In this paper, we propose a differential evolution (DE) algorithm variant with a combination of multiple mutation strategies based on roulette wheel selection, which we call MMRDE. We first propose a new, reflection-b...
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In this paper, we propose a differential evolution (DE) algorithm variant with a combination of multiple mutation strategies based on roulette wheel selection, which we call MMRDE. We first propose a new, reflection-based mutation operation inspired by the reflection operations in the Nelder-Mead method. We design an experiment to compare its performance with seven mutation strategies, and we prove its effectiveness at balancing exploration and exploitation of DE. Although our reflection-based mutation strategy can balance exploration and exploitation of DE, it is still prone to premature convergence or evolutionary stagnation when solving complex multimodal optimization problems. Therefore, we add two basic strategies to help maintain population diversity and increase the robustness. We use roulette wheel selection to arrange mutation strategies based on their success rates for each individual. MMRDE is tested with some improved DE variants based on 28 benchmark functions for real-parameter optimization that have been recommended by the Institute of Electrical and Electronics Engineers CEC2013 special session. Experimental results indicate that the proposed algorithm shows its effectiveness at cooperative work with multiple strategies. It can obtain a good balance between exploration and exploitation. The proposed algorithm can guide the search for a global optimal solution with quick convergence compared with other improved DE variants.
In this letter, we propose a single-carrier (SC) dual-mode (DM) index modulation scheme with Gray-coded pairwise index mapping. To improve the index error rate performance of DM schemes, we apply Gray-coding to the ma...
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In this letter, we propose a single-carrier (SC) dual-mode (DM) index modulation scheme with Gray-coded pairwise index mapping. To improve the index error rate performance of DM schemes, we apply Gray-coding to the mapping of modulation patterns. The error propagation within each symbol group in DM schemes can also be avoided due to the pairwise pattern design. Moreover, the mapping ideas in the proposed scheme can be easily extended to other index modulation schemes to obtain better bit error rate performance. Simulation results demonstrate the performance advantage of the proposed scheme over conventional SC and DM schemes in frequency selective fading channels.
Employing pure water, the ultimate green source of hydrogen donor to initiate chemical reactions that involve a hydrogen atom transfer (HAT) step is fascinating but challenging due to its large H-O bond dissociation e...
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Employing pure water, the ultimate green source of hydrogen donor to initiate chemical reactions that involve a hydrogen atom transfer (HAT) step is fascinating but challenging due to its large H-O bond dissociation energy (BDEH-O=5.1 eV). Many approaches have been explored to stimulate water for hydrogenative reactions, but the efficiency and productivity still require significant enhancement. Here, we show that the surface hydroxylated graphitic carbon nitride (gCN-OH) only requires 2.25 eV to activate H-O bonds in water, enabling abstraction of hydrogen atoms via dehydrogenation of pure water into hydrogen peroxide under visible light irradiation. The gCN-OH presents a stable catalytic performance for hydrogenative N-N coupling, pinacol-type coupling and dehalogenative C-C coupling, all with high yield and efficiency, even under solar radiation, featuring extensive impacts in using renewable energy for a cleaner process in dye, electronic, and pharmaceutical industries.
An optical device (100) and an electronic device (200). The optical device (100) comprises at least one waveguide substrate (104), and a coupling-in unit (101), a first relay unit (1021), a second relay unit (1022) an...
标准号:
WO2022/267610(A1)
An optical device (100) and an electronic device (200). The optical device (100) comprises at least one waveguide substrate (104), and a coupling-in unit (101), a first relay unit (1021), a second relay unit (1022) and a coupling-out unit (103) arranged on the waveguide substrate (104). The first relay unit (1021) and the second relay unit (1022) define a relay area enabling a direction of travel of a portion of a light ray coupled in by the coupling-in unit (101) to be limited to fully reflective propagation between the first relay unit (1021) and the second relay unit (1022) after entering the waveguide substrate (104), and another portion of the light ray may be redirected at the second relay unit (1022) towards the coupling-out unit (103) for fully reflective propagation. When a light ray which is fully reflected towards the coupling-out unit (103) reaches the coupling-out unit (103), a portion of the light ray continues to be fully reflected in the original direction and another portion is coupled out to a human eye. In this way, it is possible to expand an exit pupil of a light ray in two dimensions without increasing the area of a relay grating while increasing an image edge field of view angle.
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