Most of the operating vessel traffic management systems experience problems, such as track loss and track swap, which may cause confusion to the traffic regulators and lead to potential hazards in the harbour operation. The reason is mainly due to the limited adaptive capabilities of the algorithms used in the detection process. The decision on whether a target is present is usually based on the magnitude of the returning echoes. Such a method has a low efficiency in discriminating between the target and clutter, especially when the signal to noise ratio is low. The performance of radar target detection depends on the features, which can be used to discriminate between clutter and targets. To have a significant improvement in the detection of weak targets, more obvious discriminating features must be identified and extracted. This research investigates conventional Constant False Alarm Rate (CFAR) algorithms and introduces the approach of applying ar1ificial intelligence methods to the target detection problems. Previous research has been unde11aken to improve the detection capability of the radar system in the heavy clutter environment and many new CFAR algorithms, which are based on amplitude information only, have been developed. This research studies these algorithms and proposes that it is feasible to design and develop an advanced target detection system that is capable of discriminating targets from clutters by learning the .different features extracted from radar returns. The approach adopted for this further work into target detection was the use of neural networks. Results presented show that such a network is able to learn particular features of specific radar return signals, e.g. rain clutter, sea clutter, target, and to decide if a target is present in a finite window of data. The work includes a study of the characteristics of radar signals and identification of the features that can be used in the process of effective detection. The use of a general purpose marine radar has allowed the collection of live signals from the Plymouth harbour for analysis, training and validation. The approach of using data from the real environment has enabled the developed detection system to be exposed to real clutter conditions that cannot be obtained when using simulated data. The performance of the neural network detection system is evaluated with further recorded data and the results obtained are compared with the conventional CFAR algorithms. It is shown that the neural system can learn the features of specific radar signals and provide a superior performance in detecting targets from clutters. Areas for further research and development arc presented; these include the use of a sophisticated recording system, high speed processors and the potential for target classification.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (Ph.D.)--York University, 2003. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 124-126). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NQ99172

Abstract Study was made of host-guest complexation of neutral crown ethers with five- and six-membered N-heteroaromatic cations and purinium cation. Complexation of tetraphenylborate with selected N-heteroaromatic cations and tropylium cation also was studied. Crown ether complexes were characterized by mass spectrometric and 1H NMR spectrometric methods and by X-ray crystallography. Fast atom bombardment mass spectrometry (FABMS) was used as a prelimary tool to characterize the complexes and electrospray ionization mass spectrometry (ESIMS) was used to confirm the complexation stoichiometry. Crystal structures were determined by X-ray crystallography to study the complexation in solid state, and stability constants were measured in acetonitrile by 1H NMR titration at 30 °C to study the complexation in solution. Mass spectrometric studies indicated preferential 1:1 complexation stoichiometry between crown ethers and N-heteroaromatic cations. Crystal structures of crown ether complexes showed that hydrogen bonding and to a lesser degree cation-π and π-π interactions stabilize the structures in solid state. The values of stability constants for crown ether complexes with N-heteroaromatic cations and purinium cation varied between 10 and 350 M-1. Stability constants were higher for complexes with six-membered N-heteroaromatic cations and purinium cation than for complexes with five-membered cations. The values indicated that hydrogen bonding was the main interaction in solution. Tetraphenylborate formed complexes with four N-heteroaromatic cations and tropylium cation, and reacted with six N-heteroaromatic cations through the displacement of one phenyl group by N-heterocycle to form triphenylboranes. The complexes and displacement products were characterized by 1H NMR spectrometry. Four crystal structures of complexes and three crystal structures of displacement products were resolved. Stability constants of complexes were measured in methanol/acetonitrile (1:1) solution at 30 °C by 1H NMR titration method. The values of stability constants for tetraphenylborate complexes with N-heteroaromatic cations ranged from 10 to 50 M-1. C-H···π and N-H···π interactions were found to stabilize the structures both in solid state and in solution.

The aqueous speciation and hydrolysis of actinides in both the presence and absence of organic ligands has been investigated in the pH range 1 - 13. The speciation and hydrolysis of Th4+, U4+ and UO22+ with H3thme, H3tea, H3bic, H3heidi, H3NTA, H2ADA and H3cit have been investigated using various analytical techniques (1H NMR, 13C NMR, IR, UV-Vis(-nIR) spectroscopy and potentiometric titrations). The PHREEQC interactive software suite was used to predict speciation with the formation constants for various complexes calculated in the Hyperquad software suite. Formation constants of Th4+, U4+ and UO22+ hydroxide species have been calculated showing the formation of polymeric complexes. Experiments showed no complexation of actinides by H3thme and H3tea in aqueous solutions. However, 1:3 (M:L) complexation of Th4+ and U4+ was observed with H3bic along with 1:2 (M:L) complexation of UO22+. A variety of 1:1 and 1:2 (M:L) complexes were observed with H3heidi, H3NTA, H2ADA and H3cit for the actinides. Formation constants for complexes of H3NTA with Th4+ and UO22+, H2ADA with Th4+ and H3cit with UO22+ were calculated in Hyperquad. Studies of Pu3+ with H3heidi showed little complexation but 5Me-HXTAH4 showed 1:3 (M:L) speciation. Complexation of PuO22+ by saldien(Et2N)2H2 and salterpyH2 was shown and a secondary band was observed at ~944 nm after multiple days. The functionalities of organic ligands have been shown to have a profound effect on the (partial) hydrolysis of the actinides.

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We present and discuss results from a measurement of the hyperfine a constant of the 1s^(2)2s^(2)2p^(6)3p^(2)2P1/2 excited state in 25Mg+ and the linewidth of the same state in 24Mg+. We trapped a single ion in a linear Paul trap and laser-cooled it using the 2S1/2 -> 2P3/2 transition (in the case of 25Mg+) and the 2S1/2 -> 2P1/2 transition (in the case of 24Mg+). We optically pumped the ion into the (F=3, mp=±3) ground states and weakly probed it with a tunable fibre laser that was scanned to drive the ion from the ground state to the F'=3 and F'=2 manifolds of the 2P1/2 state. The final state of the ion was determined by counting fluorescence (or the reduction therein) from the 2S1/2 (F=3, mF=±3) -> 2P3/2 (F''=4, m''F=±4) cycling transition with a photomultiplier module. We determined that the hyperfine a constant is 102.16 ± 0.16 MHz and the natural linewidth is 42.4 ± 1.2 MHz. / Thesis / Doctor of Philosophy (PhD)

<p> A study is made of the effects of pairing of defects on the dynamics of impure lattices, with the prospect of calculating the properties of crystals with a reasonably high concentration of impurities. A harmonic theory is used, with a mass-defect model, i.e. mass differences only are considered.</p> <p> Various parameters of lattice dynamics are studied, such as the atomic mean square displacement, by use of the Green's functions of Zubarev (1960), as evaluated by Bruno (1971).</p> <p> Finally, a calculation is made of the shifts and widths in the phonon spectrum of Copper due to the addition of 20% Gold impurities. The theory of Aiyer et al. (1969) is used, as corrected by Nickel and Krumhansl (1971), with a derivation along the lines of Langer (1961).</p> <p> It is shown that pairing effects are small and that the high-concentration calculation does not reproduce the experimental results of Svensson and Kamitakahara (1972) so that a more detailed model must be employed, in particular the inclusion of force constant changes and volume effects appears to be necessary.</p> / Thesis / Master of Science (MSc)

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