2,841 research outputs found
Drawing Trees with Perfect Angular Resolution and Polynomial Area
We study methods for drawing trees with perfect angular resolution, i.e.,
with angles at each node v equal to 2{\pi}/d(v). We show:
1. Any unordered tree has a crossing-free straight-line drawing with perfect
angular resolution and polynomial area.
2. There are ordered trees that require exponential area for any
crossing-free straight-line drawing having perfect angular resolution.
3. Any ordered tree has a crossing-free Lombardi-style drawing (where each
edge is represented by a circular arc) with perfect angular resolution and
polynomial area. Thus, our results explore what is achievable with
straight-line drawings and what more is achievable with Lombardi-style
drawings, with respect to drawings of trees with perfect angular resolution.Comment: 30 pages, 17 figure
Distributed intelligence in pedestrian simulations
In order to accurately simulate pedestrian behaviour in complex situations, one is required to model both the physical environment and the strategic decision-making of individuals We present a method for integrating both of these model requirements, by distributing the computational complexity across discrete modules. These modules communicate with each other via XML messages. The approach also provides considerable flexibility for changing and evolving the model. The model is explained using an example of simulating hikers in the Swiss Alps.SNF, NFP 48, Habitats and Landscapes of the Alp
The blending region hybrid framework for the simulation of stochastic reaction-diffusion processes
The simulation of stochastic reaction-diffusion systems using fine-grained
representations can become computationally prohibitive when particle numbers
become large. If particle numbers are sufficiently high then it may be possible
to ignore stochastic fluctuations and use a more efficient coarse-grained
simulation approach. Nevertheless, for multiscale systems which exhibit
significant spatial variation in concentration, a coarse-grained approach may
not be appropriate throughout the simulation domain. Such scenarios suggest a
hybrid paradigm in which a computationally cheap, coarse-grained model is
coupled to a more expensive, but more detailed fine-grained model enabling the
accurate simulation of the fine-scale dynamics at a reasonable computational
cost.
In this paper, in order to couple two representations of reaction-diffusion
at distinct spatial scales, we allow them to overlap in a "blending region".
Both modelling paradigms provide a valid representation of the particle density
in this region. From one end of the blending region to the other, control of
the implementation of diffusion is passed from one modelling paradigm to
another through the use of complementary "blending functions" which scale up or
down the contribution of each model to the overall diffusion. We establish the
reliability of our novel hybrid paradigm by demonstrating its simulation on
four exemplar reaction-diffusion scenarios.Comment: 36 pages, 30 figure
Geometric Mechanics of Curved Crease Origami
Folding a sheet of paper along a curve can lead to structures seen in
decorative art and utilitarian packing boxes. Here we present a theory for the
simplest such structure: an annular circular strip that is folded along a
central circular curve to form a three-dimensional buckled structure driven by
geometrical frustration. We quantify this shape in terms of the radius of the
circle, the dihedral angle of the fold and the mechanical properties of the
sheet of paper and the fold itself. When the sheet is isometrically deformed
everywhere except along the fold itself, stiff folds result in creases with
constant curvature and oscillatory torsion. However, relatively softer folds
inherit the broken symmetry of the buckled shape with oscillatory curvature and
torsion. Our asymptotic analysis of the isometrically deformed state is
corroborated by numerical simulations which allow us to generalize our analysis
to study multiply folded structures
Measures of Fluid Loss during Surfing: A Preliminary Analysis in Recreational Surfers
Surfing is a popular sport, but little is known about the extent to which recreational surfers experience fluid loss from this activity. The principal objective of this research was to estimate fluid loss during a surfing session through changes in pre- to post-session urine color (Ucol), urine osmolality (Uosm), and body mass (BM). Data were collected from 11 recreational surfers across 14 surf sessions conducted under various environmental (mean water temperature = 22.1 SD ± 2.3; range = 20-26oC; air temperature range = 13.1-31.5oC; relative humidity range = 37.5-88.1%) and surfing conditions (e.g. winter/summer, wave type, location, environmental and water conditions). Linear mixed effects models indicated that participants experienced significant pre- to post-session changes in BM (p \u3c 0.001), but not in Ucol or Uosm. These findings suggested that recreational surfers may experience fluid loss (measured by pre- to post-surfing BM) that may impact on their performance and health, and therefore they should adopt a hydration strategy to minimize this impact
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