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26 results on '"Cheng, Mengyao"'

10. Children on the Move in China: Insights from the Census Data 2000–2020.

Author

Cheng, Mengyao, Chen, Yu, Lyu, Lidan, and Bai, Yu

Subjects
*FAMILY structure, *CHILDREN of immigrants, *CHILDREN of migrant laborers, *CENSUS, *RURAL population, POPULATION of China
Abstract

Using data from the 2000, 2010, and 2020 National Population Census of China, this study uncovers evolving trends in the experiences of children in family structures reshaped by China's massive internal migration. We develop a new framework to examine family structures from the census data, which facilitates a detailed exploration of family splits as a result of migration. Our results show a significant surge in the proportion of children in migrant families and the trend of children on the move. While the number of left‐behind children far exceeded that of migrant children in 2000, the picture became the opposite in 2020, signifying an enhanced capacity and inclination for migrant parents to bring their children to migration destinations. This shift has also engendered a more heterogeneous population of children in migrant families. Notably, a subgroup warranting particular attention is that of “left‐behind child migrants,” those moving to proximate towns or cities without both parents. This emergence blurs the traditional urban–rural dichotomies and underscores the intricacies of a family split within the migrant population. Finally, we reflect on the significant role of educational aspirations and obstacles that influence these migratory patterns. [ABSTRACT FROM AUTHOR]

Published
2024
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26. Orange, yellow and green emissions generated in Q-switched Nd:YALO3/YVO4 Raman laser

Author

Haiyong Zhu, Cheng Mengyao, Tingwei Mao, Chen Simeng, Yanmin Duan, Ge Zhang, Zhou Qingqing, and Zhang Ximei

Subjects
Pulse repetition frequency, Materials science, Biophysics, 02 engineering and technology, Orange (colour), Green-light, 010402 general chemistry, 01 natural sciences, Biochemistry, Green emission, law.invention, Nonlinear optical, symbols.namesake, law, business.industry, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Laser, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Raman laser, symbols, Optoelectronics, 0210 nano-technology, business, Raman spectroscopy
Abstract

Nd:YAlO3/YVO4 crystal Raman laser with orange, yellow and green emission switchable output was demonstrated by the second-harmonic generation and sum-frequency generation of the fundamental and the first-Stokes waves. A diode-end-pumped acousto-optic Q-switched Nd:YAlO3 crystal laser at 1080 nm was used to drive a 30 mm length YVO4 crystal for intra-cavity Raman operation. The different visible sources were achieved in an angle-tuned BBO crystal. The average output power of 539.9 nm green light, 567.2 nm yellow light and 597.4 nm orange light generated in a BBO crystal with single direction were 418, 266 and 361 mW at an absorbed pump power of 6.01 W and a pulse repetition frequency of 20 kHz, with respective to pulse widths of about 47.2, 4.8 and 5.6 ns. The results show that the angle-tuned BBO crystal with characteristics of large temperature tolerance and large nonlinear optical coefficient was a promising nonlinear optical crystal for wavelength-switching in the Q-switched Raman laser.

Published
2019

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