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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.
711

Ground motion amplification of soils in the upper Mississippi Embayment

Romero, Salome M. 05 1900 (has links)
No description available.
712

SEISMIC PERFORMANCE OF GEOSYNTHETIC-SOIL RETAINING WALL STRUCTURES

Zarnani, Saman 29 April 2011 (has links)
Vertical inclusions of expanded polystyrene (EPS) placed behind rigid retaining walls were investigated as geofoam seismic buffers to reduce earthquake-induced loads. A numerical model was developed using the program FLAC and the model validated against 1-g shaking table test results of EPS geofoam seismic buffer models. Two constitutive models for the component materials were examined: elastic-perfectly plastic with Mohr-Coulomb (M-C) failure criterion and non-linear hysteresis damping model with equivalent linear method (ELM) approach. It was judged that the M-C model was sufficiently accurate for practical purposes. The mechanical property of interest to attenuate dynamic loads using a seismic buffer was the buffer stiffness defined as K = E/t (E = buffer elastic modulus, t = buffer thickness). For the range of parameters investigated in this study, K ≤ 50 MN/m3 was observed to be the practical range for the optimal design of these systems. Parametric numerical analyses were performed to generate design charts that can be used for the preliminary design of these systems. A new high capacity shaking table facility was constructed at RMC that can be used to study the seismic performance of earth structures. Reduced-scale models of geosynthetic reinforced soil (GRS) walls were built on this shaking table and then subjected to simulated earthquake loading conditions. In some shaking table tests, combined use of EPS geofoam and horizontal geosynthetic reinforcement layers was investigated. Numerical models were developed using program FLAC together with ELM and M-C constitutive models. Physical and numerical results were compared against predicted values using analysis methods found in the journal literature and in current North American design guidelines. The comparison shows that current Mononobe-Okabe (M-O) based analysis methods could not consistently satisfactorily predict measured reinforcement connection load distributions at all elevations under both static and dynamic loading conditions. The results from GRS model wall tests with combined EPS geofoam and geosynthetic reinforcement layers show that the inclusion of a EPS geofoam layer behind the GRS wall face can reduce earth loads acting on the wall facing to values well below those recorded for conventional GRS wall model configurations. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-04-28 16:56:57.084
713

Liquefaction response of soils in Mid-America evaluated by seismic cone tests

Schneider, James A. 08 1900 (has links)
No description available.
714

Partially restrained composite connections : design and analysis of a prototype structure

Kahle, Matthew Gilbert 12 1900 (has links)
No description available.
715

Invertebrate Responses to Large-Scale Change : Impacts of Eutrophication and Cataclysmic Earthquake Events in a Southern New Zealand Estuary

Skilton, Jennifer Erin January 2013 (has links)
Environmental stress and disturbance can affect the structure and functioning of marine ecosystems by altering their physical, chemical and biological features. In estuaries, benthic invertebrate communities play important roles in structuring sediments, influencing primary production and biogeochemical flux, and occupying key food web positions. Stress and disturbance can reduce species diversity, richness and abundance, with ecological theory predicting that biodiversity will be at its lowest soon after a disturbance with assemblages dominated by opportunistic species. The Avon-Heathcote Estuary in Christchurch New Zealand has provided a novel opportunity to examine the effects of stress, in the form of eutrophication, and disturbance, in the form of cataclysmic earthquake events, on the structure and functioning of an estuarine ecosystem. For more than 50 years, large quantities (up to 500,000m3/day) of treated wastewater were released into this estuary but in March 2010 this was diverted to an ocean outfall, thereby reducing the nutrient loading by around 90% to the estuary. This study was therefore initially focussed on the reversal of eutrophication and consequent effects on food web structure in the estuary as it responded to lower nutrients. In 2011, however, Christchurch was struck with a series of large earthquakes that greatly changed the estuary. Massive amounts of liquefied sediments, covering up to 65% of the estuary floor, were forced up from deep below the estuary, the estuary was tilted by up to a 50cm rise on one side and a corresponding drop on the other, and large quantities of raw sewage from broken wastewater infrastructure entered the estuary for up to nine months. This study was therefore a test of the potentially synergistic effects of nutrient reduction and earthquake disturbance on invertebrate communities, associated habitats and food web dynamics. Because there was considerable site-to-site heterogeneity in the estuary, the sites in this study were selected to represent a eutrophication gradient from relatively “clean” (where the influence of tidal flows was high) to highly impacted (near the historical discharge site). The study was structured around these sites, with components before the wastewater diversion, after the diversion but before the earthquakes, and after the earthquakes. The eutrophication gradient was reflected in the composition and isotopic chemistry of primary producer and invertebrate communities and the characteristics of sediments across the sample sites. Sites closest to the former wastewater discharge pipe were the most eutrophic and had cohesive organic -rich, fine sediments and relatively depauperate communities dominated by the opportunistic taxa Capitellidae. The less-impacted sites had coarser, sandier sediments with fewer pollutants and far less organic matter than at the eutrophic sites, relatively high diversity and lower abundances of micro- and macro-algae. Sewage-derived nitrogen had became incorporated into the estuarine food web at the eutrophic sites, starting at the base of the food chain with benthic microalgae (BMA), which were found to use mostly sediment-derived nitrogen. Stable isotopic analysis showed that δ13C and δ15N values of most food sources and consumers varied spatially, temporally and in relation to the diversion of wastewater, whereas the earthquakes did not appear to affect the overall estuarine food web structure. This was seen particularly at the most eutrophic site, where isotopic signatures became more similar to the cleaner sites over two-and-a-half years after the diversion. New sediments (liquefaction) produced by the earthquakes were found to be coarser, have lower concentrations of heavy metals and less organic matter than old (existing) sediments. They also had fewer macroinvertebrate inhabitants initially after the earthquakes but most areas recovered to pre-earthquake abundance and diversity within two years. Field experiments showed that there were higher amounts of primary production and lower amounts of nutrient efflux from new sediments at the eutrophic sites after the earthquakes. Primary production was highest in new sediments due to the increased photosynthetic efficiency of BMA resulting from the increased permeability of new sediments allowing increased light penetration, enhanced vertical migration of BMA and the enhanced transport of oxygen and nutrients. The reduced efflux of NH4-N in new sediments indicated that the capping of a large portion of eutrophic old sediments with new sediments had reduced the release of legacy nutrients (originating from the historical discharge) from the sediments to the overlying water. Laboratory experiments using an array of species and old and new sediments showed that invertebrates altered levels of primary production and nutrient flux but effects varied among species. The mud snail Amphibola crenata and mud crab Austrohelice crassa were found to reduce primary production and BMA biomass through the consumption of BMA (both species) and its burial from bioturbation and the construction of burrows (Austrohelice). In contrast, the cockle Austrovenus stutchburyi did not significantly affect primary production and BMA biomass. These results show that changes in the structure of invertebrate communities resulting from disturbances can also have consequences for the functioning of the system. The major conclusions of this study were that the wastewater diversion had a major effect on food web dynamics and that the large quantities of clean and unpolluted new sediments introduced to the estuary during the earthquakes altered the recovery trajectory of the estuary, accelerating it at least throughout the duration of this study. This was largely through the ‘capping’ effect of the new liquefied, coarser-grained sediments as they dissipated across the estuary and covered much of the old organic-rich eutrophic sediments. For all aspects of this study, the largest changes occurred at the most eutrophic sites; however, the surrounding habitats were important as they provided the context for recovery of the estuary, particularly because of the very strong influence of sediments, their biogeochemistry, microalgal and macroalgal dynamics. There have been few studies documenting system level responses to eutrophication amelioration and to the best on my knowledge there are no other published studies examining the impacts of large earthquakes on benthic communities in an estuarine ecosystem. This research gives valuable insight and advancements in the scientific understanding of the effects that eutrophication recovery and large-scale disturbances can have on the ecology of a soft-sediment ecosystem.
716

Quality of naps in infants across home and early childhood education centre settings

Stuart, Shirley Eleanor January 2011 (has links)
Limited research has been done on naps, particularly in early childhood education centres (ECECs). The present study followed a study by Torok (2009) with sleep-disturbed infants in ECECs. The objective of the current study was to examine the quality of naps in infants described as “typical sleepers” across two settings: the home and the early childhood education centre (ECEC). Two males and two females, ranging in age from 15- to 17-months contributed to four case studies. These were: i) an infant transitioning to the ECEC; ii) and iii) infants described as “settled” in an ECEC; and iv) an infant reported to have sleeping difficulties at home after the occurrence of a major earthquake. Observations from digital recordings were coded to determine sleep states and patterns. The findings across each case study were: i) naps varied in both settings during the infant’s transition to an ECEC but settled in both settings once the infant was “settled” at the ECEC; ii) naps tended to be consistent across both settings in the “typical sleepers” who were settled at the ECEC; and iii) naps at home were varied in the infant reported to have reacted to the earthquake while her naps at the ECEC were consistent. Overall findings suggested that total nap periods tended to be longer at home, sleep efficiency tended to be higher at the ECEC, and that participants tended to engage in more active sleep than quiet sleep. Caregiver presence was a major difference between the home and ECEC setting. This study demonstrated differences and similarities across both settings with infants described as “typical sleepers”. This is an important area due to the increasing number of infants attending ECECs (Statistics NZ, 2010). Several directions for future research have been presented.
717

Semi-active smart-dampers and resetable actuators for multi-level seismic hazard mitigation of steel moment resisting frames

Hunt, Stephen J January 2002 (has links)
This thesis explores the creation and assessment of semi-active control algorithms for both squat shear buildings and tall flexible structures. If cost-effective, practicable, semi-active structural control systems can be developed, the potential reduction in loss of both property and lives due to seismic events is significant. Semi-active controllers offer many of the benefits of active systems, but have power requirements orders of magnitude smaller, and do not introduce energy to the structural system. Previous research into semi-active controllers has shown their potential in linear simulations with single earthquake excitations. The distinguishing feature of this investigation is the use of appropriate non-linear modelling techniques and realistic suites of seismic excitations in the statistical assessment of the semi-active control systems developed. Finite element time-history analysis techniques are used in the performance assessment of the control algorithms developed for three and nine story structural models. The models include non-linear effects due to structural plasticity, yielding, hysteretic behaviour, and P-delta effects. Realistic suites of earthquake records, representing seismic excitations with specific return period probability, are utilised, with lognormal statistical analysis used to represent the response distribution. In addition to displacement focused control laws, acceleration and jerk regulation control methods are developed, showing that potential damage reduction benefits can be obtained from these new control approaches. A statistical assessment of control architecture is developed and undertaken, examining the distribution of constant maximum actuator authority for both squat shear buildings, and tall slender structures, highlighting the need to consider non-linear structural response characteristics when implementing semi-active control systems. Finally, statistical analysis of all results and normalised values shows the efficacy of each control law and actuator type relative to different magnitude seismic events. As a result, this research clearly presents, for the first time, explicit tradeoffs between control law, architecture type, non-linear structural effects, and seismic input characteristics for the semi-active control of civil structures.
718

EARTHQUAKE RISK IN INDONESIA: PARAMETRIC CONTINGENT CLAIMS FOR HUMANITARIAN RESPONSE AND FINANCIAL INSTITUTION RESILIENCY

Hartell, Jason 01 January 2014 (has links)
This dissertation explores the use of an index based contingent claims mechanism against earthquake risk in Indonesia. It focuses on time critical financing needs of international humanitarian relief organizations, and on efforts to improve the resiliency of geographically constrained financial institutions whose clientele are exposed to disaster risk. The approach uses measures of ground motion intensity as the basis for the index. The humanitarian response mechanism provides a new way for private sector partners to participate and gain visibility in their support of principled humanitarian funding. Index based contingent claims for local banks are shown to enhance their ability to recover and continue lending to the community after an event. Financial risk management may also substitute for a portion of the lender's precautionary capital buffer, enabling greater financial inclusion. Wholesale lenders with local bank networks having earthquake exposure can enhance these effects by offering group policies.
719

Approaching Psychosocial Adaptation to a Post-Crisis Environment through Case Studies of Javanese Disaster Survivors and Refugees in Sweden

Mattingly, Keith January 2015 (has links)
The psychosocial well-being of survivors of armed conflicts, forced displacement, and/or natural disasters is becoming more and more an integral component of holistic humanitarian response. Yet many organisations rely on broad, generalised manuals or guidelines which do not take into account the unique characteristics of societies and target populations. This paper describes the author’s research with disaster survivors in Java, Indonesia, and refugee in Sweden, aiming to characterise the process of recovery, adaptation and integration through beneficiaries’ own words. The author looks at how theory can be applied, such as whether a hierarchy of needs can be universally relevant, how the host Swedish society affects refugees’ experiences, which so-called “states of being” subjects experience, and how religion and cultural differences like individualism and collectivism influence one’s ability to regain psychosocial well-being. The author used both in-depth interviews and quantitative questionnaires to obtain data. Results showed an incredible level of resilience and positivity among all groups, though Indonesians reported family, spirituality and the community as major helping factors, while many refugees in Sweden pointed to their own individual determination and will to succeed. Many Indonesians identified economic livelihood as the biggest remaining gap, while refugees in Sweden spoke of language skills, educational qualifications and employment as keys to success and integration. Many challenges and gaps remain, especially for newly arrived refugees facing an increasingly difficult job market and fewer opportunities.
720

Ground-Breaking Contingency Planning with Risk- & Disaster Management : A Case Study at Höganäs Japan K.K.

Häggberg, David January 2015 (has links)
Final Thesis, Master of Business Administration & Economic Program, Field of Research: Management, School of Business & Economics at Linnaeus University, Växjö, Sweden, 4FE10E, Spring 2015. Author: David Häggberg Supervisor: Richard Nakamura (Daniel Ericsson) Title: Ground-Breaking Contingency Planning with Risk- & Disaster Management Subtitle: A Case Study at Höganäs Japan K.K. Background: On the 11th of March 2011, Japan was hit with one of the largestearthquakes in modern history at a magnitude of 9.0 on the Richter scale. Thiscaused wide spreading and lasting delays in production in large parts of the worlddue to organizations supply chain being connected to Japan. Subsequently RiskManagement has received renewed and increasing attention, both in Japan and therest of the world. The proactive concept of Risk Management primary builds itsmodels around probability and utilizes this concept as a basis for determining whichrisks that should be mitigated through countermeasures and financial investments.Though when faced with an environment filled with uncertainty and an additionallevel of indirect risk exposure due to the potential domino effect of natural disasterssuch as earthquakes, can Risk Management really handle that, a world whereprobability fails? The reactive approach used by Disaster Management mightcontain clues for making Risk Management more flexible. Research Question: How can a transnational corporation adapt their RiskManagement strategy and plan for contingencies in a country with an unstablenatural environment? Purpose: This thesis seeks to investigate how a strategy for Risk Management canbe created and adapted with the regard to uncertainties such as an unstableenvironmental situation. The goal is further to highlight how traditional RiskManagement can be combined with other related areas such as DisasterManagement, in order to make a more complete strategy and a more flexible plan foraction. An adaption to the Risk Management strategy that would be made in order tomake the strategy applicable on a global level and including areas with unstableenvironmental situations. Method: This study has utilized a multi-strategy approach and the main source ofdata for this case study has come from semi-structured interviews and acomplementary survey. The author has found it necessary to adopt a pragmaticstandpoint with a qualitative focus in order to explore the research question andunderstand the collected data to its fullest extent. Conclusion: Adopting the local practices and mindset that strives to constantlysecure the supply chain and fulfill customer obligations by creating contingenciesthe risk exposure can be mitigated. Utilizing a quickly adaptable approach instead oflong-term planning in combination with concepts such as a Disaster Recovery Planthe Risk Management strategy can be altered towards becoming more flexible.

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