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Reliability analysis for lateral stabilityof tongwamen bridge
Pan Sheng-Shan,Shi Lei,Tan Yong-Gang,Zhang Zhe 국제구조공학회 2011 Steel and Composite Structures, An International J Vol.11 No.5
Tongwamen Bridge is a critical link between Dongmen Island and the land in Shipu town, Zhejiang province, China. It is a 238 m span, half-through, concrete-filled steel tubular (CFST) X-type arch bridge. The width of the deck is only 10 m, yielding a width-to-span ratio of 1/23.8. The plane truss type section rib was adopted, which made of two CFST chords and web member system. The lateral stability is the key issue to this bridge. However, the existing researches on Tongwamen Bridge’s lateral stability are all the deterministic structural analysis. In this paper, a new strategy for positioning sampling points of the response surface method (RSM), based on the composite method combining RSM with geometric method for structural reliability analysis, is employed to obtain the reliability index of lateral stability. In addition the correlated parameters were discussed in detail to find the major factors. According to the analysis results, increasing the stiff of lateral braces between the arch ribs and setting the proper inward-incline degree of the arch rib can enhance obviously the reliability of lateral stability. Moreover, the deck action of non-orienting force is less than the two factors above. The calculated results indicate that the arch ribs are safe enough to keep excellent stability, and it provides the foundation that the plane truss rib would be a competitive solution for a long-span, narrow, CFST arch bridge.
Kim, Jung Hyuk,Moon, So Ra,Kim, Yong,Chen, Zhi Gang,Zou, Jin,Choi, Duk Yong,Joyce, Hannah J,Gao, Qiang,Tan, H Hoe,Jagadish, Chennupati IOP Pub 2012 Nanotechnology Vol.23 No.11
<P>We investigate the growth procedures for achieving taper-free and kinked germanium nanowires epitaxially grown on silicon substrates by chemical vapor deposition. Singly and multiply kinked germanium nanowires consisting of 〈111〉 segments were formed by employing a reactant gas purging process. Unlike non-epitaxial kinked nanowires, a two-temperature process is necessary to maintain the taper-free nature of segments in our kinked germanium nanowires on silicon. As an application, nanobridges formed between (111) side walls of V-grooved (100) silicon substrates have been demonstrated.</P>
Jung, Jae Hun,Yoon, Hyun Sik,Kim, Yu Lee,Song, Man Suk,Kim, Yong,Chen, Zhi Gang,Zou, Jin,Choi, Duk Yong,Kang, Jung Hyun,Joyce, Hannah J,Gao, Qiang,Hoe Tan, H,Jagadish, Chennupati IOP Pub 2010 Nanotechnology Vol.21 No.29
<P>We demonstrate a method to realize vertically oriented Ge nanowires on Si(111) substrates. Ge nanowires were grown by chemical vapor deposition using Au nanoparticles to seed nanowire growth via a vapor–liquid–solid growth mechanism. Rapid oxidation of Si during Au nanoparticle application inhibits the growth of vertically oriented Ge nanowires directly on Si. The present method employs thin Ge buffer layers grown at low temperature less than 600 °C to circumvent the oxidation problem. By using a thin Ge buffer layer with root-mean-square roughness of ∼ 2 nm, the yield of vertically oriented Ge nanowires is as high as 96.3%. This yield is comparable to that of homoepitaxial Ge nanowires. Furthermore, branched Ge nanowires could be successfully grown on these vertically oriented Ge nanowires by a secondary seeding technique. Since the buffer layers are grown under moderate conditions without any high temperature processing steps, this method has a wide process window highly suitable for Si-based microelectronics. </P>
CdS/CdSe lateral heterostructure nanobelts by a two-step physical vapor transport method
Kim, Yu Lee,Jung, Jae Hun,Yoon, Hyun Sik,Song, Man Suk,Bae, Se Hwan,Kim, Yong,Chen, Zhi Gang,Zou, Jin,Joyce, Hannah J,Gao, Qiang,Tan, Hark Hoe,Jagadish, Chennupati IOP Pub 2010 Nanotechnology Vol.21 No.14
<P>The two-dimensional heterostructure nanobelts with a central CdSe region and lateral CdS structures are synthesized by a two-step physical vapor transport method. The large growth rate difference between lateral CdS structures on both ± (0001) sides of the CdSe region is found. The growth anisotropy is discussed in terms of the polar nature of the side ± (0001) surfaces of CdSe. High-resolution transmission electron microscopy reveals the CdSe central region covered with non-uniform CdS layer/islands. From micro-photoluminescence measurements, a systematic blueshift of emission energy from the central CdSe region in accordance with the increase of lateral CdS growth temperature is observed. This result indicates that the intermixing rate in the CdSe region with CdS increases with the increase of lateral CdS growth temperature. In conventional CdSSe ternary nanostructures, morphology and emission wavelength were correlated parameters. However, the morphology and emission wavelength are independently controllable in the CdS/CdSe lateral heterostructure nanobelts. This structure is attractive for applications in visible optoelectronic devices. </P>