| 1. |
- Bao, Xing, et al.
(författare)
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An efficient hybrid differential evolutionary algorithm for zbilevel optimisation problems
- 2019
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Ingår i: Ekonomska Istrazivanja. - : ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD. - 1331-677X .- 1848-9664. ; 32:1, s. 3016-3033
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Tidskriftsartikel (refereegranskat)abstract
- Bilevel problems are widely used to describe the decision problems with hierarchical upper-lower-level structures in many economic fields. The bilevel optimisation problem (BLOP) is intrinsically NP-hard when its objectives and constraints are complex and the decision variables are large in scale at both levels. An efficient hybrid differential evolutionary algorithm for BLOP (HDEAB) is proposed where the optimal lower level value function mapping method, the differential evolutionary algorithm, k-nearest neighbours (KNN) and a nested local search are hybridised to improve the computational accuracy and efficiency. To show the performance of the HDEAB, numerical studies were conducted on SMD (Sinha, Maro and Deb) instances and an application example of optimising a venture capital staged-financing contract. The results demonstrate that the HDEAB outperforms the BLEAQ (bilevel evolutionary algorithm based on quadratic approximations) greatly in solving the BLOPs with different scales.
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| 2. |
- Peng, Xiaofeng, et al.
(författare)
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Self-reconstruction of twisted Laguerre-Gaussian Schell-model beams partially blocked by an opaque obstacle
- 2020
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Ingår i: Optics Express. - : The Optical Society. - 1094-4087. ; 28:21, s. 31510-31523
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Tidskriftsartikel (refereegranskat)abstract
- Twisted Laguerre-Gaussian Schell model (TLGSM) beams are a novel type of partially coherent beams, which carry the twist phase and the vortex phase simultaneously. In this paper, the self-reconstruction (SR) of the TLGSM beam partially blocked by an opaque obstacle and propagating through a thin lens focusing system is studied in detail. Implementing the pseudo-mode expansion method, we represent the TLGSM beam as a superposition of spatially coherent modes, which is applicable for calculating the cross spectral density (CSD) and spectral degree of coherence (SDOC) of such a beam using the Fourier transform. The numerical results reveal that the twist parameter, a measure of the strength of a twist phase, determines the characteristics of the SR. In the case of the topological charge of the vortex is positive, the SR capability of spectral density is significantly improved with the increase of the twist parameter. The physical mechanism behind these phenomena is analyzed in detail from the point view of mode expansion. Further, the dependence of the side ring intensity and SR capability of the SDOC on the twist parameter are also investigated. It is found that the SR capability and side ring intensity of the SDOC are simultaneously enhanced for a large twist parameter, providing an efficient way to determine the number of topological charge. Our study results may find application in communication and information recovery applications.
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| 3. |
- Wang, Kang, et al.
(författare)
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Luminescent metal-halide perovskites: fundamentals, synthesis, and light-emitting devices
- 2024
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Ingår i: Science in China Series B. - : SCIENCE PRESS. - 1674-7291 .- 1869-1870. ; 67:6, s. 1776-1838
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Forskningsöversikt (refereegranskat)abstract
- Metal-halide perovskites have garnered considerable research attention as highly efficient light emitters in recent years due to their outstanding optoelectronic properties with remarkable tunability and excellent solution processabilities. Substantial advancements have been achieved in the development of novel halide perovskites, and the exploitations of these materials in light-emitting devices. This review comprehensively outlines recent breakthroughs in metal-halide perovskites, encompassing the rational design of perovskite materials with tunable light emission properties, the controllable growth of single crystal for a deeper understanding of their structure-property relationships, as well as the fundamental insights into the photophysics and carrier dynamics in perovskite systems. Additionally, it provides an overview of recent applications of perovskite materials in high-performance light-emitting diodes (LEDs) and lasers.
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