1,642 research outputs found
FILOU oscillation code
The present paper provides a description of the oscillation code FILOU, its
main features, type of applications it can be used for, and some representative
solutions. The code is actively involved in CoRoT/ESTA exercises (this volume)
for the preparation for the proper interpretation of space data from the CoRoT
mission. Although CoRoT/ESTA exercises have been limited to the oscillations
computations for non-rotating models, the main characteristic of FILOU is,
however, the computation of radial and non-radial oscillation frequencies in
presence of rotation. In particular, FILOU calculates (in a perturbative
approach) adiabatic oscillation frequencies corrected for the effects of
rotation (up to the second order in the rotation rate) including near
degeneracy effects. Furthermore, FILOU works with either a uniform rotation or
a radial differential rotation profile (shellular rotation), feature which
makes the code singular in the field.Comment: 6 pages, 5 figures. Astrophysics and Space Science (in press
Residents' diverse perspectives of the impact of neighbourhood renewal on quality of life and physical activity engagement: Improvements but unresolved issues
AbstractFew studies have been published on the reactions of residents to modifications of their residential landscape. We explored residents' experiences of home zone remodelling and construction of a new cycle-walkway in a deprived neighbourhood with a particular focus on aspects of quality of life and physical activity participation. Focus groups (n=5 groups, 21 individuals) were used to investigate residents' perceptions of the effects of neighbourhood change on their lives. Consultation by planners was received positively. Several aspects of the neighbourhood were perceived to have improved, including spatial aesthetics, lighting and streetscape planting. However, influence on physical activity was minimal. Car-focused behaviour and ownership remained dominant, and safety related concerns limited behavioural choices. Residents highlighted many socio-environmental challenges that remained such as sense of neighbourhood safety, poor public transport provision, people's parking behaviour locally, and problem neighbours, and these tended to dominate conversations. Infrastructural intervention may be one important part of multi-layered solutions to improved neighbourhood life
In pursuit of the dynamic optimality conjecture
In 1985, Sleator and Tarjan introduced the splay tree, a self-adjusting
binary search tree algorithm. Splay trees were conjectured to perform within a
constant factor as any offline rotation-based search tree algorithm on every
sufficiently long sequence---any binary search tree algorithm that has this
property is said to be dynamically optimal. However, currently neither splay
trees nor any other tree algorithm is known to be dynamically optimal. Here we
survey the progress that has been made in the almost thirty years since the
conjecture was first formulated, and present a binary search tree algorithm
that is dynamically optimal if any binary search tree algorithm is dynamically
optimal.Comment: Preliminary version of paper to appear in the Conference on Space
Efficient Data Structures, Streams and Algorithms to be held in August 2013
in honor of Ian Munro's 66th birthda
Bearing area curve based partitioning for the verification of theoretical supplemental geometry on additively manufactured lattice structures
The geometrical qualification of additively manufactured lattice structures has largely focused on the mea-surement of strut diameter, form variations, and surface texture. However, the exterior surfaces of the lattice structure, defined through theoretical supplemental geometry, are critical surfaces that dictate the contact area of the structure on other components within assemblies. Form variations on these surfaces complicate the measurement process by adding ambiguity into what surfaces of the component belong to the controlled ge-ometry. Previous works have developed novel methods to improve data extraction for the measurement of these surfaces using computer aided design (CAD) data for various lattice structures. This work presents an adaptation of these methods to work with additively manufactured (AM) geometries, specifically designing the methodology to account for the form variations between lattice struts. The presented results show the applicability of these methods to AM lattice structures for the measurement of form defined by a theoretical supplemental surface
Impact of Heat Pump Load on Distribution Networks
© The Institution of Engineering and Technology 2014. Heat pumps can provide domestic heating at a cost that is competitive with oil heating in particular. If the electricity supply contains a significant amount of renewable generation, a move from fossil fuel heating to heat pumps can reduce greenhouse gas emissions. The inherent thermal storage of heat pump installations can also provide the electricity supplier with valuable flexibility. The increase in heat pump installations in the UK and Europe in the last few years poses a challenge for low-voltage networks, because of the use of induction motors to drive the pump compressors. The induction motor load tends to depress voltage, especially on starting. The study includes experimental results, dynamic load modelling, comparison of experimental results and simulation results for various levels of heat pump deployment. The simulations are based on a generic test network designed to capture the main characteristics of UK distribution system practice. The simulations employ DIgSlILENT Power Factory to facilitate dynamic simulations that focus on starting current, voltage variations, active power, reactive power and switching transients
The C parameter distribution in e+e- annihilation
We study perturbative and non-perturbative aspects of the distribution of the
C parameter in e+e- annihilation using renormalon techniques. We perform an
exact calculation of the characteristic function, corresponding to the C
parameter differential cross section for a single off-shell gluon. We then
concentrate on the two-jet region, derive the Borel representation of the
Sudakov exponent in the large-beta_0 limit and compare the result to that of
the thrust T. Analysing the exponent, we distinguish two ingredients: the jet
function, depending on Q^2C, summarizing the effects of collinear radiation,
and a function describing soft emission at large angles, with momenta of order
QC. The former is the same as for the thrust upon scaling C by 1/6, whereas the
latter is different. We verify that the rescaled C distribution coincides with
that of 1-T to next-to-leading logarithmic accuracy, as predicted by Catani and
Webber, and demonstrate that this relation breaks down beyond this order owing
to soft radiation at large angles. The pattern of power corrections is also
similar to that of the thrust: corrections appear as odd powers of Lambda/(QC).
Based on the size of the renormalon ambiguity, however, the shape function is
different: subleading power corrections for the C distribution appear to be
significantly smaller than those for the thrust.Comment: 24 pages, Latex (using JHEP3.cls), 1 postscript figur
Breakdown of correspondence in chaotic systems: Ehrenfest versus localization times
Breakdown of quantum-classical correspondence is studied on an experimentally
realizable example of one-dimensional periodically driven system. Two relevant
time scales are identified in this system: the short Ehrenfest time t_h and the
typically much longer localization time scale T_L. It is shown that
surprisingly weak modification of the Hamiltonian may eliminate the more
dramatic symptoms of localization without effecting the more subtle but
ubiquitous and rapid loss of correspondence at t_h.Comment: 4 pages, 5 figures, replaced with a version submitted to PR
Event Shape/Energy Flow Correlations
We introduce a set of correlations between energy flow and event shapes that
are sensitive to the flow of color at short distances in jet events. These
correlations are formulated for a general set of event shapes, which includes
jet broadening and thrust as special cases. We illustrate the method for
electron-positron annihilation dijet events, and calculate the correlation at
leading logarithm in the energy flow and at next-to-leading-logarithm in the
event shape.Comment: 43 pages, eight eps figures; minor changes, references adde
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