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Liu Siwei,Park Sung-Hoon,Choi Young-Seo,Yeo Gi-Tae 한국해운물류학회 2022 The Asian journal of shipping and Logistics Vol.38 No.2
As the three largest central hub cities in the Pearl River Delta (PRD) region, Hong Kong, Guangzhou, and Shenzhen have played critical roles in regional growth. Nevertheless, these ports face many challenges, such as port handling capacity, environmental problems, and the expansion of the complex transportation system owing to the large volume of goods. Therefore, this study used the slacks-based measure–data envelopment analysis (SBM-DEA) and DEA-undesirable models to evaluate the efficiency of the major container terminals in these three cities between 2018 and 2019. Based on the decision-making unit values of the terminals for the past two years, Yantian and Container Terminal 9 (South) were the most efficient, followed by container terminals 6 and 7. Moreover, the efficiency of the major container terminals in Guangzhou was less satisfactory than that of terminals in Shenzhen and Hong Kong. The results provide a reliable reference for future port investment, and regional development policy in the PRD region. © 2022 The Authors. Production and hosting by Elsevier B.V. on behalf of The Korean Association of Shipping and Logistics, Inc. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). CC_BY_NC_ND_4.0
Chen Xu,Boyu Zhang,Siwei Liu,Qingtian Su 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.3
The steel-concrete double composite girder in the negative flexural region combines an additional concrete slab to the steel bottom flange to prevent the local steel buckling, however, the additional concrete slab may lower down the neutral axis of the composite section, which is a sensitive factor to the tensile stress restraint on the concrete deck. This is actually of great importance to the structural rationality and durability, but has not been investigated in detail yet. In this case, a series of 5.5 m-long composite girder specimens were tested by negative bending, among which the bottom slab configuration and the longitudinal reinforcement ratio in the concrete deck were the parameters. Furthermore, an analytical study concerning about the influence of bottom concrete slab thickness on the cracking and sectional bending-carrying capacity were carried out. The test results showed that the additional concrete at the bottom improved the composite sectional bending stiffness and bending-carrying capacity, whereas its effect on the concrete crack distribution was not obvious. According to the analytical study, the additional concrete slab at the bottom with an equivalent thickness to the concrete deck slab may provide the best contributions to the improvements of crack initiation bending moment and the sectional bending-carrying capacity. This can be applied for the design practice.
Growth of Ag3Sn and Sn Nanoparticles Based on the Variation of Reaction Conditions
Yao Wang,Wensheng Liu,Yunzhu Ma,Siwei Tang,Yufeng Huang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.7
Tin and tin-based nanoalloys especially Sn-3.5Ag (wt.%) eutectic alloys have been prepared by numerous methods as the promising alternative solder in electronic packaging application. However, issues of agglomeration and oxidation emerged owing to shrinking size of nanoparticles. In this study, the Sn/Ag3Sn nanoparticles as small as 10 nm have been synthesized successfully through chemical reduction method. Concentration of precursor and reducing agent have been studied so as to control the reaction rate, thus achieving the optimized conditions avoiding agglomeration. A centralized size distribution has been achieved by separating nucleation and growth periods. It has been revealed that the obtained nanoparticles are composed of β-Sn and Ag3Sn which represent a successful co-reduction. β-Sn and Ag3Sn NPs have various average size for their distinct critical nucleation radius and disparate mole ratio of Sn and Ag. The β-Sn surface has almost 4-nm thick amorphous tin oxide layer but Ag3Sn surface has not, because the lattice distortion caused by the replacement of silver by tin hinders the diffusion of oxygen, improving oxidation resistance and dispersing performance.
Connection Analysis of Container Ports of the Bohai Rim Economic Circle (BREC)
Wen LU,Sung Hoon PARK,Siwei LIU,Tae Hyun NAM,Gi-tae YEO 한국해운물류학회 2018 The Asian journal of shipping and Logistics Vol.34 No.2
The Bohai Rim Economic Circle (BREC) is an emerging economic area that has been developing rapidly and has benefited from support from the Chinese government; however, due to the unique geographic location and the late start of development, the cargo volumes and capacities of the ports in the Northern Region are comparatively smaller than the Yangtze River Delta, and the Pearl River Delta. To resolve this issue, one effective strategy is to create additional connections with ports and container ports of nearby countries. Consequently, a Social Network Analysis (SNA), including degree centrality, betweenness centrality, and hub and authority centrality, was used to analyze the route networks of the top three ports (ports of Tianjin, Qingdao, and Dalian) of BREC. A list of ports that are highly influential to these three ports in building additional connections to obtain higher cargo volumes is provided.
Peng Jiang,Xiujuan Fu,Hong Niu,Siwei Chen,Feifei Liu,Yu Luo,Dan Zhang,Hui Lei 대한약학회 2023 Archives of Pharmacal Research Vol.46 No.6
Strains of the fungal genus Pestalotiopsis are reported as large promising sources of structurally varied biologically active metabolites. Many bioactive secondary metabolites with diverse structural features have been derived from Pestalotiopsis. Moreover, some of these compounds can potentially be developed into lead compounds. Herein, we have systematically reviewed the chemical constituents and bioactivities of the fungal genus Pestalotiopsis, covering a period ranging from January 2016 to December 2022. As many as 307 compounds, including terpenoids, coumarins, lactones, polyketides, and alkaloids, were isolated during this period. Furthermore, for the benefit of readers, the biosynthesis and potential medicinal value of these new compounds are also discussed in this review. Finally, the perspectives and directions for future research and the potential applications of the new compounds are summarized in various tables.
Impact of high-temperature-water cooling damage on the mechanical properties of concrete
Zhai, Yue,Li, Yan,Li, Yubai,Wang, Siwei,Liu, Yi,Song, Ki-Il Elsevier 2019 Construction & building materials Vol.215 No.-
<P><B>Abstract</B></P> <P>A series of impact tests were conducted on split Hopkinson pressure bar equipment to study the influence of high-temperature-cooling damage on the mechanical properties of concrete. The experimental investigation showed the influence on the peak stress, peak strain, and fracture mode. The results indicate that the strain rate is directly related to the loading rate and heating temperature. The test results of natural cooling and water immersion cooling treatment were compared, which showed that the strength of water-cooled specimens is higher than that of naturally cooled specimens before the heating temperature reaches 400 °C and becomes much lower when the heating temperature is higher than 400 °C. Based on the experimental study, a dynamic non-linear elastic constitutive equation was established using a particle swarm optimization algorithm and an inversion analysis method. These results could provide theoretical references for the design of the ultimate strength of concrete materials for practical applications, such as fire and explosion prevention.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High temperature-cooling damage on mechanical properties for concrete is tested. </LI> <LI> The strain rate is directly related to the loading rate and heating temperature. </LI> <LI> 400 °C can be considered as the threshold of high temperature-water cooling damage. </LI> <LI> Dynamic non-linear elastic constitutive equation is established. </LI> </UL> </P>