Imperial College London

DrTimothyEvans

Faculty of Natural SciencesDepartment of Physics

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 7837t.evans Website

 
 
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Assistant

 

Mrs Graziela De Nadai-Sowrey +44 (0)20 7594 7843

 
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Location

 

H/609Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

75 results found

Clough JR, Evans TS, 2017, Embedding graphs in Lorentzian spacetime, PLoS ONE, Vol: 12

© 2017 Clough, Evans. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Geometric approaches to network analysis combine simply defined models with great descriptive power. In this work we provide a method for embedding directed acyclic graphs (DAG) into Minkowski spacetime using Multidimensional scaling (MDS). First we generalise the classical MDS algorithm, defined only for metrics with a Riemannian signature, to manifolds of any metric signature. We then use this general method to develop an algorithm which exploits the causal structure of a DAG to assign space and time coordinates in a Minkowski spacetime to each vertex. As in the causal set approach to quantum gravity, causal connections in the discrete graph correspond to timelike separation in the continuous spacetime. The method is demonstrated by calculating embeddings for simple models of causal sets and random DAGs, as well as real citation networks. We find that the citation networks we test yield significantly more accurate embeddings that random DAGs of the same size. Finally we suggest a number of applications in citation analysis such as paper recommendation, identifying missing citations and fitting citation models to data using this geometric approach.

JOURNAL ARTICLE

Evans TS, Rivers RJ, 2017, Was Thebes Necessary? Contingency in Spatial Modeling, Frontiers in Digital Humanities, Vol: 4

JOURNAL ARTICLE

Clough JR, Evans TS, 2015, Time & Citation Networks, 15th International Conference of the International-Society-for-Scientometrics-and-Informetrics (ISSI) on Scientometrics and Informetrics, Publisher: INT SOC SCIENTOMETRICS & INFORMETRICS-ISSI, Pages: 1073-1078, ISSN: 2175-1935

CONFERENCE PAPER

Goldberg SR, Anthony H, Evans TS, 2015, Do we need global and local knowledge of the citation network?, Pages: 282-283

CONFERENCE PAPER

Loach TV, Evans TS, 2015, Ranking Journals Using Altmetrics, 15th International Conference of the International-Society-for-Scientometrics-and-Informetrics (ISSI) on Scientometrics and Informetrics, Publisher: INT SOC SCIENTOMETRICS & INFORMETRICS-ISSI, Pages: 89-94, ISSN: 2175-1935

CONFERENCE PAPER

Rivers RJ, Evans TS, 2014, New approaches to Archaic Greek settlement structure, Les nouvelles de l'archéologie, Pages: 21-27, ISSN: 0242-7702

JOURNAL ARTICLE

Reiss DS, Price JJ, Evans TS, 2013, Sculplexity: Sculptures of Complexity using 3D printing, EPL, Vol: 104, ISSN: 0295-5075

JOURNAL ARTICLE

Rivers R, Knappett C, Evans T, 2013, Network Models and Archaeological Spaces, Computational Approaches to Archaeological Spaces, Editors: Bevan, Lake, Publisher: Left Coast Press, ISBN: 978-1-61132-346-7

BOOK CHAPTER

Rivers R, Knappett C, Evans T, 2013, What makes a site important? Centrality, gateways and gravity, Network Analysis in Archaeology: New Approaches to Regional Interaction, Editors: Knappett, Publisher: OUP, Pages: 125-150

BOOK CHAPTER

Wilting J, Evans TS, 2013, Oscillator Synchronization in Complex Networks with Non-uniform Time Delays, Complex Networks IV, Publisher: Springer, Pages: 93-100

We investigate a population of limit-cycle Kuramoto oscillators coupled in a complex network topology with coupling delays introduced by finite signal propagation speed and embedding in a ring. By numerical simulation we find that in complete graphs velocity waves arise that were not observed before and analytically not understood. In regular rings and small-world networks frequency synchronization occurs with a large variety of phase patterns. While all these patterns are nearly equally probable in regular rings, small-world topology sometimes prefers one pattern to form for a large number of initial conditions.We propose implications of this in the context of the temporal coding hypothesis for information processing in the brain and suggest future analysis to conclude the work presented here.

BOOK CHAPTER

Clemson T, Evans TS, 2012, The emergence of leadership in social networks, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, Vol: 391, Pages: 1434-1444, ISSN: 0378-4371

JOURNAL ARTICLE

Evans TS, 2012, Turnover Rate of Popularity Charts in Neutral Models

It has been shown recently that in many different cultural phenomena the turnover rate on the most popular artefacts in a population exhibit some regularities. A very simple expression for this turnover rate has been proposed by Bentley et al. 2007 and its validity in two simple models for copying and innovation is investigated in this paper. It is found that the formula in Bentley et al. is an approximation of the real behaviour of the turnover rate in the Wright-Fisher model, while it is not valid in the Moran model.

CONFERENCE PAPER

Evans TS, Hopkins N, Kaube BS, 2012, Universality of performance indicators based on citation and reference counts, SCIENTOMETRICS, Vol: 93, Pages: 473-495, ISSN: 0138-9130

JOURNAL ARTICLE

Evans TS, Kaube BS, Hopkins N, 2012, Temporal Evolution Of Universal Performance Indicators For Academic Publication, ECCS 2012

We show universal behaviour for two indicators of the quality of publications taken from two different data sets, papers from a single institution and those on arXiv. We demonstrate this universality for different years and subjects. This distribution is well fitted by a lognormal with a variance of around 1.3, consistent with Radicchi et al (2008). We will also discuss the evolution over time of our measures describing the data and note that simple models do not have the correct temporal behaviour for our parameters. Based on arXiv:1110.3271 with additional new material.Poster given at ECCS 2012

POSTER

Evans TS, Rivers RJ, 2012, Interactions in Space for Archaeological Models, Advances in Complex Systems, Vol: 15

In this article we examine a variety of quantitative models for describingarchaeological networks, with particular emphasis on the maritime networksof the Aegean Middle Bronze Age. In particular, we discriminate betweenthose gravitational networks that are most likely (maximum entropy) andmost efficient (best cost/benefit outcomes).

JOURNAL ARTICLE

Evans TS, Rivers RJ, Knappett C, 2012, INTERACTIONS IN SPACE FOR ARCHAEOLOGICAL MODELS, ADVANCES IN COMPLEX SYSTEMS, Vol: 15, ISSN: 0219-5259

JOURNAL ARTICLE

Evans TS, Giometto A, 2011, Turnover Rate of Popularity Charts in Neutral Models

It has been shown recently that in many different cultural phenomena theturnover rate on the most popular artefacts in a population exhibit someregularities. A very simple expression for this turnover rate has been proposedby Bentley et al. and its validity in two simple models for copying andinnovation is investigated in this paper. It is found that Bentley's formula isan approximation of the real behaviour of the turnover rate in theWright-Fisher model, while it is not valid in the Moran model.

JOURNAL ARTICLE

Evans TS, Lambiotte R, Panzarasa P, 2011, Community structure and patterns of scientific collaboration in Business and Management, SCIENTOMETRICS, Vol: 89, Pages: 381-396, ISSN: 0138-9130

JOURNAL ARTICLE

Expert P, Evans TS, Blondel VD, Lambiotte Ret al., 2011, Uncovering space-independent communities in spatial networks, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 108, Pages: 7663-7668, ISSN: 0027-8424

JOURNAL ARTICLE

Knappett C, Rivers R, Evans T, 2011, The Theran eruption and Minoan palatial collapse: new interpretations gained from modelling the maritime network, ANTIQUITY, Vol: 85, Pages: 1008-1023, ISSN: 0003-598X

JOURNAL ARTICLE

Lambiotte R, Sinatra R, Delvenne J-C, Evans TS, Barahona M, Latora Vet al., 2011, Flow graphs: Interweaving dynamics and structure, PHYSICAL REVIEW E, Vol: 84, ISSN: 2470-0045

JOURNAL ARTICLE

Rivers RJ, Evans TS, Knappett C, 2011, Modelling maritime interaction in the Aegean Bronze Age, II. The Theran eruption and Minoan palatial collapse, Antiquity: a quarterly review of archaeology, Vol: 85, Pages: 1008-1023

What was the effect on Late Minoan civilisation of the catastrophic destruction of Akrotiri on Thera (Santorini) by volcanic eruption? Not much, according to the evidence for continuing prosperity on Crete. But the authors mobilise their ingenious mathematical model (published in Antiquity 82: 1009–1024), this time to show that the effects of removing a major port of call could have impacted after an interval, as increased costs of transport gradually led to ever fewer routes and eventual economic collapse.

JOURNAL ARTICLE

Evans TS, 2010, Clique graphs and overlapping communities, JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT, ISSN: 1742-5468

JOURNAL ARTICLE

Evans TS, Hook D, Gurney K, 2010, Collaboration Profiling in UK Higher Education, INORMS 2010 conference entitled 'Collaboration Profiling in UK Higher Education'.

POSTER

Evans TS, Lambiotte R, 2010, Line graphs of weighted networks for overlapping communities, EUROPEAN PHYSICAL JOURNAL B, Vol: 77, Pages: 265-272, ISSN: 1434-6028

JOURNAL ARTICLE

Evans TS, Plato ADK, You T, 2010, Are Copying and Innovation Enough?, 15th European Conference on Mathematics for Industry, Publisher: SPRINGER-VERLAG BERLIN, Pages: 825-+, ISSN: 1612-3956

CONFERENCE PAPER

Evans TS, Knappett C, Rivers RJ, 2009, Using Statistical Physics To Understand Relational Space: A Case Study From Mediterranean Prehistory, Complexity Perspectives on Innovation and Social Change, Editors: Lane, Pumain, Leeuw, West, Lane, Pumain, Leeuw, West, Publisher: Springer Science + Business Media, Pages: 451-479, ISBN: 9781402096624

BOOK CHAPTER

Evans TS, Lambiotte R, 2009, Line graphs, link partitions, and overlapping communities, PHYSICAL REVIEW E, Vol: 80, ISSN: 2470-0045

JOURNAL ARTICLE

Evans TS, Lambiotte R, 2009, Overlapping Communities, Link Partitions and Line Graphs

In this paper, we use a partition of the links of a network in order to uncover its community structure. This approach allows for communities to overlap at nodes, so that nodes may be in more than one community. We do this by making a node partition of the line graph of the original network. In this way we show that any algorithm which produces a partition of nodes can be used to produce a partition of links. We discuss the role of the degree heterogeneity and propose a weighted version of the line graph in order to account for this.

CONFERENCE PAPER

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