Browsing by Author "Liu, HB"

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    Mechanism of the abnormal thermal expansion of nearly stoichiometric LiNbO3
    (Elsevier Science, 2011-03-01) Yao, SH; Wang, JY; Liu, HB; Yan, T; Yu, DH; Chen, YF
    High temperature X-ray diffraction, thermal expansion and Raman spectroscopic measurements have been conducted to investigate the structural behavior of nearly stoichiometric LiNbO3. Abnormal thermal expansion has been observed within the temperature range of 1021-1373 K. The mechanism responsible for the abnormal phenomena and the structure deformation has been identified as the competition between the thermal vibration in the x-y plane and the antiphase motion along the z-axis of the [NbO6] framework as a function of temperature through the analysis of the temperature dependent Raman spectra. (C) 2010 Elsevier B.V.
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    Use of coal in the bronze age in China
    (Sage, 2014-03-03) Dodson, JR; Li, XQ; Sun, N; Atahan, P; Zhou, XY; Liu, HB; Zhao, KL; Hu, SM; Yang, ZM
    People in northern and western China were probably the first in the world to use coal as a source of energy in a consistent way. The ages cluster around 1900–2200 BC in modern day Inner Mongolia and Shanxi provinces. These are areas where near-surface coal is abundant today and woody vegetation was scant in the Bronze Age. Since coal is bulky to transport, it was probably not a cost-effective energy source in areas with abundant wood supply. The sites where coal was first used were probably occupied for a century to a few centuries at most and were associated with Bronze Age societies. The earliest age is about 3490 BC from a house site at Xiahe in Shaanxi Province; however, the coal is not securely tied to the radiocarbon ages and is assumed to have been used at this site sometime after 3490 BC. The elemental composition of modern mine and sedimentary coal in nearby archaeological contexts suggests that coal was used from local sources, and that elemental composition of coal may be a useful tool in identifying site origin of coal.
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    Zonal vegetation change in the Chinese Loess Plateau since MIS 3
    (Elsevier Science, 2014-06-15) Zhou, XY; Li, XQ; Dodson, JR; Yang, SL; Long, H; Zhao, KL; Sun, N; Yang, Q; Liu, HB
    Three pollen records from different regions of the Chinese Loess Plateau (CLP) show that the zonal differentiation of vegetation was not large in late MIS 3 time, all the areas were covered by warm semi-humid grass-shrub land, with some conifer-broad leaf mixed forest in the valleys. It appears that the zonal differentiation of vegetation nearly disappeared in the Last Glacial Maximum (LGM), while the semi-arid steppe expanded to the southern margin of the CLP. During the Holocene Thermal Maximum (HTM), the zonal differentiation became complex, with warm humid forest in the southeastern part and semi-arid steppe in the northern CLP. The zonal degree of vegetation differentiation of the CLP decreased again during the late Holocene as a result of climate change and increasing human influence on the landscape. In recent centuries, the transformation of the grass communities caused by land clearance for agriculture on the loess tablelands has been significant. © 2014, Elsevier Ltd.