Alternatives for jet engine control

Research centered on basic topics in the modeling and feedback control of nonlinear dynamical systems is reported. Of special interest were the following topics: (1) the role of series descriptions, especially insofar as they relate to questions of scheduling, in the control of gas turbine engines; (2) the use of algebraic tensor theory as a technique for parameterizing such descriptions; (3) the relationship between tensor methodology and other parts of the nonlinear literature; (4) the improvement of interactive methods for parameter selection within a tensor viewpoint; and (5) study of feedback gain representation as a counterpart to these modeling and parameterization ideas

Finite settling time stabilization for linear multivariable time-invariant discrete-time systems: An algebraic approach

The problem of Total Finite Settling Time Stabilization of linear time-invariant discrete-time systems is investigated in this thesis. This problem falls within the same area of the well-known deadbeat (time-optimal) control and in particular, constitutes a generalization of this problem. That is, instead of seeking time-optimum performance, it is required that all internal and external variables (signals) of the closed-loop system settle to a new steady state after a finite time from the application of a step change to any of its inputs and for every initial condition. The state/output deadbeat control is a special case of the Total FSTS problem. Using a mathematical and system theory framework based on sequences and the polynomial equation (algebraic) approach, we are able to tackle the FSTS problem in a unifying manner. The one-parameter (unity) feedback configuration is mainly used for the solution of the FSTS problem and FSTS related control strategies. The whole problem is reduced to the solution of a polynomial matrix Diophantine equation which guarantees not only internal stability but also internal FSTS and is further reduced to the solution of a linear algebra problem over R. This approach enables the parametrizat ion of the family of all FSTS controllers, as well as those which are causal, in a Youla-Bongiorno-Kucera type parametrization. The minimal McMillan degree FSTS problem is completely solved for vector plants and a parametrization of the FSTS controllers according to their McMillan degree is obtained. In the MIMO case bounds of the minimum McMillan degree controllers are derived and families of FSTS controllers with given lower/upper McMillan degree bounds are provided in parametric form. Having parametrized the family of all FSTS controllers, the state deadbeat regulation is treated as a special case of FSTS and complete parametrization of all the deadbeat regulators is presented. In addition, further performance criteria, or design constraints are imposed such as, FSTS tracking and/or disturbance rejection, partial assignment of controller dynamics, l1-, l∞-optimization and robustness to plant parameter variations. Finally, the Simultaneous-FSTS problem is formulated, and necessary as well as sufficient conditions for its solution are derived. Also, a two-parameter control scheme is introduced to alleviate some of the drawbacks of the one-parameter control. A parametrization of the family of FSTS controllers as well as the FSTS controllers for tracking and/or disturbance rejection is given as an illustration of the particular advantages of the two-parameter FSTS controllers

A study of some molecular interactions on alumina surfaces by inelastic electron tunnelling spectroscopy

Further developments have been carried out to improve the resolution and sensitivity of the spectrometer by introducing a dual phase lock-in amplifier and using new software to enhance the flexibility of the computer interfaced with the spectrometer. The spectrometer has been utilised to study a variety of molecular orientations on an alumina substrate. These have included an investigation to distinguish optical and geometrical isomers together with some alkynes in order to explore the validity of the previously proposed Selection Rule. The new observation that the triple bond is detected even when parallel to the substrate surface is reported. An attempt to study the polymerisation of ethylene on an alumina substrate has been carried out and some evidence is presented to support an increase in polymerisation with time. It has been shown that formic acid is produced 'in situ' within an aluminium-aluminium oxide-lead tunnelling junction from atmospheric carbon dioxide and water. A mechanism to account for this reaction is proposed. Junction structure has been studied particularly by utilising a modified crystal oscillator thickness monitor to investigate the influence of electrode and insulating oxide thickness both on junction electrical integrity and the mechanism of doping completed tunnelling junctions

Algebraic synthesis methods for linear multivariable control systems

The mathematical formulation of various control synthesis problems , (such as Decentralized Stabilization Problem , (DSP) , Total Finite Settling Time Stabilization for discrete time linear systems, (TFSTS) , Exact Model Matching Problem, (EMMP), Decoupling and Noninteracting Control Problems) , via the algebraic framework of Matrix Fractional Representation . (MFR) - i.e. the representation of the transfer matrices of the system as matrix fractions over the ring of interest - results to the study of matrix equations over rings , such as : A . X + B . Y = C , (X. A + Y . B =C) (1) A· X = B , (y. A = B) (2) A·X·B = C (3) A·X + Y·B = C, X·A + B·Y = C, A·X·B + C·Y·D = E (4) The main objective of this dissertation is to further investigate conditions for existence and characterization of certain types of solutions of equation (1) ; develop a unifying algebraic approach for solvability and characterization of solutions of equations (1) - (4), based on structural properties of the given matrices, over the ring of interest. The standard matrix Diophantine equation (1) is associated with the TFSTS for discrete time linear systems and issues concerning the characterization of solutions according 'to the Extended McMillan Degree, (EMD) , (minimum EMD , or fixed EMD) , of the stabilizing controllers they define , are studied . A link between the issues in question and topological properties of certain families of solutions of (1) is established . Equation (1) is also studied in association with the DSP and Diagonal DSP (DDSP) , for continuous time linear systems . Conditions for characterizing block diagonal solutions of (1) , (which define decentralized stabilizing controllers) , are derived and a closed form description of the families of diagonal and two blocks diagonal decentralized stabilizing controllers is introduced. The set of matrix equations (1) - (4) is assumed over the field of fractions of the ring of interest , ℛ , (mainly a Euclidean Domain, (ED) , and thus a Principal Ideal Domain , (PID)) , and solvability as well as parametrization of solutions over ℛ is investigated under the unifying algebraic framework of extended non square matrix divisors , projectors and annihilators of the known matrices over ℛ . In practice the ring of interest is either the ring of polynomials ℝ [s] , or the rings of proper

Switched-capacitor networks for image processing : analysis, synthesis, response bounding, and implementation

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (p. 279-284).by Mark N. Seidel.Sc.D