Chen Xu – författare

The age and stratigraphic division of the Wufeng Shale has buried an unresolved issue in the Chinese geological community for a long time since its birth. A paper "On the Wufeng Shale" was published in 1954 (Mu, 1954) with a reliable conclusion obtained that the Wufeng Formation belongs to the Upper Ordovician.There are too much insignificant species or subspecies and many wrong identification in the monograph "Upper Ordovician Graptolites of Central China Region� (Mu et al., 1993). It makes confusion of age duration of the Wufengian species. This is the one of reasons for the need to restudy the Wufengian graptolites.In the past two decades, two black shales, the Wufeng Formation (uppermost Ordovician) and the Lungmachi Formation (lower Silurian) in the Yangtze Region have become important shale gas production horizons. Among them, the division and precise comparison of graptolite biozones is an important basis for downhole determination and comparison of shale gas sweet spots. This requires the accuracy and recognized graptolite classification. This is the other one of most important reasons for restudying the Wufengian graptolites.Since 1990s of last century, a large number of Ordovician graptolites, including Wufengian graptolites have been collected for the research on the global boundary stratification of the Ordovician stages in South China. Recently some better preserved graptolite specimens, in particular a few three-dimensional graptolite specimens, have been obtained from Shuibatang section in Guizou. It provided a good opportunity for restudying the Wufengian graptolites. In this book, all the Wufengian graptolites in South China are restudied and revised, in order to clarify their morphological characteristics, systematic classification, temporal and spatial distribution, and evolutionary significance.In the book, the authors make major revisions and further discussions on the upper Ordovician graptolite monograph published in 1993 in Central ChinaA total of 25 genera and 80 species are described, with a large number of pictures of graptolite specimensReaders can learn and identify the graptolite fossils of the Late Ordovician through this book, and then realize their geological agesAt the same time, the large amount of graptolite classification, geographical distribution and temporal range information provided in this book can provide basic data for studying the macroevolutionary processes and characteristics of graptolite in the End-Ordovician Mass Extinction

Device-to-Device (D2D) communication will become a key feature supported by next generation cellular networks, a topic of enormous importance to modern communication. Currently, D2D serves as an underlay to the cellular network as a means to increase spectral efficiency. Although D2D communication brings large benefits in terms of system capacity, it also causes interference as well as increased computation complexity to cellular networks as a result of spectrum sharing. Thus, efficient resource management must be performed to guarantee a target performance level of cellular communication.This brief presents the state-of-the-art research on resource management for D2D communication underlaying cellular networks. Those who work with D2D communication will use this book’s information to help ensure their work is as efficient as possible. Along with the survey of existing work, this book also includes the fundamental theories, key techniques, and applications.