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Xu, Zhaokai,Li, Tiegang,Clift, Peter D.,Wan, Shiming,Qiu, Xiaohua,Lim, Dhongil Elsevier 2018 Chemical geology Vol.476 No.-
<P><B>Abstract</B></P> <P>We present a new high-resolution multiproxy data set of mass accumulation rates, Sr-Nd isotopes, as well as major and trace elements for the siliciclastic sediment fraction from International Marine Global Change Study Core MD06-3052, located on the continental slope of the western Philippine Sea. We integrate our new data with published grain sizes and sea surface temperatures from the same core, as well as with Equatorial Pacific sea level, and East Asian summer monsoon precipitation, in order to constrain at high-resolution changes in physical erosion and chemical weathering intensities on Luzon, and sediment source-to-sink processes. We assess the potential significance of chemical weathering of arc silicates in regulating global atmospheric CO<SUB>2</SUB> since 156kyr BP. Sr-Nd isotopes show that the siliciclastic sediments were dominantly sourced from volcanic rocks exposed on Luzon (~68–100%), with a lesser contribution from Asian dust (~0–32%). Different indices indicate that stronger physical erosion and chemical weathering occurred during Marine Isotope Stage (MIS) 6 (130–156kyr BP), as well as in the latter stage of MIS 3 and MIS 2 (14–40kyr BP). The large sea-level lowstands and associated significant exposure of continental shelf in the western Philippine Sea during these two cold periods should favor physical erosion and chemical weathering of unconsolidated sediments on the exposed shelf. Furthermore, we notice the relatively good coherence between chemical weathering intensities on Luzon and global atmospheric CO<SUB>2</SUB> concentrations over these cold intervals. We suggest that strengthening of chemical weathering of silicates on Luzon and other tropical arcs (within 20° of the Equator) during the Quaternary glacial sea-level lowstands may significantly contribute to the lowering of atmospheric CO<SUB>2</SUB> concentrations during ice ages. We estimate that a significant fraction, up to ~16% (i.e., ~8ppmv), of all atmospheric CO<SUB>2</SUB> ultimately sequestered by silicate weathering may be processed through an area corresponding to only ~1% of the exorheic drainage area worldwide.</P> <P><B>Highlights</B></P> <P> <UL> <LI> First high-resolution silicate weathering study of the western Philippine Sea. </LI> <LI> Glacial sea-level lowstands favored silicate weathering of sediments on exposed shelf. </LI> <LI> Enhanced weathering on tropical arcs significantly sequestered atmospheric CO2. </LI> </UL> </P>
Advanced Structural Silicone Glazing
Kimberlain, Jon,Carbary, Larry,Clift, Charles D.,Hutley, Peter Council on Tall Building and Urban Habitat Korea 2013 International journal of high-rise buildings Vol.2 No.4
This paper presents an advanced engineering technique using finite element analysis to improve structural silicone glazing (SSG) design in high-performance curtain wall systems for building facade. High wind pressures often result in bulky SSG aluminum extrusion profile dimensions. Architectural desire for aesthetically slender curtain wall sight-lines and reduction in aluminum usage led to optimization of structural silicone bite geometry for improved stress distribution through use of finite element analysis of the hyperelastic silicone models. This advanced design technique compared to traditional SSG design highlights differences in stress distribution contours in the silicone sealant. Simplified structural engineering per the traditional SSG design method lacks accurate forecasting of material and stress optimization, as shown in the advanced analysis and design. Full scale physical specimens were tested to verify design capacity in addition to correlate physical test results with the theoretical simulation to provide confidence of the model. This design technique will introduce significant engineering advancement to the curtain wall industry and building facade.