@InProceedings{RitsonWelch07,
  title =        "{A} {P}rocess-{O}riented {A}rchitecture for {C}omplex {S}ystem {M}odelling",
  author=        "Ritson,  Carl G. and Welch, Peter H.",
  editor=        "McEwan,  Alistair A. and Schneider,  Steve and Ifill,  Wilson and Welch, Peter H.",
  pages =        "249--266",
  booktitle=     "{C}ommunicating {P}rocess {A}rchitectures 2007",
  isbn=          "978-1-58603-767-3",
  year=          "2007",
  month=         "jul",
  abstract=      "A fine-grained massively-parallel process-oriented model of
     platelets (potentially
artificial) within a blood vessel is
     presented. This is a CSP inspired design,
expressed and
     implemented using the occam-pi language. It is part of the
     TUNA pilot
study on nanite assemblers at the universities
     of York, Surrey and Kent. The aim for
this model is to
     engineer emergent behaviour fromthe platelets, such that
     they respond
to a wound in the blood vessel wall in a way
     similar to that found in the human body
\&\#8211; i.e.
     the formation of clots to stem blood flow from the wound and
     facilitate healing.
An architecture for a three dimensional
     model (relying strongly on the dynamic and
mobile
     capabilities of occam-pi) is given, along with mechanisms
     for visualisation and
interaction. The biological accuracy
     of the current model is very approximate. However,
its
     process-oriented nature enables simple refinement (through
     the addition of
processes modelling different
     stimulants/inhibitors of the clotting reaction,
     different
platelet types and other participating
     organelles) to greater and greater realism. Even
with the
     current system, simple experiments are possible and have
     scientific interest
(e.g. the effect of platelet density on
     the success of the clotting mechanism in stemming
blood
     flow: too high or too low and the process fails). General
     principles for
the design of large and complex system
     models are drawn. The described case study
runs to millions
     of processes engaged in ever-changing communication
     topologies. It
is free from deadlock, livelock, race
     hazards and starvation by design, employing a
small set of
     synchronisation patterns for which we have proven safety
     theorems."
}