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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.
801

Fracture modeling by the eigenfracture approach for the implicit material point method framework

Chihadeh, Ahmad, Storm, Johannes, Kaliske, Michael 05 March 2024 (has links)
The material point method (MPM) is efficiently applied for the simulation of structures undergoing large deformations where fracture and crack initiation are expected. The eigenfracture approach is introduced in the paper at hand for the implicit MPM to model crack development and propagation in static and dynamic fracture of brittle elastic materials. Eigenfracture is an energetic fracture formulation applied in the postprocessing step of the implicit MPM, making its implementation relatively straightforward. Furthermore, the driving energy used to check crack propagation is evaluated using the representative crack elements (RCE), by which the crack is modeled as a discrete phenomenon. The RCE approach shows more realistic results compared to other split models. Additionally, the fracture description of reinforced materials within the MPM is also presented in this article by coupling truss finite elements to the MPM, considering the bond stress-slip constitutive model. Two- and three-dimensional problems in static and dynamic applications are presented to assess the efficacy of the approach.
802

Development of a Performance-Based Procedure for Assessment of Liquefaction-Induced Lateral Spread Displacements Using the Cone Penetration Test

Coutu, Tyler Blaine 01 October 2017 (has links)
Liquefaction-induced lateral spread displacements cause severe damage to infrastructure, resulting in large economic losses in affected regions. Predicting lateral spread displacements is an important aspect in any seismic analysis and design, and many different methods have been developed to accurately estimate these displacements. However, the inherent uncertainty in predicting seismic events, including the extent of liquefaction and its effects, makes it difficult to accurately estimate lateral spread displacements. Current conventional methods of predicting lateral spread displacements do not completely account for uncertainty, unlike a performance-based earthquake engineering (PBEE) approach that accounts for the all inherent uncertainty in seismic design. The PBEE approach incorporates complex probability theory throughout all aspects of estimating liquefaction-induced lateral spread displacements. A new fully-probabilistic PBEE method, based on results from the cone penetration test (CPT), was created for estimating lateral spread displacements using two different liquefaction triggering procedures. To accommodate the complexity of all probabilistic calculations, a new seismic hazard analysis tool, CPTLiquefY, was developed. Calculated lateral spread displacements using the new fully-probabilistic method were compared to estimated displacements using conventional methods. These comparisons were performed across 20 different CPT profiles and 10 cities of varying seismicity. The results of this comparison show that the conventional procedures of estimating lateral spread displacements are sufficient for areas of low seismicity and for lower return periods. However, by not accounting for all uncertainties, the conventional methods under-predict lateral spread displacements in areas of higher seismicity. This is cause for concern as it indicates that engineers in industry using the conventional methods are likely under-designing structures to resist lateral spread displacements for larger seismic events.
803

Development of a Performance-Based Procedure for Assessment of Liquefaction-Induced Lateral Spread Displacements Using the Cone Penetration Test

Coutu, Tyler Blaine 01 October 2017 (has links)
Liquefaction-induced lateral spread displacements cause severe damage to infrastructure, resulting in large economic losses in affected regions. Predicting lateral spread displacements is an important aspect in any seismic analysis and design, and many different methods have been developed to accurately estimate these displacements. However, the inherent uncertainty in predicting seismic events, including the extent of liquefaction and its effects, makes it difficult to accurately estimate lateral spread displacements. Current conventional methods of predicting lateral spread displacements do not completely account for uncertainty, unlike a performance-based earthquake engineering (PBEE) approach that accounts for the all inherent uncertainty in seismic design. The PBEE approach incorporates complex probability theory throughout all aspects of estimating liquefaction-induced lateral spread displacements. A new fully-probabilistic PBEE method, based on results from the cone penetration test (CPT), was created for estimating lateral spread displacements using two different liquefaction triggering procedures. To accommodate the complexity of all probabilistic calculations, a new seismic hazard analysis tool, CPTLiquefY, was developed. Calculated lateral spread displacements using the new fully-probabilistic method were compared to estimated displacements using conventional methods. These comparisons were performed across 20 different CPT profiles and 10 cities of varying seismicity. The results of this comparison show that the conventional procedures of estimating lateral spread displacements are sufficient for areas of low seismicity and for lower return periods. However, by not accounting for all uncertainties, the conventional methods under-predict lateral spread displacements in areas of higher seismicity. This is cause for concern as it indicates that engineers in industry using the conventional methods are likely under-designing structures to resist lateral spread displacements for larger seismic events.
804

Integration inequality among compact IDP settlements of Georgia: Settlement design and its impact on sustainable income generation

Omari, Nishnianidzze January 2021 (has links)
Georgia, the Post-Soviet, transition country with struggling economy and territorial disputes has been dealing with forced migration since 1990s. In 2008, the country experienced another internal displacement wave and about 30,000 people were forced to flee from their homes. The state constructed compact IDP settlements and provided housing to affected households. After more than a decade, there is a significant gap in economic livelihoods of the IDP households in those settlements. The location and the size of the IDP settlements has had impact on the economics of IDP population and acted as main drivers of inequalities in integration across the settlements of forcibly displaced persons. The thesis will explore how the settlement facilitates or hampers employment and income-generation process for IDPs.  The conceptual framework utilized will be the combination of asset-based approach and cumulative disadvantage theory, push and pull factors theory of migration and the three key framework dimensions of camp design. The methodology used will include primary data collection through semi-structured interviews, secondary data collection through scholarly articles and reports, and the analysis and discussion of both.
805

Displacement and Emotional Well-Being among Married and Unmarried Syrian Adolescent Girls in Lebanon: An Analysis of Narratives

Roupetz, Sophie, Bartels, Susan A., Michael, Saja, Najjarnejad, Negin, Anderson, Kimberley, Davison, Colleen 19 April 2023 (has links)
Lebanon hosts over one million refugees displaced from Syria as a result of the armed conflict—of whom, approximately 15% are adolescents aged between 12 and 17 years of age. Many female adolescent migrants report a decrease in quality of life and an increase in family tensions. This study sought to investigate the emotional well-being of adolescent Syrian girls in Lebanon. We hypothesized that married girls may experience additional hardships and thus greater feelings of dissatisfaction in daily life, given their young marriage and responsibilities at home. This study was part of a large mixed-methods study on the experiences of Syrian refugee girls in Lebanon (n = 1422). Using line-by-line coding and thematic analysis, 188 first-person narratives from Syrian girls were analysed. Our results highlight poor emotional well-being among married and unmarried girls, with sadness, fear and anger commonly mentioned. Some participants expressed feelings of hope, happiness, gratefulness and empowerment. Unmarried girls (n = 111) were more likely to associate their shared stories with negative feelings such as sadness (47% vs. 22%), disappointment (30% vs. 19%), and frustration (32% vs. 22%) than were married girls (n = 77). Four themes emerged as important determinants: access to education, perceived safety, peer support, and longing for life back in Syria. Continued efforts to improve emotional well-being for married and unmarried refugee girls are needed in Lebanon, in particular those that address the nuances for these groups.
806

'Ukraine Is Alive' Ukrainian Music-Making in Swedish Emergency Residencies : The impact of war, displacement, migration and networks

Hellström, Hanna January 2023 (has links)
In February 2022 Russia’s invasion of Ukraine started the war that would lead to the largest refugee crisis in Europe since World War II. In response to the war, SWAN, the Swedish Artists Residency Network, initiated the project Emergency residencies. During 2022, the network’s artist residencies opened up to provide safety for Ukrainian artists fleeing the war. Through an ethnographic case study and in-depth interviews, this thesis explores the experiences of four Ukrainian musicians in times of war and displacement, that took part of the Emergency residencies. It also investigates the function of SWAN’s Emergency residencies for musicians facing forced migration. The purpose is to shed light on the experience of musicians in a refugee position and the residency as a space that may contribute to uphold music-making and musical labour for refugee artists.   This thesis uses a transdisciplinary approach. It draws on notions of music as an emotional resource, music becoming political, and theoretical concepts regarding identity, belonging, and detachment, as well as translocality and transcultural capital. SWAN’s Emergency residencies is shown to provide several benefits for musicians displaced during Russia’s war on Ukraine. It includes the contribution of economic resources, opportunities for artistic practice and development, and promotion of cultural understanding and social inclusion. It also suggests that typical benefits provided by artist residencies gain added value for artists experiencing war and displacement, as it answers to losses typically experienced in forced migration. The war and refugee position are embedded in the daily experience of musicians facing war and displacement. This thesis suggests that musicians can use various strategies to either enforce, dismiss, expand or change the view of their prescribed identity in relation to the war and the refugee position. A Ukrainian identity is enhanced to show pride of their country, create awareness of Ukraine’s situation or foster a sense of belonging. Music can also be used to detach from positions and preconceptions surrounding such labels and connections, either through performing other identities or releasing from all categories. Furthermore, music and music-making can act as an emotional resource that helps regulate emotions or become a vehicle for political mobilisation and support for Ukraine. The politicisation of music is also actualised by the refugee position in itself and public perceptions of such positions. Transcultural capital highlights the capacities and strategies of musicians to create various economic, cultural and social opportunities through links to both their host and home country.
807

Optimalt antal stagade spann som krävs för att stomstabilisera en stålkonstruktion : Jämförelse av olika modeller för att hitta den optimala lösningen

Al matar, Leen, Taleb, Mohamad, Abdalnour, Geolle January 2023 (has links)
Purpose: The horizontal stabilization of a building is of great importance in the design of its structural system. Insufficient counteraction of horizontal loads can lead to problems where columns and beams deflect more than the allowable margins. One common horizontal load arises from wind hitting an exterior wall. In this study, four bracing types were analyzed using software to evaluate and compare them, taking various factors into account. The building upon which the study is based is an industrial four-story structure located in Västerås. The building is designed with hinged column bases, which require a stabilization system to maintain its stability. This study aimed to determine the optimal solution for the stabilization system by comparing multiple proposals (X, V, inverted V, and diagonal) considering all factors that significantly influence stabilization. The different proposals were compared in terms of material usage, horizontal displacement, and the number of spans required for steel bracing. Method: Hand calculations were used in this report to design various structural components such as columns, beams, and bracing, which were compared with FEM (Finite Element Method) designs. Additionally, different perspectives were considered within the relevant subject framework, including steel properties, general loads, characteristics, and descriptions of the examined models. Results: After conducting the calculations, it was found that the optimal number of spans required for bracing the industrial steel structure was 32 diagonal braces, placed in the outermost bays on all sides of the building at each floor. This proposal resulted in reduced material usage with a secure horizontal displacement, ensuring stability and durability of the building. Conclusions: In conclusion, this report provides a deep understanding of the importance of stability in buildings, especially when it comes to the safety of occupants and the structural integrity of the building. Proposal 1 has likely met the requirements based on all the calculations and analyzed models that have been conducted, and therefore, diagonal bracing has been chosen as the optimized solution.
808

Generalizing mechanisms of secondary structure dynamics in biopolymers

Irmisch, Patrick 26 February 2024 (has links)
Secondary structure dynamics of biopolymers play a vital role in many of the complex processes within a cell. However, due to the substantial number of atoms in the involved biopolymers along with the multitude of interactions that occur between the molecules, understanding these processes in detail is challenging and often involves computationally demanding simulations. In this thesis, the secondary structure dynamics of three different biopolymer systems were modeled using a single approach, which is based on intuitive principles that facilitate the interpretation. To this end, the kinetic behavior of each system was experimentally determined, and described by simplified reaction schemes, which were then connected to Markov chain models encompassing all principal secondary structural conformations. Firstly, we investigated the toehold-mediated strand displacement reaction, which is widely applied in nanotechnology to create DNA-based nano-devices and biochemical reaction networks. Our model correctly described the impact of base pair mismatches on the kinetics of these reactions, as measured by bulk fluorescence experiments. Additionally, it revealed that incumbent dissociation, base pair fraying, and internal loop formation are important processes during strand displacement. Furthermore, we established two dissipative elements to enhance temporal control over toehold-mediated strand displacement reactions. The first element allowed a reversible and repeatable incumbent strand release, whereas the second element provided the possibility to start the displacement reaction after a programmable temporal delay. Secondly, we studied the target recognition by the CRISPR-Cas effector complex Cascade, a highly promising protein for applications in genome engineering. Our model successfully reproduced all aspects of the torque- and mismatch-dependent R-loop formation time by Cascade obtained by single-molecule torque and bulk fluorescence measurements. Furthermore, we demonstrated that the seed effect observed for Cascade results from DNA supercoiling, rather than a structural property of the protein complex. Lastly, we explored the folding/unfolding of α-helices, which plays a critical role in the folding and function of proteins. Our model accurately described α-helix unfolding kinetics obtained by fast triplet-triplet energy transfer. Moreover, we showed that the complex α-helix unfolding does not follow a simple Einstein-type diffusion but is a combination of the sub-diffusive boundary diffusion and the rather peptide-length-independent coil nucleation. The presented models enabled access to the diverse timescales of the characterized processes, which are generally difficult to access experimentally, despite utilizing just a single approach. In particular, we obtained: tens of microseconds for the branch migration step time of the toehold-mediated strand displacement, hundreds of microseconds for the R-loop formation steps by Cascade, and tens of nanoseconds for folding or unfolding of an α-helix by a single residue. Given the simplicity and accessibility of the established models, we are confident that they will become useful tools for researchers to analyze the dynamics of biomolecules, and anticipate that similar modeling approaches can be applied to other biopolymer systems, being well-described by probabilistic models. / Die Sekundärstrukturdynamik von Biopolymeren spielt eine entscheidende Rolle bei vielen komplexen Prozessen innerhalb einer Zelle. Aufgrund der beträchtlichen Anzahl von Atomen in den beteiligten Biopolymeren und der Vielzahl an Wechselwirkungen zwischen den Molekülen ist es jedoch eine Herausforderung diese Prozesse im Detail zu verstehen, und erfordert oft rechenintensive Simulationen. In dieser Arbeit wurde die Sekundärstrukturdynamik von drei verschiedenen Biopolymersystemen mit einem einzigen Ansatz modelliert, welcher auf intuitiven Prinzipien beruht und somit eine erleichterte Interpretation der Ergebnisse ermöglicht. Hierzu wurde das kinetische Verhalten jedes Systems experimentell bestimmt und durch vereinfachte Reaktionsschemata beschrieben. Diese wurden anschließend mit Markov-Kettenmodellen verknüpft, welche alle wichtigen Konformationen der Sekundärstruktur abbilden. Als erstes System untersuchten wir die DNA Strangaustauschreaktion, welche in der Nanotechnologie häufig zur Herstellung von DNA-basierten Nanomaschinen und biochemischen Reaktionsnetzwerken eingesetzt wird. Unser Modell beschrieb die durch Ensemble-Fluoreszenz-Experimente gemessenen Auswirkungen von Basenfehlpaarungen auf die Kinetik dieser Reaktionen korrekt. Des Weiteren zeigte sich, dass die vorzeitige Strangablösung, das Ausfransen von Basenpaaren und die Bildung interner Schleifen wichtige Prozesse während des Strangaustausches sind. Darüber hinaus konnten wir zwei dissipative Elemente etablieren, um die zeitliche Kontrolle über die Strangaustauschreaktionen zu verbessern. Das erste Element ermöglicht eine reversible und wiederholbare Strangablösung, während das zweite Element die Möglichkeit bietet die Strangaustauschreaktionen nach einer programmierbaren zeitlichen Verzögerung zu starten. Zweitens untersuchten wir den Zielerkennungsprozess durch den CRISPR-Cas Komplex Cascade, ein vielversprechendes Protein für Anwendungen in der Genomtechnologie. Unser Modell reproduzierte erfolgreich alle Aspekte der torsions- und fehlpaarungs-abhängigen R-Schleifenbildung durch Cascade, welche durch Einzelmolekül-Torsions- und Ensemble-Fluoreszenz-Messungen ermittelt wurden. Zusätzlich konnten wir nachweisen, dass der für Cascade beobachtete „seed“-Effekt auf DNA-Verdrehung und nicht auf eine strukturelle Eigenschaft des Proteinkomplexes zurückzuführen ist. Schließlich untersuchten wir die Faltung/Entfaltung von α-Helices, welche eine entscheidende Rolle bei der Faltung und Funktion von Proteinen spielen. Unser Modell beschrieb die durch schnelle Triplett-Triplett-Energietransfer Experimente ermittelte α-Helix-Entfaltungskinetik exakt. Darüber hinaus konnten wir zeigen, dass die komplexe α-Helix-Entfaltung nicht einer einfachen Diffusion vom Einstein-Typ folgt, sondern eine Kombination aus subdiffusiver Grenzdiffusion und der eher peptidlängenunabhängigen Coil-Nukleation ist. Obwohl nur ein einziger Ansatz verwendet wurde, ermöglichten die vorgestellten Modelle den Zugang zu den vielschichtigen Zeitskalen der charakterisierten Prozesse, welche im Allgemeinen experimentell schwer zugänglich sind. Insbesondere konnten die folgenden zeitlichen Bereiche bestimmt werden: Dutzende von Mikrosekunden für die Schrittzeit der Strangaustauschreaktion, Hunderte von Mikrosekunden für die Schritte der R-Schleifenbildung durch Cascade, und Dutzende von Nanosekunden für die Faltung oder Entfaltung einer α-Helix um ein einzelnes Segment. Angesichts der Simplizität und Zugänglichkeit der etablierten Modelle sind wir zuversichtlich, dass sie zu nützlichen Werkzeugen für Forscher werden, um die Dynamik von Biomolekülen zu analysieren. Zusätzlich gehen wir davon aus, dass ähnliche Modellierungsansätze auf andere Biopolymersysteme angewendet werden können, sofern sie gut durch probabilistische Modelle beschrieben werden.
809

The Effect of Gender-Based Development Policies on Child Recruitment into Conflict

Atkinson, Kelly E. January 2017 (has links)
No description available.
810

A Preliminary Study of Pump/Probe Angular Dependence of Zeeman Electromagnetically Induced Transparency

Jackson, Richard Aram, Jr. 12 August 2015 (has links)
No description available.

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