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Your search keyword '"Wen, Zheng"' showing total 207 results
Start Over Author "Wen, Zheng" Publisher elsevier b.v.
207 results on '"Wen, Zheng"'

30. A novel lever-type elastic metamaterial model for low-frequency wave attenuation.

Author

Que, Wen-Zheng, Yang, Xiao-Dong, and Pu, Huayan

Subjects
*WAVE packets, *BAND gaps, *THEORY of wave motion, *DISPERSION relations, *WAVE analysis, *METAMATERIALS, *ELASTIC waves
Abstract

• A novel one-dimensional lever-type elastic metamaterial model for wave attenuation is proposed. • Low-frequency band gap is obtained by setting appropriate lever ratio and initial rotation angle. • The potential of the proposed metamaterial in attenuation of shock wave is demonstrated by spatial wave packet analysis. Elastic metamaterials have received extensive attention due to their proven track record in wave attenuation. In this study, a novel one-dimensional lever-type elastic metamaterial model is designed to achieve low-frequency wave attenuation by introducing an adjustable lever mechanism in a conventional mass-spring resonator. The dispersion relation and effective mass expression of the proposed metamaterial are theoretically derived. Then, the band structure characteristics and the effect of parameters on the band gap are analyzed in detail. The results show that by selecting appropriate lever ratio and initial rotation angle, a low frequency band gap can be obtained and the wave attenuation capability within the band gap can be enhanced. Finally, the dynamic response of the proposed structure is calculated by direct numerical integration method to verify the analytical results. Furthermore, the application potential of the proposed elastic metamaterial in shock wave attenuation is demonstrated by analyzing the spatial propagation of wave packets along the proposed structure. This study provides a meaningful reference for the design of other tunable elastic metamaterials to attenuate waves. [ABSTRACT FROM AUTHOR]

Published
2023
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46. Catechyl lignin extracted from candlenut by biphasic 2-methyltetrahydrofuran/water: Characterization and depolymerization.

Author

Yin, Wen-Zheng, Zou, Shuang-Lin, Xiao, Ling-Ping, and Sun, Run-Cang

Subjects
*DEPOLYMERIZATION, *LIGNIN structure, *LIGNANS, *LIGNINS, *HYDROGENOLYSIS, *MONOMERS
Abstract

[Display omitted] • Microwave assisted 2-MeTHF/H 2 O system was effective for C-lignin extraction. • C-lignin revealed acid-resistant properties during the isolation process. • C-lignin exhibited representative benzodioxane structure. • Pd/C-catalyzed hydrogenolysis of C-lignin afforded 37.2 wt% monomer yield. • The selectivity of catechylpropanol was up to 90.6% Catechyl lignin, also known as C-lignin, is consisted mainly of caffeyl alcohol units and serves as a green carbon resource for the production of catechols. Herein, we report that 2-MeTHF/H 2 O as a green and recyclable solvent to extract C-lignin from candlenut with the aid of acid and microwave-assisted heating, resulting in 35.3% of lignin yield. The acid-resistant of C-lignin avoid the destruction of its structures during the extraction process. Characterization analyses reveal that the isolated lignin is abundant in benzodioxane units, which is considered as the unique structure in C-lignin. Additional, Pd/C-catalyzed hydrogenolysis of C-lignin afford 37.2 wt% monomer yield with a selectivity of catechylpropanol product up to 90.6%. Notably, the biphasic system facilitates the subsequent separation process. This work provides a impactful and sustainable C-lignin isolation process from candlenut, contributing to the comprehensive utilization of seed coats. [ABSTRACT FROM AUTHOR]

Published
2024
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48. Longitudinal wave attenuation and bandgap analysis of a novel type hybrid tunable resonator metamaterial.

Author

Que, Wen-Zheng and Yang, Xiao-Dong

Subjects
*LONGITUDINAL waves, *METAMATERIALS, *RESONATORS, *ELECTROMAGNETIC devices, *DISPERSION relations, *DISPLACEMENT (Mechanics), *ATTENUATION (Physics), *ELASTIC waves
Abstract

Achieving vibration suppression or wave attenuation of tunable local resonance metamaterials without physical modification of the resonator has received a lot of attention recently. In this paper, a hybrid tunable metamaterial with a resonator containing a lever mechanism, an electromagnetic device, and a feedback system is proposed to achieve tunable bandgap and longitudinal wave attenuation. Unlike ordinary metamaterials, inertial amplification mechanisms and negative stiffness elements are involved in our proposed metamaterials. The function of the electromagnetic device and the feedback control are considered to theoretically derive the dispersion relation. The effective mass, the effective stiffness, the displacement transmission rate, and the band structure of the proposed metamaterial are analyzed, and the contributions of some key parameters on the bandgap are investigated. The accuracy of the analytical band structure is verified by the wave transmittance curves obtained by numerical simulation and the transient displacement response of a single oscillator. The results show that the proposed metamaterial yields broadband tunable bandgap in the low-frequency range, which enables the isolation of low-frequency longitudinal vibrations. This study provides a novel option for constructing integrated metamaterials to achieve vibration suppression and wave attenuation. • A novel hybrid tunable metamaterial with inertial amplification and negative stiffness is proposed. • The contributions of some key parameters on the bandgap are investigated. • The bandgap is effectively widened in the low-frequency range by combining inertial amplification and negative stiffness. • Numerical simulations are conducted to validate the theoretical results. • The attenuation performance of the proposed metamaterial to longitudinal waves is evaluated. [ABSTRACT FROM AUTHOR]

Published
2024
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