Past Industrial and Interdisciplinary Workshops

13 February 2015
10:00
Abstract

VerdErg Renewable Energy Ltd is developing a new hydropower unit for cost-effective energy generation at very low heads of pressure. The device is called the VETT after the underlying technology – Venturi Enhanced Turbine Technology. Flow into the VETT is split into two. The larger flow at low head transfers its energy to the smaller flow at a greater head. The smaller flow powers a conventional turbo-generator which can be a smaller, faster unit at an order of magnitude lower cost. Further, there are significant environmental benefits to fish and birds compared to the conventional hydropower solution. After several physical model test programmes* in the UK, France and The Netherlands along with CFD studies the efficiency now stands at 50%. We wish to increase that by understanding the major loss mechanisms and how they might be avoided or minimised.

The presentation will explain the VETT’s working principles and key relationships, together with some possible ideas for improvement. The comments of attendees on problem areas, potential solutions and how an enhanced understanding of key phenomena may be applied will be most welcome.

*(One was observed by Prof John Ockendon who identified a fairly extreme flow condition in a region previously thought to be benign.)

  • Industrial and Interdisciplinary Workshops
12 December 2014
10:00
Abstract

Most sensing systems exhibit so-called ‘sidelobe’ responses, which can be interpreted as an inevitable effect in one domain of truncation of the signal in the Fourier-complement domain.  Perhaps the best-known example is in antenna theory where sidelobes are an inevitable consequence of the fact that the antenna aperture must be finite.  The effect also appears in many other places, for example in time-frequency conversions and in the range domain of a pulse-compressed radar which radiates a signal only over a finite frequency band.  In the range domain these sidelobes extend over twice the length of the transmitted pulse.  For a conventional radar with relatively short pulses the effect of these unwanted returns is thus confined to a relatively short part of the range swathe.

 

Some of the most modern radar techniques, however, use continuous, noise-like transmissions.  ‘Primary’ noise-modulated radars are in their infancy but so-called ‘Passive’ radars using broadcast transmissions as their power source receive similar signals.  The sidelobes of even a small target at very short range can be larger than the main return from a target at much greater range.  This limits the dynamic range of the radar.

 

Since, however, the sidelobe pattern is predictable if the illuminating signal is known sufficiently accurately, the expected sidelobes due to a large target can be estimated and removed to tidy up the image.  This approach was first described formally in:

Hoegbom, J. A., ‘Aperture Synthesis with a Non-Regular Distribution of Interferometer Baselines,’ Astrom. Astrophys. Suppl. 15, pp417-26, 1974.

And is generally known by the name of the ‘CLEAN’ algorithm.

 

The seminar will outline the problem, outline the basic form of the algorithm and ask questions about what is possible with non-iterative versions of the algorithms, how to process the data coherently and how to understand any stability issues associated with the algorithm.

  • Industrial and Interdisciplinary Workshops
21 November 2014
10:00
Abstract

Abstract:

(i) We consider the modelling of freezing of fluids which contain particulates and fibres (imagine orange juice “with bits”) flowing in channels. The objective is to design optimum geometry/temperatures to accelerate freezing.

(ii) We present the challenge of setting-up a model for lithium or sodium ion stationary energy storage cells and battery packs to calculate the gravimetric and volumetric energy density of the cells and cost. Depending upon the materials, electrode content, porosity, packing electrolyte and current collectors. There is a model existing for automotive called Batpac.

  • Industrial and Interdisciplinary Workshops

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