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Your search keyword '"Jia, Hai-Long"' showing total 137 results
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137 results on '"Jia, Hai-Long"'

1. Ringing Thick Braneworld with Finite Extra Dimension

Author

Jia, Hai-Long, Guo, Wen-Di, Tan, Qin, and Liu, Yu-Xiao

Subjects
General Relativity and Quantum Cosmology
Abstract

In this work, we investigate the quasinormal modes of the Poincar\'e thick brane with a finite extra dimension. Unlike the case with an infinite extra dimension, the gravitational effective potential exhibits three distinct shapes within different ranges of the parameter $n$ in the warp factor: harmonic oscillator potential, P\"oschl-Teller potential, and volcano-like potential. We then study various types of perturbations in this system. Utilizing a combination of analytical, semi-analytical, and numerical methods, we obtain the quasinormal modes of the perturbed fields. Our findings reveal a set of discrete quasinormal modes for the thick brane, similar to those of black holes. Interestingly, when $n=1$, the quasinormal modes exhibit purely imaginary behavior. This study may provide a new way to detect the existence of extra dimensions.

Published
2024

41. Twinning-mediated plasticity by a novel multistage twinning mode in an Mg-Al-Gd alloy.

Author

Zhao, Lei, Zha, Min, Gao, Yipeng, Guan, Kai, Chen, Peng, Zhang, Meng-Na, Hua, Zhen-Ming, Jia, Hai-Long, and Wang, Hui-Yuan

Subjects
STRAIN hardening, TWIN boundaries, ALLOYS, DEFORMATIONS (Mechanics), MAGNESIUM alloys
Abstract

Twinning-mediated plasticity has great potential for enhancing the strength and plasticity of Mg alloys, which is limited due to the lack of twin types. Here, we report a novel multistage twinning mode, i.e. the dominant twinning mode changes from single { 10 1 ¯ 2 } twins to the co-existence of { 10 1 ¯ 2 } and { 11 2 ¯ 6 } twins, in a deformed Mg-Al-Gd alloy. Introducing novel multistage twinning mode to accommodate strains appreciably along c-axes, combined with the interactions of high-density dislocations and dense twin boundaries, guarantees the high strain hardening of Mg alloys. These findings provide new insights into deformation mechanisms and mechanical properties of Mg-alloys. Introducing novel multistage twinning mode to accommodate strains appreciably along c-axes, combined with the interactions of high-density dislocations and dense twin boundaries, guarantees the high strain hardening of Mg alloys. [ABSTRACT FROM AUTHOR]

Published
2023
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45. Anisotropic segregation-driven texture weakening in a dilute Mg-Al-Ca alloy during isothermal annealing

Author

Zhang, Meng-Na, Jia, Hai-Long, Zha, Min, Zhao, Lei, Hua, Zhen-Ming, Wang, Cheng, Gao, Yi-Peng, and Wang, Hui-Yuan

Abstract

Tailoring recrystallization via particle-stimulated nucleation (PSN) and pinning effects from secondary phase particles effectively weakens textures, which is still challenging for low-alloyed rare earth-free Mg alloys. Herein, the texture of a dilute cold-rolled Mg-2.2Al-0.33Ca (wt.%) alloy is found to reduce with the appearance of transverse direction (TD) texture components during static recrystallization. The texture transition is mainly attributed to the preferential growth of TD-oriented recrystallized grains, resulting from the preferential segregation of Al and Ca atoms on basal-oriented grain boundaries with low misorientation angles. The findings provide an in-depth understanding of texture modification in Mg alloys. The anisotropic co-segregation of Al and Ca on grain boundaries is responsible for the texture weakening of a dilute Mg-Al-Ca alloy, which provides a strategy for texture modification in such alloys.

Published
2023
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46. Developing high-strength and ductile Mg-Gd-Y-Zn-Zr alloy sheet via bimodal grain structure coupling with heterogeneously-distributed precipitates

Author

Zha, Min, Wang, Si-Qing, Wang, Tong, Jia, Hai-Long, Li, Yong-Kang, Hua, Zhen-Ming, Guan, Kai, Wang, Cheng, and Wang, Hui-Yuan

Abstract

Achieving high strength-ductility synergy in hard-to-deform high-alloyed Mg-Gd-Y-Zn-Zr alloys by rolling remains a great challenge. In this work, a Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt.%) alloy sheet possessing a high yield strength (YS) of ∼385 MPa, ultimate tensile strength (UTS) of ∼420 MPa and elongation of ∼19% was achieved via a single-pass hard-plate rolling (HPR) process. The high YS is mainly from amounts of submicron FGs and strong interactions between densely distributed γ′ precipitates and pyramidal dislocations in CGs. The activation of multiple slip systems, HDI-hardening effect, and crack suppression effect from γ′ particles, endow the excellent ductility. The hard-to-deform WE94 alloy sheet exhibiting a superior strength-ductility synergy has been prepared by a single-pass HPR process. The bimodal grain structure containing substantial ultrafine grains coupling with inhomogeneously-distributed nano-scale precipitates accounts for the superior mechanical properties.

Published
2023
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49. High strength and high ductility achieved in a heterogeneous lamella-structured magnesium alloy.

Author

Wang, Tong, Zha, Min, Du, Chunfeng, Jia, Hai-Long, Wang, Cheng, Guan, Kai, Gao, Yipeng, and Wang, Hui-Yuan

Subjects
DUCTILITY, DISCLINATIONS, TENSILE strength, DEFORMATIONS (Mechanics), MAGNESIUM alloys
Abstract

By introducing heterogeneous lamella-structure, we obtained a superior strength-ductility synergy in Mg-alloy associated with excellent strain-hardening ability, i.e. yield strength of ∼251 MPa, tensile strength of ∼393 MPa and elongation of ∼23%. By using advanced characterization techniques, we showed that strengthening was mainly caused by the non-uniform distribution of hetero-deformation induced (HDI) stress associated with grain-boundary disclinations, which are mediated by heterogeneous multi-grain interactions. Induced by grain-boundary disclinations and intergranular slip transfers, a variety of abnormal deformation modes have been activated，which contributed significantly to enhanced ductility. This work suggests a new avenue to evade strength-ductility trade-off dilemma in Mg-alloys. The heterogeneous lamella-structure leads to sustained strain-hardenability in Mg-alloy with unique accommodating deformation modes (extensive abnormal slips and feather-shaped twins), induced by grain-boundary disclinations and intergranular slip transfers. [ABSTRACT FROM AUTHOR]

Published
2023
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50. The Internal Labor Market and the Transformation of Labor Relations in China: Based on Survey Data and Fieldwork on Migrant Workers in the Pearl River Delta

Author

Jia Hai-long, Sun Zhong-wei, and Liu Mingwei

Subjects
Pearl river delta, Migrant workers, 05 social sciences, General Social Sciences, Internal labor market, Labor contract, 0506 political science, Labor relations, 0502 economics and business, 050602 political science & public administration, Survey data collection, Demographic economics, Business, 050207 economics, China
Abstract

Our survey data on migrant workers in the Pearl River Delta region from 2006 to 2010 and recent fieldwork show that the enactment of the Labor Contract Law encouraged both the signing of labor cont...

Published
2020

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