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Within the aircraft industry, a large number of the aluminium components are milled entirely from single solid billets of metal. Current practice is to machine at conservative and constant feed-rates. This avoids damage to the workpiece and therefore reduces costly scrap. On-board monitoring systems on milling machines within the aerospace industry have introduced the possibility of continuously and adaptively varying the feed-rate online. It is proposed that this variation could be based on cutting power. Machining parameters, such as depth and width of cut, and tool efficiency, can vary considerably during the manufacture of a single component. It is therefore likely that an adaptive controller should be used. NICS is an adaptive controller algorithm that has been under development since 1990 Stoten et al. It is known to have good properties with respect to robustness and controller performance and is therefore being investigated for use on the milling machines for aluminium components. Substructuring is a dynamic testing technique that combines numerical models and physical tests into a single hybrid experiment. Briefly, it allows the engineer to "glue" a real component (in a lab) and a virtual component (implemented on a computer) together. These real and virtual components can then be tested dynamically and in real-time as if they were a single, complete component. Hence, substructuring provides the engineer with a framework to allow testing of individual components from entire structures at full scale without requiring the complete structure to be physically present. Accurate, hi-fidelity control is essential to the successful reproduction of structures using this technique. Hence, the goal of the work presented in this thesis is the development and implementation of control strategies for use in the field of metal machining. A scheme that the controls the cutting force transmitted to aluminium workpieces by varying the feed-rate is developed. A requirement of this scheme is that it be simple to set up and implement whilst, at the same time, regulate the cutting power in the face of process para peter variations. The ability of the adaptive controller to meet these requirements is demonstrated both in simulation and on a pilot rig developed in the work. A model that relates peak cutting force to measured cutting power is developed for use with the aforementioned control scherne along with high-level control software implementing this scheme. Rirther, controllers both fixed-gain and adaptive, are developed and tailored for use in the substructuring technique. The performance of the developed controllers is investigated both in simulation and in the laboratory on a linear large-scale hydraulic system. The advantages of using the adaptive controller scheme over a fixed-gain linear equivalent are presented. An example demonstrating the use of the substructuring technique in the field of machining is discussed, including a specific application.

This thesis describes an investigation into the application and performance of direct sequence spread spectrum techniques for land mobile radio systems. There is a brief description of the basic principles of operation of direct sequence systems. The multiple user facility is analysed and values obtained for the maximum number of simultaneous system users in terms of system parameters. This clearly illustrates the need for power control. A possible method of providing power control is described. Comparison of user density is made against conventional narrowband modulation methods. There is some discussion of the effect of sequence cross-correlations on the number of system users. The system organisation is mentioned, showing possible application of a calling channel. Consideration is given to the possibilities of bandsharing with narrowband modulation systems. Figures are derived for the resulting interference to existing systems which would be caused by such an arrangement. A brief resume of the pertinent features of the land mobile radio channel is given. The effects of shadowing on the output quality and spectral efficiency of direct sequence systems is discussed. There is an analysis of the effects of shadowing on the user density in small cell schemes. An analysis shows the effects of multipath propagation on direct sequence performance by reference to a simple two path channel. Details are given of a simple experimental direct sequence spread spectrum transmitter and receiver constructed. The measured results for the performance of the system against various forms of interference and channel degredation are compared with their theoretical values. Finally ideas for future work are discussed.

Senecio is the largest angiosperm genus, taking in about 1/7 of all Compositae and exhibiting nearly the whole range of vegetative diversity encompassed by the family. There is satisfactory definition of the genus, and the oft-quoted 'diagnostic' features are commonly lacking, especially among extra-european species. In fact, in the Genera Plantarum of Bentham and Hooker, the diagnosis of Senecio is essentially the same as that of the tribe Senecionideae. It is a commentary on taxonomic progress that the only comprehensive account is that of De Candolle (1837), although since his time the number of named Senecio species has increased fourfold. Clearly a reappraisal of the taxonomy of Senecio and of its relationships with other Compositae is long overdue. Regarding the classification of Compositae, one finds that despite nama changes the tribes have altered very little since their delimitation and establishment by Cassini (1816-34). This is remarkable because the largest angiosperm family, taking in about 1/10 of the flowering plants, would seem to provide plenty of scope for discordant taxonomic opinion. Nevertheless Table 1 shows that of the 13 tribes recognised by Bentham (I873A), seven (i.e. 2, 3, 6, 7, 9, 10 and I3) are identical with or practically the same as Cassini's; and four (i.e. 5, 8, 11 and 12) incorporate or are merely fusion products of short sequences of Cassini's tribes with his groups adopted as subtribes. Only 2 of Cassini's tribes (i.e. 12 and 20) had suffered significant changes.