Thesis (M. Sc.)--University of Hong Kong, 1968. / Mimeographed.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

As technological advances throughout the field of satellite geodesy improve the accuracy of satellite measurements, numerical methods and algorithms must be able to keep pace. This becomes increasingly important for high precision applications, such as high degree/order gravity field recovery. Currently, the Gravity Recovery and Climate Experiment's (GRACE) dual one-way microwave ranging system can determine changes in inter-satellite range to a precision of a few microns; however, with the advent of laser measurement systems nanometer precision ranging is a realistic possibility. With this increase in measurement accuracy, a reevaluation of the accuracy inherent in the numerical integration algorithms is necessary. This study attempts to quantify and minimize these numerical errors in an effort to improve the accuracy of modeling and propagation of various orbital perturbations; helping to provide further insight into the behavior and evolution of the Earth's gravity field from the more capable gravity missions in the future. The numerical integration errors are examined for a variety of satellite accelerations. The propagation of orbits similar to those of the GRACE satellites using a gravitational model that assumes the Earth is a perfect sphere show integration errors, using double precision numerical representations, on the order of 1 micron in inter-satellite range and 0.1 nanometers per second in inter-satellite range-rate. In addition, when the Earth's gravitational field is formulated in spherical harmonics these numerical integration errors begin to contaminate signals to due harmonics approximately above degree 220, for an orbit at GRACE altitudes. Also, when examining the effect of mass anomalies on the Earth's surface, simulated as point masses, it is apparent that numerical integration methods are easily capable of resolving point mass anomalies as small as 0.05 gigatonnes. Finally, a numerical integration procedure is determined to accurately simulate the effect of numerous, small step accelerations applied to the satellite's center of mass due to misalignment and misfiring of the attitude thrusters. Future studies can then use this procedure as a metric to evaluate the accuracy and effectiveness of an accelerometer in reproducing these non-gravitational forces and how these errors might affect gravity field recovery. / text

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Field performance of micropropagated (MP) and conventionally propagated (CP) red raspberry (Rubus idaeus L. cv. Comet and Festival) was examined under hedgerow and stool cane management systems for 3 seasons (1989 to 1991). All MP plants established well compared to 58% survival rates 45 days after planting and 92% survival rates after replanting for CP plants. The MP plants were more vigorous compared with the CP plants for the duration of this study as indicated by more and taller canes. MP 'Festival' in 1990 yielded 2.2 MT$ cdot$ha$ sp{-1}$, almost half the yield of established commercial plantings in Quebec, while yields from CP 'Festival' and MP and CP 'Comet' were negligible. The MP 'Festival' crop (8.42 MT$ cdot$ha$ sp{-1}$) also outyielded CP 'Festival' (6.8 MT$ cdot$ha$ sp{-1}$) and both MP (5.72 MT$ cdot$ha$ sp{-1}$) and CP (4.91 MT$ cdot$ha$ sp{-1}$) 'Comet' in the second fruiting year. Propagation method had no effects on winter hardiness, photosynthetic capacity nor leaf and stem morphology of either cultivar. The results indicated that MP plants were superior to CP plants for both nursery propagation and fruit production due to their more consistent establishment and increased vigor. Red raspberry plantlets were successfully hardened in vitro on low-sucrose or sucrose-free media through CO$ sb{2}$ enrichment (1500 ppm) and relative humidity reduction (90%) using a forced ventilation system in specially constructed plexiglass chambers. Enriched CO$ sb{2}$ significantly increased general vigor, root formation, root growth, plantlet growth and plantlet photosynthetic capacities. Sucrose in the medium promoted plantlet growth but depressed photosynthesis. In vitro relative humidity at 90% decreased stomatal apertures and improved plantlet ex vitro performance but did not affect the CO$ sb{2}$ uptake rates of cultured plantlets or ex vitro transplants. The maximum CO$ sb{2}$ uptake rates of plantlet leaves were about 52-69% that of greenhouse control pla

Immature, green female cones of Pinus patula Scheide et Deppe. were collected on a weekly basis during the South African summer months from December 1991 to February 1992 and from December 1992 to March 1993. Embryogenic tissue was initiated from excised megagametophyte explants containing immature zygotic embryos. Embryogenic induction was achieved using both MSG (BECWAR, NAGMANI & WANN 1990) and DCR (GUPTA & DURZAN 1985) media. The highest induction frequency was obtained on DCR1 (Douglas-fir Cotyledon Revised) medium supplemented with 0.5 mg 1 ¯¹ BA and 3.0 mg 1 ¯¹ 2,4-D, using L-glutamine as the major nitrogen source. Embryogenic tissue was translucent-to- white and mucilaginous in nature, composed of elongated, suspensor-like cells. The tissue was extruded from the micropylar end of the female gametophyte. In comparison, nonembryogenic tissue was produced from the gametophytic tissue itself and consisted of small, compact, spherical cells, crystalline in nature. Anatomical studies of developing patula seed demonstrated that the production of embryogenic tissue from the immature explants co-incided with the period, approximately two weeks after fertilization and with the occurrence of cleavage polyembryony in the developing zygotic embryos. Embryogenic tissue was maintained in culture by a recapitulation of the cleavage process. Transfer of the embryogenic tissue to DCR2 medium containing 1.3 mg 1 ¯¹ ABA resulted in tissue maturation and in the subsequent development of somatic embryos. Presence of ABA in the culture medium stimulated the development of cotyledonary initials in the apical region of the embryos. Elongated embryos, possessing small cotyledons, were rooted (50 to 60 %) on MSG6 medium containing no plant growth regulators. Somatic plantlets were successfully hardened-off under greenhouse conditions. Liquid culture methods were found to be a useful means of rapidly increasing the volume of embryogenic suspensor masses. Maturation , in terms of somatic embryo development and the production of cotyledonary initials, though , was not obtained in suspension. Reestablishment onto agar-solidified medium (DCR2) was required before maturation could occur. ABA is also responsible for stimulating reserve deposition and mobilization. In this regard, lipid accumulation in the developing somatic embryos was quantified and found to be significantly lower than in developing zygotic embryos. Similarly, non-matured embryogenic tissue contained less lipid deposits than matured (ABA-treated) tissue, indicating the requirement for ABA during maturation. Quantification of the lipids deposits is useful in determining the potential for somatic embryos to acclimatize to ex vitro conditions since their further growth and development is based on their ability to accumulate storage reserves. Somatic embryogenesis was found to be a useful method of propagation, producing plantlets with seedling-like qualities. This development has important consequences for the production of clonal plantlets in the Forestry Industry. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.

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The objective of the presented research is to develop a novel, ink-jet printed, chipless, passive, wireless sensor topology, which can radiate in a near isotropic pattern without interference from embedded devices, for use in dispersed sensor networks. This objective includes the development of a hardware based, uniquely identifiable, collision avoidance communication method, and an integrated sensor system that is easily integrated into the topology. Wireless sensor networks can be and are used in military, medical and industrial applications; and the demand for them is ever growing. However, current sensor networks have various trade-offs and limitations, including cost, number of distinguishable nodes, and ease of manufacturing. These trade-offs lead to unique sensors needing to be designed for each situation. To develop a widely used module, a topology must be developed that can meet as many demands as possible with fair tradeoffs. Many of the above proposed criteria for the topology are already integrated into RFID technology. Therefore, much of the research is the application and advancement of current RFID technology for the purpose of designing the topology. The research begins with the theory and design of conformal artificial magnetic conductors, which is used in the design of a near isotropic radiator and isolated core for device embedding. Then, novel fabrication techniques will be investigated and deployed in the fabrication of the topology. Next, a novel "smart skin" sensor is developed which is easily integrated into the desired fabrication technique. Finally, an anti-collision RFID circuit for on-tag placement, which is based on frequency-doubling transceivers, is designed, which can also be easily integrated into the final topology. This module is designed for use with a variety of different sensors. This versatility gives it ruggedness for use in many different environments. For proof of concept, this topology is fabricated and tested against current commercially sold tags. Through the design and testing of the radiator, circuitry, and embedded sensors, it is shown that this design is a suitable topology for use in many different environments and applications.

The identification of possible hazards in chemical plants is a very important part of the design process. This is because of the potential danger that large chemical installations pose to the public. One possible route for speeding up the identification of hazards in chemical plants is to use computers to identify hazards automatically. This will facilitate safe plant design and will avoid late design changes which can be very costly to implement. Previous research at Loughborough has concentrated on developing a model-based approach and an analysis algorithm for automating hazard identification. The results generated have demonstrated the technical feasibility of the approach. This approach requires a knowledge-base of unit models. This library of models describes how different plant equipment behaves in qualitative terms. The research described in this thesis develops a method for creating and testing the equipment models. The model library was previously achieved by an expert writing the models in a format that could be directly used by the system described above. An engineer unfamililar with the system would find this difficult. An alternative method would have been to use an intermediary (a knowledge engineer) to gather information from the engineer and convert it into the system format. This would be expensive. Both methods would take up a lot of the engineer's time. An engineer should be able to enter information personally in order to maintain efficiency and avoid information loss through the intermediary. A front end interface has been built to the system which enables an expert to enter information directly without needing to understand details of the application system. This interface incorporates ideas from the knowledge acquisition field in order to produce a tool that is simple to use. Unit-based qualitative modelling can lead to incorrect or ambiguous inference. The method developed here identifies situations where ambiguities may arise. A new modular approach is presented to overcome this type of problem. This method also presents a technique to verify that the models created are both complete and correct.