We extend to more than one spatial dimension the semiclassical full-wave vector Maxwell-Bloch equations for the purpose of achieving an adequate and rigorous description of ultrashort pulse propagation in optical waveguides containing resonant nonlinearities. Our considerations are based on the generalized pseudospin formalism introduced by Hioe and Eberly ͓Phys. Rev. Lett. 47, 838 ͑1981͔͒ for treatment of the resonant coherent interactions of ultrashort light pulses with discrete-multilevel systems. A self-consistent set of coupled curl Maxwell-pseudospin equations in two spatial dimensions and time for the special case of a degenerate three-level system of quantum absorbers is originally derived. Maxwell's curl equations are considered to be coupled via macroscopic medium polarization to the three-level atom model for the resonant medium. Two distinct sets of pseudospin equations are obtained corresponding to the TE-and TM-polarized optical waves. For the case of TM polarization, the electromagnetic wave is polarized in a general direction in the plane of incidence inducing two dipole transitions in a degenerate three-level system by each E-field component along the propagation axis and in transverse direction. We introduce a dipole-coupling interaction Hamiltonian allowing Rabi flopping of the population difference along and perpendicular to the propagation axis with frequencies depending on the corresponding field components. The relationship between the induced polarization and the state vector components that describe the evolution of the discrete-level system is derived in order to couple the quantum system equations to the Maxwell's curl equations. The pseudospin equations are phenomenologically extended to include relaxation effects by introducing nonuniform decay times corresponding to the various dipole transitions occurring in a three-level system. The system has been discretized using finite differences on a Yee grid and solved numerically by an iterative predictor-corrector finite-difference time-domain method. Self-induced transparency soliton propagation through a degenerate three-level quantum system of absorbers in two spatial dimensions and time is demonstrated in planar parallel-mirror waveguide geometries.

This thesis is concerned with the results of a joint academic and industrial study on the development of a detailed nonlinear dynamic model of a turbofan jet engine to be used for research into advanced control strategies for civil turbofan aircraft engines. The model is representative of a dual shaft engine with variable bleed, variable stator vanes, turbine cooling, heat transfer, and a duct and exhaust nozzle. A switched, gain-scheduled, feedback control system incorporating bumpless transfer and antiwindup functionality has been designed and implemented according to current industrial practice. This baseline implementation permits realistic transient operation of the simulation and may act as a reference design for further control work. The simulation computes a non-iterative solution, by progressing calculations in the direction of the gas stream flow. Where possible the underlying physics are used and empirical approximations are avoided so that the model requires minimum data. This approach also makes a future inclusion of component failure easier to implement. The simulation is modular in nature so that engine or control modules can be easily replaced or modified if an improved design becomes available. The Simulink implementation of the control architecture has been redesigned to permit the addition or removal of control loops, also during the simulation's operation, to allow testing of advanced control strategies. The entire controller can also be easily replaced. A detailed description of the modeling process, the various simulation issues that arise with a model of this complexity, and the results of the overall aero-engine system are presented. The design of the switched, gain-scheduled aero-engine controller with bumpless transfer and antiwindup which achieves dynamic performance that closely matches that of a real aero-engine is also discussed.i

This paper describes the use of variable kernels based on the normalized Chamfer distance transform (NCDT) for mean shift, object tracking in colour video sequences. This replaces the more usual Epanechnikov kernel, improving target representation and localization without increasing the processing time, minimising the distance between successive frame RGB distributions using the Bhattacharya coefficient. The target shape which defines the NCDT is found either by regional segmentation or background-difference imaging, dependent on the nature of the video sequence. The improved performance is demonstrated on a number of colour video sequences.

We present experimental results of the dynamics in a semiconductor laser operating on several longitudinal modes subject to external feedback. Both low-frequency fluctuations (LFFs) and locked states are studied through observing the outputs from the dominant mode, all modes except the dominant mode, and all modes. Synchronized dropout events of LFFs are observed among each of the solitary modes while energy competition and trading occurs among these modes when the total output exhibits the locked state.

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