arXiv subjects

Jack Liddle

Publications and source records attributed to Jack Liddle.

6 recordsLinked to original sources

arXiv2011

Microscopic insights into pedestrian motion through a bottleneck, resolving spatial and temporal variations

The motion of pedestrians is subject to a wide range of influences and exhibits a rich phenomenology. To enable precise measurement of the density and velocity we use an alternative definition using Voronoi diagrams which exhibits smaller fluctuations than the standard definitions. This method permits examination on scales smaller than the pedestrians. We use this method to investigate the spatial and temporal variation of the observables at bottlenecks. Experiments were performed with 180 test subjects and a wide range of bottleneck parameters. The anomalous flow through short bottlenecks and non-stationary states present with narrow bottlenecks are analysed.

physics.soc-ph↗

arXiv2010

Analysis of bottleneck motion using Voronoi diagrams

Standard definitions of the density exhibit large fluctuations when the size of the measurement area is comparable with the size of a pedestrian. An alternative measurement method exists where a personal space, calculated through the Voronoi diagram, is assigned to each pedestrian. In this contribution this method is applied to an experiment studying motion through a bottleneck and the reduced fluctuations demonstrated. The integrated density also permits examination on much smaller spatial scales than the standard definition, the insights into the pedestrian motion this provides are discussed.

physics.soc-ph↗

arXiv2009

An Experimental Study of Pedestrian Congestions: Influence of Bottleneck Width and Length

The placement and dimensioning of exit routes is informed by experimental data and theoretical models. The experimental data is still to a large extent uncertain and contradictory. In this contribution an attempt is made to understand and reconcile these differences with our own experiments.

physics.soc-ph↗

arXiv2008

The deconfining phase transition in D=2+1 SU(N) gauge theories

We study the deconfining transition of SU(N) gauge theories in 2+1 dimensions for N ranging between N=2 and N=8. We confirm that the transition is second order for N<4 and first order for N>4. For the more delicate case of SU(4) all our evidence points to the transition being weakly first order. After extrapolating to the continuum limit, we obtain a deconfining temperature that can be well fitted by Tc/sqrt(sigma) = 0.9026(23) + 0.880(43)/N^2 for all N.

hep-lat↗

arXiv2007

The spatial string tension and dimensional reduction in QCD

The spatial string tension for 3+1 dimensional QCD at finite temperature is measured. The gauge configurations we re generated with two light and one heavier strange quark on lattices of size $16^3 4$ and $24^3 6$. This spatial string tension is compared with the string tension of the 3 dimensional pure gauge theory together with the temperature dependent 2-loop running coupling. Further comparison is made with predictions from dimensionally reduced effective theories.

hep-lat↗

arXiv2005

The deconfining phase transition for SU(N) theories in 2+1 dimensions

The critical temperatures for the 2+1 dimensional $SU(N_c)$ gauge theories are calculated, for $N_c = 4,5,6$. The transition is shown to be first order for $N_c \geq 5$. The critical temperature and latent heat are extrapolated to $N_c = \infty$.

hep-lat↗