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207 results on '"Wang, Guangqing"'

3. Sharp function and weighted $L^{p}$ estimates for pseudo-differential operators with symbols in general H\'{o}rmander classes

Author

Wang, Guangqing

Subjects
Mathematics - Analysis of PDEs
Abstract

The purpose of this paper is to prove pointwise inequalities and to establish the boundedness on weighted $L^{p}$ spaces for pseudo-differential operators $T_{a}$ defined by the symbol $a\in S^{m}_{\varrho,\delta}$ with $0\leq\varrho\leq1,$ $0\leq\delta<1$. Firstly, we prove that if $m\leq-n(1-\varrho)/2$, then $$(T_{a}u)^{\sharp}(x)\lesssim M(|u|^{2})^{1/2}(x)$$ for all $x\in\mathbb{R}^{n}$ and all Schwartz function $u$. Secondly, it is shown that if $1\leq r\leq2$ and $m\leq-\frac{n}{r}(1-\varrho)$, then for any $\omega$ belongs to the class of Muckenhoupt weights $A_{p/r}$ with $r

Published
2022

35. Weighted estimates for rough pseudo-differential operators and their commutators

Author

Wang, Guangqing and Chen, Wenyi

Abstract

By using a class of new weight functions including the Muckenhoupt class weight functions, we study weighted Lpinequalities for pseudo-differential operators with rough amplitudes. And weighted weak-type (1, 1) estimate for their commutators defined by the new BMO spaces that is larger then classical BMO spaces is established.

Published
2024
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46. 3D Dirac Semimetal Elliptical Fiber Supported THz Tunable Hybrid Plasmonic Waveguides

Author

Wang, Guangqing, Cao, Wenhan, and He, Xiaoyong

Abstract

A novel tunable terahertz hybrid plasmonic waveguide based on a 3D Dirac semimetal (DSM) elliptical fiber separated from a silicon layer by a dielectric gap is explored. Interestingly, the results manifest that as the elliptical ratio increases, the real part of the effective mode index and the propagation length both monotonically increase. Importantly, the figure of merit strikingly reaches more than 1500. The propagation length shows a peak near the interface between the near filed and dissipation regions. The near field region is significantly affected by the Fermi level, in that the critical transition thickness is from 10.8 μm to 0.92 μm when the Fermi level varies in the range from 0.03 eV to 0.10 eV. The propagation properties of hybrid modes can be modulated in a wide scope via the Fermi level of the 3D DSM fiber, the propagation length can be modulated from 6.27 × 103 μm to 1.16 × 105 μm on the condition that the Fermi level changes in the range of 0.04 eV--0.15 eV, and the corresponding modulation depth is about 95%. The results are very useful to aid the design of novel plasmonic devices, e.g., low threshold lasers, modulators and polarizer.

Published
2023
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49. Cobalt Sulfide (Co 9 S 8)-Based Materials with Different Dimensions: Properties, Preparation and Applications in Photo/Electric Catalysis and Energy Storage.

Author

Wang, Chuantao, Pang, Xiangxiang, Wang, Guangqing, Gao, Loujun, and Fu, Feng

Subjects
COBALT sulfide, ENERGY storage, PHOTOCATALYSIS, WATER electrolysis, HYDROGEN evolution reactions
Abstract

Due to their excellent properties and unique structures, transition metal sulfides play an important role in the development of efficient and stable photoelectric catalysts. In recent years, their potential applications have expanded from photoelectric catalysis to energy storage, especially as materials for key components of electrochemical energy storage. As a typical multifunctional metal sulfide catalyst, Co9S8 is highly attractive due to its high conductivity, better stability, suitable band structure, enhanced performance and wide applications. A large number of studies have shown that strategically modified Co9S8-based materials have greater advantages in various applications compared with pure Co9S8. Therefore, this review will evaluate the physicochemical properties and the preparation of different dimensions of Co9S8-based materials, and the influence of different structures on the photoelectrochemical energy of materials will be described. In addition, the research progress regarding the evolution of hydrogen photocatalytic, electrocatalytic water splitting and various electrochemical energy storage materials will be emphasized. Finally, the challenges faced by Co9S8-based materials and the research directions for their future applications will be discussed. [ABSTRACT FROM AUTHOR]

Published
2023
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