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Temperature distribution analysis of steel box-girder based on long-term monitoring data
Hao Wang,Qingxin Zhu,Zhongqin Zou,Chenxi Xing,Dongming Feng,Tianyou Tao 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.5
Temperature may have more significant influences on structural responses than operational loads or structural damage. Therefore, a comprehensive understanding of temperature distributions has great significance for proper design and maintenance of bridges. In this study, the temperature distribution of the steel box girder is systematically investigated based on the structural health monitoring system (SHMS) of the Sutong Cable-stayed Bridge. Specifically, the characteristics of the temperature and temperature difference between different measurement points are studied based on field temperature measurements. Accordingly, the probability density distributions of the temperature and temperature difference are calculated statistically, which are further described by the general formulas. The results indicate that: (1) the temperature and temperature difference exhibit distinct seasonal characteristics and strong periodicity, and the temperature and temperature difference among different measurement points are strongly correlated, respectively; (2) the probability density of the temperature difference distribution presents strong non-Gaussian characteristics; (3) the probability density function of temperature can be described by the weighted sum of four Normal distributions. Meanwhile, the temperature difference can be described by the weighted sum of Weibull distribution and Normal distribution.
Band Structure Engineering of Layered WSe<sub>2</sub><i>via</i> One-Step Chemical Functionalization
Park, Jun Hong,Rai, Amritesh,Hwang, Jeongwoon,Zhang, Chenxi,Kwak, Iljo,Wolf, Steven F.,Vishwanath, Suresh,Liu, Xinyu,Dobrowolska, Malgorzata,Furdyna, Jacek,Xing, Huili Grace,Cho, Kyeongjae,Banerjee, S American Chemical Society 2019 ACS NANO Vol.13 No.7
<P>Chemical functionalization is demonstrated to enhance the p-type electrical performance of two-dimensional (2D) layered tungsten diselenide (WSe<SUB>2</SUB>) field-effect transistors (FETs) using a one-step dipping process in an aqueous solution of ammonium sulfide [(NH<SUB>4</SUB>)<SUB>2</SUB>S(aq)]. Molecularly resolved scanning tunneling microscopy and spectroscopy reveal that molecular adsorption on a monolayer WSe<SUB>2</SUB> surface induces a reduction of the electronic band gap from 2.1 to 1.1 eV and a Fermi level shift toward the WSe<SUB>2</SUB> valence band edge (VBE), consistent with an increase in the density of positive charge carriers. The mechanism of electronic transformation of WSe<SUB>2</SUB> by (NH<SUB>4</SUB>)<SUB>2</SUB>S(aq) chemical treatment is elucidated using density functional theory calculations which reveal that molecular “SH” adsorption on the WSe<SUB>2</SUB> surface introduces additional in-gap states near the VBE, thereby, inducing a Fermi level shift toward the VBE along with a reduction in the electronic band gap. As a result of the (NH<SUB>4</SUB>)<SUB>2</SUB>S(aq) chemical treatment, the p-branch ON-currents (<I>I</I><SUB>ON</SUB>) of back-gated few-layer ambipolar WSe<SUB>2</SUB> FETs are enhanced by about 2 orders of magnitude, and a ∼6× increase in the hole field-effect mobility is observed, the latter primarily resulting from the p-doping-induced narrowing of the Schottky barrier width leading to an enhanced hole injection at the WSe<SUB>2</SUB>/contact metal interface. This (NH<SUB>4</SUB>)<SUB>2</SUB>S(aq) chemical functionalization technique can serve as a model method to control the electronic band structure and enhance the performance of devices based on 2D layered transition-metal dichalcogenides.</P> [FIG OMISSION]</BR>