2 research outputs found
A Cluster-Based Opposition Differential Evolution Algorithm Boosted by a Local Search for ECG Signal Classification
Electrocardiogram (ECG) signals, which capture the heart's electrical
activity, are used to diagnose and monitor cardiac problems. The accurate
classification of ECG signals, particularly for distinguishing among various
types of arrhythmias and myocardial infarctions, is crucial for the early
detection and treatment of heart-related diseases. This paper proposes a novel
approach based on an improved differential evolution (DE) algorithm for ECG
signal classification for enhancing the performance. In the initial stages of
our approach, the preprocessing step is followed by the extraction of several
significant features from the ECG signals. These extracted features are then
provided as inputs to an enhanced multi-layer perceptron (MLP). While MLPs are
still widely used for ECG signal classification, using gradient-based training
methods, the most widely used algorithm for the training process, has
significant disadvantages, such as the possibility of being stuck in local
optimums. This paper employs an enhanced differential evolution (DE) algorithm
for the training process as one of the most effective population-based
algorithms. To this end, we improved DE based on a clustering-based strategy,
opposition-based learning, and a local search. Clustering-based strategies can
act as crossover operators, while the goal of the opposition operator is to
improve the exploration of the DE algorithm. The weights and biases found by
the improved DE algorithm are then fed into six gradient-based local search
algorithms. In other words, the weights found by the DE are employed as an
initialization point. Therefore, we introduced six different algorithms for the
training process (in terms of different local search algorithms). In an
extensive set of experiments, we showed that our proposed training algorithm
could provide better results than the conventional training algorithms.Comment: 44 pages, 9 figure
Improving the efficiency of GaAs solar cells using a double semi-transparent carbon nanotubes thin layer
To investigate the efficiency of a single-junction solar cell that was performed using a numerical analysis method, the effect of creating several different surface-enhancer layer structures on the efficiency of the solar cell was performed. In this study, several carbon nanotube structures adapted to the solar cell structure of the gallium arsenide (GaAs) substrate were used. These elements have two important features of transparency and conductivity. Here, the effect of various parameters such as structure type, dimensions, number of layers, usable impurities and their arrangement on the solar cell efficiency was investigated. In this research, the layer added on the surface of a solar cell can be modeled on a heterogeneous carbon nanotube network. Finally, an optimized single-junction solar cell was obtained by examining the performance of the solar cell using the final carbon nanotube layers. This work resulted, the solar cell with a combination of a double-layer carbon nanotube enhancer by about 30% of efficiency, due to the ability to absorb more photons in one layer of the nanotubes, and better electrical transferability in the other layer of the nanotubes. In this solar cell, two different layers of carbon nanotube with a surface ratio of 10% and 90% of the total surface enhancer layer were used, with a cellular efficiency of about 1% improvement in performance compared with the previous one