78 research outputs found
Requiescant in Pace. Staging Nature as a Socio-Religious Practice in Highgate Cemetery
No full textFrom Highgate Cemetery, a few select examples are taken as a case in point, and focused on historical and current source material that presents and represents a particular performativity attributed to nature. The author discusses facets of the theatricality of the landscape, be it the melancholic atmosphere ascribed to it, its aura of wild, romantic seclusion or its role as a peaceful abode. Indeed, such talk of ‹nature› was part of a carefully chosen rhetoric already in the first decades of the 19th century, when the cemetery was realized. It aimed at relating a specific, chosen space to a largely shared imaginary—whereby the term ‹imaginary› refers to a product of imagination, to a framework of mental and material images, to a common ground and dimension of society
Novel hydrophilic polymer couplant for application in ultrasonic non destructive testing
No full textUltrasonic Non Destructive Testing (NDT) is used to inspect materials and
structures for defects. Water is commonly used in NDT as a couplant to
improve ultrasonic transfer between an interrogating probe and test piece.
Unfortunately, the presence of water can cause corrosion and/or degradation
of the test piece material. The aim of this investigation was to evaluate
hydrated cross-linked hydrophilic polymers as candidate solid contact
ultrasonic couplant for use in the field of ultrasonic NDT.
The fact that hydrophilic polymers can absorb and retain large quantities of
water suggested that they might demonstrate the desirable ultrasonic
properties of water without the risks associated with conventional water
coupling. To test this, the ultrasonic properties of a range of hydrophilic
polymers were assessed. Excellent results were achieved, attenuation as low
as 0.36 and 0.71dB mm-1 at 5 and 1OMHz respectively being measured.
Great potential for efficient coupling was established due to acoustic
impedance in the region of 1.81VIN S M-3.
A polymer dependant coupling pressure of less that 1kg CM-2 was required to
achieve optimum coupling to a smooth steel block. Mechanical longevity,
evaluated by life testing, showed that polymers of up to 70% equilibrium water
content were best suited for dynamic testing applications. Temperature was
shown to effect ultrasonic properties; a drop from 5 to
-120C caused an
increase in attenuation of 3dB mm-1 and velocity of 350m s-1. Pressure
demonstrated no influence on attenuation but affected an increase in velocity
of 44m s-1 per kg CM-2
.
Further investigation into the unique ultrasonic
properties of hydrophilic polymers showed that the water sorption process
caused an increase in attenuation prior to saturation being reached. This was
attributed to the absorption of sound during the polymer transformation from
the glassy to rubbery condition observed during hydration. Dehydration from
100 to 37% saturation in a 60% equilibrium water content polymer caused an
increase in attenuation of 1.8dB mm-1 at 5MHz.
The research concluded with the design and development of a prototype
wheel probe employing hydrophilic polymer as the tyre. Operation at 5MHz in
pulse echo mode demonstrated results competitive to conventional immersion
testing. An MMA-VP cross-linked hydrophilic polymer of approximately 60%
equilibrium water content was found most suitable to this application.
This thesis suggests that there is a clear role for hydrophilic polymers in
ultrasonic NDT. The success of the wheel probe design developed as a result
of this research has resulted in patent application in both the UK and USA
Low-Temperature Thermal-Energy Storage and Transmission Systems Employing Hydrophilic Polymeric Materials
No full textThe wide fluctuations that occur in the aggregate electrical demand of a generating
utility are punitive with respect to total system efficiency. Demand side management
techniques have been applied to reduce such fluctuations including the conversion of
electrical energy to thermal energy during periods of low demand for use during peak
demand periods. For thermal processes requiring energy above ambient temperature it
is feasible to use sensible heat due to the existence of stable storage mediums and
efficient methods of heating at the high temperatures required. However where energy
is required below ambient temperatures, efficiency of cooling limits the use of sensible
heat, hence latent heat storage has been adopted. Conventional cold storage systems use
ice banks to store cooling energy at 0°C in order to capture the high latent heat of
fusion of water. The rate of discharge for such stores is limited by thermal resistance in
the store and the thermal capacity of secondary coolants (such as glycol solutions).
This investigated the use of hydrophilic materials to overcome the limitations of
current cold-storage technology. Such materials have the capacity to absorb and retain
up to 95% by mass of water (or other aqueous solutions) regardless of how the
materials is subdivided. Furthermore the thermal properties of the polymers in their
hydrated state resemble those of the free hydration fluid, including any phase
transitions. By supporting the hydrated materials in a non-freeing, non-aqueous fluid
the resultant mixture provides a medium for cold storage that can be pumped and used
at the point of load, and is not limited by the thermal resistance of an encapsulating
material.
Three aspects concerning the utilisation of hydrophilic materials for thermal
engineering applications have been investigated; (i) the physical properties of the
materials
in their hydrated state, (ii) methods of fluidising material in a high density
store, and (iii) the heat transfer properties of hydrophilic based slurries while
undergoing phase transition.
Material tests have shown that currently available hydrophilic materials have thermo-
physical properties that depend principally upon the hydrating fluid, regardless of
particle size, and are stable over long periods (>3years). Suitable hydration fluids can
lower the temperature of the phase transition thus extending their potential as storage
mediums beyond those of ice-based technologies. Novel materials, of very high water
content (95%) have been produced and investigated. These appear to be very suitable
for thermal storage because they increase the maximum achievable energy densities of
a fluidised storage system and potentially reduce cost.
A number of thermal storage devices to utilise hydrophilic based slurries have been
designed and evaluated. The resultant devices has been shown to provide a means of
taking hydrophilic materials to, and from, a packed bed and feeding them at a
controlled rate into a fluid stream. The thermal charge/discharge rates of such a device
are limited only by the choice of external heat exchange systems. An experimental apparatus has been designed to investigate the effects of phase change
particles on the heat transfer properties of flowing mixtures. The results have shown
that (i) at temperatures above the phase transition temperature the presence of the
particles causes an increase in the measured heat transfer coefficient for concentrations
above 10% by volume, (ii) there is a significant interaction of particles at the heat
transfer surface, and (iii) that under high flow rate conditions, with phase change
occurring, heat transfer coefficients are considerably enhanced (ie 80%) above those of
the support fluid when used alone or with non-active particles.
Further work is recommended to extend this study to produce an engineering prototype
storage system for trial evaluation
Refrigeration appliances : Performance enchancements via novel thermal-energy storage
No full textIn recent
*
years there has been increasing concern for the environmental impacts
of economic and technological development. This (principally socio-political) con-
cern has led to the well-known series of environmentall
,y
motivated (global and
local) conventions, agreements and legislation put forward in a bid to manage these
environmental impacts, which in turn has led to research and commercial activ-
ity on environmental issues. One of the major activities identified as adversely
impacting the environment is the manner in which energy is currently harnessed,
inter-converted and utilised. Cont/d
Article about Beryl Bainbridge: Part 3
No full textArticle profiling 1973 Booker shortlisted author Beryl Bainbridg
View from lookout, New Lake View Hotel, Highgate Springs, Vt.
No full textCopyright deposit; R. H. Cassens; October 15, 1920
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