D. Tech. Mathematical technology Tshwane University of Technology 2013. / Proposes a tool or technique that greatly reduces the mathematical difculties encountered when investigating the stability of predator-prey models. The technique replaces the need to deal with complex Lienard systems, Dulac and Lyapunov functions, and the required mathematics thus becomes accessible to researchers in a wide range of disciplines.

Thesis (M.Ed.)--University of Hong Kong, 2008.

Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, Sept. 2001. / Thesis advisor: Morgan, Michael A. "September 2001." Includes bibliographical references (p. 87-88). Also Available in print.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 154-163).

Thesis (B.A.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

No description available.

A simple model of surface and sub -surface soil temperature was developed at the watershed scale ( -100 km2) in a semi -arid rangeland environment. The model consisted of a linear combination of air temperature and net radiation and assumed: 1) topography controls the spatial distribution of net radiation, 2) near- surface air temperature and incoming solar radiation are relatively homogeneous at the watershed scale and are available from ground stations and 3) soil moisture dominates transient soil thermal property variability. Multiplicative constants were defined to account for clear sky diffuse radiation, soil thermal inertia, an initially fixed ratio between soil heat flux and net radiation and exponential attenuation of solar radiation through a partial canopy. The surface temperature can optionally be adjusted for temperature and emissivity differences between mixed hare soil and vegetation canopies. Model development stressed physical simplicity and commonly available spatial and temporal data sets. Slowly varying surface characteristics, such as albedo, vegetation density and topography were derived from a series of Landsat TM images and a 7.5" USGS digital elevation model at a spatial resolution of 30 m. Diurnally variable atmospheric parameters were derived from a pair of ground meteorological stations using 30 -60 min averages. One site was used to drive the model, the other served as a control to estimate model error. Data collected as part of the Monsoon '90 and WG '92 field experiments over the ARS Walnut Gulch Experimental. Watershed in SE Arizona were used to validate and test the model. Point, transect and spatially distributed values of modeled surface temperature were compared with synchronous ground, aircraft and satellite thermal measurements. There was little difference between ground and aircraft measurements of surface reflectance and temperature which makes aircraft transects the preferred method to "ground truth" satellite observations. Mid- morning modeled surface temperatures were within 2° C of observed values at all but satellite scales, where atmospheric water vapor corrections complicate the determination of accurate temperatures. The utility of satellite thermal measurements and models to study various ground phenomena (eg. soil thermal inertia and surface energy balance) were investigated. Soil moisture anomalies were detectable, but were more likely associated with average near -surface soil moisture levels than individual storm footprints.

A simple model of surface and sub-surface soil temperature was developed at the watershed scale (-100 km²) in a semi-arid rangeland environment. The model consisted of a linear combination of air temperature and net radiation and assumed: (1) topography controls the spatial distribution of net radiation, (2) near-surface air temperature and incoming solar radiation are relatively homogeneous at the watershed scale and are available from ground stations and (3) soil moisture dominates transient soil thermal property variability. Multiplicative constants were defined to account for clear sky diffuse radiation, soil thermal inertia, an initially fixed ratio between soil heat flux and net radiation and exponential attenuation of solar radiation through a partial canopy. The surface temperature can optionally be adjusted for temperature and emissivity differences between mixed bare soil and vegetation canopies. Model development stressed physical simplicity and commonly available spatial and temporal data sets. Slowly varying surface characteristics, such as albedo, vegetation density and topography were derived from a series of Landsat TM images and a 7.5" USGS digital elevation model at a spatial resolution of 30 m. Diurnally variable atmospheric parameters were derived from a pair of ground meteorological stations using 30-60 min averages. One site was used to drive the model, the other served as a control to estimate model error. Data collected as part of the Monsoon '90 and WG '92 field experiments over the ARS Walnut Gulch Experimental Watershed in SE Arizona were used to validate and test the model. Point, transect and spatially distributed values of modeled surface temperature were compared with synchronous ground, aircraft and satellite thermal measurements. There was little difference between ground and aircraft measurements of surface reflectance and temperature which makes aircraft transects the preferred method to "ground truth" satellite observations. Mid-morning modeled surface temperatures were within 2° C of observed values at all but satellite scales, where atmospheric water vapor corrections complicate the determination of accurate temperatures. The utility of satellite thermal measurements and models to study various ground phenomena (e.g. soil thermal inertia and surface energy balance) were investigated. Soil moisture anomalies were detectable, but were more likely associated with average near-surface soil moisture levels than individual storm footprints.

About the intraday volatility modeling, the limitations and potential problems of using Andersen & Bollerslev's approach are addressed and distinct modifications are proposed to tackle the corresponding issues. The first suggestion is about the utilization of the interaction between the intraday periodicity and the heteroskedasticity while the second is about the modified normalization for the estimation of the intraday periodicity. / Furthermore, it is demonstrated that the inclusion of overnight variance can improve the prediction accuracy of the Chicago Board of options Exchange (CBOE) volatility indexes (VIX and VXD) under specific weight combinations. The findings contradict the common perception that overnight return does not contain useful information for daily volatility modeling. / On the other hand, the third suggestion is about the inclusion of overnight information for the estimation of daily volatility. This study explores the possibility of incorporating the overnight variance indirectly through the use of linearly combined daily volatility estimators. The empirical results demonstrate that the inclusion of overnight variance can produce substantial influence when the minimum-variance constraints are relaxed. Besides, the influence is revealed to be not monotonic as an increase of the overnight proportion does not necessarily produce a larger influence. / The proposed modifications are tested with different ARCH structures, including GARCH(1,1), FIGARCH(1,d,1) and HYGARCH(1,d,1), by using simulated data and market data. Apart from studying the 1-step-ahead out-of-sample performance, several multiple-step-ahead forecasting results are also addressed. Under the same level of model flexibility (parameterized portions), our proposed modifications always outperform the original method in both in-sample fitness and out-of-sample performance on various forecasting horizons. / This research study investigates three new considerations for improving the performance of volatility modeling of financial returns. Two of them are related to the intraday volatility modeling and the other one is about the use of overnight information for daily volatility modeling. / Chu, Chun Fai Carlin. / Adviser: Kai Pui Lam. / Source: Dissertation Abstracts International, Volume: 73-04, Section: A, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 180-186). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest dissertations and theses, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Song Xiping. / "August 2006." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 136-142). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.