Details of the problems and links to reports
AKZO: Optimal blower design
In some spinning processes, split blowers are used to transport and
stretch filaments. Pressurised air is forced through a nozzle to create a
high speed flow. The objective of the study is to minimise the
pressurised air while maintaining sufficient frictional forces on the
surface of the filaments. Probably one of the main variables is the
geometry of the blower.
[Download report (postscript file)]
WS Atkins: Cracking and buckling in ship bulkheads
An important cause of bulk carrier loss [1] is ingress of sea water owing
to cracks in the side shell as a consequence of main frame deterioration
and the subsequent failure of transverse bulkheads adjacent to the flooded
hold. When the hold is flooded the stresses in the bulkhead are known to
exceed yield and the bulkhead to have undergone slight distortion [2].
The vertical bulkheads are corrugated and have upper support from cross
deck strips. Typical initial damages are cracks in the joint between
bulkhead corrugations and deck plating due partly to corrosion. These can
lead to portions of the cross deck strip becoming detached from the
bulkhead. Pressure on the ship sides can then cause the bulkhead and
cross deck strip to buckle, with minor and local buckles on the bulkhead
leading to shear buckling of the whole structure.
The purpose of the Study Group will be an investigation of this cracking
and buckling process.
[1] Det Norske Veritas report, Bulk carrier losses, Nov. 1991
[2] Lloyd's List, Letter from J Bell (IACS President), Feb. 1997
[Download report (postscript file)]
AEA Technology: Risk estimates (obtained from highly skewed
distributions)
In radiological exposure, risk is the probability of a serious health
effect as a result of that exposure. This is proportional to the
expectation of annual dose. The aim of probability safety assessment is
to estimate the estimated dose as a function of time, however there is no
expert opinion of the PDF of the dose information on which comes from the
observed distribution. Errors arise in estimations when this is highly
skewed.
The problem is to estimate this error given various assumptions on the
form of the distribution.
[Download report (postscript file)]
ELKEM: (i) Electrode paste briquette softening
In electrical smelting, current is supplied through electrodes which are
gradually consumed. These electrodes are made of paste which flows under
increasing temperature. The paste is charged by adding paste briquettes
on top of the electrode which soften and flow to form a dense fluid which
is baked to form the solid electrode. When producing electrodes rapidly
the softening/flow process can be incomplete due to trapped air leading
to breakages.
The objective of the Study Group is a mathematical analysis of this
process which will allow a transfer of laboratory measurements to
conditions for real electrodes.
[Download report (postscript file)]
ELKEM: (ii) Homogenisation of thermal and electrical properties of
the Søderberg electrode
Current is supplied to a Søderberg electrode by copper clamps that are
attached to the steel casing around the electrode. From this casing
steel fins run into the paste to enhance current transport, creating a
non-uniform distribution of current and temperature within the paste.
The aim for the Study Group is to determine whether a homogneisation
approach can be used to reduce the problem to one with axial symmetry.
[Download report (postscript file)]
Food Sciences: (i) Determining thermal properties of food
The composition of a food substance can be inferred (in part) from its
thermal properties. These can in turn be measured using a thermal probe.
In a previous Study Group the effectiveness of using a single probe was
considered. The current investigation will extend this to look at
optimal placings of several probes so that repeated thermal measurements
are made (with associated errors), the food composition
can be accurately calculated and errors in the determined composition
estimated.
[Download report (postscript file)]
Food Sciences: (ii) Micro-waving food
Susceptors are food containers made to absorb electromagnetic energy
which heat up and brown the food. Unfortunately components of the plastics
on the containers migrate into the food.
The questions for the Study Group are of estimating the temperature of the
receptors and also in improving the uniformity of the micro-wave heating.
[Download report (postscript file)]
ICI: Mudcracking in drying paint
Thicker coatings of paint made up of water, polymer latex, titanium dioxide
pigment and with no organic solvents, exhibit mudcracking when they dry.
This is due to a build up of stress in the drying film. There is a need to
develop a theory of mud mechanics which shows the role of the pigment
volume concentration in the paint thickness and the latex viscosity in
developing stress in the film.
The aim is to reduce the build up of stress in the drying film to avoid
crack initiation.
[Download report (postscript file)]
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