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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.
1

Improved CWM platform for modelling welding procedures and their effects on structural behaviour

Lindström, Per January 2015 (has links)
A welding procedure specification is the document describing how a weld joint should be constructed. Arc weld processes are characterized by transient thermal behavior, leading to rapid changes in material properties and dynamic interaction between weld and base material. The objective of the project is to explore how the use of an improved CWM-platform affects representative stress and strain fields in order to assess welding procedure qualification records. Forthis project, the accumulated thermal and mechanical influences from the first run to the final run are brought forward, in one and the same meshed geometrical model. Both the thermal and mechanical material model of the platform are designed to be used for modelling of the base- and weld material,promoting the simulation of the intricate combination of the thermal, elastic,and plastic strains on the plastic strain hardening and the formation of residual stress fields. The output of the simulation is mainly weld cooling times, residual stresses, and deformations. This analysis is taken further by examining how residual stresses influence crack driving force under elastic and plastic loading. In addition, the output from the simulations can be used to assess the realism of the proposed welding parameters. The main experimental welding procedure examined comes from the IIW RSDP Round Robin Phase II benchmark project, where the main aim was to benchmark residual stress simulations. This work was found to contain many applicable challenges of a CWM-analysis project.
2

Metodika vývoje IS / Methodology of IS Development

Synáček, Václav January 2007 (has links)
Tato práce se zabývá provázáním modelu business intelligence a metodik vývoje informačních systémů. Specifikuje způsob propojení meta-modelu CWM (Common Warehouse Meamodel) s meta-modely business procesů ? BPMN (Business Process Modeling Notation), EPC (Event-driven Process Chain), MMABP (Methodology for Modeling and Analysis of Business Process) a Meta-modelem standardů modelovacích jazyků. Propojení je realizováno jako rozšíření meta-modelů odkazovaných standardů o abstraktní třídy, které umožňují začlenit třídy z CWM do každého ze čtyř typů procesních modelů. Prezentované provázání je chápáno jako rozšířené Metodiky vývoje informačních systémů se Sybase Powerdesignerem, ale díky navázání na více typů procesních standardů může být použito i společně s jinými metodikami vývoje informačních systémů, které používají modelování business procesů.
3

Improved CWM platform for modelling welding procedures and their effects on structural behaviour

Lindström, Per January 2015 (has links)
A welding procedure specification is the document describing how a weld joint should be constructed. Arc weld processes are characterized by transient thermal behavior, leading to rapid changes in material properties and dynamic interaction between weld and base material. The objective of the project is to explore how the use of an improved CWM-platform affects representative stress and strain fields in order to assess welding procedure qualification records. Forthis project, the accumulated thermal and mechanical influences from the first run to the final run are brought forward, in one and the same meshed geometrical model. Both the thermal and mechanical material model of the platform are designed to be used for modelling of the base- and weld material,promoting the simulation of the intricate combination of the thermal, elastic,and plastic strains on the plastic strain hardening and the formation of residual stress fields. The output of the simulation is mainly weld cooling times, residual stresses, and deformations. This analysis is taken further by examining how residual stresses influence crack driving force under elastic and plastic loading. In addition, the output from the simulations can be used to assess the realism of the proposed welding parameters. The main experimental welding procedure examined comes from the IIW RSDP Round Robin Phase II benchmark project, where the main aim was to benchmark residual stress simulations. This work was found to contain many applicable challenges of a CWM-analysis project.
4

Linking simulations and experiments for the multiscale tracking of thermally induced martensitic phase transformation in NiTi SMA

Gur, Sourav, Frantziskonis, George N 01 October 2016 (has links)
Martensitic phase transformation in NiTi shape memory alloys (SMA) occurs over a hierarchy of spatial scales, as evidenced from observed multiscale patterns of the martensitic phase fraction, which depend on the material microstructure and on the size of the SMA specimen. This paper presents a methodology for the multiscale tracking of the thermally induced martensitic phase transformation process in NiTi SMA. Fine scale stochastic phase field simulations are coupled to macroscale experimental measurements through the compound wavelet matrix method (CWM). A novel process for obtaining CWM fine scale wavelet coefficients is used that enhances the effectiveness of the method in transferring uncertainties from fine to coarse scales, and also ensures the preservation of spatial correlations in the phase fraction pattern. Size effects, well-documented in the literature, play an important role in designing the multiscale tracking methodology. Molecular dynamics (MD) simulations are employed to verify the phase field simulations in terms of different statistical measures and to demonstrate size effects at the nanometer scale. The effects of thermally induced martensite phase fraction uncertainties on the constitutive response of NiTi SMA is demonstrated.
5

Vespas e abelhas são equivalentes quanto aos seus padrões de visitação floral ?

Klein, Ricardo Pablo January 2018 (has links)
Interações ecológicas mutualísticas são aquelas que trazem benefícios para todos os organismos envolvidos. A visitação floral fornece alimento para os animais visitantes, enquanto possibilita a reprodução sexuada em plantas. Enquanto isso, a teoria da síndrome de dispersão supõe que existem certos atributos florais (incluindo recompensas) capazes de atrair certos polinizadores e afastar outros. O declínio de abelhas tem sido reportado em todo o mundo, e encontrar espécies ecologicamente equivalentes é crucial para a preservação da biodiversidade. Vespas possuem funções ecológicas semelhantes às abelhas apesar de não dependerem exclusivamente de pólen e néctar para sobreviver. O objetivo deste projeto de pesquisa foi avaliar as diferenças da visitação floral entre abelhas/plantas e vespas/plantas. O primeiro capítulo possui uma abordagem de redes de interação. O segundo capítulo apresenta uma abordagem multivariada onde avaliamos as diferenças entre as plantas de acordo com os himenópteros visitantes florais. Nós realizamos as coletas em unidades de conservação do município de Porto Alegre. Em cada área de estudo, foram definidas transecções em três ambientes distintos: campo, mata e borda entre estes. As amostragens em cada transecção ocorreram entre horários de 9h e 17h. Durante este período, foram observadas as plantas em floração, entre 20 cm a 4 m de altura, e seus himenópteros visitantes florais coletados com o auxílio de rede entomológica durante 10 minutos em cada planta. As métricas de rede foram calculadas do programa R com o pacote Bipartite. Vespas e abelhas são visitantes florais distintos quanto a seus padrões de redes de interação. Vespas seriam capazes de manter apenas a metade da diversidade vegetal através da polinização após eventos hipotéticos de extinção de abelhas. Através da abordagem multivariada, as plantas visitadas por vespas e por abelhas não formaram grupos distintos. Quanto maior a abertura da corola da flor, menor é a visitação floral de vespas. Concluímos que vespas podem ser polinizadores auxiliares para a manutenção da diversidade vegetal, apesar de serem capazes de manter menor diversidade vegetal em cenários de extinção de abelhas. Além disso, os atributos florais de vespas e abelhas não são diferentes entre si, apontando para o fato de que vespas podem ser polinizadores de um maior número de plantas do que o previsto. / Mutualistic ecological interactions are those that bring benefits to all involved organisms. Floral visitation provides food for visiting animals, while allowing sexual reproduction in plants. Meanwhile, the dispersion syndrome theory assumes that there are certain floral attributes (including rewards) that can attract certain pollinators and drive away others. The decline of bees has been reported worldwide and finding ecologically equivalent species is crucial to the preservation of biodiversity. Wasps have ecological functions like bees although they do not depend exclusively on pollen and nectar to survive. The objective of this research was to evaluate the differences in floral visitation between bees/plants and wasps/plants. The first chapter has an interaction network approach. The second chapter presents a multivariate approach where we evaluate differences between plants according to the floral visiting wasps and bees. We carried out sampling in conservation units of the municipality of Porto Alegre. In each study area, transects were defined in three distinct environments: grassland, forest and edges between them. Sampling at each transection occurred between 9 and 17 h. During this period, flowering plants from 20 cm to 4 m tall were observed, and their floral visiting Hymenoptera collected with the aid of an entomological net for 10 min on each plant. The network metrics were calculated with R software with the Bipartite package. Wasps and bees are distinctive floral visitors given their different patterns of interaction networks. Wasps maintain half of the plant diversity after the hypothetical events of bee extinction. Under a multivariate approach, plants visited by wasps and bees did not form distinct groups. The widder the corolla of the flower, the less is the floral visitation of wasps. We conclude that wasps can be secondary pollinators for the maintenance of plant diversity, although they are able to maintain lower plant diversity in bee’s extinction scenarios. In addition, the floral attributes of wasps and bees are not different from each other, pointing to the fact that wasps may be pollinators of a larger number of plants than predicted.
6

Konceptualiųjų apribojimų transformacija į SQL kodą / Transformation of conceptual constraints to SQL code

Armonas, Andrius 24 May 2005 (has links)
In this paper, the method is proposed for transforming UML class diagrams with OCL constraints to relational database schemas, having advantages over “UML Profile for Databases” models. The proposed method consists of two phases supplementing each other: metamodel based transformations and pattern-based transformations. All transformations are based on OMG official standards or RFPs (Request for Proposals) and are prepared for use in MDA (Model Driven Architecture) context. This means, that resulting models, created using the described method, are long-lasting, independent from platform and abstract enough to be independent from technology. This work covers analysis of the field of object – relational transformations, analysis of support of OCL in currently used UML tools, transformation rule sets of metamodel transformations and pattern-based transformations, a lot of examples illustrating every transformation. Metamodel transformations are designed to transform object models written in UML language to corresponding relational models: types, classes, attributes, association classes, associations to tables, columns, foreign keys and other concepts. Pattern-based transformations are designed for generating static relational concepts such as check constraints, views, stored procedures and triggers. Using the two described transformation types and the whole method described, one can generate full-fledged relational database schemas, have precise UML models and keep much more... [to full text]
7

Mediation Strategy and Quality Peace

Yamaguchi, Mariko January 2021 (has links)
Many scholars have researched on the effects of individual mediation strategy following the categorization by Touval and Zartman (1985), and Bercovitch (1991). Despite the growing recognition of the potential synergetic effects among different strategies, not many systematic studies have been done on that aspect. This thesis contributes to this understudied aspect of mediation approach by asking What is the impact of mediation strategy on quality peace after civil war? The study adopts the method of structured, focused comparison along with the detailed process tracing on four cases of peace agreements and their mediation process from Northern Ireland, Mindanao, Bosnia and Herzegovina, and Niger. The study aims to test a theoretical argument linking combined-application of mediation strategies with high quality peace. The empirical findings provide a modest support to hypothesis and a weak support to the causal mechanism, as not all cases, having applied all three strategies, have achieved high quality peace and have promoted third-party guarantee and inclusivity. While the empirical findings point to other contextual factors that may affect the peace agreement implementation, the findings also indicate a potential promising mediation approach that combines directive strategy either with communicative-facilitative or procedural strategy putting more weight on the latter strategy.
8

Direct Measurement of Itinerant Magnetism & Interface States in Semiconductors using Time-varying Magnetic Fields

Choudhury, Aditya N Roy January 2016 (has links) (PDF)
Magnetism in a solid | dia, para, ferro, or of other forms | originates majorly from its electrons; one could, infact, ignore the nuclear contribution. There are two types of electrons in a solid: bound, and free (also called itinerant). It is interesting to note that although several experimental techniques exist that measure the total magnetization/ susceptibility of a solid, no experiment directly probes the individual magnetic contributions from the bound and the itinerant electrons. In the past couple of decades, owing to the advent of sophisticated fabrication facilities, certain man-made, (ferro)magnetic materials have come into existence whose carrier concentrations can be tuned extrinsically: doped semiconductors like DMS (diluted magnetic semiconductors) and hexaborides are two such examples. However, whether the (ferro) magnetism in these materials originate from their itinerant carriers is still an open question. A conclusive answer to this question is eagerly awaited by the scientific community; the answer is not only supposed to solve debates related to the physics of ferromagnetism, but, also, should lend a helping hand in selecting right materials to build devices for upcoming exotic technologies such as Spintronics. A novel experimental technique is proposed in this work that directly measures the itinerant carrier magnetism of a solid. The technique is practically demonstrated on the bulk semiconductor: n-type GaAs. A Landau-Peierls itinerant (dia)magnetic susceptibility as low as 1 10 8 cm 3/mol | which is 10 3 times smaller than the magnetic background stemming from the bound electrons in the GaAs host lattice, and 10 times lower than the sensitivity limit of the SQUID | was clearly, and reproducibly detected from samples having carrier concentrations as low as 5 10 15 cm 3. The technique relies on measurements with MIS capacitors fabricated out of the given semiconductor. Unfortunately, as an artifact, such MIS fabrication processes unintentionally, but unavoidably, introduce certain energy levels in the semiconductor band-gap that unwantedly communicate with its bands by trapping and releasing carriers. Such traps lie along the interface of the semiconductor and the oxide. Though clear signals, which match with theoretically estimated signals within acceptable accuracy, have been measured from the itinerant electrons in GaAs, this work demonstrates theoretical calculations showing that the signals decrease in magnitude owing to the presence of such interface traps. Quantifying this decrement comes as an added advantage of this work, because such measurements can then directly probe the MIS interface and find the concentration of the interface traps (Dit) more accurately and precisely than what is done at present. Thus, the experimental technique this work proposes can also probe a given MIS interface, using time-varying magnetic fields, and reveal a more accurate and precise measure of Dit. Otherwise, the existing techniques for measuring Dit su er from imprecision caused by several theoretical assumptions. A more general technique which can extract Dit accurately and precisely, without needing to know the particular physical model that the interface traps follow for a given MIS capacitor, is what one requires at present, to give CMOS technology the direction and impetus it needs to cross-over to the non-Silicon territory. Such a technique is theoretically developed in this work. How a magnetic field a effects the MIS Energy Band Diagram is also derived in the process. The technique that is developed and demonstrated in this thesis, capable of directly probing both the itinerant magnetism and the MIS interface of a given semiconductor, depends on successfully measuring a very small voltage drop across a MIS capacitor when the latter is externally subjected to a high, time-varying magnetic field. This voltage signal originates because the semiconductor's electronic density of states depends on the magnetic field, thus rendering the semiconductor's electron chemical potential, i.e. the Fermi level, magnetic field dependent. The idea of detecting such magnetic field dependence of electron chemical potential was theoretically proposed more than five decades back, but an experimental detection of the phenomenon, in any bulk (i.e. three dimensional) solid, had remained elusive despite numerous trials. Virtually, the topic had been `dead' for the past couple of decades with very few reports (of trials) getting published on it. The primary reason behind such a failure is an interesting spurious effect that arises and overshadows the signal otherwise coming from the magnetic shift of the electron chemical potential. This is the spurious Hall voltage caused by the time-varying magnetic field and the eddy current it induces in the semiconductor following Faraday's Law of Electromagnetic Induction. Unless this Hall voltage can be reduced below a threshold, there is no hope of successfully measuring the sample signal. In this work, we have discussed about this spurious effect in details and have given experimental recipes to avoid it from interfering with the data. Infact the data we publish for n-GaAs is free from any such spurious effects. From that viewpoint, this work becomes the first to report the experimental detection of the magnetic field dependence of a Fermi level in any bulk solid. A common pulse magnet capable of producing high magnetic field pulses, lasting for only some tens of milliseconds, was built and used for the purpose of this work. For certain samples other than GaAs, however, the spurious Hall voltage may be larger and the proposed technique may fail as one may not be able to rule out the spurious effect with the simple recipe demonstrated here for GaAs. In such a case, measurements are encouraged, instead, in a special magnet uniquely developed to rule out the Hall voltage. This magnet was constructed in-house, and can sit on a table-top and generate magnetic fields as high as a few Teslas that can, further, be `temporally shaped' by the user. Such a class of pulse magnets whose pulse waveforms can be programmed over time are called controlled waveform magnets (CWMs) and the work presented in this thesis also demonstrates the construction and calibration of such a CWM.
9

Impacts de l'urbanisation sur la diversité spécifique et fonctionnelle dans les forêts riveraines

Brice, Marie-Hélène 06 1900 (has links)
L'urbanisation représente une menace majeure pour la biodiversité. Ce mémoire de maîtrise vise à comprendre ses effets sur la composition fonctionnelle et l'homogénéisation biotique dans les forêts riveraines. Des inventaires floristiques ont été réalisés dans 57 forêts riveraines de la région de Montréal. Afin d'étudier la variation de la composition fonctionnelle avec l'urbanisation, des moyennes pondérées de traits par communauté ont été calculées pour les arbres, arbustes et herbacées. Chaque forêt a été caractérisée par des variables relatives au paysage urbain environnant, aux conditions locales des forêts et aux processus spatiaux. Les conditions locales, notamment les inondations, exerçaient une pression de sélection dominante sur les traits. L'effet du paysage était indirect, agissant via l'altération des régimes hydrologiques. La dispersion le long des rivières était aussi un processus important dans la structuration des forêts riveraines. Les changements dans la diversité β taxonomique et fonctionnelle des herbacées ont été étudiés entre trois niveaux d'urbanisation et d'inondation. Alors que l'urbanisation a favorisé une différenciation taxonomique, les inondations ont favorisé une homogénéisation taxonomique, sans influencer la diversité β fonctionnelle. L'urbanisation était l'élément déclencheur des changements de la diversité β, directement, en causant un gain en espèces exotiques et une diminution de la richesse totale dans les forêts très urbanisées, et, indirectement, en entraînant un important turnover d'espèces par l'altération des régimes hydrologiques. Globalement, ces résultats suggèrent que la modification des processus naturels par les activités anthropiques est le principal moteur de changements dans les communautés riveraines urbaines. / Urbanization is a major threat to biodiversity worldwide. This thesis aims at understanding its effects on plant functional composition and biotic homogenization in riparian forests. Floristic inventories were carried out in 57 riparian forests of the Montreal area. To investigate changes in functional composition with urbanization, community weighted means were computed for trees, shrubs and herbs using eight functional traits. Each forest was characterized by variables related to the surrounding urban landscape, local forest conditions and spatial processes. The relative importance of these three subsets on the functional composition was quantified by variation partitioning using redundancy analyses. Local conditions, especially flood intensity, exerted an overriding selection pressure on riparian functional communities. The effect of the landscape was suspected to be indirect, acting on trait patterns likely through alteration of hydrological disturbances in riparian forests. In addition to environmental filtering, dispersal along rivers was also an important process structuring riparian forests. Changes in taxonomic and functional β-diversity for herb species were studied between three urbanization and flood levels. While urbanization led to taxonomic differentiation, flood intensity fostered taxonomic homogenization, both without influence on functional β-diversity. Urbanization was the main trigger for all β-diversity changes, as it directly caused a gain in exotic species and a net species loss in highly urban forests, and indirectly fostered an important species turnover through alteration of the hydrological regime. Overall, these results suggest that the alteration and interruption of natural landscape-scale processes by human activities are major mechanisms underlying changes in urban riparian communities.

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