now. Of the many parameters used as sensitive indices of the dynamics of insulation degradation, temporal changes in temperatures at different locations in the body of the transformer, more precisely, the winding hot spots (HST) and top oil temperature (TOT) are believed to give a fairly accurate indication of the rate of degradation. Further, an accurate estimation of the temperatures would enable to determine the loading limit (loadability) of power transformer. To estimate the temperature rise reasonably accurately, one has to resort to classical mathematical techniques involving formulation and solution of boundary value problem of heat conduction under carefully prescribed boundary conditions. Several complications are encountered in the development of the governing equations for the emergent heat transfer problems. The more important among them are, the inhomogeneous composition of the insulation structure and of the conductor, divergent flow patterns of the oil phase and inordinately varying thermal properties of conductor and insulation. Validation and reconfirmation of the findings of the thermal models can be made using state of the art methods, such as, Artificial Intelligence (AI) techniques, Artificial Neural Network (ANN) and Genetic Algorithm (GA). Over the years, different criteria have been prescribed for the prediction of terminal or end of life (EOL) of equipment from the standpoint of its insulation. But, thus far, no straightforward and unequivocal criterion is forth coming. Calculation of elapsed life in line with the existing methodology, given by IEEE, IEC, introduces unacceptable degrees of uncertainty. It is needless to say that, any conformal procedure proposed in the accurate prediction of EOL, has to be based on a technically feasible and economically viable consideration. A systematic study for understanding the dynamical nature of ageing in transformers in actual service is precluded for reasons very well known. Laboratory experiments on prototypes or pro-rated units fabricated based on similarity studies, are performed under controlled conditions and at accelerated stress levels to reduce experimental time. The results thereof can then be judiciously extrapolated to normal operating conditions and for full size equipment. The terms of reference of the present work are as follows; 1. Computation of TOT and HST Theoretical model based on Boundary Value Problem of Heat Conduction Application of AI Techniques 2. Experimental Investigation for estimating the Elapsed Life of transformers Based on the experimental investigation a semi-empirical expression has been developed to estimate the loss of life of power and station transformer by analyzing gas content and furfural dissolved in oil without performing off-line and destructive tests.
78

Evolution magmatique d'un volcan bouclier océanique avant et après une déstabilisation massive de ses flancs : Fogo, Cap Vert et Tenerife, Canaries / Magmatic evolution of oceanic shield volcano before and after a flanc collapse : Fogo, Cape Verde and Tenerife, Canary Islands

Cornu, Mélodie-Neige 19 December 2017 (has links)
Les effondrements massifs de flancs sont des évènements destructeurs qui affectent tous les édifices volcaniques. Ces effondrements peuvent impliquer quelques dizaines, voire centaines de km3 de roche. Les volcans boucliers océaniques, bien que possédant de faibles pentes, sont également affectés par ces épisodes destructeurs, entraînant la formation de tsunamis. Dans le contexte de bouclier océanique, ces déstabilisations n’ont jamais été observées. Actuellement, seules des reliques sont présentes sur les îles volcaniques, avec la présence de cicatrices d’effondrements, de dépôts détritiques en mer ou de dépôts de tsunami sur les îles voisines. Les relations entre le magmatisme des volcans boucliers et les effondrements de flanc sont peu contraintes. Afin de mieux comprendre ces relations, deux effondrements de flanc de volcans boucliers océaniques ont été étudiés : l’effondrement de Monte Amarelo sur l’île de Fogo, dans l’archipel du Cap Vert, et l’effondrement de Güímar, situé sur la rift-zone Nord-Est de Tenerife, dans l’archipel des Canaries. Les deux archipels résultent de l’activité d’un panache mantellique sous la plaque africaine.Les produits volcaniques pré et post-effondrement de ces deux secteurs ont été étudiés d’un point de vue géochimique (majeurs, traces, isotopes Sr-Nd-Pb), pétrologique et géochronologique (K-Ar, Ar-Ar), de manière à identifier à la fois les sources et les processus magmatiques mis en jeu lors de leur formation. L’évolution temporelle des sources, ainsi que des processus magmatiques, a été reconstruite afin d’identifier d’éventuels liens avec l’effondrement de flanc étudié.Les résultats montrent que l’évolution du magmatisme de l’île de Fogo amène à la formation de zones superficielles de stockage, de complexes intrusifs et d’éruptions explosives conduisant à de nouvelles instabilités de l’édifice. Suite à l’effondrement, ces zones de stockage sont déstabilisées en quelques milliers d’années. Les processus magmatiques lithosphériques (assimilation, fusion partielle) sont également perturbés mais sur une période plus longue (plusieurs dizaines de milliers d’années). L’effondrement de Güímar ne montre aucun lien avec le magmatisme de l’île de Tenerife.La différence principale entre ces deux contextes est la localisation de la zone effondrée par rapport au système magmatique. En effet, l’effondrement de Güímar est situé en périphérie du système magmatique et ne montre aucun lien avec ce dernier ; à l’inverse l’effondrement du Monte Amarelo, situé à l’aplomb du système magmatique, se répercute rapidement sur ce système à faible profondeur, mais également à des profondeurs lithosphériques avec un délai plus long. / Massive flank collapses are destructive events that affect all volcanic edifices. They can take off huge volumes of rock, from tens to hundreds km3. Oceanic shield volcanoes are also affected by such events even if they have shallow slopes, thus, tsunamis could also be generated in this context. However, a shield volcano flank collapse has never been observed. Nowadays, only relics are visible, such as collapse scars, detritic deposit offshore or tsunami deposits on nearby islands. The relationships between collapse and magmatic history of oceanic shield volcanoes are poorly constrained. Two flank collapses are studied in this thesis, with the aim to better understand these relationships: the Monte Amarelo collapse, on Fogo Island (Cape Verde), and the Güímar collapse, located on North-East rift-zone of Tenerife (Canary Islands). Those archipelagos are the result of hot spot activity below the African plate. Geochemical (major and trace elements, and Sr-Nd-Pb isotopes), petrological and geochronological (K-Ar and Ar-Ar) analyses were carried out on volcanic samples as to identify the source and magmatic processes at stake during magma genesis. The temporal evolution of source and magmatic processes is reconstructed in order to track possible links with the flank collapse. The magmatic system of Fogo Island evolves through time, favouring the formation of superficial storage zones, intrusive complex and explosive eruptions prior to the collapse, which participate to the instability of the edifice. Following the Monte Amarelo collapse, shallow storage zones are destabilized within a few thousand years. Lithospheric magmatic processes (assimilation, partial melting) are also affected but on a longer timescale (tens of thousands years). The Güímar collapse shows no links with the magmatic evolution of Tenerife Island. The main difference between the two collapses is the location of the collapse area with respect to the plumbing system. Güímar collapse is located at the periphery of the plumbing system and show no link with the magmatic history. Contrariwise, the Monte Amarelo collapse is located directly above the plumbing system and influence rapidly the superficial plumbing system, and the deep plumbing system in the long term.
79

Analys och vidareutveckling av lyftok till Dendro Lift ABs lyftbock LB2.5

Levin, Niklas January 2016 (has links)
Dendro Lift AB är ett företag som utvecklar och tillverkar lyftbockar för tunga lyft. Tillsammans med konstruktionsföretaget Mk3D tar Dendro Lift AB fram ett nytt koncept för en lyftbocksmodell till lyft av stödbenstruckar. Syftet med examensarbetet är att vidareutveckla lyftoket till lyftbocken LB2.5 genom att minska materialanvändningen och bereda plats för ett nytt damm- och petskydd. Målet med examensarbetet är att ta fram underlag för tillverkning av ett nytt lyftok som uppfyllde ställda krav. Vid genomförandet av examensarbetet gjordes en förstudie kring dimensioneringskraven, spänningar i skruvförband, utvärdering av spänningar i svetsar, finita elementmetoden och hållbar utveckling. Förstudien följdes av analyser och vidareutveckling av lyftoket med finita elementanalyser i mjukvaran ANSYS Workbench 17.2. Modeller togs fram i Autodesk Inventor Professional 2016. Resultatet visade att det nya lyftokets plåttjocklek kunde minskas från 15 mm till 10 mm och därmed reducerades materialanvändningen med cirka 66 kg. I det nya lyftoket bereddes även plats för en ny typ av damm- och petskydd. Slutsatsen blir att det gamla lyftoket är överdimensionerat och mindre material kan användas utan att funktionen i lyftoket försämras. / Dendro Lift AB is a company that develops and manufactures lifting jacks for heavy lifting. Along with the construction company Mk3D, Dendro Lift AB introduces a new concept for a lifting trestle designed to lift stackers. The aim of the thesis is to further develop the yoke fitted in the lifting jack LB2.5 by reducing its material use and make way for a new dust and finger protection. The goal of the thesis is to develop manufacturing plans for the production of a new lifting yoke that meets the applicable requirements. In the implementation of the thesis there was a preliminary study on the design requirements, tension in bolted joints, evaluation of stresses in welds, finite element method analysis and sustainable development. The pilot study was followed by analysis and further development of the yoke with finite element analysis in software ANSYS Workbench 17.2. Models were developed in Autodesk Inventor Professional 2016. The results showed that the plate thickness could be reduced from 15 mm to 10 mm in the new yoke and thus reduced material usage by about 66 kg. The new yoke was also prepared for a new type of dust and finger protection. The conclusion was that the old yoke is oversized and less material can be used without compromising the operation of the lifting jack.
80

Étude du schéma d'allumage par choc en fusion par confinement inertiel / Study of the shock ignition scheme in inertial confinement fusion

Lafon, Marion 07 December 2011 (has links)
Le schéma d'allumage par choc représente une alternative aux schémas d'allumage classiques en Fusion par Confinement Inertiel. Sa singularité repose sur la relaxation des contraintes sur la phase de compression et l'atteinte des conditions d'allumage par l'envoi d'une impulsion laser brève (~500 ps) et très puissante (~300 TW) sur le combustible en fin d'implosion.Au cours de ce travail de thèse, il a été établi que ce procédé induit une configuration non-isobare du combustible au moment de l'allumage, modifiant ainsi les critères d'inflammation du Deutérium-Tritium (DT) par rapport aux schémas conventionnels d'allumage. Un modèle de gain pour la combustion est ensuite développé et des courbes de gain pour l'allumage par choc sont alors obtenues puis validées numériquement. La modélisation hydrodynamique présentée a démontré qu'il est ainsi possible d'obtenir de hauts gains à plus faibles énergies laser que l'allumage conventionnel du fait de la haute pression du point chaud au moment de l'allumage résultante de la propagation du choc d'allumage.Le code d'hydrodynamique radiative CHIC du CELIA a été utilisé afin de développer des dépendances paramétriques définissant les conditions optimales en termes de paramètres de dimensionnement de cibles pour l'atteinte des conditions d'ignition. Ces études numériques ont mis en lumière le potentiel du procédé d'allumage par choc en termes d'économie d'énergie laser, de hauts gains mais aussi de marges de sécurité et de robustesse pour l'allumage. Enfin, les résultats des premières campagnes expérimentales d'allumage par choc en symétrie sphérique effectuées sur l'installation laser OMEGA (NY, USA) sont présentés. Une interprétation des résultats est proposée à partir de simulations hydrodynamiques mono et bidimensionnelles. Différentes pistes sont alors explorées afin d'expliquer les différences observées et des solutions potentielles pour l'amélioration des performances à l'échelle de l'installation OMEGA sont proposées. / The Shock Ignition (SI) scheme is an alternative to classical ignition schemes in Inertial Confinement Fusion. Its singularity relies on the relaxation of constraints during the compression phase and fulfilment of ignition conditions by launching a short and intense laser pulse (~500 ps, ~300 TW) on the preassembled fuel at the end of the implosion.In this thesis, it has been established that the SI process leads to a non-isobaric fuel configuration at the ignition time thus modifying the ignition criteria of Deuterium-Tritium (DT) against the conventional schemes. A gain model has been developed and gain curves have been infered and numerically validated. This hydrodynamical modeling has demonstrated that the SI process allows higher gain and lower ignition energy threshold than conventional ignition due to the high hot spot pressure at ignition time resulting from the ignitor shock propagation.The radiative hydrodynamic CHIC code developed at the CELIA laboratory has been used to determine parametric dependences describing the optimal conditions for target design leading to ignition. These numerical studies have enlightened the potential of SI with regards to saving up laser energy, obtain high gains but also to safety margins and ignition robustness.Finally, the results of the first SI experiments performed in spherical geometry on the OMEGA laser facility (NY, USA) are presented. An interpretation of the experimental data is proposed from mono and bidimensional hydrodynamic simulations. Then, different trails are explored to account for the differences observed between experimental and numerical data and alternative solutions to improve performances are suggested.

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