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Mixed Pixel Decomposition Based on Extended Fuzzy Clustering for Single Spectral Value Remote Sensing Images
摘要： The presence of mixed pixels in remote sensing images is the major issue for accurate classification. In this paper, we have focused on two aspects of mixed pixel problem: firstly, to identify mixed pixels from an image and secondly to label them to their appropriate class. In phase I, extraction of mixed pixels has been performed from the RSI images-based super-pixel algorithm and RGB model by using fuzzy C-means (FCM). In phase II, the extracted mixed pixel from phase I has been decomposed to the appropriate class. This new proposed technique is the amalgamation of PSO-FCM (particle swarm optimization-fuzzy C-means) for clustering of mixed pixels and ANN-BPO (artificial neural network-biogeography-based particle swarm optimization) for the classification purpose. Experimental results reveal that the proposed method has improved the accuracy as compared to the existing techniques and succeeds in better classification of the remote sensing images.
关键词： Fuzzy C-means,BBO,Remote sensing images,Pure pixels,Mixed pixels,PSO,Neural network
更新于2025-09-23 15:22:29
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Numerical Investigation of Broadband OPCPA Configurations for Direct Amplification of TW-Level, Two-Cycle Pulses
摘要： Generation of intense, isolated attosecond pulses is the main motivation for the development of laser systems which are producing few-cycle, TW-level pulses. The ELI-ALPS Single Cycle Laser (SYLOS) aims to provide 20 TW single cycle pulses at 1 kHz repetition rate. Due to the requirements for stability and high average power the most promising approach for generating mJ-level, few-cycle pulses is noncollinear optical parametric chirped pulse amplification (NOPCPA). BBO and LBO are the two most favoured nonlinear materials in the visible and near-infrared spectral range, due to their broad gain bandwidth and high damage threshold. It was demonstrated that BBO and LBO can support 5.5 fs and 7 fs pulse durations respectively when 450 nm and 515 nm pumping was used. Even shorter, sub-5 fs pulse durations can be achieved by utilizing two-color pumping, that is, the second- and third-harmonic of a Nd:YAG pump laser in subsequent amplifier stages. The latter solution is the most promising, however at 1 kHz repetition rate there is a risk of optics degradation due to high average power UV light. In this work, two alternative solutions were examined numerically for few-cycle pulse amplification. In the first one, single LBO crystal is used in a phase-matching configuration when the gain bandwidth supports 5 fs pulse duration. In the other solution, spectral multiplexing was utilized in a so-called BBO-sandwich configuration. The principle of the BBO-sandwich is that two thin BBO crystals packed close to each other with slightly different phase-matching angles, but the non-collinear angle between the signal and pump beams is the same in both crystals. As a result, a broader gain bandwidth can be achieved which can support 5 fs pulse duration. These broadband phase-matching configurations were numerically examined using an advanced 3D, OPCPA modelling software. The results of these simulations were well applicable either to rule out or to confirm certain configurations during the experimental development of ELI-ALPS SYLOS laser system. In most cases, the predicted total bandwidths were matched well with the experimental results, even when the spectrum shapes showed difference due to the model approximations. Numerical simulations predicts that the amplified spectrum supports 5 fs Fourier-limited duration and the spectral phase does not contain any fast oscillations thus the pulses are compressible to 5.5 fs. The output pulse energy is 50 mJ before pulse compression and the calculated Strehl-ratio is 0.77. The theoretical findings are also proved by the experimental results, which indicates that these phase-matching configuration are viable candidates for the production of TW-level, few-cycle pulses.
关键词： TW-level pulses,few-cycle pulses,broadband OPCPA,noncollinear optical parametric chirped pulse amplification,LBO,BBO
更新于2025-09-12 10:27:22