This thesis describes a new method of calculating data priority by using adaptive mobile user and device profiles which change with user location, time of the day, available networks and data access history. The profiles are used for data prefetching, selection of most suitable wireless network and cache management on the mobile device in order to optimally utilize the device�s storage capacity and available bandwidth. Some of the inherent characteristics of mobile devices due to user movements are �non-persistent connection, limited bandwidth and storage capacity, changes in mobile device�s geographical location and connection (eg. connection can be from GPRS to WLAN to Bluetooth). New research is being carried out in making mobile devices work more efficiently by reducing and/or eliminating their limitations. The focus of this research is to propose, evaluate and test a new user profiling technique which specifically caters to the needs of the mobile device users who are required to access large amounts of data, possibly more than the device storage capability during the course of the day or week. This work involves the development of an intelligent user profiling system along with mobile device caching system which will first allocate weight (priority) to the different sets and subsets of the total given data based on user�s location, user�s appointment information, user�s preferences, device capabilities and available networks. Then the profile will automatically change the data weights with user movements, history of cached data access and characteristics of available networks. The Adaptive User and Device Profiles were designed to handle broad range of the issues associated with: �Changing network types and conditions �Limited storage capacity and document type support of mobile devices �Changes in user data needs due to their movements at different times of the day Many research areas have been addressed through this research but the primary focus has remained on the following four core areas. The four core areas are : selecting the most suitable wireless network; allocating weights to different datasets & subsets by integrating user�s movements; previously accessed data; time of the day with user appointment information and device capabilities.

Thesis (Habilitation)--Universität Leipzig, 2008. / Includes bibliographical references (p. 156-177).

Thirty-one strains from the genus Bacteriods (12 species and subspecies) were tentatively identified using cellular fatty acid analysis. The procedures were slightly modified to permit use of packed-column, thermal conductivity instruments, such as would be found in clinical laboratories currently using analysis of volatile/non volatile fatty acids as part of a scheme for the identification of anaerobes. Different types of rapid extraction and commonly used meida . Teh overall rate of correct identification for the black-pigmented and related species of Bacteriodes was 67%. The considerable savings of time in obtaining presumed identification using inexpensive material may be of interest for the routine clinical microbiology laboratory.

Okra (Abelmoschus esculentis) is a warm weather vegetable crop with seed characteristics similar to cotton. Putative similarities between these crops make okra a potential candidate as a biodiesel feedstock. The objectives of this research are to determine an optimal inter and intra-row spacing combination to maximize seed yield, and determine optimal plant characteristics for seed yield, oil production, and fatty acid profiles. Data indicated treatments of (22.86 x 7.62, 22.86 x 22.86, and 45.72 x 30.48 cm) were better than 91.44 x 15.24 cm with respect to seed yield, although, 45.72 x 30.48 and 91.44 x 15.24 cm are the same plant population. Variety trials indicated that Annie Oakley II produced substantial seed and oil yields of 3547 kg ha-1 and 1376 L ha-1, respectively in 2009. Data indicated palmitic, linoleic, and linolenic acids to be the primary constituents of okraseed oil.

No / The determination of velocity profiles in turbulent narrow open channels is a difficult task due to the significant effects of the anisotropic turbulence that drives the Prandtl’s second kind of secondary flow in the cross section. Due to these currents the maximum velocity appears below the free surface. This is called the dip phenomenon. The classical log law describes the velocity distribution in the inner region of the turbulent boundary layer. The Coles law and its wake function are not able to predict the velocity profile in the outer region of narrow channels. This paper relies on an analysis of the Navier-Stokes equations and yields a new formulation of the vertical velocity profile in the outer region of the boundary layer in the central cross section area of steady, fully developed turbulent flows in open channels. This formulation is able to predict primary velocity profiles for both narrow and wide open channels. This new law is a modification of the classical one, it involves an additional parameter CAr that is a function of the position of the maximum velocity ξdip and roughness height (kS).ξdip may be derived either from measurements or from an empirical equation given in this paper. A wide range of longitudinal velocity profile data for narrow open channel has been used for validating the new law. The agreement between the experimental data and the profile given by the law is very good, despite the simplification used.

The increasing demand for energy and the effect on climate change are some of the big drivers in support of the nuclear renaissance. A great amount of energy is spent on studies to determine the contribution of nuclear power to the future energy supply. Many countries are investing in generation III and IV reactors such as the Westinghouse AP1000 because of its passive cooling system, which makes it attractive for its safety. The pebble bed high temperature gas cooled reactors are designed to be intrinsically safe, which is one of the main drivers for developing these reactors. A pebble bed reactor is a high temperature reactor which is helium–cooled and graphitemoderated using spherical fuel elements that contain triple–coated isotropic fuel particles (TRISO). The success of its intrinsic safety lies in the design of the fuel elements that remain intact at very high temperatures. When temperatures significantly higher than 1600 °C are reached during accidents, the fuel elements with their inherent safety features may be challenged. A pebble bed reactor has an online fuelling concept, where fuel is circulated through the core. The fuel is loaded at the top of the core and through gravity, moves down to the bottom where it is unloaded to either be discarded or to be re–circulated. This is determined by the burnup measuring system. By circulating the fuel spheres more than once through the reactor a flattened axial power profile with lower power peaking and therefore lower maximum fuel temperatures can be achieved. This is an attractive approach to increase the core performance by lowering the important fuel operating parameters. However, the circulation has an economic impact, as it increases the design requirements on the burnup measuring system (faster measuring times and increased circulation). By adopting a multi–pass recycling scheme of the pebble fuel elements it is shown that the axial power peaking can be reduced The primary objective for this study is the investigation of the influences on the core design with regards to the number of fuel passes. The general behaviour of the two concepts, multi–pass refuelling and a once–through circulation, are to be evaluated with regards to flux and power and the maximum fuel temperature profiles. The relative effects of the HTR–Modul with its cylindrical core design and the PBMR 400 MW with its annular core design are also compared to verify the differences and trends as well as the influences of the control rods on core behaviour. This is important as it has a direct impact on the safety of the plant (that the fuel temperatures need to remain under 1600 °C in normal and accident conditions). The work is required at an early stage of reactor design since it influences design decisions needed on the fuel handling system design and defuel chute decay time, and has a direct impact on the fuel burnup–level qualification. The analysis showed that in most cases the increase in number of fuel passes not only flattens the power profile, but improves the overall results. The improvement in results decreases exponentially and from ten passes the advantage of having more passes becomes insignificant. The effect of the flattened power profile is more visible on the PBMR 400 MW than on the HTR–Modul. The 15–pass HTR–Modul design is at its limit with regards to the measuring time of a single burnup measuring system. However, by having less passes through the core, e.g. tenpasses, more time will be available for burnup measurement. The PBMR 400 MW has three defuel chutes allowing longer decay time which improves measurement accuracy, and, as a result could benefit from more than six passes without increasing the fuel handling system costs. The secondary objective of performing a sensitivity analysis on the control rod insertion positions and the effect of higher fuel enrichment has also been achieved. Control rod efficiency is improved when increasing the excess reactivity by means of control rod insertion. However, this is done at lower discharge burnup and shut down margins. Higher enrichment causes an increase in power peaking and more fuel–passes will be required to maintain the peaking and temperature margins than before. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.

The increasing demand for energy and the effect on climate change are some of the big drivers in support of the nuclear renaissance. A great amount of energy is spent on studies to determine the contribution of nuclear power to the future energy supply. Many countries are investing in generation III and IV reactors such as the Westinghouse AP1000 because of its passive cooling system, which makes it attractive for its safety. The pebble bed high temperature gas cooled reactors are designed to be intrinsically safe, which is one of the main drivers for developing these reactors. A pebble bed reactor is a high temperature reactor which is helium–cooled and graphitemoderated using spherical fuel elements that contain triple–coated isotropic fuel particles (TRISO). The success of its intrinsic safety lies in the design of the fuel elements that remain intact at very high temperatures. When temperatures significantly higher than 1600 °C are reached during accidents, the fuel elements with their inherent safety features may be challenged. A pebble bed reactor has an online fuelling concept, where fuel is circulated through the core. The fuel is loaded at the top of the core and through gravity, moves down to the bottom where it is unloaded to either be discarded or to be re–circulated. This is determined by the burnup measuring system. By circulating the fuel spheres more than once through the reactor a flattened axial power profile with lower power peaking and therefore lower maximum fuel temperatures can be achieved. This is an attractive approach to increase the core performance by lowering the important fuel operating parameters. However, the circulation has an economic impact, as it increases the design requirements on the burnup measuring system (faster measuring times and increased circulation). By adopting a multi–pass recycling scheme of the pebble fuel elements it is shown that the axial power peaking can be reduced The primary objective for this study is the investigation of the influences on the core design with regards to the number of fuel passes. The general behaviour of the two concepts, multi–pass refuelling and a once–through circulation, are to be evaluated with regards to flux and power and the maximum fuel temperature profiles. The relative effects of the HTR–Modul with its cylindrical core design and the PBMR 400 MW with its annular core design are also compared to verify the differences and trends as well as the influences of the control rods on core behaviour. This is important as it has a direct impact on the safety of the plant (that the fuel temperatures need to remain under 1600 °C in normal and accident conditions). The work is required at an early stage of reactor design since it influences design decisions needed on the fuel handling system design and defuel chute decay time, and has a direct impact on the fuel burnup–level qualification. The analysis showed that in most cases the increase in number of fuel passes not only flattens the power profile, but improves the overall results. The improvement in results decreases exponentially and from ten passes the advantage of having more passes becomes insignificant. The effect of the flattened power profile is more visible on the PBMR 400 MW than on the HTR–Modul. The 15–pass HTR–Modul design is at its limit with regards to the measuring time of a single burnup measuring system. However, by having less passes through the core, e.g. tenpasses, more time will be available for burnup measurement. The PBMR 400 MW has three defuel chutes allowing longer decay time which improves measurement accuracy, and, as a result could benefit from more than six passes without increasing the fuel handling system costs. The secondary objective of performing a sensitivity analysis on the control rod insertion positions and the effect of higher fuel enrichment has also been achieved. Control rod efficiency is improved when increasing the excess reactivity by means of control rod insertion. However, this is done at lower discharge burnup and shut down margins. Higher enrichment causes an increase in power peaking and more fuel–passes will be required to maintain the peaking and temperature margins than before. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.

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