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Hi, I'm Graeme. Nice to meet you!
I'm a Computer Scientist, programmer and UNIX systems administrator.
I'm also the author of an award winning Chemistry package for students,
MollyCule - (Free to download for
MacOS, Windows and Linux!).
This page provides some basic information about my interests and
publications.
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Professional Background
My resume and CV are available upon request.
Personal Background
I grew up in the town of Aberfeldy, Scotland, and went to school at
Breadalbane Academy. In 1997 I began studying at St Andrews
University, Scotland, where I obtained a 1st class BSc (Hons), followed
by a Ph.D. in Computer Science. In 2006, after passing my viva and
travelling around China for a couple of months, I moved to Taiwan (also
known as the Republic of China) for almost 3 years, where I worked as
an Assistant Professor at Ming Chuan University in Taoyuan.
I'm now working in Perth in Western Australia.
Interests
- Computing
I'm interested in most areas of computing, both theory
and practice. My research background is in computer science theory:
A.I., robotics, computer games, potential fields, and navigation.
Recently, I've been working in image processing and analysis -
steganography, steganalysis, and CAPTCHA design. I have previously
enjoyed working in visual bio-informatics. I'm currently keen to
learn more about: protein folding; openCL programming; Scala programming.
- Economics/Finance
I'm interested in several areas, particularly neuro-economics, and other niches where there is a genuinely scientific approach to understanding how humans and money go together.
- General Science
Physics, astronomy, maths, evolutionary biology, medical science, ...
- Rationality
Cognitive biases and other built-in weaknesses of
the human mind, and improving my ability to overcome them...
Contact Details
Publications
PhD thesis.
"Forward Chaining for Potential Field Based Navigation"
by Graeme Bell, University of St Andrews, UK (January 2006).
Abstract
A key ability for any real world robotic agent and for many simulated agents in virtual environments is the ability to navigate successfully to goal positions within their world. It is often necessary to do this in the presence of obstacles that limit access to parts of the agent's world.
This thesis addresses the problem of agent navigation in the situation where an agent is seeking a goal in the presence of obstacle configurations. Potential fields are used to model the navigational problems, and purely potential field based heuristics are given as solutions.
Existing potential field based techniques and alternative navigation approaches are shown to lack certain desirable properties that might allow them to be considered completely successful.
The general problem of potential field navigation is addressed here using subgoal chaining. A series of novel potential field based subgoal selection heuristics are developed that guide the agent to success in the presence of the stated problem conditions. Development of the heuristic begins by modelling a solution for the simplest two dimensional environments, and then extending it to solutions for problems of greater complexity.
The techniques developed here are shown to be successful on a wide variety of problems. Applications for these solutions are suggested in robotics, animation and computer games as well as in other areas of potential field research such as neural networks. Suggestions are given for ways in which competing techniques within navigation can be augmented by applying the results of this research. The remaining problems for potential field based agent navigation are highlighted for future study.
Download PDF | Download BibTex
Papers, most recent first.
NEWS (January 2010): 1 journal paper accepted and
awaiting publication, 2 journal papers under review, 2 journal papers
completed and awaiting submission, 2 journal papers under preparation, 1
conference paper completed and awaiting submission. Busy
month!
(Accepted/Forthcoming) "An Efficient Segmentation Algorithm
for CAPTCHAs with Line Cluttering and Character Warping"
by Shih-Yu Huang, Yeuan-Kuen Lee, Graeme Bell and Zhan-he Ou. Multimedia Tools and
Applications Journal, Springer.
"An Advanced Least-Significant-Bit Embedding Scheme for Steganographic Encoding"
by Yeuan-Kuen
Lee, Graeme Bell, Shih-Yu Huang, Ran-Zan Wang, and Shyong Jian Shyu, Advances in Image and Video Technology
(PSIVT2009), Tokyo, Japan, LNCS 5414, Springer, p349-360.
Abstract:
The advantages of Least-Significant-Bit (LSB) steganographic data embedding are that it is simple to understand, easy
to implement, and it results in stego-images that contain hidden data yet appear to be of high visual fidelity.
However, it can be shown that under certain conditions, LSB embedding is not secure at all. The fatal drawback of LSB
embedding is the existence of detectable artefacts in the form of pairs of values (PoVs). The goals of this paper are
to present a theoretic analysis of PoVs and to propose an advanced LSB embedding scheme that possesses the advantages
of LSB embedding suggested above, but which also provides an additional level of communication security. The proposed
scheme breaks the regular pattern of PoVs in the histogram domain, increasing the difficulty of steganalysis and
thereby raising the level of security. The experimental results show that both the Chi-square index and RS index are
less than 0.1, i.e., the hidden message is undetectable by the well-known Chi-square and RS steganalysis attacks.
Download PDF | Download BibTex
"A Projection-based Segmentation Algorithm for Breaking MSN and YAHOO CAPTCHAs"
by Shih-Yu Huang, Yeuan-Kuen Lee, Graeme Bell, and Zhan-he Ou, Proceedings of the 2008 International Conference of Signal and Image Engineering (ICSIE'08), London, UK, IAENG, p727-730. (2008).
Abstract:
Defeating a CAPTCHA test requires two procedures: segmentation and recognition. Recent research shows that the problem of segmentation is much harder than
recognition. In this paper, a new projection-based segmentation algorithm is proposed for the MSN and Yahoo CAPTCHAs. Experimental results show that the proposed algorithm can improve correct segmentation rates ranging from 9% to 14% over the traditional one.
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"The Existence of Local Minima in Local-Minimum-Free Potential Surfaces"
by Graeme Bell and Mike Livesey, Proceedings of Towards Autonomous Robotic Systems, (TAROS 2005), Imperial College, London, UK, p15-20. (2005).
Abstract:
Existing approaches to potential field based navigation, such as
(Khatib, 1986) and (Rimon and Koditschek, 1992), have traditionally seen the local minimum problem as the only significant obstacle. This is because they have
concentrated on the problem of "classical" local minima, characterised by a positive definite Hessian. This paper demonstrates, via the notion of "saddle minimum", that the navigational problems associated with local minima can also arise in connection with points other than classical local minima. The existing approaches, in concentrating on the classical definition, do not acknowledge or address such local minimum problems.
Download PDF | Download BibTex | Download PDF with embedded fonts
"Forward Chaining for Robot and Agent Navigation using Potential Fields"
by Graeme Bell and Michael Weir, ACM International Conference Proceeding Series, Proceedings of 27th Australasian Computer Science Conference (ACSC2004), Dunedin, New Zealand, p265-274. (2004).
Abstract:
The ability to navigate successfully is a crucial part of the behaviour of many agents and systems, ranging from
robots and computer game characters to neural networks. Navigation in robotics is addressed here using an approach that is extensible to other areas. Potential fields are acknowledged to be a very powerful representation of robot navigation environments. This representation has been largely abandoned though, due to its susceptibility to premature termination of progress caused by local minima. We seek to encourage the reopening of research into this method by introducing a new approach called Forward Chaining. This technique avoids premature termination of progress by dynamically reshaping the potential field using subgoals which chain forwards towards the goal. A number of increasingly competent and robust navigation heuristics yielding efficient paths are demonstrated. Various avenues for future research are given.
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"Agent Navigation using Potential Fields and Forward Chaining"
by Graeme Bell and Michael Weir, Proceedings of Postgraduate Research Conference in Electronics, Photonics,
Communications and Networks and Computing Science, (PREP2004), University of Hertfordshire, UK. (2004).
Abstract:
Increasingly competent heuristics produce the novel Forward Chaining heuristic, allowing navigation past
obstacle configurations that are impossible for traditional potential field methods.
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"The Incorporation of Intentional Action into Robots"
by Michael Weir and Graeme Bell, St Andrews University School of Computer Science Technical Report. (2001).
Abstract:
Robot design has recently become a burgeoning area of research for intelligent
computation and applications range over diverse scales, from robot insects to Mars explorers.
Despite the human associations, standard robot dynamics has more in common with inanimate
action than animate action. The Carnegie Trust Scholarship Research Project described herein is
intended to redress the balance by addressing the question: How does a robot become able to
act intentionally?
Download PDF | Download BibTex
Please note: I may no longer be the copyright holder for some
of these papers; therefore these electronic draft editions of my papers
are available for your personal use only.
Software.
I am the author of the award-winning Chemistry visualisation
package,
MollyCule. Visit MollyCule.org for a
free download.
Coming soon: CSP solver, Z-buffer/Polygon-sorter, various other old
practicals and projects...
Other things...
- My Chinese name is:
 (bei4 er3 mu4).
The first two characters, Bei-er, are the standard Chinese
transliteration for the western family name "Bell", and Mu... well, I chose Mu for lots of reasons. Particularly though, because I grew up in a country town in an area of the UK with many trees and forests, where my dad worked for most of his life as a forester. 'Mu' means 'wood' or 'tree'.
- My Japanese name is:
 (geremu beru).
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I enjoy... photography, badminton, some basketball, programming for fun,
reading, exploring Taiwan on foot, watching films (martial arts, science fiction, comedy), board games, more reading. Hoping to get back into TaeKwonDo again...
Visiting Tokyo for PSIVT 2009 with my Taiwanese buddies.
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