A generalized approach to construct benchmark problems for dynamic optimization

Copyright @ Springer-Verlag Berlin Heidelberg 2008.There has been a growing interest in studying evolutionary algorithms in dynamic environments in recent years due to its importance in real applications. However, different dynamic test problems have been used to test and compare the performance of algorithms. This paper proposes a generalized dynamic benchmark generator (GDBG) that can be instantiated into the binary space, real space and combinatorial space. This generator can present a set of different properties to test algorithms by tuning some control parameters. Some experiments are carried out on the real space to study the performance of the generator.This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/1

Concepts of microdosimetry

This is the first part of an investigation of microdosimetric concepts relevant to numerical calculations. The definitions of the microdosimetric quantities are reviewed and formalized, and some additional conventions are adopted. The common interpretation of the quantities in terms of energy imparted to spherical sites is contrasted with their interpretation as the result of a diffusion process applied to the initial spatial pattern of energy transfers in the irradiated medium

An algorithm for LET-analysis

An algorithm for the derivation of LET-distributions from pulse- height spectra obtained with proportional counters is described. The method is based on Fourier transformation: it is applicable to spherical as well as non-spherical proportional counters. The relation between the energy mean, LD, of LET and the energy mean, yD, of the lineal energy density is given

Radiobiological studies with monoenergetic neutrons

The Radiological Research Accelerator Facility (RARAF) has the capability of producing essentially monoenergetic neutron beams, ranging in energy from 16.4 MeV down to 220 keV. In addition, two lower energy neutron beams are available which consist of a wide spectrum of energies and are described as the 110 keV and 60 keV spectra. Seedlings of Vicia faba have been used to measure the oxygen enhancement ratio (OER) and the relative biological effectiveness (RBE) of each of these neutron beams. The OER decreases as the neutron energy is reduced between 15.4 MeV and 220 keV, but does not appear to decrease further for lower energy neutrons. RBE increases as the neutron energy is reduced from 15.4 AleV to 440 keV; the curve then goes through a maximum at around 350 keV, and for lower energies the RBE falls again

Studies of the dose-effect relation

Dose-effect relations and, specifically, cell survival curves are surveyed with emphasis on the interplay of the random factors — biological variability, stochastic reaction of the cell, and the statistics of energy deposition —that co-determine their shape. The global parameters mean inactivation dose, , and coefficient of variance, V, represent this interplay better than conventional parameters. Mechanisms such as lesion interaction, misrepair, repair overload, or repair depletion have been invoked to explain sigmoid dose dependencies, but these notions are partly synonymous and are largely undistinguishable on the basis of observed dose dependencies. All dose dependencies reflect, to varying degree, the microdosimetric fluctuations of energy deposition, and these have certain implications, e.g. the linearity of the dose dependence at small doses, that apply regardless of unresolved molecular mechanisms of cellular radiation action

On the statistical evaluation of dose-response functions

The linear-quadratic dependence of effect on the dose of ionizing radiation and its biophysical implications are considered. The estimation of the parameters of the response function and the derivation of the joint confidence region of the estimates are described. The method is applied to the induction of pink mutations inTradescantia which follows the linear-quadratic model. The statistical procedure is also suitable for other response functions