Sökning: "David Zhang"

Hittade 3 avhandlingar innehållade orden David Zhang.

  1. 1. Ion escape from Mars

    Författare :Qi Zhang; Mats Holmström; Xiao-Dong Wang; Shahab Fatemi; Hans Nilsson; David Andrews; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : When the solar wind reaches the Mars obstacle, mass loading by planetary ions slows down the solar wind and raises the bow shock. The Martian atmosphere is undergoing the a scavenging by the solar wind without the protection of a global magnetic field. Atmospheric escape is an important process for the evolution of the Martian climate. LÄS MER

  3. 2. Supply Chain Risk Management : Identification, Evaluation and Mitigation Techniques

    Författare :S.Nurmaya Musa; Ou Tang; Jan Olhager; David Zhang; Linköpings universitet; []
    Nyckelord :Supply chain risk management; risk analysis; risk control; co-citation; system dynamics; modelling;

    Sammanfattning : Supply chains have expanded rapidly over the decades, with the aim to increase productivity, lower costs and fulfil demands in emerging markets. The increasing complexity in a supply chain hinders visibility and consequently reduces one’s control over the process. LÄS MER

  4. 3. Origin and Lifestyles of early Brachiopods and other Lophotrochozoans : Insights from the Chengjiang and Guanshan Fossil-Lagerstätten

    Författare :Haizhou Wang; Lars E. Holmer; Zhifei Zhang; Michael Streng; David A.T. Harper; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cambrian Explosion; Chengjiang; Guanshan; Lagerstätten; Lophotrochozoa; Brachiopoda; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

    Sammanfattning : One of the great unsolved evolutionary questions concerns the origin and phylogeny of the major animal phyla that appeared in the fossil record more than 540 million years ago, during the Cambrian explosion. Although new molecular information has been very useful, we still have little understanding about the origin of most of the phyla of bilaterians living today. LÄS MER