- 标题
- 摘要
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- 实验方案
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Fabrication and electromagnetic wave absorption property of quartz ceramics with a gradient distribution of BaTiO3
摘要： Quartz ceramics with a uniform/gradient distribution of BaTiO3 (U/G–SO–BTO) are fabricated by cold pressing a powder blend with BTO followed by sintering and using a combined technique of spreading the powder blends with gradually increased BTO layer–by–layer and sintering. The electromagnetic wave absorption properties of these two ceramics are studied in detail. For U–SO–BTO samples, the primary electromagnetic re?ection is strong due to the aggravated impedance mismatch at their surfaces. The electromagnetic wave re?ectivity of U–SO–BTO could only reach ?7.0 dB when the sample thickness is 6 mm and the BTO content is 8.0 wt%, and it decreases slightly to ?8.1 dB when the sample thickness is increased to 10.0 mm and the BTO content is decreased to 5.0 wt% simultaneously. For G–SO–BTO samples, electromagnetic waves could enter with little re?ection due to the weak surface impedance mismatch, and the electromagnetic waves entering these samples could propagate forward while being absorbed gradually with little re?ection because of the weak impedance mismatch at the interfaces. The G–SO–BTO samples are promising excellent electromagnetic absorbing materials because their electromagnetic wave re?ectivity could reach a level lower than ?12.0 dB and could decrease further from –12.2 to ?13.1 dB as the layer thickness increases from 1.0 to 2.0 mm.
关键词： Impedance mismatch,Electromagnetic wave absorption,Quartz ceramics,Electromagnetic re?ection,Gradient distribution,BaTiO3
更新于2025-09-23 15:22:29
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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Operation verification of tunable plasmonic color filter composed by metal-insulator-metal subwavelength grating and MEMS actuator
摘要： Signal processing in light-microscopy and cell imaging is concerned with reconstructing latent ground truth from imperfect images. This typically requires assuming prior knowledge about the latent ground truth. While this assumption regularizes the problem to an extent where it can be solved, it also biases the result toward the expected. It thus often remains unclear what prior to use for a given practical problem. We argue here that the gradient distribution of natural-scene images may provide a versatile and well-founded prior for light-microscopy images that does not impose assumptions about the geometry of the ground-truth signal, but only about its gradient spectrum. We provide motivation for this choice from different points of view, and we illustrate the resulting regularizer for use on light-microscopy images. We provide a simple parametric model for the resulting prior, leading to ef?ciently solvable variational problems. We demonstrate the use of these models and solvers in a variety of common image-processing tasks, including contrast enhancement, noise-level estimation, denoising, blind deconvolution, and dehazing. We conclude by discussing the limitations and possible interpretations of the prior.
关键词： parametric prior,gradient distribution,noise-level estimation,dehazing,naturalization,denoising,Deconvolution,variational method
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - 1,55 mkm fiber laser with electronic controlled mode-locking
摘要： Signal processing in light-microscopy and cell imaging is concerned with reconstructing latent ground truth from imperfect images. This typically requires assuming prior knowledge about the latent ground truth. While this assumption regularizes the problem to an extent where it can be solved, it also biases the result toward the expected. It thus often remains unclear what prior to use for a given practical problem. We argue here that the gradient distribution of natural-scene images may provide a versatile and well-founded prior for light-microscopy images that does not impose assumptions about the geometry of the ground-truth signal, but only about its gradient spectrum. We provide motivation for this choice from different points of view, and we illustrate the resulting regularizer for use on light-microscopy images. We provide a simple parametric model for the resulting prior, leading to ef?ciently solvable variational problems. We demonstrate the use of these models and solvers in a variety of common image-processing tasks, including contrast enhancement, noise-level estimation, denoising, blind deconvolution, and dehazing. We conclude by discussing the limitations and possible interpretations of the prior.
关键词： variational method,naturalization,gradient distribution,dehazing,parametric prior,noise-level estimation,denoising,Deconvolution
更新于2025-09-19 17:13:59
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Strain Improving the Performance of a Flexible Monolayer MoS <sub/>2</sub> Photodetector
摘要： Electromagnetic wave absorbing foamed ceramics (FCs) with high closed porosity and gradient SiC distribution were prepared from the powder blend containing quartz, talc, CaCO3, Si3N4 and SiC by sintering at 1200 °C for 1 h in air. The retention in the temperature holding process of the continuous and gradual SiC distribution arising from the inward oxidation of SiC in the temperature rising process is the formation mechanism of the gradient SiC distribution in FCs. As to the FC prepared from the powder blend with 3 wt% of SiC, it shows the best comprehensive performance with low bulk density of 0.48 g/cm3 and relatively high compressive strength of 9.6 MPa, good thermal insulation performance for its high total porosity of 82%, good water resistance performance for its high closed porosity of 80%, and excellent electromagnetic wave absorption performance for its low mean re?ectivity of ?11.9 dB in the frequency range of 8.0–18.0 GHz and especially low minimum re?ectivity of ?14.2 dB at 12.7 GHz. More importantly, it is also an excellent high temperature electromagnetic wave absorbing material for its little increased mean re?ectivity of ?11.3 dB after heat treating at 1000 °C for 20 h in air.
关键词： Electromagnetic wave re?ectivity,High closed porosity,Electromagnetic wave absorption performance,Foamed ceramics,Gradient distribution
更新于2025-09-19 17:13:59