This thesis is split into two parts: first a statistical analysis of multi-hop MIMO relay networks, followed by a simulation of the perfomance of a P25 SISO multi-hop relay network. The basis of the MIMO section is the developement of an end to end statistical model of the multiple relay channel. This end to end model simplifies the statistics involved, making the analysis of systems with large numbers of relays and antennas more practical. A partial system model is obtained. This is exact for a multiple input single output network and can be used to describe the received signal at a single antenna in a multiple output system. We go on to look at the relationship between end to end system parameters and the paramters of individual inter-relay channels. The SISO section contains a characterisation of BER for P25 relay chains. The effect of the SNR at each relay node, the nature of the channel and the number of relay hops on the BER is determined. Furthermore, the performance trends are compared for a range of common relaying protocols, including amplify and forward and two types of decode and forward.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

In phase shift interferometry (PSI), several factors affect measurement accuracy, such as piezoelectric transducer (PZT) calibration (i.e. PZT slope error) and PZT nonlinearity, vibration, spurious reflection, source bandwidth, detector nonlinearity, and detector noise. The effects of these error sources on several algorithms to solve the phase of the wavefront are studied. When the simple arctangent formula is used, if the PZT slope is properly adjusted, the error due to the PZT quadratic nonlinearity can be tremendously reduced. An exact solution is derived to remove the error when the PZT quadratic nonlinearity is large. Although Carre's formula is insensitive to PZT slope, this formula is more sensitive to the detector nonlinearity than the simple arctangent formula. For most error sources, the error of the phase solved has a double-frequency characteristic. Thus, averaging two measured phases of two runs, which have a ninety degree phase shift related to each other, can effectively reduce the error. For a small vibration, the phase error has a very simple relation to the vibration amplitude, and a very complex relation to the vibration frequency. Although the error caused by vibration has this double-frequency characteristic, the averaging technique does not apply. The error caused by spurious reflection does not have such a characteristic. A new algorithm is proposed to eliminate the phase error caused by certain types of spurious reflection. When detector noise is concerned, the phase error is inversely proportional to the modulation of the intensity times the square root of the number of steps/buckets. For the shot noise, the phase error is inversely proportional to the fringe contrast times the square root of the total number of photons. In practice, the shot noise is very much smaller than the detector noise. In a practical environment, PZT calibration, vibration, and spurious reflection have much more prominent effects on the PSI than the source bandwidth, detector nonlinearity, and detector noise. When spurious reflection and vibration are under control, and the signal-to-noise ratio is about 20, the PSI has an accuracy of 2 degrees, i.e. 3.3nm at 633nm. Because vibration and detector noise are random error sources, the errors caused by them can be reduced by averaging many measurements. However, the error caused by the other discussed sources cannot be reduced by averaging many measurements.

This dissertation formulates and applies a theory describing how one or two strong classical waves and one or two weak quantum mechanical waves interact in a two-level medium. The theory unifies many topics in quantum optics, such as resonance fluorescence, saturation spectroscopy, modulation spectroscopy, the build up of laser and optical bistability instabilities, and phase conjugation. The theory is based on a quantum population pulsation approach that resembles the semiclassical theories, but is substantially more detailed. Calculations are performed to include the effects of inhomogeneous broadening, spatial hole burning, and Gaussian transverse variations. The resonance fluorescence spectrum in a high finesse optical cavity is analyzed in detail, demonstrating how stimulated emission and multiwave processes alter the spectrum from the usual three peaks. The effects of quantum noise during the propagation of weak signal and conjugate fields in phase conjugation and modulation spectroscopy are studied. Our analysis demonstrates that quantum noise affects not only the intensities of the signal and conjugate, but also their relative phase, and in particular we determine a quantum limit to the semiclassical theory of FM modulation spectroscopy. Finally, we derive the corresponding theory for the two-photon, two-level medium. This yields the first calculation of the two-photon resonance fluorescence spectrum. Because of the greater number of possible interactions in the two-photon two-level model, the theoretical formalism is considerably more complex, and many effects arise that are absent in the one-photon problem. We discuss the role of the Stark shifts on the emission spectrum and show how the Rayleigh scattering is markedly different.

This work firstly reviews the experimental data for centrifugal pumps operating in steady-state and transient two-phase flow. The pump head and torque become degraded in two-phase pumping operation. This degradation becomes increasingly severe and abrupt as pump specific speed falls, and is chiefly due to the reduced impeller performance. Degradation depends primarily on specific speed and pump geometry, void fraction and flow coefficient. Degradation also depends on flow regime, fluid viscosity, flow rate and system pressure. The evidence suggests that transient pump performance can be accurately predicted by steady-state tests.A pseudo-two-dimensional analysis is then presented of two-phase flow through a centrifugal pump to predict the head and torque performance over the full range of operating conditions. The loss of performance in the impeller in pumping operation is caused by the large slip that develops between the two phases as the gas slows dramatically compared to the liquid, particularly in stratified flow. In these conditions there is little or no pressure recovery by diffusion in the pump casing, with further energy losses at the impeller exit due to flow impact against the casing.The head and torque performance predicted by the model compared favourably with the results from the single-phase and two-phase experimental pump tests. The comparisons cover all 4 quadrants of pump operation over the whole voidage range for a comprehensive range of pump designs and fluid mixtures. A number of recommendations are made to improve two-phase pump performance for industrial applications.