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Analysis on the temperature dependent electrical properties of graphene/ Al–ZnO Schottky contact
Yapeng Li,Yingfeng Li,Jianhua Zhang,Xiangyu Zou,Yongshan Wang 한국물리학회 2019 Current Applied Physics Vol.19 No.10
The electrical characteristics of the graphene/Al–ZnO schottky contact with the temperature of 180 K–300 K have been discussed in detail. Based on the TE model, the barrier height increased and the ideal factor decreased with the increasing of temperature from 180 K to 300 K, which can be interpreted by the lateral inhomogeneities of schottky barrier height. Combined with the single gauss distribution function of barrier height, the lateral inhomogeneities distribution of barrier height at the interface was confirmed. By DLTS measurement, one electron trap centers were observed at the interface.
Vision-based full-field panorama generation by UAV using GPS data and feature points filtering
Yapeng Guo,Yang Xu,Haowei Niu,Zhonglong Li,Yuhui E.,Xinghua Jiao,Shunlong Li 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.5
To meet the urgent requirements of safety surveillance from civil engineering management authorities, this study proposes a refined and efficient approach to generate full-field high-resolution panorama of construction sites using cameraamounted UAV (Unmanned Aerial Vehicle). GPS (Global Position System) information extraction for pre-registration, feature points filtering for efficient registration and optimal seaming line seeking for fusion are performed in sequence to form the full-field panorama generation framework. Advantages of the proposed method are as follows. First, GPS information can sort images for pre-registration, avoiding inefficient repeated pairwise calculations and matching. Second, the feature points are filtered according to the characteristics of the construction site images to reduce the amount of calculation. The proposed framework is validated on a road construction site and results demonstrate that it can generate an accurate and high-quality full-site panorama for the safety supervision in a much efficient manner.
Mathematical model for the nonlinear mechanical behavior of shape memory alloy springs
Yapeng Li,Xiao Li 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12
This study proposes a new model to describe the nonlinear mechanical behavior of shape memory alloy (SMA) springs. This model is applied to the shape memory effect and the superelastic effect. The formation conditions and changing process of each solid phase region on the cross section of the SMA spring wire, which are subject to the entire loading -unloading cycle, are analytically determined. Special attention is given to the unloading stages, for which the proposed solution improves upon existing literature. Then, the model is validated by comparing the numerical results with experimental data. Subsequently, the model is employed to investigate the influence of temperature, wire diameter, and mean diameter on the mechanical behavior of SMA springs.
Real-time geometry identification of moving ships by computer vision techniques in bridge area
Shunlong Li,Yapeng Guo,Yang Xu,Zhonglong Li 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.4
As part of a structural health monitoring system, the relative geometric relationship between a ship and bridge has been recognized as important for bridge authorities and ship owners to avoid ship–bridge collision. This study proposes a novel computer vision method for the real-time geometric parameter identification of moving ships based on a single shot multibox detector (SSD) by using transfer learning techniques and monocular vision. The identification framework consists of ship detection (coarse scale) and geometric parameter calculation (fine scale) modules. For the ship detection, the SSD, which is a deep learning algorithm, was employed and fine-tuned by ship image samples downloaded from the Internet to obtain the rectangle regions of interest in the coarse scale. Subsequently, for the geometric parameter calculation, an accurate ship contour is created using morphological operations within the saturation channel in hue, saturation, and value color space. Furthermore, a local coordinate system was constructed using projective geometry transformation to calculate the geometric parameters of ships, such as width, length, height, localization, and velocity. The application of the proposed method to in situ video images, obtained from cameras set on the girder of the Wuhan Yangtze River Bridge above the shipping channel, confirmed the efficiency, accuracy, and effectiveness of the proposed method.
Jiaying Zhang,Hui Zheng,Haibo Geng,Ying Li,Yapeng Guan,Yuanbin Sun,Cunjian Zhu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.4
Environmental friendly poly (propylene carbonate)-based waterborne polyurethane (PPC-based WPU) isprepared with PPC and isophorone diisocyanate (IPDI) as the soft segment and the hard segment, respectively. In thisreaction system, 2,2-dimethylolbutyric acid (DMBA) is used as the hydrophilic donor and trimethylolpropane (TMP)as the crosslinking agent. The effect of co-doping of layered montmorillonite (MMT) and mesoporous material MCM-41 on corrosion resistance of PPC-based WPU resin was studied. The properties of the samples were characterizedwith N2 physical adsorption, XRD, FT-IR, TG-DTA, DSC and water absorption testing. Potentiodynamic polarizationcurves, electrochemical impedance spectroscopy (EIS) and salt spray test were employed to investigate the corrosionperformance of all the coatings. The results of XRD indicate that the MMT in the composite polyurethane resin ispeeled off and MCM-41 maintains the hexagonal framework structure after grinding. Compared with the WPU coatingswith MMT or MCM-41 single incorporation, those with MMT and MCM-41 co-incorporation show the best corrosionresistance, which is due to the different interface structure between filler and resin matrix.