Data-based mechanistic modelling, forecasting, and control.

This article briefly reviews the main aspects of the generic data based mechanistic (DBM) approach to modeling stochastic dynamic systems and shown how it is being applied to the analysis, forecasting, and control of environmental and agricultural systems. The advantages of this inductive approach to modeling lie in its wide range of applicability. It can be used to model linear, nonstationary, and nonlinear stochastic systems, and its exploitation of recursive estimation means that the modeling results are useful for both online and offline applications. To demonstrate the practical utility of the various methodological tools that underpin the DBM approach, the article also outlines several typical, practical examples in the area of environmental and agricultural systems analysis, where DBM models have formed the basis for simulation model reduction, control system design, and forecastin

Controllable forms for stabilising pole assignment design of generalised bilinear systems

Bilinear structures are able to represent nonlinear phenomena more accurately than linear models, and thereby help to extend the range of satisfactory control performance. However, closed loop characteristics are typically designed by simulation and stability is not guaranteed. In this reported work, it is shown how bilinear systems are a special case of the more general state dependent parameter (SDP) model, which can subsequently be utilised to design stabilising feedback controllers using a special form of nonlinear pole assignment. To establish the link, however, an important generalisation of the SDP pole assignment method is developed

Theory and computation of the stability of shear flows over compliant boundaries

Thread annular injection is a minimally invasive technique that entails transporting medical implants into the body via a thread moving through a fluid. It is desirable for this flow to remain laminar so as to ensure that the flow remains predictable and the thread does not suffer any lateral deviations. It is thus of practical interest to determine the range of Reynolds numbers for which this flow is stable. This flow can be modelled by annular Poiseuille-Couette flow (APCF), which is the flow driven by an axial pressure gradient through the annular region between a stationary outer cylinder and a sliding inner cylinder. In this thesis, the linear stability properties of APCF to infinitesimal, axisymmetric disturbances are studied when the inner cylinder possesses a degree of flexibility. A cylindrical version of the Orr-Sommerfeld equation is derived with appropriate boundary conditions that encompass the compliance of the cylinder. This forms the foundation of our numerical studies at finite Reynolds numbers. It is found that there exist modes of instabilities that are not present in the case of a rigid inner cylinder. At large Reynolds numbers, an asymptotic approach is used to gain insights into the different physical balances that give rise to neutrally stable modes. Distinguished scalings are found, including those that have no counterpart for a rigid inner cylinder. These asymptotic results are compared to those from our numerical studies. The inviscid linear stability of this problem is also studied, and analogues to classical inviscid theorems for planar flow over rigid boundaries are provided. In the final chapter of this thesis, our stability analysis focuses on vortex-wave interaction for planar Couette flow when the lower wall is modelled as compliant. The nonlinear equations governing this interaction are solved numerically, and finite-amplitude solutions are found.Open Acces

Nonminimal state space approach to multivariable ramp metering control of motorway bottlenecks

The paper discusses the automatic control of motorway traffic flows utilising ramp metering, i.e. traffic lights on the on-ramp entrances. A multivariable ramp metering system is developed, based on the nonminimal state space (NMSS) approach to control system design using adaptive proportional-integral-plus, linear quadratic (PIP–LQ) optimal controllers. The controller is evaluated on a nonlinear statistical traffic model (STM) simulation of the Amsterdam motorway ring road near the Coen Tunnel

Stability Assessment Using Contraction Conditions For Unknown Multivariable Feedback Systems

The purpose of this paper is to illustrate, using specific examples, the stability region, the contraction condition region and the monotonic condition region in parameter plane. It is our intention to show that contraction condition region is a substantial part of the complete stability region for high gain (continuous) or for fast sampling (discrete)systems and hence gives considerable insight into the system robustness

Proportional-integral-plus (PIP) control of the ALSTOM gasifier problem

Although it is able to exploit the full power of optimal state variable feedback within a non-minimum state-space (NMSS) setting, the proportional-integral-plus (PIP) controller is simple to implement and provides a logical extension of conventional proportional-integral and proportional-integral-derivative (PI/PID) controllers, with additional dynamic feedback and input compensators introduced automatically by the NMSS formulation of the problem when the process is of greater than first order or has appreciable pure time delays. The present paper applies the PIP methodology to the ALSTOM benchmark challenge, which takes the form of a highly coupled multi-variable linear model, representing the gasifier system of an integrated gasification combined cycle (IGCC) power plant. In particular, a straightforwardly tuned discrete-time PIP control system based on a reduced-order backward-shift model of the gasifier is found to yield good control of the benchmark, meeting most of the specified performance requirements at three different operating points

Cost effective combined axial fan and throttling valve control of ventilation rate

This paper is concerned with Proportional-Integral-Plus (PIP) control of ventilation rate in mechanically ventilated agricultural buildings. In particular, it develops a unique fan and throttling valve control system for a 22m3 test chamber, representing a section of a livestock building or glasshouse, at the Katholieke Universiteit Leuven. Here, the throttling valve is employed to restrict airflow at the outlet, so generating a higher static pressure difference over the control fan. In contrast with previous approaches, however, the throttling valve is directly employed as a second control actuator, utilising airflow from either the axial fan or natural ventilation. The new combined fan/valve configuration is compared with a commercially available PID-based controller and a previously developed scheduled PIP design, yielding a reduction in power consumption in both cases of up to 45%

Proportional-integral-plus (PIP) control of time delay systems

The paper shows that the digital proportional-integral-plus (PIP) controller formulated within the context of non-minimum state space (NMSS) control system design methodology is directly equivalent, under certain non-restrictive pole assignment conditions, to the equivalent digital Smith predictor (SP) control system for time delay systems. This allows SP controllers to be considered within the context of NMSS state variable feedback control, so that optimal design methods can be exploited to enhance the performance of the SP controller. Alternatively, since the PIP design strategy provides a more flexible approach, which subsumes the SP controller as one option, it provides a superior basis for general control system design. The paper also discusses the robustness and disturbance response characteristics of the two PIP control structures that emerge from the analysis and demonstrates the efficacy of the design methods through simulation examples and the design of a climate control system for a large horticultural glasshouse system

Standardization of ethanol addiction model in Swiss albino Mice

Background: Addiction is compulsive need for use of a habit-forming substance. World Health Organization (WHO) reported that worldwide 3.3 million people died due to alcohol addiction in 2012-13 and 11% of the population in India indulged in heavy drinking in 2014. Addiction is a prime socio-economical problem of society. Studying alcohol dependence in humans involved many ethical issues and experimental difficulties. Hence nonhuman animal experimental model has been used for a research on the topic of alcohol intoxication and dependence. Ethanol dependence has been preferred to develop in genetically modified strain of mice, C-57 which has a natural inclination to consume and develop addiction. But studying addiction in this special strain requires top end experimental facilities and financial aids. Authors reported the animal model to study ethanol dependence in Swiss albino mice. Aim of the study was to develop ‘Ethanol Dependence in Swiss albino mice animal model’ by intermitted access of 20% ethanol.Methods: Dependence was developed in Swiss albino mice by intermitted access of 20% ethanol in two groups having six animals in each group. Dependence was confirmed by presence of the withdrawal symptoms like anxiety, muscular incoordination and behavioral changes of animals on abstinence of ethanol.Results: Significant difference was noted on withdrawal symptoms, i.e. anxiety, muscular coordination, muscle spasm and other behavior related to withdrawal.Conclusions: Ethanol dependence can be successfully developed in Swiss albino mice in 14 days