46,580 research outputs found
A mechatronic approach to supernormal auditory localisation
Remote audio perception is a fundamental requirement for telepresence and teleoperation in applications that range from work in hostile environments to security and entertainment. The following paper presents the use of a mechatronic system to test the efficacy of audio for telepresence. It describes work to determine whether the use of supernormal inter-aural distance is a valid means of approaching an enhanced method of hearing for telepresence. The particular audio variable investigated is the azimuth angle of error and the construction of a dedicated mechatronic test rig is reported and the results obtained. The paper concludes by observing that the combination of the mechatronic system and supernormal audition does enhance the ability to localise sound sources and that further work in this area is justified
You Tube if you want to â a Web 2.0 approach to staff development in web conferencing
How can we identify and make best use of potential resources in a staff development programme promoting web conferencing? What are the resources we should use? This paper regards web conferencing as a potentially powerful tool at the disposal of an institution intent on exploring new models of blended and online learning appropriate to the changing needs of 21st-century learners. It presents web conferencing in the user-centric context of Web 2.0 â the social web technologies whose educational impact is to empower online communication, collaboration, participation and sharing of resources. Based on findings from an 18-month period of evaluation and initial implementation at Leeds Met, it outlines practical staff development approaches in the related areas of user-created content and community involvement that could promote a more efficient and focused dissemination of the insights and experiences of a local, national and world-wide user group
Finite pseudo orbit expansions for spectral quantities of quantum graphs
We investigate spectral quantities of quantum graphs by expanding them as
sums over pseudo orbits, sets of periodic orbits. Only a finite collection of
pseudo orbits which are irreducible and where the total number of bonds is less
than or equal to the number of bonds of the graph appear, analogous to a cut
off at half the Heisenberg time. The calculation simplifies previous approaches
to pseudo orbit expansions on graphs. We formulate coefficients of the
characteristic polynomial and derive a secular equation in terms of the
irreducible pseudo orbits. From the secular equation, whose roots provide the
graph spectrum, the zeta function is derived using the argument principle. The
spectral zeta function enables quantities, such as the spectral determinant and
vacuum energy, to be obtained directly as finite expansions over the set of
short irreducible pseudo orbits.Comment: 23 pages, 4 figures, typos corrected, references added, vacuum energy
calculation expande
Domestic UK retrofit challenge: Barriers, incentives and current performance leading into the green deal
Copyright @ 2012 Elsevier - The official published version can be accessed from the link below.This paper reviews the thermal performance of the existing UK housing stock, the main fabric efficiency incentive schemes and the barriers to obtaining deep energy and CO2 savings throughout the stock. The UK faces a major challenge to improve the thermal performance of its existing housing stock. Millions of dwellings possess âhard-to-treatâ solid walls and have glazing which is not cost effective to improve. A range of fabric efficiency incentive schemes exist, but many do not target the full range of private and social housing. From now on, the Green Deal will be the UK's key energy efficiency policy. However, the scheme is forecasted to have low consumer appeal and low incentives for investors. Moreover, calculated Green Deal loan repayments will be reliant upon estimated energy savings, yet it is claimed that retrofit measures may only be half as effective as anticipated due to a lack of monitoring, poor quality installation and the increased use of heating following refurbishment. Looking to Germany, there has been success through the Passivhaus standard, but the UK currently lacks appropriate skills and cost effective components to replicate this approach. In addition, the embodied energy in retrofit products and materials threatens to counter operational savings.This study is funded by the EPSRC, Brunel University and Buro Happold Ltd
Positive recurrence of reflecting Brownian motion in three dimensions
Consider a semimartingale reflecting Brownian motion (SRBM) whose state
space is the -dimensional nonnegative orthant. The data for such a process
are a drift vector , a nonsingular covariance matrix
, and a reflection matrix that specifies the boundary
behavior of . We say that is positive recurrent, or stable, if the
expected time to hit an arbitrary open neighborhood of the origin is finite for
every starting state. In dimension , necessary and sufficient conditions
for stability are known, but fundamentally new phenomena arise in higher
dimensions. Building on prior work by El Kharroubi, Ben Tahar and Yaacoubi
[Stochastics Stochastics Rep. 68 (2000) 229--253, Math. Methods Oper. Res. 56
(2002) 243--258], we provide necessary and sufficient conditions for stability
of SRBMs in three dimensions; to verify or refute these conditions is a simple
computational task. As a byproduct, we find that the fluid-based criterion of
Dupuis and Williams [Ann. Probab. 22 (1994) 680--702] is not only sufficient
but also necessary for stability of SRBMs in three dimensions. That is, an SRBM
in three dimensions is positive recurrent if and only if every path of the
associated fluid model is attracted to the origin. The problem of recurrence
classification for SRBMs in four and higher dimensions remains open.Comment: Published in at http://dx.doi.org/10.1214/09-AAP631 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
UK Soils: their phosphorus sorption capacity and potential for P removal from sewage effluents in emergent hydrophyte treatment systems
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