Thèse de doctorat : HISTOIRE : Metz : 1996. / 1996METZ008L. 115 ref.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cressler, John; Committee Member: Deo, Chaitanya; Committee Member: Doolittle, Alan; Committee Member: Keezer, David; Committee Member: May, Gary; Committee Member: Papapolymerou, John. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This study consists of developing descriptive, parametric, linear and non-linear statistical models for such natural phenomena as hurricanes, lightning, flooding, red tide and volcanic fallout. In the present study, the focus of research is determining the stochastic nature of phenomena in the environment. These statistical models are necessary to address the variability of nature and the misgivings of the deterministic models, particularly when considering the necessity for man to estimate the occurrence and prepare for the aftermath.The relationship between statistics and physics looking at the correlation between wind speed and pressure versus wind speed and temperature play a significant role in hurricane prediction. Contrary to previous studies, this study indicates that a drop in pressure is a result of the storm and less a cause. It shows that temperature is a key indicator that a storm will form in conjunction with a drop in pressure. This study demonstrates a model that estimates the wind speed within a storm with a high degree of accuracy. With the verified model, we can perform surface response analysis to estimate the conditions under which the wind speed is maximized or minimized. Additional studies introduce a model that estimates the number of lightning strikes dependent on significantly contributing factors such as precipitable water, the temperatures within a column of air and the temperature range. Using extreme value distribution and historical data we can best fit flood stages, and obtain profiling estimate return periods. The natural logarithmic count of Karenia Brevis was used to homogenize the variance and create the base for an index of the magnitude of an outbreak of Red Tide. We have introduced a logistic growth model that addresses the subject behavior as a function of time and characterizes the growth rate of Red Tide. This information can be used to develop strategic plans with respect to the health of citizens and to minimize the economic impact. Studying the bivariate nature of tephra fallout from volcanoes, we analyze the correlation between the northern and eastern directions of a topological map to find the best possible probabilistic characterization of the subject data.

The current thesis is structured in four parts. Vector smoothing methods are used to study environmental data, in particular records of extreme precipitation, the models utilized belong to the vector generalized additive class. In the statistical analysis of observational studies the identification and adjustment for prognostic factors is an important component of the analysis; employing flexible statistical methods to identify and characterize the effect of potential prognostic factors in a clinical trial, namely "generalized additive models", presents an alternative to the traditional linear statistical model. The classes of models for which the methodology gives generalized additive extensions include grouped survival data from the Surveillance, Epidemiology, and End Results tumors of the brain and the central nervous system database; we are employing piecewise linear functions of the covariates to characterize the survival experienced by the population. Finally, both descriptive and analytical methods are utilized to study incidence rates and tumor sizes associated with the disease.

In the past two decades, the popularity of Extreme Sport (X-Sport) has rapidly increased in Hong Kong. “Exploration of Excitement” would be the main reason why teenagers and young adults would like to play X-Sport. Unlike other sports, X-Sport does not require any rules, restrictions or physical requirements for its players, which provides more freedom and creativity. However, the general public does not agree with this particular interest group due to their misunderstanding with limited knowledge of the X-Sport. Also, there are only few existing X-Sport park and related facilities in Hong Kong and most of them are located at unwanted spaces with poor environmental and facilities qualities, which leads X-Sport player would play at local parks and unused space in their neighbourhood. Damages on landscape feature are normally appeared in these local parks recreational spaces. Due to the lack of societal supports and deficiencies in government, there are only six existing X-Sport park in Hong Kong, where they are all inaccessible and far apart. This thesis aims to promote X-Sport by using an X-Sport park as a median to integrate both young and old generations in physical and social aspects, not just exists as a functional space for X-Sport players. A roundabout site, Chai Wan Roundabout Garden, in major transport interchange in Hong Kong Island is selected for the development of this concept. Three stages design process has been incorporated. The first design stage has developed based on the primary site-observation and comprehensive site analysis. The second design stage is to conduct a special study of a landscape technique with both local and international case studies. The third design stage is to combine both first and second stages development and formulate the final design solution. Comments from first and second juries has been addressed and amended accordingly. / published_or_final_version / Architecture / Master / Master of Landscape Architecture

The dissertation focuses on developing statistical models in environmental and life sciences. The Generalized Extreme Value distribution is used to model annual monthly maximum rainfall data from 44 locations in Florida. Time dependence of the rainfall data is incorporated into the model by assuming the location parameter to be a function of time, both linear and quadratic. Estimates and confidence intervals are obtained for return levels of return periods of 10, 20, 50, and 100 years. Locations are grouped into statistical profiles based on their similarities in return level graphs for all locations, and locations within each climatic zone. A family of extreme values distributions is applied to model simulated maximum drug concentration (Cmax) data of an anticoagulant drug. For small samples (n <̲ 100) data exhibited bimodality. The results of investigating a mixture of two extreme value distributions to model such bimodal data using two-parameter Gumbel, Pareto and Weibu ll concluded that a mixture of two Weibull distributions is the only suitable FTSel.For large samples , Cmax data are modeled using the Generalized Extreme Value, Gumbel, Weibull, and Pareto distributions. These results concluded that the Generalized Extreme Value distribution is the only suitable model. A system of random differential equations is used to investigate the drug concentration behavior in a three-compartment pharmacokinetic model which describes coumermycin's disposition. The rate constants used in the differential equations are assumed to have a trivariate distribution, and hence, simulated from the trivariate truncated normal probability distribution. Numerical solutions are developed under different combinations of the covariance structure and the nonrandom initial conditions. We study the dependence effect that such a pharmacokinetic system has among the three compartments as well as the effect of variance in identifying the concentration behavior in each compartment. We identify the time delays in each compartment. We extend these models to incorporate the identified time delays. We provide the graphical display of the time delay effects on the drug concentration behavior as well as the comparison of the deterministic behavior with and without the time delay, and effect of different sets of time delay on deterministic and stochastic behaviors.

<p>With the extensive use of outsourcing and more frequent technological innovations, global supply chains become vastly stretched and dynamic networks. As a result, firms face increasingly significant challenges to managing their fragile supply networks and responding to more rapidly changing demand evolutions. In this dissertation, we analyze three aspects of these challenges and summarize the findings in three essays. The first essay considers firms' problem of managing social and environmental non-compliance risk at its sub-tier suppliers. We figure out under what circumstances the firms should delegate the sub-tier supplier non-compliance management to its direct suppliers and under what directly control. In the second essay, we analyze the firm's strategy to deal with random demand surges. We develop a new demand model that captures important non-Markov characteristics of possible random demand surge trajectories and derive the optimal safety stock and reactive capacity strategy. Eventually, we establish a useful framework for supply chain planning under a variety of surge demand characteristics (e.g., frequency, intensity, duration, and shape). In the third essay, we examine a dynamic customer-base management problem for a firm with finite capacity, when its customers are prone to disruption and retention risks. We show that the optimal base size is an adding-up-to policy and derive the firm's optimal capacity allocation policy when capacity shortage occurs. In summary, our studies in this dissertation provide useful modeling ideas, decision tools, insights, and guidance for firms to build up resilient supply chains from both the supply and demand sides.</p> / Dissertation

In the United States (U.S.), extreme temperature-related deaths account for far more deaths than hurricanes, lightning, tornadoes, floods, and earthquakes combined. An extreme heat event (EHE) or a heat wave is a sustained period of substantially hotter and/or more humid weather. EHEs cause a wide range of health problems such as rashes, cramps, heat exhaustion, heat stroke, and, in some instances, death. Further, meteorology plays a dominant role in the formation of air pollutants. In particular, extremely high temperatures are conducive to the formation of certain air pollutants. In order to understand the adverse health impacts of extreme heat and air pollution levels prevailing during EHEs, it is necessary to define what constitutes a heat episode; however, there is a lack of scientific consensus on definitions and procedures to accurately identify EHEs. This work employs a hierarchical clustering technique to group 92 different EHE definitions into homogeneous sets and uses negative binomial rate regression approach to identify those definitions that are most strongly associated with mortality. Our findings suggest that definitions with thresholds that are either too extreme or too moderate are poorly associated with heat-related mortality for most climate regions. Additionally, the association between air pollution and health, especially mortality, is well understood. However, the role of air pollutants in modifying the relationship between EHEs and mortality is not well characterized in the U.S., yet is critical to generating accurate estimates of health burden. Our results indicate that air pollution confounds the relationship between EHE and mortality, and the extent of confounding varies with climate regions. Further, through this work, the sensitivities associated with selecting an EHE definition is taken into consideration when providing region-specific health and economic burden associated with EHEs. Ideally, the excess deaths and costs presented in this work could be useful to study and quantify the public health risk associated with EHEs, either in a prospective or a retrospective setting.

Snowboard media producers attempt to create subculturally relevant videos that connect with the audience. Videos provide the opportunity to report and document snowboarding activity, highlight new developments and provide visibility to prominent participants and associated businesses. Being a well-known and esteemed snowboarding participant is advantageous to being a producer, as it provides an identifiable cultural capital and implies a trustworthy ‘by-riders-for-riders’ philosophy. Connecting with the viewers is vital, as the audience plays a role in the distribution of videos by sharing and endorsing them through their social networks. Motivating factors in audience media sharing, also known as media spreading, include status seeking, improving credibility, personal satisfaction and personal expression. Snowboarding was founded on anti-mainstream and anti-commercialism beliefs, which means that incorporating advertising and promotional messaging could negatively impact on audience connection. Yet, filming and producing snowboarding videos is difficult and expensive. Advertising represents an opportunity to attract funding and support to assist with production costs and, ultimately, provide profit. In order to accommodate advertising into their videos, producers are sometimes required to compromise their standards. This compromise represents a threat to audience connection. Producers believe that high quality, innovative snowboarding action footage provides the best opportunity to wow the audience. Various forms of advertising, including stealth marketing, sponsored journalism, and hybrid messaging, are often displayed in the moments between action footage shots, but advertising compromise can also affect action footage, particularly on client-funded projects. How advertising is incorporated can also depend on the industry the advertiser operates in. Alcohol brand advertising is identified as highly restrictive due to legal implications and public perceptions. Advertisers from businesses strongly related to the snowboarding subculture are more aware of their competitors’ presence in videos, which can cause conflict. Ski field support can be varied, despite high levels of visibility in the videos.

Atmospheric rivers (ARs) are important contributors to cool season precipitation in the Southwestern US, and in some cases can lead to extreme hydrometeorological events in the region. We performed a climatological analysis and identified two predominant types of ARs that affect the central mountainous region in Arizona: Type 1 ARs originate in the tropics near Hawaii (central Pacific) and enhance their moisture in the midlatitudes, with maximum moisture transport over the ocean at low-levels of the troposphere. On the other hand, moisture in Type 2 ARs has a more direct tropical origin and meridional orientation with maximum moisture transfer at mid-levels. We then analyze future projections of Southwest ARs in a suite of global and regional climate models used in the North American Regional Climate Change Assessment Program (NARCCAP), to evaluate projected future changes in the frequency and intensity of ARs under warmer global climate conditions. We find a consistent and clear intensification of the water vapor transport associated with the ARs that impinge upon Arizona and adjacent regions, however, the response of AR-related precipitation intensity to increased moisture flux and column-integrated water vapor is weak and no robust variations are projected either by the global or the regional NARCCAP models. To evaluate the effect of horizontal resolution and improve our physical understanding of these results, we numerically simulated a historical AR event using the Weather Research and Forecasting (WRF) model at a 3-km resolution. We then performed a pseudo-global warming experiment by modifying the lateral and lower boundary conditions to reflect possible changes in future ARs (as projected by the ensemble of global model simulations used for NARCCAP). Interestingly we find that despite higher specific humidity, some regions still receive less rainfall in the warming climate experiments - partially due to changes in thermodynamics, but primarily due to AR dynamics. Therefore, we conclude from this analysis that overall future increase in atmospheric temperature and water content as projected by global climate models will not necessarily translate into generalized heavier AR-related precipitation in the Southwestern US.