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Investigating Dielectric Properties of Sintered Polymers for Rapid Manufacturing
Selective Laser Sintering (SLS) of polymers is the leading technology in the growing field of
Rapid Manufacturing. High Speed Sintering (HSS) is a process that offers the potential to reduce
costs and processing times and thus open significant new markets for Rapid Manufactured parts.
Much academic research has been performed with respect to mechanical properties of Rapid
Manufactured parts, however the area of electrical properties has received little attention to date.
Electrical properties are obviously important in applications that will involve embedding of
circuits with Rapid Manufactured 3D objects. However electrical properties are also important
for a wide variety of electrical products where Rapid Manufactured parts can be used as housings
etc.
This paper focuses on the dielectric properties of parts made by SLS and HSS and compares
properties with those for conventionally processed polymers. Dielectric strength results show
that SLS parts are comparable with injection moulded parts, while HSS parts are inferior to SLS
parts. Dielectric constant and dissipation factor results show that HSS parts are comparable with
injection moulded parts, whilst SLS parts have superior properties. The presence of porosity
(SLS and HSS) and the presence of carbon (HSS) are suggested as reasons behind the variation in
dielectric properties when compared with injection moulded parts.Mechanical Engineerin
LISA Source Confusion
The Laser Interferometer Space Antenna (LISA) will detect thousands of
gravitational wave sources. Many of these sources will be overlapping in the
sense that their signals will have a non-zero cross-correlation. Such overlaps
lead to source confusion, which adversely affects how well we can extract
information about the individual sources. Here we study how source confusion
impacts parameter estimation for galactic compact binaries, with emphasis on
the effects of the number of overlaping sources, the time of observation, the
gravitational wave frequencies of the sources, and the degree of the signal
correlations. Our main findings are that the parameter resolution decays
exponentially with the number of overlapping sources, and super-exponentially
with the degree of cross-correlation. We also find that an extended mission
lifetime is key to disentangling the source confusion as the parameter
resolution for overlapping sources improves much faster than the usual square
root of the observation time.Comment: 8 pages, 14 figure
Serial Position Effects in Short-term Visual Memory: A SIMPLE Explanation?
A version of Sternberg’s (1966) short-term, visual memory recognition paradigm with pictures of unfamiliar faces as stimuli was used in three experiments to assess the applicability of the distinctiveness based SIMPLE model proposed by Brown, Neath & Chater (2002). Initial simulations indicated that the amount of recency predicted increased as the parameter measuring the psychological distinctiveness of the stimulus material (c) increased, and that the amount of primacy was dependent on the extent of proactive interference from previously presented stimuli. The data from experiment 1, which used memory lists of four and five faces varying in visual similarity confirmed the predicted, extended recency effect. However, changes in visual similarity were not found to produce changes in c. In Experiments 2 and 3, the conditions that influence the magnitude of c were explored. These revealed that both the familiarity of the stimulus class before testing, and changes in familiarity due to perceptual learning, influenced distinctiveness as indexed by the parameter c. Overall the empirical data from all three experiments were well-fit by SIMPLE
Mine and me: exploring the neural basis of object ownership.
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Multiple goals and time constraints : perceived impact on physicians' performance of evidence-based behaviours
Peer reviewedPublisher PD
Goal conflict, goal facilitation, and health professionals' provision of physical activity advice in primary care : An exploratory prospective study
Peer reviewedPublisher PD
Darwin Meets Einstein: LISA Data Analysis Using Genetic Algorithms
This work presents the first application of the method of Genetic Algorithms
(GAs) to data analysis for the Laser Interferometer Space Antenna (LISA). In
the low frequency regime of the LISA band there are expected to be tens of
thousands galactic binary systems that will be emitting gravitational waves
detectable by LISA. The challenge of parameter extraction of such a large
number of sources in the LISA data stream requires a search method that can
efficiently explore the large parameter spaces involved. As signals of many of
these sources will overlap, a global search method is desired. GAs represent
such a global search method for parameter extraction of multiple overlapping
sources in the LISA data stream. We find that GAs are able to correctly extract
source parameters for overlapping sources. Several optimizations of a basic GA
are presented with results derived from applications of the GA searches to
simulated LISA data.Comment: 8 pages, 12 figure
Ringing the eigenmodes from compact manifolds
We present a method for finding the eigenmodes of the Laplace operator acting
on any compact manifold. The procedure can be used to simulate cosmic microwave
background fluctuations in multi-connected cosmological models. Other
applications include studies of chaotic mixing and quantum chaos.Comment: 11 pages, 8 figures, IOP format. To be published in the proceedings
of the Cleveland Cosmology and Topology Workshop 17-19 Oct 1997. Submitted to
Class. Quant. Gra
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