Bibliography: leaves 267-292. This study aimed at finding better ways of storing ram semen at refrigerator or room temperature with particular reference to ingredients readily available in Indonesia, namely coconut extract and quail egg yolk. Coconut extract showed consistent advantages with regard to sperm motility and quail egg yolk was as effective as hen egg yolk. Investigations were extended to examine storage for subnormal semen such as would be produced during periods of heat stress. Motility was assessed visually and using a Hamilton Thorn semen evaluation apparatus.

The synthesis, characterisation and performance of lithium manganese oxide spinels have been studied in terms of their application as cathode materials in rechargeable lithium batteries. A new air stable synthesis based on a solution route has been proposed. Powder X-ray diffraction demonstrates that formation of single phase spinel is possible at temperatures as low as 200 &deg;C. Chemical analysis indicates that the compositions of the spinels prepared by the new solution route depend on the firing temperature. A temperature of 200 &deg;C gives a composition of LiMn2O4.1 and the oxygen content decreases with increasing firing temperature, reaching LiMn2O4 .02 at 600 &deg;C and LiMn2O4 at 800 &deg;C. TEM indicates that the solution based spinels possess small particle sizes, less than 1 ?m. All these characteristics differ markedly from the highly stoichiometric and crystalline spinel prepared by traditional solid state reaction over 800 &deg;C. Electrochemical cells based on the new spinel cathodes were constructed and subjected to galvanostatical cycling at a high discharge rate of C/2 for 300 cycles (charging at C/4). The material fired at 200 &deg;C exhibits excellent performance at 3 V cells. An initial capacity of around 140 mAhg-1 is obtained, very close to the theoretical capacity (148 mAhg-1 ) expected for LiMn2O4 . An enhancement of capacity retention by nearly 50 % after 300 cycles is obtained if < 1 wt % of carbon is added to the solution during synthesis. After 300 cycles, 64 % of the initial capacity remains. The spinel prepared by the solution route and fired at 600 &deg;C gives excellent performance in 4 V cells. An initial capacity of 120 mAhg-1 is obtained and around 75 % of capacity remains after 300 cycles. Ex-situ X-ray diffraction and electrochemical studies such as ac impedance and cyclic voltammetry including the use of microelectrodes were carried out to understand self-discharge and capacity loss on cycling. Spinel dissolution in the electrolyte as well as layer formed on the electrode surface may play an important part in the cycle life of the 4 V spinel cathode. The capacity loss in the 3 V cells arises from incomplete reversibility of the phase transition between cubic and tetragonal spinel which accompanies each cycle.

No description available.

The focus of this project is the storage of thermal energy in packed beds for bulk electricity storage applications. Packed beds are composed of pebbles through which a heat transfer fluid passes, and a thermodynamic model of the heat transfer processes within the store is described. The packed beds are investigated using second law analysis which reveals trade-offs between several heat transfer processes and the importance of various design parameters. Parametric studies of the reservoir behaviour informs the design process and leads to a set of design guidelines. Two innovative design features are proposed and investigated. These features are segmented packed beds and radial-flow packed beds respectively. Thermal reservoirs are an integral component in a storage system known as Pumped Thermal Energy Storage (PTES). To charge, PTES uses a heat pump to create a difference in internal energy between two thermal stores; one hot and one cold. The cycle reverses during discharge with PTES operating as a heat engine. The heat pumps/engines require compression and expansion devices, for which simple models are described and are integrated with the packed bed models. The PTES system behaviour is investigated with parametric studies, and alternative design configurations are explored. A multi-objective genetic algorithm is used to undertake thermo-economic optimisations of packed-bed thermal reservoirs and PTES systems. The algorithm generates a set of optimal designs that illustrate the trade-off between capital cost and round-trip efficiency. Segmentation is found to be particularly beneficial in cold stores, and can add up to 1% to the round-trip efficiency of a PTES system. On the basis of the assumptions made, PTES can achieve efficiencies and energy densities comparable with other bulk electricity storage systems. However, the round-trip efficiency is very sensitive to the efficiency of the compression–expansion system. For designs that utilised bespoke reciprocating compressors and expanders, PTES might be expected to achieve electricity-to-electricity efficiencies of 64%. However, using compression and expansion efficiencies typical of off-theshelf devices the round-trip efficiency is around 45%.

In an age where information has become a crucial commodity, accessing appropriate information quickly is essential to economic success. Developing ways of improving information retrieval is therefore of central concern to human factors and technologists alike. One aspect of information access relates to the ability of individual office workers to manage and retrieve their own information effectively, and this is what the present research addresses. Previous work in the area has been dominated by designing computer interfaces for the average user. This research investigates how people's needs might differ according to circumstance and examines a wider range of design possibilities. Specifically it sets out to relate retrieval problems (specific information retrieval rather than e.g. browsing or reminding) to job and individual (personality) differences within the general context of personal information management in offices using traditional technologies of paper, filing cabinets and desks. This is achieved by both extensive fieldwork and the use of simulated filing-retrieval systems in a controlled context.

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No description available.

As the worldwide energy demand continues to increase, scientists and engineers are faced with the increasingly difficult task of meeting these needs. Currently, the major energy sources, consisting of oil, coal, and natural gas, are non-renewable, contribute to climate change, and are rapidly depleting. Renewable technology research has become a major focus to provide energy alternatives which are environmentally-friendly and economically competitive to sustain the future worldwide needs. Thermal energy storage using adsorption is a promising technology which can provide energy for heating and cooling applications using solar and waste heat sources. The current work aims to improve adsorption systems to provide higher energy outputs and therefore, more economical systems. New adsorbents and operating conditions were tested with the goal of storing the available energy more efficiently. A model was also developed to gain a better understanding of the adsorption system to improve this developing technology.

The technology of magnetic recording, which is involved in most aspects of modem life from credit cards to video tapes, is evolving at an ever quickening pace. As the industry strives to produce greater recording capacity and increased information density the demands on the development of improved magnetic storage and recording head materials cannot always keep up with the pace of change. The materials being considered are not only required to have the desired magnetic properties but also to have the necessary corrosion resistance in the operating environment. It is often the latter which can limit the rate of development of new devices since many of the new materials considered for magnetic storage applications consist of very reactive metals with low corrosion resistances. In establishing how research on the corrosion properties of new magnetic materials should be approached, two different experimental routes are explored in this thesis. These studies were a) a combined electrochemical and surface analysis study and b) a novel 'in-situ' SIMS study. The electrochemical study proved to be a very valuable route in obtaining information on the corrosion properties of the magnetically-active alloy FeMn and such a study can be highly recommended for the application to other magnetic materials. The complete electrochemical properties (anodic and cathodic) of FeMn were determined. A region of passivity was revealed through the application of the very sensitive solution analysis technique of ICPMS. The passive layer is associated with a manganese hydroxide rich surface layer. Passivity in the alloy is very vulnerable to corrosion attack by sodium sulphate active ions. The influence of temperature and pH was investigated. Only under low values of pH with the conditions investigated was the corrosion attack increased compared to neutral conditions. The application of sodium chromate inhibitor was found to enhance the passive layer formed. Using the second route the application of a novel 'in-situ' SIMS technique to look at the oxidation properties of magnetic metals and alloys was explored. The interpretation of the SIMS data for the oxidised and unoxidised components of cobalt was achieved and a model for the reaction of cobalt with oxygen at the initial stages of oxidation was successfully produced. At this present stage it is not possible to model the oxidation of more reactive metals than cobalt.

No description available.