Robust polynomial controller design

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The work presented in this thesis was motivated by the desire to establish an alternative approach to the design of robust polynomial controllers. The procedure of pole-placement forms the basis of the design and for polynomial systems this generally involves the solution of a diophantine equation. This equation has many possible solutions which leads directly to the idea of determining the most appropriate solution for improved performance robustness. A thorough review of many of the aspects of the diophantine equation is presented, which helps to gain an understanding of this extremely important equation. A basic investigation into selecting a more robust solution is carried out but it is shown that, in the polynomial framework, it is difficult to relate decisions in the design procedure to the effect on performance robustness. This leads to the approach of using a state space based design and transforming the resulting output feedback controller to polynomial form. The state space design is centred around parametric output feedback which explicitly represents a set of possible feedback controllers in terms of arbitrary free parameters. The aim is then to select these free parameters such that the closed-loop system has improved performance robustness. Two parametric methods are considered and compared, one being well established and the other a recently proposed scheme. Although the well established method performs slightly better for general systems it is shown to fail when applied to this type of problem. For performance robustness, the shape of the transient response in the presence of model uncertainty is of interest. It is well known that the eigenvalues and eigenvectors play an important role in determining the transient behaviour and as such the sensitivities of these factors to model uncertainty forms the basis on which the free parameters are selected. Numerical optimisation is used to select the free parameters such that the sensitivities are at a minimum. It is shown both in a simple example and in a more realistic application that a significant improvement in the transient behaviour in the presence of model uncertainty can be achieved using the proposed design procedure.UK Science and Engineering Research Counci

The Role of Control and System Theory in Systems Biology

The use of new technology and mathematics to study the systems of nature is one of the most significant scientific trends of the century. Driven by the need for more precise scientific understand, advances in automated measurement are providing rich new sources of biological and physiological data. This data provides information with which to create mathematical models of increasing sophistication and realism - models that can emulate the performance of biological and physiological systems with sufficient accuracy to advance our understanding of living systems and disease mechanisms. New measurement and modelling methods set the stage for control and systems theory to play their role in seeking out the mechanisms and principles that regulate life. It is of inestimable importance for the future of control as a discipline that this role is performed in the correct manner. If we handle the area wisely then living systems will present a seemly boundless range of important new problems - just as physical and engineering systems have done in previous centuries. But there is a crucial difficulty. Faced with a bewildering array of choices in an unfamiliar area, how does a researcher select a worthwhile and fruitful problem? This lecture is an attempt to help by offering a control oriented guide to the labyrinthine world of biology/physiology and the control research opportunity that it holds

Mainstreaming and beyond: Policy capacity and climate change decision-making

Mainstreaming involves integrating climate adaptation measures into existing policies and programs. This article reviews the policy process and policy capacity of government organizations and suggests that both need to be incorporated into climate change adaptation assessments. A critical part of mainstreaming is evidence-based decision-making, which emphasizes that decision makers should have the best available information in order to make knowledgeable decisions. This requires policy work that involves a wide variety of statistical methods, applied research, and advanced modeling techniques to gauge broad public opinion and attitudes as well as more routine research techniques. A review of previous past quantitative studies conducted mainly in Canada identifies factors driving policy capacity within government departments responsible for formulating, choosing, implementing, and evaluating climate change adaptation policies and programs. Policy capacity has traditionally been objectively measured and includes indicators such as the number of policy staff, their education levels, resources available, roles and tasks, and ongoing training. More attention needs to be paid to the subjective perceptions of individuals who undertake policy work, in particular the attitudes towards the policy-making process. This paper concludes by proposing a policy capacity framework that includes individual, organizational, and sectoral policy capacity considerations

Derivative-based optimization in colour image filtering: an application for derivative learning

[EN] Related to the notion of derivative of a function, its application to function optimization is an interesting and illustrative problem for Engineering students. In the present work, we develop an application of the derivative concept to optimize the filtering of a colour image. This implies to optimize the value of the filter parameter to maximize performance. We propose to maximize the quality of the filtered image represented by the Peak Signal to Noise Ratio (PSNR), which is a function of the filter parameter. The optimal value for the parameter is obtained by means of an algorithm based on the approximation of the derivative of the PSNR function so that finally the optimum filtered image is obtained.[ES] La noción de derivada de una función y su aplicación a la optimización de funciones es un problema interesante e ilustrativo para los estudiantes de ingeniería. En este trabajo, desarrollamos un aplicación del concepto de derivada para la optimización del filtrado de imágenes en color. Ello implica ajustar el parámetro del filtro para obtener un rendimiento óptimo de filtrado. Proponemos maximizar la calidad de la imagen filtrada representada por la relación señal-ruido (Peak Signal-to-Noise Ratio, PSNR), que es una función del parámetro del filtro. El valor óptimo del parámetro se obtiene mediante un algoritmo basado en la aproximación de la derivada de la función del PSNR de manera que se obtenga la imagen filtrada óptima.Sapena, A.; Morillas, S.; Camacho, J. (2009). Derivative-based optimization in colour image filtering: an application for derivative learning. Modelling in Science Education and Learning. 2:45-55. doi:10.4995/msel.2009.3117SWORD4555

Information-seeking to support wellbeing: A pilot study of New Zealand men

In New Zealand, compared to women men have poor health outcomes in a range of domains. Men also report barriers (both personal and structural) in seeking information to improve health and wellbeing. This paper reports a pilot project that investigated the information-seeking of New Zealand men during episodes of mental and physical ill health. The research investigated the ways in which information can be provided to encourage men to engage in information-seeking in a more timely way to improve their health and wellbeing. Results suggest that New Zealand men face considerable barriers accessing information and support and that the pathways to care are often unclear or absent. These findings demonstrate challenges and opportunities to service providers in terms of engaging men. Further research opportunities are also discussed.

Aspects of real-time digital spectral analysis

In the field of control engineering there is a need to study the dynamic behaviour of systems which are subjected to random disturbances. A technique which is of great practical use is to describe the dynamic properties as a function of frequency. This involves determining the frequency content, or spectrum, of the disturbances, and the frequency response function of the system. There are many analogue and digital techniques which are designed for this type of spectral analysis. However, digital computer techniques are often avoided because they are slow, and data must be collected 'off-line'. A recently discovered computational method, termed the fast- Fourier-transform (FFT), enables digital spectral analysis to be carried- out in a much shorter time than was previously possible. In view of this discovery it was decided to develop digital computer programmes which would overcome the disadvantages of conventional digital spectral analysis. Using these programmes a computer would be connected, via an analogue to digital interface, to the signal source, and would process the data as it entered the computer. In the jargon of computing, the computer would be 'on-line' and analyzing the spectra in 'real-time'. The first part of the project consisted of an investigation of the FFP when programmed for an on-line digital computer. The results of this investigation showed that a rapid, accurate, and compact FFT could be programmed by using fixed-point arithmetic, and coding in an assembly language. The speed of the transform was sufficient to allow spectral analysis over a frequency range useful in control applications. Two on-line computer programmes based upon the YPP were then written; one for 'real-time' spectral analysis of a single record, and another for the 'real-time' estimation of the frequency response function relating two signals. In order that the results of these programmes could be sensibly interpreted, a statistical study was made of the spectral estimators used in the programmes. Arising from this study, several contributions to the field of digital spectra. analysis were made. These were : - 1) A more general covariance relationship for cross-spectral estimators. 2) An examination of aliasing in digital spectral estimators. 3) Some theoretical results concerning spectral estimators for closed loop systems with random disturbances inside the loop, Some experimental work was conducted with the real-time' spectral analysis programmes, and it was concluded that the tec: inique is more powerful than conventional digital. methods because it is on- line, and can provide estimates with improved resolution and statistical stability. Real-time digital spectral analysis methods also have the advantage that they may be simply and quickly modified to suit specific applications

Responding to a forest catastrophe: The emergence of new governance arrangements in Southern California

The San Bernardino National Forest in southern California experienced an unprecedented bark beetle outbreak in the early 2000s. The outbreak, coupled with a looming threat of catastrophic wildfire, droughts, changing forest management priorities, and a legacy of poor forest management practices coalesced to create a challenge that existing institutions and management agencies could not address. In response, an interagency collaborative effort, the Mountain Area Taskforce (MAST), was initiated. Based on key informant interviews, this paper details how this new governance organization emerged and how it effectively addressed a landscape scale forest challenge. Forest governance analyses often focus attention on macroscales, overlooking the microlevel arrangements that set MAST apart from other responses to bark beetle outbreaks. Interagency collaboration has taken on greater importance in efforts to address forest management at landscape scales and this case study provides important insights into the challenges and opportunities of these new governance arrangements

Active alignment for two-beam interferometers

An active control system is described for the automatic alignment of the mirrors in a two-beam interferometer. From an initial unaligned position the active control system determines the degree of misalignment and adjusts the relative mirror positions accordingly. An embodiment of the system is described for a Michelson interferometer in which one of the mirrors is mounted upon three piezoelectric transducers PZT arranged so that they can both tilt and retard the mirror. Laser sources and corresponding photodetectors are also incorporated such that a control system can use the PZT actuators to produce a series of mirror movements relative to the fixed mirror and give a set of two-dimensional diffraction patterns one for each of the laser photodetectors. Amplitude and phase information is extracted from these patterns which enables the control system to align the mirrors such that the diffraction pattern maxima is at the center of the instrument central photodetector. In a further stage of the control algorithm, the alignment accuracy is refined using information from the laser photodetectors during retardation of the mirror. In this manner, the initial mirror alignment, maintaining that alignment during retardation and diagnosis of possible misalignment, become part of a single active control technology for instrument alignment

Policy dialogue and engagement between non-governmental organizations and government: A survey of processes and instruments of canadian policy workers

Various analysts have raised concerns respecting declining research, evaluation and analytical capacities within public services. Typically, the decline is attributed to reforms associated with neoliberal restructuring of the state and its concomitant managerial expression in New Public Management (NPM). This has given rise to a conceptual shift now commonly captured as a movement from ‘government’ to ‘governance’. Policy advising from a new governance perspective entails an image of a more distributed policy advisory system where a plurality of actors, including non-state actors, engages with government in deliberating policy interventions to address collective problems. The original research presented here suggests that those responsible for policy work across four policy communities in the three Canadian provinces surveyed differ in terms of their capacities, depth of commitment to a specific policy file/field, roles and functions, as well as perceptions of the policy work that they undertake. Over the past several years, a number of primarily quantitative analyses examining the processes, tools and perspectives of Canadian federal and provincial government policy analysts have been published. Consequently, a significant knowledge-base has been acquired respecting what government policy analysts do and their attitudes toward their work but very little is known about external interactions with non-governmental organizations (NGOs)