Thesis (Ph. D.) -- Lincoln University, 2005. / Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

No description available.

Local descriptors are increasingly used for the task of object recognition because of their perceived robustness with respect to occlusions and to global geometrical deformations. Such a descriptor--based on a set of oriented Gaussian derivative filters-- is used in our recognition system. We report here an evaluation of several techniques for orientation estimation to achieve rotation invariance of the descriptor. We also describe feature selection based on a single training image. Virtual images are generated by rotating and rescaling the image and robust features are selected. The results confirm robust performance in cluttered scenes, in the presence of partial occlusions, and when the object is embedded in different backgrounds.

Th.--Sci.--Bordeaux 1, 1979. N°: 564. / Extr. en partie de Nuclear physics, A 192, 1972, 372-390 ; A 271, 1976, 477-494 et de Physical review letters, 39, 1977, 15, 922-924.

The study focused on four research objectives: 1. To identify the species and provenances of eucalypts most suitable for biomass production in Great Britain. 2. To compare growth of eucalypts with other promising short rotation forestry genera. 3. To develop volume and biomass functions for E. gunnii. 4. To estimate yields and patterns of growth for E. gunnii. Searches on CAB abstracts and World of Science showed that there was limited research conducted on eucalypts in the UK. This research provides an original contribution to knowledge through; a long term assessment of the performance of species of cold tolerant eucalypts across a range of sites, identification of the basis for the rapid growth of eucalypts in comparison with trees from other genera, identification of the best fit function to describe stem form in E.gunnii and a characterisation of the pattern of growth in this species. The thesis provides an account of the long history of eucalypts in the UK, the first record of a eucalypt being planted in Britain probably being Eucalyptus obliqua in the late 1700s (Aiton 1789). A review is then provided of the experience and constraints to growing nine eucalypt species in the UK and their potential for short rotation forestry are described. The rapid growth of eucalypts makes them well suited to short rotation forestry, but there are considerable risks from frosts and extreme winters. Results from a trial established in Cumbria, north west England are described. Survival and growth was compared between E.gunnii, E. nitens and native or naturalised species, identified by Hardcastle (2006) as having potential for short rotation forestry. The rapid rate of growth of E. gunnii was attributed to a combination of large leaf area, a long period of growth during the year and a high specific leaf area. There was 99% mortality of E. nitens at the trial over winter, preventing comparison with other species. At the same trial and assessment was made of frost damage during the winter of 2009-2010, which proved to be the coldest for thirty years (Met Office 2010). E. gunnii was found to be more cold-tolerant than E. nitens, with 35% of the former surviving the winter and less than 1% of the latter. Larger trees were damaged more so than smaller trees reinforcing the argument for good silviculture to promote rapid, early growth. The study on stem form and growth of E. gunnii represents the first in the UK. Volume, height and dbh of a total of 636 trees, measured by felling, optical dendrometer and terrestrial laser scanner were used to test the goodness of fit of a volume function developed in France by AFOCEL and is South America by Shell Oil. The AFOCEL function was found to predict volume with less bias and be suitable for all but the smallest trees. Characterisation of growth curves using mined historic data indicated yields of 16 m3 ha-1 y-1 or approximately 8 t ha-1 y-1 at 20 years old. In contrast, growth curves derived from stem analysis of nine trees from Chiddingfold (south east England) and Glenbranter (central western Scotland) indicated lower yields at 7 m3 ha-1 y-1 at age 28 years and 4.5 m3 ha-1 y-1 at age 30 years respectively. Evidence from plantings elsewhere in the UK show that higher rates of growth are possible, but also that yields are often compromised by high mortality.

The degradation of soil quality due to undesirable farming practices has reached alarming scales in the Eastern Cape and this has had negative repercussions on soil productivity and the environment in general. There is growing evidence that conservation agriculture (CA) practices involving minimal mechanical disturbance, maintaining permanent surface cover and embracing diverse crop rotations increase soil organic carbon (SOC) and therefore has potential to mitigate soil quality deterioration. A study was carried out at two sites located in two ecotopes to investigate the effects of crop residue retention and crop rotations in a no till system on overall soil quality using the Soil Management Assessment Framework (SMAF) as the soil quality assessment tool. The CA study trials were laid out in 2012 at two different locations, one at the Phandulwazi Agricultural High school within the Phandulwazi Jozini ecotope and the other one at University of Fort Hare Research Farm within the Alice Jozini ecotope. The experiment was laid out as a split-split plot arrangement in a randomized complete block design with three replicates. Tillage treatments were applied on the main plots while crop rotation treatments were applied as subplots. Crop residue retention treatments were applied as sub-sub plots. The rotational treatments were maize-fallow-maize (MFM), maize-fallow-soybean (MFS), maize-wheat-maize (MWM) and maize-wheat-soybean (MWS). The initial assessment of the overall soil quality of the two ecotopes using the SMAF soil quality index (SQI) revealed that the soils at the Alice site were functioning at 80% while the soils at the Phandulwazi site were functioning at 79 percent of their optimum capacity. The slight difference in the soil quality of the two ecotopes could be attributed to their different soil organic C contents where the Alice Jozini ecotope had significantly higher soil organic C contents than the Phandulwazi Jozini ecotope. After 3 years of continuous treatment application, crop residue retention significantly improved most of the measured soil quality parameters. Generally across the sites, more soil organic C, microbial biomass C (MBC), ß-glucosidase (BG) activity, mineral N, extractable P and K, Cu, Zn, Mn, Fe, and macro-aggregates were recorded in treatments where crop residues were retained. Crop rotations alone did not have a significant impact on most of the measured soil quality indicators. The crop rotations influenced significantly the availability of mineral N across the two sites, highlighting the importance of using a legume in rotations on available N for the subsequent crops. Most of the measured soil attributes were not significantly influenced after 3 years of continuously applying combined treatment of CA components. Mineral N (NO3 + NH4), K, Zn and Fe were significantly impacted on by the interactions of CA components at the Phandulwazi site, while N, Cu, Zn and Mn were significantly increased at the Alice site. Low response of SOC to combined CA treatments in the short-term prompted the need to examine treatment effects on individual soil carbon fractions. The interaction of crop rotation and residue management techniques were significant on the fine particulate organic matter – C fractions and microbially respired C. These soil C fractions were more sensitive to short-term treatments of combined CA components than SOC and MBC, therefore they can be used as short-term indicators of CA effects on SOM. Soil organic carbon, MBC, extractable P and K, soil pH, EC, b, AGS (aggregate stability) and BG activity were measured and the Soil Management Assessment Framework (SMAF) used to calculate soil quality index (SQI) values for each treatment. The combination of the crop rotations with crop residue retention showed the potential to significantly improve SQI values in the long term. The highest soil quality improvement at both sites was achieved by the maize-wheat-soybean (MWS) rotation with crop residue retention.

In the canonical model of a pulsar, rotational energy is transmitted through the surrounding plasma via two electrical circuits, each connecting to the star over a small region known as a "polar cap." For a dipole-magnetized star, the polar caps coincide with the magnetic poles (hence the name), but in general, they can occur at any place and take any shape. In light of their crucial importance to most models of pulsar emission (from radio to X-ray to wind), we develop a general technique for determining polar cap properties. We consider a perfectly conducting star surrounded by a force-free magnetosphere and include the effects of general relativity. Using a combined numerical-analytical technique that leverages the rotation rate as a small parameter, we derive a general analytic formula for the polar cap shape and charge-current distribution as a function of the stellar mass, radius, rotation rate, moment of inertia, and magnetic field. We present results for dipole and quadrudipole fields (superposed dipole and quadrupole) inclined relative to the axis of rotation. The inclined dipole polar cap results are the first to include general relativity, and they confirm its essential role in the pulsar problem. The quadrudipole pulsar illustrates the phenomenon of thin annular polar caps. More generally, our method lays a foundation for detailed modeling of pulsar emission with realistic magnetic fields.

The Jupiter Trojan asteroids are minor bodies that orbit 60 degrees before and 60 degrees behind Jupiter. Because these orbits are stable over the lifetime of the Solar System, the properties of these objects may inform us about the conditions under which the Solar System formed. We present BVRI photometry for 110 of the intrinsically brightest and presumably largest members of the L4 and L5 Jupiter Trojans. We use a new principal color component derived by Chatelain et al. (2016) that is indicative of taxonomic types relevant to the Jupiter Trojan asteroids. We find that 83% of the largest Jupiter Trojans are consistent with a D-type classification, while 17% show shallower slopes more consistent with X-type and C-type classifications. We show the L4 and L5 populations to be taxonomically indistinguishable at large sizes, as well as include findings about certain objects that have resulted from these data. Specifically, multi-filter light curves for twelve objects show signs of V-I color variation in as many as two thirds of these objects, and our richest datasets allow for the determination of phase curves and shapes for some asteroids including a new shape model and pole solution for (1173) Anchises. Our goal is to use this study to shed light on these fascinating objects and to place the Trojans in context in the larger Solar System.

No description available.