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, Embedding Graphs in Lorentzian Spacetime

Geometric approaches to network analysis combine simply defined models withgreat descriptive power. In this work we provide a method for embeddingdirected acyclic graphs into Minkowski spacetime using Multidimensional scaling(MDS). First we generalise the classical MDS algorithm, defined only formetrics with a Euclidean signature, to manifolds of any metric signature. Wethen use this general method to develop an algorithm to be used on networkswhich have causal structure allowing them to be embedded in Lorentzianmanifolds. The method is demonstrated by calculating embeddings for both causalsets and citation networks in Minkowski spacetime. We finally suggest a numberof applications in citation analysis such as paper recommendation, identifyingmissing citations and fitting citation models to data using this geometricapproach.

JOURNAL ARTICLE

Goldberg SR, Anthony H, Evans TS, Modelling citation networks, Scientometrics, ISSN: 1588-2861

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, Pages: 1073-1078

Citation networks emerge from a number of different social systems, such as academia (from published papers), business (through patents) and law (through legal judgements). A citation represents a transfer of information, and so studying the structure of the citation network will help us understand how knowledge is passed on. What distinguishes citation networks from other networks is time; documents can only cite older documents. We propose that existing network measures do not take account of the strong constraint imposed by time. We will illustrate our approach with two types of causally aware analysis. We apply our methods to the citation networks formed by academic papers on the arXiv, to US patents and to US Supreme Court judgements. We show that our tools can reveal that citation networks which appear to have very similar structure by standard network measures, turn out to have significantly different properties. We interpret our results as indicating that many papers in a bibliography were not directly relevant to the work and that we can provide a simple indicator of the important citations. We suggest our methods may highlight papers which are of more interest for interdisciplinary research. We also quantify differences in the diversity of research directions of different fields.

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, Pages: 89-94

The rank of a journal based on simple citation information is a popular measure. The simplicity and availability of rankings such as Impact Factor, Eigenfactor and SciMago Journal Rank based on trusted commercial sources ensures their widespread use for many important tasks despite the well-known limitations of such rankings. In this paper we look at an alternative approach based on information on papers from social and mainstream media sources. Our data comes from altmetric.com who identify mentions of individual academic papers in sources such as Twitter, Facebook, blogs and news outlets. We consider several different methods to produce a ranking of journals from such data. We show that most (but not all) schemes produce results, which are roughly similar, suggesting that there is a basic consistency between social media based approaches and traditional citation based methods. Most ranking schemes applied to one data set produce relatively little variation and we suggest this provides a measure of the uncertainty in any journal rating. The differences we find between data sources also shows they are capturing different aspects of journal impact. We conclude a small number of such ratings will provide the best information on journal impact.

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

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