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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

Modeling the complex ejecta on 2017 September 6-9 with WSA-ENLIL+Cone and EUHFORIA

Werner, Anita Linnéa Elisabeth January 2018 (has links)
Three CMEs which erupted on 2017 Sep 4 and 6 underwent mutual interaction before reaching Earth on Sep 6-9, where it gave rise to a complex and unexpectedly geoeffective structure as detected by WIND at L1. The spacecraft first observed an interplanetary (IP) shock on Sep 6 followed by a turbulent sheath. The leg of the CME flux rope is detected on Sep 7, in which clear signatures of a shock-in-a-cloud can be distinguished, coming from the third CME which propagated into the preceding flux rope. We model the source of this complex ejecta with WSA-ENLIL+Cone and EUHFORIA to assess and compare the overall performance for interacting CMEs as opposed to single CME events. We find that following the conventional algorithm for determination of input parameters give large deviation in the event prediction at L1. The overestimated density of the IP shock 1 is due to the way of implementation of the magnetogram in WSA model. Excluding the slow CME from the input leads to even larger deviation. The prediction of IP shock 1 drastically improves by introducing of a customized density enhancement factor (dcld) based on coronagraph image observations. This novel approach, is simple and accessible, and could be applied to improve the forecast for fast, undisturbed CMEs. The deviation in the prediction of IP shock 2 comes from its interaction with the low proton temperature environment of the preceding magnetic cloud, giving rise to an expansion of the shock front. Additionally, the properties of the background solar wind plasma have been preconditioned by passage of the previous IP shock. This was confirmed from the kilometric type II radio burst emission following the eruption of the third CME. The propagation profile of this CME implies an almost non-existent deceleration in the interplanetary medium, in contrast to the expected CME deceleration due to interaction with the background plasma. In summary, this study presents clear indications that magnetic interaction must be taken into account to reliably forecast multiple CME events. Preconditioning of previous CMEs must also be considered in more depth, and ultimately requires a realistic, time-dependent model of the ambient solar wind which responds well to propagating shock waves. Models in space physics presents us with the perfect tools for understanding not only the physical processes that the simplified models can predict, but perhaps more importantly, help us begin to understand what the models fail to predict.
2

Discourses of multicultural teams : implications for policy practice in open and distance learning

Nyoni, Jabulani 12 December 2012 (has links)
Although a number of researchers have attempted to identify measures to account for the core elements of effective intercultural/multicultural teams of community of practice (CoP) in open and distance learning (ODL) formal institutions, there is no consensus on those measures. Previous studies also suggest important differences in teamwork across cultures but they do not adequately address the complexity of issues affecting culturally diverse teams and do not identify the specific factors that contribute to these differences (Earley & Gibson 2002). The purpose of the study was to collect views and experiences of multicultural lecturers from the six Unisa colleges and the Directorate for Curriculum and Learning Development (DCLD) personnel on the operationalization of Unisa Framework for the implementation of a team approach to curriculum and learning development. Soon after South Africa’s independence in 1994, Unisa had to respond to a new paradigm shift by re-aligning their curricula to meet the new national and global economic demands and social justice. The process relates to major revisions of programmes and modules, as well as new programmes and modules. The study adopts a qualitative research approach and uses Van Dijk (2009) critical discourse analysis (CDA) as a methodology and data analysis strategy. Sociocognitive Approach (SCA) theory as espoused by Van Dijk (2009) is underpinned by a narrative research design. A purposive sampling method was employed to collect data and critically analysed views and experiences of interracial/multicultural academic lecturers, a Director and DCLD education consultants engaged in collective partnerships in the craft of ODL curriculum and learning development at Unisa in South Africa. I used the Unisa Framework for a team approach to curriculum and learning development at Unisa as a model. Previous discourse studies in this area suggest that differences in communication practices may be attributed to power differentials or language competence. In particular it surfaces key tensions within subject expertise autonomy, such as those between commitments to reform and efficiency that may have a significant impact on the outcomes of subsequent policy compliance. In my analysis of the research participants’ discourses, it emerged that a culture of dichotomy; “us and them” inhibits the operationalization of the Unisa Framework for the implementation of team approach to curriculum and learning development which may be attributed to the failure to manage multicultural identity issues. / Educational Leadership and Management / D. Ed. (Education Management)
3

Discourses of multicultural teams : implications for policy practice in open and distance learning

Nyoni, Jabulani 12 December 2012 (has links)
Although a number of researchers have attempted to identify measures to account for the core elements of effective intercultural/multicultural teams of community of practice (CoP) in open and distance learning (ODL) formal institutions, there is no consensus on those measures. Previous studies also suggest important differences in teamwork across cultures but they do not adequately address the complexity of issues affecting culturally diverse teams and do not identify the specific factors that contribute to these differences (Earley & Gibson 2002). The purpose of the study was to collect views and experiences of multicultural lecturers from the six Unisa colleges and the Directorate for Curriculum and Learning Development (DCLD) personnel on the operationalization of Unisa Framework for the implementation of a team approach to curriculum and learning development. Soon after South Africa’s independence in 1994, Unisa had to respond to a new paradigm shift by re-aligning their curricula to meet the new national and global economic demands and social justice. The process relates to major revisions of programmes and modules, as well as new programmes and modules. The study adopts a qualitative research approach and uses Van Dijk (2009) critical discourse analysis (CDA) as a methodology and data analysis strategy. Sociocognitive Approach (SCA) theory as espoused by Van Dijk (2009) is underpinned by a narrative research design. A purposive sampling method was employed to collect data and critically analysed views and experiences of interracial/multicultural academic lecturers, a Director and DCLD education consultants engaged in collective partnerships in the craft of ODL curriculum and learning development at Unisa in South Africa. I used the Unisa Framework for a team approach to curriculum and learning development at Unisa as a model. Previous discourse studies in this area suggest that differences in communication practices may be attributed to power differentials or language competence. In particular it surfaces key tensions within subject expertise autonomy, such as those between commitments to reform and efficiency that may have a significant impact on the outcomes of subsequent policy compliance. In my analysis of the research participants’ discourses, it emerged that a culture of dichotomy; “us and them” inhibits the operationalization of the Unisa Framework for the implementation of team approach to curriculum and learning development which may be attributed to the failure to manage multicultural identity issues. / Educational Leadership and Management / D. Ed. (Education Management)

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