An application of the individual channel analysis and design approach to control of a two-input two-output coupled-tanks system

Frequency-domain methods have provided an established approach to the analysis and design of single-loop feedback control systems in many application areas for many years. Individual Channel Analysis and Design (ICAD) is a more recent development that allows neo-classical frequency-domain analysis and design methods to be applied to multi-input multi-output control problems. This paper provides a case study illustrating the use of the ICAD methodology for an application involving liquid-level control for a system based on two coupled tanks. The complete nonlinear dynamic model of the plant is presented for a case involving two input flows of liquid and two output variables, which are the depths of liquid in the two tanks. Linear continuous proportional plus integral controllers are designed on the basis of linearised plant models to meet a given set of performance specifications for this two-input two-output multivariable control system and a computer simulation of the nonlinear model and the controllers is then used to demonstrate that the overall closed-loop performance meets the given requirements. The resulting system has been implemented in hardware and the paper includes experimental results which demonstrate good agreement with simulation predictions. The performance is satisfactory in terms of steady-state behaviour, transient responses, interaction between the controlled variables, disturbance rejection and robustness to changes within the plant. Further simulation results, some of which involve investigations that could not be carried out in a readily repeatable fashion by experimental testing, give support to the conclusion that this neo-classical ICAD framework can provide additional insight within the analysis and design processes for multi-input multi-output feedback control systems

A mathematical model of the human respiratory system during exercise

This paper describes a respiratory control system model and the associated computer simulations for human subjects during incremental exercise, involving work rates from zero up to the highest level in the heavy exercise domain. Modelling the respiratory control system for conditions above lactate threshold has rarely been attempted because many subsystems begin to lose proportionality in their responses. Our model is built on the basis of putative mechanisms and is based on information identified from a large body of published work. Simulation results are presented and validated using experimental results from published sources. The model confirms that the human body employs an open-loop control strategy for ventilation during exercise, which contrasts with the negative feedback control mode employed for the rest condition. It is suggested that control of ventilation simultaneously involves at least two variables, one being proportional to the pulmonary CO2 output and another being proportional to blood acidity

The impact of boundary conditions on CO2 capacity estimation in aquifers

The boundary conditions of an aquifer determine the extent to which fluids (including formation water and CO2) and pressure can be transferred into adjacent geological formations, either laterally or vertically. Aquifer boundaries can be faults, lithological boundaries, formation pinch-outs, salt walls, or outcrop. In many cases compliance with regulations preventing CO2 storage influencing areas outside artificial boundaries defined by non-geological criteria (international boundaries; license limits) may be necessary. A bounded aquifer is not necessarily a closed aquifer. The identification of an aquifer’s boundary conditions determines how CO2 storage capacity is estimated in the earliest screening and characterization stages. There are different static capacity estimation methods in use for closed systems and open systems. The method used has a significant impact on the final capacity estimate. The recent EU Directive (2009/31/EC) stated that where more than one storage site within a single “hydraulic unit” (bounded aquifer volume) is being considered, the characterization process should account for potential pressure interactions. The pressure interplay of multiple sites (or even the pressure footprint of just one site) is heavily influenced by boundary conditions

The Statistical Relationship between Imports of Investment Goods and Gross Domestic Product in Developing Countries

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The relation between questions indicating transient ischaemic attack and stroke in 20 years of follow up in men and women in the Renfrew/Paisley Study

<b>STUDY OBJECTIVE</b> Transient ischaemic attack (TIA) is often a precursor to stroke, so identification of people experiencing TIA could assist in stroke prevention by indicating those at high risk of stroke who would benefit most from intervention for other stroke risk factors. The objective of this study was to investigate whether answers to a simple questionnaire for TIA could predict the occurrence of stroke in the following 20 years. DESIGNProspective cohort study, conducted between 1972 and 1976, with 20 years of follow up. <b>SETTING</b> Renfrew and Paisley, Scotland. <b>PARTICIPANTS</b> 7052 men and 8354 women aged 45-64 years at the time of screening completed a questionnaire and attended a physical examination. The questionnaire asked participants if they had ever, without warning, suddenly lost the power of an arm, suddenly lost the power of a leg, suddenly been unable to speak properly or suddenly lost consciousness. These four questions were taken as indicators of TIA and were related to subsequent stroke mortality or hospital admission. <b>MAIN RESULTS</b> For women, each question was significantly related to stroke risk, whereas for men only the question on loss of power of arm was significantly related to stroke risk. Men and women answering two or more questions positively had double the relative rate of stroke compared with men and women answering none of the questions positively, even after adjusting for other risk factors for stroke. <b>CONCLUSIONS</b> A simple questionnaire for TIA could help predict stroke over 20 years of follow up. Targeting men and women who report TIA with early treatment could help to prevent strokes from occurring

Optimisation of the weighting functions of an H_∞ controller using genetic algorithms and structured genetic algorithms

In this paper the optimisation of the weighting functions for an H<sub>∞</sub> controller using genetic algorithms and structured genetic algorithms is considered. The choice of the weighting functions is one of the key steps in the design of an H<sub>∞</sub> controller. The performance of the controller depends on these weighting functions since poorly chosen weighting functions will provide a poor controller. One approach that can solve this problem is the use of evolutionary techniques to tune the weighting parameters. The paper presents the improved performance of structured genetic algorithms over conventional genetic algorithms and how this technique can assist with the identification of appropriate weighting functions' orders

Suicide in Scottish military veterans: a 30-year retrospective cohort study

Background: Although reassuring data on suicide risk in UK veterans of the 1982 Falklands conflict and 1991 Gulf conflict have been published, there have been few studies on long-term overall suicide risk in UK veterans. Aims: To examine the risk of suicide in a broad population-based cohort of veterans in Scotland, irrespect ive of length of service or exposure to conflict, in comparison with people having no record of military service. Methods: A retrospective 30-year cohort study of 56205 veterans born 1945–85 and 172741 matched non-veterans, using Cox proportional hazard models to compare the risk of suicide and fatal self-harm overall, by sex, birth cohort, length of service and year of recruitment. Results: There were 267 (0.48%) suicides in the veterans compared with 918 (0.53%) in non-veterans. The difference was not statistically significant overall [adjusted hazard ratio (HR) 0.99; 95% confidence interval (CI) 0.86–1.13]. The incidence was lower in younger veterans and higher in veterans aged over 40. Early service leavers were at non-significantly increased risk (adjusted HR 1.13; 95% CI 0.91–1.40) but only in the older age groups. Women veterans had a significantly higher risk of suicide than non-veteran women (adjusted HR 2.44; 95% CI 1.32–4.51, P < 0.01) and comparable risk to veteran men. Methods of suicide did not differ significantly between veterans and non-veterans, for either sex. Conclusions: The Scottish Veterans Health Study adds to the emerging body of evidence that there is no overall difference in long-term risk of suicide between veterans and non-veterans in the UK. However, female veterans merit further study

Die verhouding tussen kerk en staat: Enkele modelle met verwysing na die reg van opstand teen die staat

The interrelationship between church and state: Some theological models with reference to the right to revolt against the state  In this paper consideration is given to the theological models concerning the relation church and state, as accepted by the Roman Catholic Church, Luther, Calvin, Karl Barth and the theologies with a revolutionary inclination like the Political Theology, Theology of Liberation, Revolutionary Theology and the Kairos Document. The right to revolt against the state, as perceived within each model, is also dealt with.

Wat beteken ‘die Bybel sê’? ’n Tipologie van leserskonstrukte

What does ‘the Bible says’ mean? A typology of reader constructsIt is argued that the unity of the Bible, so important to (Reformed) theology, ethics and life, is inevitably the result of constructs on the part of reader communities. A typology of such constructs is suggested, organising of ‘the Bible’ in diverse ways, in order to facilitate discussion between systematic theologians and biblical scholars

Operations Report : BGS Project 04/04 marine geophysics survey 2004 Outer Bristol Channel

This report describes the operation for BGS Project, managed and run by BGS Marine Operations and Engineering. The report covers the mobilisation on the 18th August, the geophysical survey and the demobilisation on the 28th August 2004. The main objective of the survey was to provide baseline physical and geological data for the sustainable development of sea-bed resources. This survey is part of a larger BGS project ‘The Outer Bristol Channel Marine Habitat Study’ The operational aims of the survey project were: • To continue with a planned programme, (started last year) of 100% data coverage for 11 corridors, 1km wide of multibeam and sidescan sonar • Additionally run the centre line for each corridor with surface tow boomer • Map any interesting features found during the survey The geophysical techniques employed were high-resolution multibeam bathymetry, highresolution sidescan sonar and single channel seismic reflection, (surface tow boomer). All systems were digitally recorded. The vessel used was the RV Prince Madog. This platform proved reliable. Laboratory space was adapted to provide an adequate area. An over the side pole mounted multibeam transducer produced good data collected in marginal weather conditions, the data suffering slightly from pole vibrations. Line steerage was vastly improved from the 2003 survey and was adequate for this project. Although an improvement upon project 03/03 the poor weather played a large part in the survey. This only allowed 4 lines of surface tow boomer to be completed