Exploration and exploitation are the two cornerstones of problem solving by search. For more than a decade, Eiben and Schippers' advocacy for balancing between these two antagonistic cornerstones still greatly influences the research directions of evolutionary algorithms (EAs). This article revisits nearly 100 existing works and surveys how such works have answered the advocacy. The article introduces a fresh treatment that classifies and discusses existing work within three rational aspects: (1) what and how EA components contribute to exploration and exploitation; (2) when and how exploration and exploitation are controlled; and (3) how balance between exploration and exploitation is achieved. With a more comprehensive and systematic understanding of exploration and exploitation, more research in this direction may be motivated and refined.
COBISS.SI-ID: 17009430
We propose an environmental framework for simulation and visualization of woody plant forests. A complex application software system develops and animates a spontaneous afforestation process within this environment. The system considers several environmental properties and combines computer animation with artificial life. The main goal of the presented software systemis to use it in computer animation for synthesis of natural environments and visual analysis of their natural look credibility. The afforestation process is modeled as an ecosystem simulation, where trees struggle for survival based on several growth factors. A detailed description of the procedures for simulating tree growth and the factors that might influence tree growth is provided. All the tree growth simulation procedures and factors are biologically inspired. They have been defined mathematically in the paper by designing a bottom-up agent model which emerges the artificial tree distribution by mediating to the simulation. A flexible and adaptable procedural 3D model is used to visualize trees. Also, growth of individual trees is animated, from development of branch complexity to per-leaf precision, which allows a very realistic perception of the emerging ecosystem. The visualization of trees is sped up so that the models of trees have progressively lower-details proportional to the distance from a certain point of view. Locations and maturity of visualized trees are obtained from the ecosystem simulation results, and the afforestation process is animated over several centuries. The natural look of the artificial tree distribution is confirmed visually and statistically. Visually, it is confirmed from rendered sequences, and statistically, from graphs of tree species populations. Several patterns emerge permanentely, such as the number of trees in the ecosystem simulation increasing exponentially and trees growing in communities.
COBISS.SI-ID: 16157206
This paper presents a vectorized matrix parameters encoding aspect for an evolutionary computer vision approach to procedural tree modeling. A serialized fixed-size floating-point encoded tree parameter set consists of a set of auxiliary local and other global parameters. The main goal of paper is to lower problem dimensionality needed for encoding local parameters. For evolution simulation, differential evolution algorithm is used. The optimizer evolves a parameterized procedural model by fitting a set of its rendered images to a set of automatically preprocessed reference photo images. The reconstructed tree morphology is then used for reconstructed tree animation, to generate similar geometrical tree models based on similar morphology. Examples of reconstructed model animation are shown, such as simulation of its growth, sway in the wind, or adding leaves.
COBISS.SI-ID: 17793558
Teaching-Learning-Based Optimization (TLBO) seems to be a rising star from amongst a number of metaheuristics with relatively competitive performances. It is reported that it outperforms some of the well-known metaheuristics regarding constrained benchmark functions, constrained mechanical design, and continuous non-linear numerical optimization problems. Such a breakthrough has steered us towards investigating the secrets of TLBO's dominance. This paper reports our findings on TLBO qualitatively and quantitatively through code-reviews and experiments, respectively. Our findings have revealed three important mistakes regarding TLBO: (1) at least one unreported but important step; (2) incorrect formulae on a number of fitness function evaluations; and (3) misconceptions about parameter-less control. Additionally, unfair experimental settings/conditions were used to conduct experimental comparisons(e.g., different stopping criteria). The experimental results for constrained and unconstrained benchmark functions under fairly equal conditions failed to validate its performance supremacy. The ultimate goal of this paper is to provide reminders for metaheuristics' researchers and practitioners in order to avoid similar mistakes regarding both the qualitative and quantitative aspects, and to allow fair comparisons of the TLBO algorithm to be made with other metaheuristic algorithms.
COBISS.SI-ID: 16111638
The presented source separation method represents the breakthrough novelty in biomedical research as it allows, for the first time, fully automatic and completely noninvasive insight into the discharge properties of human skeletal muscles in neurodegenerative diseases, such as essential and Parkinsonian tremor. First, a mathematical derivation is provided to theoretically prove the possibility of decomposing high-density surface electromyograms into motor unit spike trains with high correlation, which are typical of tremor contractions. Further, the proposed decomposition method is tested on simulated signals and on experimental signals from 14 tremor-affected patients. In the case of simulated tremor, the method identified ~8 motor units per contraction with sensitivity in spike timing identification ≥ 95 % and false alarm and miss rates ≤ 5%. In experimental signals, the number of identified motor units varied substantially (range 0-21) across patients and contractions types. The method provides a new means for physiological investigations of pathological tremor as well as for the development of closed-loop technologies for suppression of pathological tremor. The latter affects about 5% of population in western civilization.
COBISS.SI-ID: 16676630