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294 results on '"Han, Weiqiang"'

13. Multidimension‐Regulated Dynamic Timing Control Over Multicolor Emission of Host–Guest Assemblies for Information Encryption and Advanced Anti‐Counterfeiting.

Author

Zhang, Qi, Chang, Zhidong, Han, Weiqiang, Wang, Chaofan, Liu, Guoxin, Li, Hongjuan, Sun, Shiguo, and Xu, Yongqian

Subjects
FLUORESCENCE resonance energy transfer, DIARYLETHENE
Abstract

Dynamical control over molecular luminescence, especially in a time‐dependent manner, holds great promise for the development of smart luminescent materials for anti‐counterfeiting and preventing information leakage. Herein, a series of self‐assembled systems are reported using pillar[5]arene (DMP[5]) and spiropyran derivatives (SP‐C4‐Py). The assemblies rely on the time‐encoded locking and unlocking ring‐switching and fluorescence resonance energy transfer (FRET) units for information camouflage and multilevel encryption. DMP[5] with cyan solid fluorescence color acts as the host and energy transfer (EnT) donor, while photochromic SP‐C4‐Py with the ring‐opened and closed isomers acts as guest and EnT acceptor. When irradiated, the assemblies undergo a time‐dependent luminescence color change ranging from cyan to yellow to red through a FRET process. The molar ratio of host and guest in the assembly systems affects the FRET efficiency, and the power of the irradiation source influences the isomerization degree and rate of SP‐C4‐Py, allowing for precise control over the fluorescent color transition time. The combination of molecular composition and external stimuli governs the kinetics of color change, resulting in a difference in the appearance time of a specific fluorescent color pre‐designed as correct authorized information. By combining these diverse assembles in one label, information encryption and dynamic information identification are achieved in the dimensions of time, ratio, and light power. This time‐dependent feature offers the assembly materials with a multilevel security and provides new possibilities for anti‐counterfeiting and blocking information leakage. [ABSTRACT FROM AUTHOR]

Published
2024
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20. MXenes

Author

Han, Weiqiang, primary, Huang, Qing, additional, and Wang, Guoxiu, additional

Published
2023
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22. Spin Waves and Switching: The Dynamics of Exchange - Biased Co Core - CoO Shell Nanoparticles

Author

Feygenson, Mikhail, Teng, Xiaowei, Inderhees, Sue E., Yiu, Yuen, Du, Wenxin, Han, Weiqiang, Wen, Jinsheng, Xu, Zhijung, Podlesnyak, Andrey A., Niedziela, Jennifer L., Hagen, Mark, Qiu, Yiming, Brown, Craig M., Zhang, Lihua, and Aronson, Meigan C.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The utility of nanoscaled ferromagnetic particles requires both stabilized moments and maximized switching speeds. During reversal, the spatial modulation of the nanoparticle magnetization evolves in time, and the energy differences between each new configuration are accomodated by the absorption or emission spin waves with different wavelengths and energy profiles. The switching speed is limited by how quickly this spin wave energy is dissipated. We present here the first observation of dispersing spin waves in a nanoscaled system, using neutron scattering to detect spin waves in the CoO shells of exchange biased Co core- CoO shell nanoparticles. Their dispersion is little affected by finite size effects, but the spectral weight shifts to energies and wave vectors which increase with decreasing system size. Core-shell coupling leads to a substantial enhancement of the CoO spin wave population above its conventional thermal level, suggesting a new mechanism for dissipating core switching energy.

Published
2009

26. True random coded photon counting Lidar

Author

Liu Bo, Yu Yang, Chen Zhen, and Han Weiqiang

Subjects
lidar, photon counting, true random coded, pseudo-random coded, Optics. Light, QC350-467
Abstract

A true random coded photon counting Lidar system is proposed in this paper, in which a single photon detector acts as the true random sequence signal generator instead of the traditional function generator. Compared with the traditional pseudo-random coded method, the true random coded method not only improves the anti-crosstalk capability of the system, but more importantly, it effectively overcomes the adverse effect of the detector's dead time on the ranging performance. The experiment results show that the ranging performance of the true random coded method is obviously better than that of the pseudo-random coded method. As a result, a three-dimensional scanning imaging of a model car is completed by the true random coded method.

Published
2020
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38. Analysis and test of transmit-receive isolation of off-axis three-mirror anastigmat optical antenna applied to laser communication

Author

Chao Deng, Hua Li, Fan Zhenjie, Han Weiqiang, and Wei Sun

Subjects
Physics, business.industry, Duplex (telecommunications), Three-mirror anastigmat, macromolecular substances, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010309 optics, Optics, Optical antenna, 0103 physical sciences, sense organs, 010306 general physics, business, Free-space optical communication
Abstract

The bi-directional duplex working mode of a transmit-receive integrated optical antenna in laser communication systems has a rigorous requirement on transmission and receiver(T/R) isolation. By usi...

Published
2020

43. Combined effect of inlet pressure, total cycle energy, and start of injection on low load reactivity controlled compression ignition combustion and emission characteristics in a multi-cylinder heavy-duty engine fueled with gasoline/diesel

Author

Lu Yao, Li Bolun, Pan Suozhu, Han Weiqiang, and Li Xin

Subjects
Materials science, 020209 energy, Analytical chemistry, 02 engineering and technology, medicine.disease_cause, Combustion, Industrial and Manufacturing Engineering, Cylinder (engine), law.invention, Diesel fuel, 020401 chemical engineering, law, 0202 electrical engineering, electronic engineering, information engineering, medicine, 0204 chemical engineering, Electrical and Electronic Engineering, Gasoline, Civil and Structural Engineering, Mechanical Engineering, Building and Construction, Compression (physics), Pollution, Soot, Ignition system, General Energy, Particle
Abstract

Reactivity controlled compression ignition (RCCI) is demonstrated as a controllable high efficiency and clean combustion strategy, which is confirmed to be affected by either inlet pressure (IP), total cycle energy (E total ), or start of injection (SOI). This paper discussed their combined effect on low load RCCI combustion and emission characteristics in a multi-cylinder heavy-duty engine fueled with gasoline/diesel. Results show that low temperature heat release (LTHR) only occurs when SOI is sufficiently advanced. Combustion duration (CD) is lengthened, shortened and unchanged with SOI advance under different E total s, while lengthened with IP increase. NO X emission first increases and then decreases with SOI advance, and declines with IP increase or E total decrease. Trend CO changes with SOI or IP becomes opposite at the lowest E total , comparing with that at relatively high E total s. HC emission decreases with SOI advance or E total increase, while it is insensitive to IP. Trend number of nuclear particle ( N u m n ) changes with IP becomes opposite at the highest E total , comparing with that at relatively low E total s, while N u m n decreases with SOI advance or E total increase. Both number of aggregated particle ( N u m a ) and soot first decreases and then increases with SOI advance, and decreases with E total decrease or IP increase.

Published
2018

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