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This project uses concepts from modern robust control
theory to develop algorithms for determining the optimal policy that both
achieves sustainable levels of emissions of CO2 (and other greenhouse gases)
and minimises the impact on the economy, but also explicitly addresses the high
levels of uncertainty associated with predictions of future emissions. The aim
of the optimal policy is to adjust factors such as the mix of energy generation
methods and policies for reducing emissions from housing, industry and
transport, in order to achieve a rate of emissions that will allow the
Participants:
Bing Chu, Stephen Duncan, Antonis Papachristodoulou, Cameron Hepburn1,
Simon Roberts2.
Partners:
1Smith School for Enterprise and the Environment, University of
Oxford; 2Arup.
Duration: 2010-2012.
Funding: EPSRC.
Design of Fast Orbit
Feedback Stabilisation System for a Synchrotron
Synchrotrons
can produce very intense of X-rays and ultra violet light for a range of
applications including protein crystallography, materials characterisation and
high resolution imaging. The Diamond Light
Source is a recently constructed synchrotron that produces a 3GeV electron
beam in a ring of circumference 560m. A key component of the process is the
fast beam stabilisation system that regulates the horizontal and vertical
position of the beam in the presence of disturbances in the range 1 to 100Hz
using 178 sensors and actuators positioned around the ring. Using concepts from
the design of cross-directional control systems for web industries, a control
system has been designed and successfully implemented on the synchrotron.
Current research is focussing on implementing the control system on the booster
synchrotron.
Participants: Sandira Gayadeen, Ashley Napier,
Stephen Duncan, James Rowland1, Michael Abbott1, Isa Uzun1,
Günther Rehm1, Mark Heron1
Partners: 1Diamond Light Source.
Duration: 2007-2013
Funding: Diamond Light Source
Keywords: Synchrotron, Beam stabilisation,
Control
Keyphrases: Synchrtron,
Fast orbit beam stabilisation
Incremental
sheet forming is a novel small-scale, production process, which is relevant for
prototyping, low volume production and customisation and which potentially may
lead to environmental improvements, primarily through locating production
nearer to customers. The process is an alternative to the standard sheet
pressing processing currently used in many manufacturing industries, in which a pair of specially-made dies press a flat sheet into a
required geometry. This is efficient, but it is expensive for low volume
manufacture, due to the cost of making the dies. Incremental sheet
forming uses a small indentor, which is dragged
around the sheet, creating a small 'kinked' track. As the tool continues
to track over the sheet, a deformed shape is built up as the sheet undergoes
plastic deformation. Any shape that can be made by pressing,
can also be made by incremental forming, the difference being that incremental
forming does not require any special tooling.
The project
is carried out in conjunction with the Production Processes group in the
Institute for Manufacturing at the
Participants: Hao Wang, Ankor Raithatha, Stephen
Duncan, Kathryn Jackson2, Omer Music2, Julian Allwood2
Partners: 2Institute for
Manufacturing,
Duration: 2005-2011
Funding: EPSRC
Keywords: Manufacturing, Optimal control, Modelling
Key phrases: Incremental sheet forming,
Flexible manufacturing
Control of Fluidised-bed
Dryers using Process Tomography
The aim of the project is
to develop new technologies for product quality control by combining
inferential sensing, online process modelling, tomographic imaging of physical
properties and distributed parameter control. To demonstrate the benefits of
this strategy, a real-time closed-loop control system will be developed to
regulate spatial distribution of gas-solids and moisture content distribution
in a fluidised bed dryer. A typical application of a fluidised
bed dryer is in the drying of tablets for the pharmaceutical industry. Air is
blown from the bottom through a vessel containing the tablets, which are dried
as they “float” in the air flow and a typical quality specification is to
ensure that moisture content of the all tablets in the dryer is uniform. At present, fluidised bed
dryers are "black boxes", i.e. it is difficult to know what is going
on inside, but industrial process tomography allows the variations in the
moisture of the tablets within the dryer to be measured. In the past,
tomography has primarily been used solely for process monitoring, but this
project offers the first opportunity of using tomography for product quality
control. The proposed control scheme will be based on online modelling of
desired gas-solids distribution and moisture content distribution, from which
desired capacitance and loss-conductance profiles can be derived. Both
capacitance and loss conductance measurements from tomographic sensors will be
used as feedback signals for controlling the process in terms of the difference
between the desired profile within the dryer and the measured profile. The
system will control both the gas-solids distribution and the moisture content
distribution in the dryer.
Participants: Javier Villegas, Mingzhong Li,
Stephen Duncan, Haigang Wang3, Rambadi Ragavan4, Wuqiang
Yang3, Peter Senior4
Partners: 3Department
of Electrical Engineering and Electronics and 4Department
of Chemical Engineering,
Duration:
2005-2008
Funding: EPSRC
Keywords: Sensing, Process control
Key phrases: Industrial process tomography,
Distributed parameter control
The sprayform process creates tools and dies by spraying molten
metal from arc spray guns onto a ceramic former. The key step in this
technology is to ensure that as the metal cools, it undergoes a specific
expansive phase transformation that offsets the thermal contraction experienced
by the metal. This allows the formation of dimensionally accurate tools. In
order that the metal undergoes the required transformation, the temperature
profile of the surface has to be accurately controlled throughout the spraying
process. This is achieved by measuring temperature variations in real time with
a thermal imaging camera and then using this information to adjust the rate of
spraying as the guns are moved over the surface by a robot. A full-scale spray
cell has been built and an online control system has been successfully
demonstrated along with offline path planning tools. A commercial version of
the system has been developed. Discussions are currently being held with Ford
Motor Company to continue this research for a further three years during which
time, the process will be scaled up to allow larger tools to be sprayed. This
will involve extending the cell to enable metal to be sprayed simultaneously
form guns mounted on two robots. The ideas are also being used to control a
plasma spraying process.
Participants: Paul Jones, Vassilios Tsachouridis,
Pubudu Pathirana, Stephen Duncan, Tim Rayment5, Sarah Hoile5,
Zoran Djuric5, Patrick Grant5
Partners: 5Department of Materials Science,
Duration: 2000-2006
Funding: EPSRC
Keywords: Manufacturing, Spraying, Control
Key phrases: Spray forming, Optimal
path planning, Tooling
Cross-directional
(CD) control systems have been common in the web processing industries (such as
paper making, metal rolling and plastic film extrusion) since the 1980’s. In
the past two decades, considerable research has taken place in the field of CD
control and a range of alternative strategies have been proposed. This study
will benchmark an existing CD controller installed on a plastic film extrusion
line against state of the art controllers, in order to identify opportunities
for improved profile control and extend modern control design methods to
multi-array CD control systems.
Participants: Andrew
Taylor6, Stephen Duncan, William Heath7.
Partners: 6DuPont Teijin
Films (
Duration: 2006-2010
Funding: Scottish
Keywords: Process control, Performance
monitoring, Bayesian methods
Key phrases: Cross-directional control, Web
processes
Vacuum
plasma spraying is an industrial technique used to coat substrates onto a wide
range of materials. Historically, vacuum plasma spraying processes have been
open-loop processes with, at the most, closed-loop control of the spray
parameters. The key control variable for these processes is the coating quality
and in particular, the microstructure of the coated material. It has been shown
that control of surface temperature during spraying has a direct effect on the
microstructure and this project is designing and implementing a system for
controlling temperature online so that the improvements in coating quality and
process repeatability can be assessed.
Participants: Ewan Davis, Stephen Duncan,
Patrick Grant8
Partner: 8Department of
Materials Science,
Funding: EPSRC
Keywords: Spraying, Control
Key phrases: Thermal spray processes, Vacuum
plasma spraying
Industrial
process tomography systems can measure the concentration profile of different
components or phases of a fluid flow within a pipe. The tomographic
system works by measuring the capacitance or impedance between successive pairs
of electrodes within an array that is mounted around the pipe. A state
estimation scheme is then used to determine the concentration profile.
2-dimensional simulation studies carried out in conjunction with the Department
of Applied Physics at the University of Kuopio, Finland, have indicated that a tomographic sensor can be combined with an array of
injectors in a feedback loop to regulate the concentration profile in the pipe.
The results of this research have been used in the project to control fluidised-bed dryers.
Participants: Anna Ruuskanen9,
Stephen Duncan, Jari Kaipio9
Partners: 9Department of Applied Physics,
Duration: 2003-2005
Funding:
Keywords: Sensing, process control, flow
control
Key phrases: Industrial process tomography,
Distributed parameter control
Cancer
can be treated by using ultra-sound to heat tumours. A key component of the
treatment is the ability to control the temperature profile during heating as
it is necessary to ensure that the temperature within the tumour is
sufficiently high to kill the cancerous cells without affecting the surrounding
healthy tissue. A feedforward strategy for
determining the power that should be applied to an array of ultra-sound sources
has been developed, together with a feedback mechanism that uses images from an
MRI scanner to control the temperature profile within and around the tumour. An
alternative system, that uses ultra-sound for both sensing and actuation, is
currently being investigated.
Participants: Matti
Malinen10, Stephen Duncan, Jari Kaipio10
Partner: 8Department of Applied Physics,
Duration: 2003-2005
Funding:
Keywords: Ultra-sound, cancer
Key phrases: Distributed parameter control
Current
systems for monitoring and regulating the flow of gases during anaesthesia are
relatively crude and there is a considerable scope for using modern sensing
technology to improve both the concentration of gases delivered to the patient
and the overall amount of gas used during the procedure. In conjunction with
the Nuffield Department of Anaesthetics, a prototype control system is being
developed that will be tested. It is intended that the system will be used to
determine the fraction of the blood that is not oxygenated as it passes through
the lungs, directly from the difference between the composition of the inspired
and expired air. Currently, this has to be inferred from the composition of the
blood taken from a separate measurement.
Participants: Sara van
der Hoeven, Stephen Duncan, Andrew Farmery11, Clive Hahn11
Partner: 11Nuffield Department of Anaesthetics,
Duration: 2004-2008
Funding: EPSRC
Keywords: Anaesthesia, Control
Key phrases: Flow control, Concentration
control
The
spread of a disease through a population can be modelled by as a dynamic spatio-temporal system. My work has concentrated on the
spread of smallpox and interest in modelling the spread of this disease has
increased recently, due to the possibility of smallpox being used in a
bio-terrorist attack. The design of strategies for vaccination and quarantine
and other public health measures to combat an outbreak of smallpox started by
bio-terrorist action is critically dependent on an accurate measure of the
transmissibility of the virus. By modelling the dynamics of the disease as a
linear system with a non-linear feedback term, the transmissibility of the
virus can be estimated from the frequency of outbreaks in populations where the
disease is endemic. This approach has been used to derive an estimate of the
value for the transmissibility for
Participants: Stephen Duncan, Susan Scott12
Partners: 12School of Biological
Sciences,
Duration: 2001-2009
Keywords: Epidemics, Modelling,
Transmissibility
Key phrases: Distributed parameter modelling,
System Identification
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