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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

Control Theoretic Approaches to Computational Modeling and Risk Mitigation for Large Crowd Management

Alrashed, Mohammed 11 1900 (has links)
We develop a computational framework for risk mitigation in high population density events. With increased global population, the frequency of high population density events is naturally increased. Therefore, risk-free crowd management plans are critical for efficient mobility, convenient daily life, resource management and most importantly mitigation of any inadvertent incidents and accidents such as stampedes. The status-quo for crowd management plans is the use of human experience/expert advice. However, most often such dependency on human experience is insufficient, flawed and results in inconvenience and tragic events. Motivated by these issues, we propose an agent-based mathematical model describing realistic human motion and simulating large dense crowds in a wide variety of events as a potential simulation testbed to trial crowd management plans. The developed model incorporates stylized mindset characteristics as an internal drive for physical behavior such as walking, running, and pushing. Furthermore, the model is combined with a visualisation of crowd movement. We develop analytic tools to quantify crowd dynamic features. The analytic tools will enable verification and validation to empirical evidence and surveillance video feed in both local and holistic representations of the crowd. This work addresses research problems in computational modeling of crowd dynamics, specifically: understanding and modeling the impact of a collective mindset on crowd dynamics versus mixtures of heterogeneous mindsets, the effect of social contagion of behaviors and decisions within the crowd, the competitive and aggressive pushing behaviors, and torso and steering dynamics.
2

Epidemiological studies of Oral Health, development and influencing factors in the county of Dalarna, Sweden 1983–2013

Edman, Kristina January 2016 (has links)
The aim of this thesis is to describe the development of oral health and possible associations with socioeconomic and socio-behavioural factors, in an adult population over a period of 30 years. A further aim is to describe attitudes to, and demands of dental care, and the impact of oral conditions on quality of life. The study sample consisted of 787-1158 individuals, aged between 35-85 years, randomly selected from Dalarna’s population register in 1982, 2002, 2007 and 2012. The studies were carried out in 1983, 2003, 2008 and 2013, and the participants responded to a questionnaire and a clinical examination of oral status. There has been a substantial improvement in oral status in regard to the mean number of teeth, intact teeth, and less removable dentures over this period of 30 years. The proportion of individuals with alveolar bone loss decreased significantly between 1983 and 2008, but increased significantly between 2008 and 2013. Smoking was the overall strongest factor associated with alveolar bone loss, after adjustment for socioeconomic and socio-behaviour factors, age and number of teeth. Calculus, visible on radiographs, increased significantly between 2003 and 2013. The proportion of individuals with manifest caries declined significantly between 1983 and 2008, but seems to level out between 2008 and 2013. Socioeconomic and socio-behaviour factors were significantly associated with manifest caries. Preventive treatment, meeting the same caregiver as on previous visits, and information about treatment cost was reported to a significantly lower degree as important in 2013, compared with 2003 and 2008, and booking time for treatment was reported as more difficult in 2013, compared with earlier years. Regular recalls was reported as less important in 2013, compared with 2008. A third of the respondents reported oral impact on daily performance and irregular dental visits, limited economy for dental care, less than 20 remaining teeth, manifest caries and temporomandibular disorder were significantly associated with oral impact on daily performance.

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