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- 저자 : Masser, Hanqing (검색결과 3 건)
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Understanding Urban Growth : a Conceptual Model
Jianquan Cheng, Henk Ottens, Ian Masser, Jan Turkstra 서울시립대학교 도시과학연구원 2003 International journal of urban sciences (IJUS) Vol. No.
Understanding the urban growth system is a prerequisite for modelling and forecasting future trends of urban land use/cover change and its ecological impacts. As urban growth involves various actors with different patterns of behaviour, we argue that scientific understanding must be based on elaborated complexity theory and a multidisciplinary framework. The theoretical analysis can provide a guideline for selecting modelling methods currently available in complexity modelling and in remote sensing and GIS environments. This paper first proposes a conceptual model for defining urban growth and its complexity, in which spatial, temporal and decision-making complexity are distinguished as separate domains. Second, this paper links the conceptual model with the major current methods of modern urban modelling, such as cellular automata, fractals, neural networks, multi-agent, spatial statistics etc. This confrontation enables the possibilities of various modelling methods to understand urban growth complexity to be indicated. Third, this paper evaluates the operational implementation of representative methods based on criteria such as interpretability, data need and GIS embedded ness. Finally, two case studies are used to test the conceptual model.
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Dynamics of Precise Ethylene Ionomers Containing Ionic Liquid Functionality
Choi, U Hyeok,Middleton, L. Robert,Soccio, Michelina,Buitrago, C. Francisco,Aitken, Brian S.,Masser, Hanqing,Wagener, Kenneth B.,Winey, Karen I.,Runt, James American Chemical Society 2015 Macromolecules Vol.48 No.2
<P>This paper presents the first findings on the molecular dynamics of the remarkable new class of linear and precisely functionalized ethylene copolymers. Specifically, we utilize broadband dielectric relaxation spectroscopy to investigate the molecular dynamics of linear polyethylene (PE)-based ionomers containing 1-methylimidazolium bromide (<B>ImBr</B>) pendants on exactly every 9th, 15th, or 21st carbon atom, along with one pseudorandom analogue. We also employed FTIR spectroscopy to provide insight into local ionic interactions and the nature of the ordering of the ethylene spacers between pendants. Prior X-ray scattering experiments revealed that the polar ionic groups in these ionomers self-assemble into microphase-separated aggregates dispersed throughout the nonpolar PE matrix. We focus primarily on the dynamics of the segmental relaxations, which are significantly slowed down compared to linear PE due to ion aggregation. Relaxation times depend on composition, the presence of crystallinity, and microphase-separated morphologies. Segmental relaxation strengths are much lower than predicted by the Onsager theory for mobile isolated dipoles but much higher than linear PE, demonstrating that at least some <B>ImBr</B> pendants participate in the segmental process. Analysis of the relaxation strengths using the Kirkwood <I>g</I> correlation factor demonstrates that ca. 10–40% of the <B>ImBr</B> ion dipoles (depending on copolymer composition and temperature) participate in the segmental motions of the precise ionomers under study, with the remainder immobilized or having net antiparallel arrangements in ion aggregates.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2015/mamobx.2015.48.issue-2/ma502168e/production/images/medium/ma-2014-02168e_0011.gif'></P>
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