Volume 83, Number 2, July 2008
Article Number 28003
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 02 July 2008
EPL, 83 (2008) 28003
DOI: 10.1209/0295-5075/83/28003

Parameter-tuning networks: Experiments and active-walk model

Xiao-Pu Han1, Chun-Dong Hu2, Zhi-Min Liu2 and Bing-Hong Wang1, 3

1  Department of Modern Physics, University of Science and Technology of China - Hefei, 230026, China
2  Institute of Plasma Physics, Chinese Academy of Sciences - Hefei, 230031, China
3  Shanghai Academy of System Science and University of Shanghai for Science and Technology Shanghai, 230093, China

received 23 March 2008; accepted in final form 2 June 2008; published July 2008
published online 2 July 2008

The tuning process of a large apparatus of many components could be represented and quantified by constructing parameter-tuning networks. The experimental tuning of the ion source of the neutral beam injector of the HT-7 Tokamak is presented as an example. Stretched-exponential cumulative degree distributions are found in the parameter-tuning networks. An active-walk model with eight walkers is constructed. Each active walker is a particle moving with friction in an energy landscape; the landscape is modified by the collective action of all the walkers. Numerical simulations show that the parameter-tuning networks generated by the model also give stretched exponential functions, in good agreement with experiments. Our methods provide a new insight to understand the action of humans in the parameter-tuning of experimental processes, and our model could be helpful for the experimental research and other optimization problems.

89.75.-k - Complex systems.
89.75.Hc - Networks and genealogical trees.
05.40.Fb - Random walks and Levy flights.

© EPLA 2008