based algorithm was described in studies (Dao et al.,
2014), (Fukunaga, 1988) and (Beligiannis et al.,
2004). In this paper we consider another criterion for
deciding when to apply the restart; we estimate the
speed at which the best solution fitness value
changes and if it is less than a certain parameter, the
algorithm restarts. In the study (Loshchilov et al.,
2012) the population properties and algorithm
settings take on new values at each restart. In the
current paper, the values of the settings are kept the
same.
The second implementation was made in order to
detect whether the current population is close to the
point, where it was decided that a restart would be
made. For this reason, a dataset is required. The
dataset saves the histories of all restarts that have
been performed. If the distance between a current
solution and any other solution from the dataset is
less than a certain parameter, the operator will stop
the search and cause a restart.
In our previous studies a dynamical system
identification problem was considered, an inverse
mathematical modelling problem with the solution
being searched for in a symbolic form. We describe
single input and single output systems and suppose
that the input control function is known. We also
suppose that the observations are the distorted
measurements of the system output.
The identification of LDE parameters requires a
certain order of equation and an initial value. The
automatic and simultaneous estimation of linear
differential equation coefficients, initial value and
order lead to the implementation of problem-
oriented algorithm modifications. The proposed
approach is based on the reduction of the
identification problem to an extremum problem on a
real value vector field. The objective function of the
reduced problem is complex and multimodal (as
previous studies prove) and can be evaluated only
numerically. To solve this problem, a specific
evolution-based optimization tool was developed; its
origin is the evolutionary strategies optimization
algorithm. The proposed algorithm is modified and
designed for solving the described problem; its
performance is sufficiently higher than the
performance of standard evolution-based algorithms.
Population search algorithms had already been
applied to parameter identification problem solving
and experimental results show its reliability. A
genetic algorithm is applied to the parameter
identification problem for ordinary differential
equations (Sersic et al., 1999), but in that study the
structure of the system is already known. Another
study where the genetic algorithm is used to estimate
the coefficients of second order LDE is (Parmar et
al., 2007). In that study the order reduction problem
was considered. A similar problem is considered in
(Narwal et al., 2016) but the cuckoo optimization
algorithm is used. Another nature-inspired
optimization algorithm, partial swarm optimization,
was applied to nonlinear dynamical system
linearization, (Naiborhu et al., 2013).
The results of previous studies (Ryzhikov and
Semenkin, 2013) allow us to conclude that the
proposed modified hybrid evolutionary strategies
optimization algorithm is a reliable and efficient tool
for solving optimization problems of the considered
class in comparison with the evolutionary strategies
algorithm with particular modifications and tuned
parameters. In any event, the algorithm tends to be
stacked in local optimum area.
In this study the proposed algorithm is
supplemented with a meta-heuristic. The
performance of the algorithm with different meta-
heuristic settings was examined on a set of
identification problems and its performance is
compared to the initial algorithm performance.
2 IDENTIFIACTION PROBLEM
AND MODIFIED HYBRID
EVOLUTIONARY ALGORITHM
A linear dynamic system can be determined with its
parameters: coefficients and order. Let the object to
be identified be described with a linear differential
equation of some unknown order
k
. So the system
output
()