13,560 research outputs found
Differential evolution with an evolution path: a DEEP evolutionary algorithm
Utilizing cumulative correlation information already existing in an evolutionary process, this paper proposes a predictive approach to the reproduction mechanism of new individuals for differential evolution (DE) algorithms. DE uses a distributed model (DM) to generate new individuals, which is relatively explorative, whilst evolution strategy (ES) uses a centralized model (CM) to generate offspring, which through adaptation retains a convergence momentum. This paper adopts a key feature in the CM of a covariance matrix adaptation ES, the cumulatively learned evolution path (EP), to formulate a new evolutionary algorithm (EA) framework, termed DEEP, standing for DE with an EP. Without mechanistically combining two CM and DM based algorithms together, the DEEP framework offers advantages of both a DM and a CM and hence substantially enhances performance. Under this architecture, a self-adaptation mechanism can be built inherently in a DEEP algorithm, easing the task of predetermining algorithm control parameters. Two DEEP variants are developed and illustrated in the paper. Experiments on the CEC'13 test suites and two practical problems demonstrate that the DEEP algorithms offer promising results, compared with the original DEs and other relevant state-of-the-art EAs
SQG-Differential Evolution for difficult optimization problems under a tight function evaluation budget
In the context of industrial engineering, it is important to integrate
efficient computational optimization methods in the product development
process. Some of the most challenging simulation-based engineering design
optimization problems are characterized by: a large number of design variables,
the absence of analytical gradients, highly non-linear objectives and a limited
function evaluation budget. Although a huge variety of different optimization
algorithms is available, the development and selection of efficient algorithms
for problems with these industrial relevant characteristics, remains a
challenge. In this communication, a hybrid variant of Differential Evolution
(DE) is introduced which combines aspects of Stochastic Quasi-Gradient (SQG)
methods within the framework of DE, in order to improve optimization efficiency
on problems with the previously mentioned characteristics. The performance of
the resulting derivative-free algorithm is compared with other state-of-the-art
DE variants on 25 commonly used benchmark functions, under tight function
evaluation budget constraints of 1000 evaluations. The experimental results
indicate that the new algorithm performs excellent on the 'difficult' (high
dimensional, multi-modal, inseparable) test functions. The operations used in
the proposed mutation scheme, are computationally inexpensive, and can be
easily implemented in existing differential evolution variants or other
population-based optimization algorithms by a few lines of program code as an
non-invasive optional setting. Besides the applicability of the presented
algorithm by itself, the described concepts can serve as a useful and
interesting addition to the algorithmic operators in the frameworks of
heuristics and evolutionary optimization and computing
Simulations of the Hyades
Context: Using the recent observational data of R\"oser et al. we present
-body simulations of the Hyades open cluster. Aims: We make an attempt to
determine initial conditions of the Hyades cluster at the time of its formation
in order to reproduce the present-day cumulative mass profile, stellar mass and
luminosity function (LF). Methods: We performed direct -body simulations of
the Hyades in an analytic Milky Way potential that account for stellar
evolution and include primordial binaries in a few models. Furthermore, we
applied a Kroupa (2001) IMF and used extensive ensemble-averaging. Results: We
find that evolved single-star King initial models with King parameters and initial particle numbers provide good fits to the
observational present-day cumulative mass profile within the Jacobi radius. The
best-fit King model has an initial mass of and an average mass
loss rate of . The K-band LFs of models and
observations show a reasonable agreement. Mass segregation is detected in both
observations and models. If 33% primordial binaries are included the initial
particle number is reduced by 5% as compared to the model without primordial
binaries. Conclusions: The present-day properties of the Hyades can be well
reproduced by a standard King or Plummer initial model when choosing
appropriate initial conditions. The degeneracy of good-fitting models can be
quite high due to the large dimension of the parameter space. More simulations
with different Roche-lobe filling factors and primordial binary fractions are
required to explore this degeneracy in more detail.Comment: 14 pages, 16+1 figures, hopefully final version, contains a note
added in proo
- …