Fabrication and Interface Structural Behavior of Mg/Al Thickness-Oriented Bonding Sheet via Direct Extrusion

Lei Gao,Feng Li,Ye Wang,Xing Mao Xiao,Peng Da Huo 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

Solid-state bonding of heterogeneous materials is one of the effective ways to achieve light weight. An extrusion formingprocess for Mg/Al thickness-oriented bonding sheet was carried out. Due to triaxial compressive stress in the extrusion container,the AZ31 and AA6061 billets were deformed and the bonding and forming of Mg/Al thickness-oriented sheet can berealized by this method. The observation results of the bonding position by using XRD, SEM and EDS showed that: at theforming temperature with 360–420 °C, it had a good bonding interface, and the width of the transition layer increased withthe increase of the forming temperature. The presence of brittle intermetallic compounds in the transition layer indicated thatmetallurgical bonding had occurred at the interface. Considering all factors comprehensively, when the forming temperaturewas 390 °C, the bonding quality was appropriate. Its tensile-shear strength was 42 MPa, the width of the interface transitionlayer was about 10 μm, and the microhardness was about 164.3 HV. This method provided scientific guidance and technicalreserves for green forming of Mg/Al sheets.

A Study of the Satisfaction with the operation of design courses-Based on PJBL(Project Based Learning): An analysis of a University of Applied Sciences in China

WANG LEI(LEI WANG),Choi Wonjae(Wonjae Choi) 한국스마트미디어학회 2023 스마트미디어저널 Vol.12 No.5

As the definition and role of design changes over time with the times and society, design education needs to update teaching methods to match it. The course design in this study began with an optimisation of the learning model based on previous research and analysis, followed by in-depth interviews, the application of the interview results to the final curriculum design, and finally a questionnaire to verify the positive effects of this teaching model. This teaching model has been applied to teach a pilot class in a university of applied sciences in China. The main characteristics of the course design are Project-Based Learning (PJBL) oriented, team cooperation centric, and an educational model developed based on peer assessment. In every stage of the UI design course, realistic project simulations are adopted, enhancing students' abilities through practical experience, teamwork, and peer assessment. The innovation lies in validating the effectiveness and advantages of this model at every stage of the UI design course, innovating existing teaching methods, optimizing learning models, and combining practice with evaluation. This research found that a project-oriented team course design based on PJBL has a high degree of effectiveness and relevance in each stage of the UI design course, significantly improving students' overall competence. It is expected that the results of this study can be applied in various ways to the course design of the courses that similar to design majors.

Research on Large‑scale Photovoltaic Planning Based on Risk Assessment in Distribution Network

Lei Wang,Minyu Yuan,Fan Zhang,Xuli Wang,Jing Ma,Lei Dai,Xianjun Qi,Rui Bi 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

Risks caused by large amounts of distributed photovoltaic (PV) feeding into distribution networks, have an impact on PV planning, which has become a critical consideration for distribution networks’ operation. In this paper, a large-scale PV planning method is proposed which based on risk assessment in distribution networks. Cluster division is used to group large-scale distributed PVs. A risk assessment is performed on the distribution network, considering the correlation between PVs and loads. The efects of load fuctuations, PV quantity, capacity and location on the operational risk of the distribution network are analyzed and discussed. A large-scale PV planning model is established with the goal of maximizing the comprehensive benefts, considering the penalty cost of node voltage over-limit and branch power fow over-limit risk. Finally, the genetic algorithm is used to solve the planning model. The simulation results demonstrate the efectiveness of the proposed method.

LiFePO₄ quantum-dots composite synthesized by a general microreactor strategy for ultra-high-rate lithium ion batteries

Wang, Bo,Xie, Ying,Liu, Tong,Luo, Hao,Wang, Bin,Wang, Chunhui,Wang, Lei,Wang, Dianlong,Dou, Shixue,Zhou, Yu Elsevier 2017 Nano energy Vol.42 No.-

<P><B>Abstract</B></P> <P>Due to the relatively slow, diffusion-controlled faradaic reaction mechanisms of conventional LiFePO<SUB>4</SUB> (LFP) materials, which is hard to deliver satisfied capacity for high rate applications. In this work, ultrafine LFP quantum dots (LFP-QDs) co-modified by two types of carbonaceous materials - amorphous carbon and graphitized conductive carbon (graphene) have been successfully synthesized through a novel microreactor strategy. Because of the very limited area constructed by the dual-carbon microreactor for the growth of LFP crystal, it's demension was furthest suppressed to a very small level (~ 6.5nm). Such a designed nano-composite possesses a large specific surface area for charge adsorption and abundant active sites for faradaic reactions, as well as ideal kinetic features for both electron and ion transport, and thus exhibits ultra-fast, surface-reaction-controlled lithium storage behavior, mimicking the pseudocapacitive mechanisms for supercapacitor materials, in terms of extraordinary rate capability (78mAhg<SUP>−1</SUP> at 200C) and remarkable cycling stability (~ 99% over 1000 cycles at 20C). On the other side, due to the quasi-2D structure of the synthesized LFP-QDs composite, which can be used as the basic unit to further fabricate free-standing film, aerogel and fiber electrode without the addition of binder and conductive agent for different practical applications. In addition, to deeper understand its electrochemical behavior, a combined experimental and density functional theoretical (DFT) calculation study is also introduced.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A general microreactor strategy has been developed for structure-optimized Li-contained electrode materials. </LI> <LI> Ultrafine LiFePO<SUB>4</SUB> quantum dots are first reported through the designed microreactor strategy. </LI> <LI> The synthesized G/LFP-QDs@C exhibits ultra-fast, surface-reaction-controlled Li storage behavior. </LI> <LI> A combined experimental and DFT calculation study is introduced to reveal the energy storage mechanism of G/LFP-QDs@C. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Ultrafine LiFePO<SUB>4</SUB> quantum dots (~ 6.5nm) co-modified by two types of carbonaceous materials - amorphous carbon and graphitized conductive carbon (graphene) have been successfully synthesized through a novel microreactor strategy, which exhibit ultra-fast, surface-reaction-controlled energy storage behavior, mimicking the pseudocapacitive mechanisms for supercapacitor materials, in terms of excellent rate capability and outstanding cycling stability.</P> <P>[DISPLAY OMISSION]</P>

증강현실을 이용한 패턴 인식

왕레이(Wang Lei),신성윤(Wang Lei),이양원(Seong-Yoon Shin) 한국컴퓨터정보학회 2009 한국컴퓨터정보학회 학술발표논문집 Vol.16 No.2

분 논문은 카메라 장비와 마커, DB를 이용하여 문자의 색감과 모음, 자음을 인식하여 문자에 해당되는 이미지 및 영상을 HMD 및 모니터, 가정에서 사용하는 화상 카메라 등을 이용하여 보다 구체적인 정보를 전달할 수 있게 해준다. DB에는 각 텍스트의 모음과 자음에 관한 텍스트가 등록되어 있으며, 각각의 색과 텍스트를 비교하여 해당하는 이미지를 출력하게 된다. 기존의 증강현실 기법은 해당 마크에 관한 패턴을 인식하여 그에 해당하는 이미지 및 영상을 출력하는데, DB를 이용한 문자인식을 사용할 경우 사용자에게 텍스트를 인식하여 연관된 많은 정보를 제공할 수 있게 된다. 제안된 인터페이스는 다양한 모습을 어려 시야를 통해 기존의 카탈로그보다 사용자의 접근성을 향상시키고, 미리 정의된 DB에 접근하여 해당 문자에 관한 여러가지 정보를 사용자에게 전달한다. 여러 전달 매체를 이용, 가상현실 및 증강현실 등을 다양한 카탈로그 뿐만 아니라 교육 및 신문 잡지, 광고 등 문자가 등장하는 여러 분야에 활용이 가능하다.

Hybrid dynamic modeling and analysis of a ball-screw-drive spindle system

Lei Zhang,Taiyong Wang,Guofeng Wang,Songling Tian 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

We propose a comprehensive modeling approach to investigate the rigid-flexible coupling vibration of a Ball-screw-drive spindle system (BSDSS). Taking into account the rigid-flexible coupling between the ball screw and rigid components, a hybrid dynamic model for the BSDSS is established. The ball screw shaft was modeled by a flexible beam with axial, torsional, and transverse deformations, and the Ritz series expansion was used to approximate the continuous deformations. The motion equations were obtained using the Lagrange method. The analytical solution was derived and verified. According to the proposed model, the dynamic behavior of the system for various operating conditions was simulated and discussed. The numerical simulation result is useful for the controller design or tuning and the stiffness matching design of ball screw drives.

APPLYING PERSONA AS AN EFFECTIVE APPROACH IN HOTEL DEMAND FORCASTING

Wang Lei,Ni Xuan,Fan Ling 글로벌지식마케팅경영학회 2020 Global Marketing Conference Vol.2020 No.11

Protective Effect of Diphlorethohydroxycarmalol Isolated from Ishige okamurae against Particulate Matter-Induced Skin Damage by Regulation of NF-B, AP-1, and MAPKs Signaling Pathways In Vitro in Human Dermal Fibroblasts

Lei Wang,Hyun Soo Kim,Jun-Geon Je,Jae Young Oh,Young-Sang Kim,Seon-Heui Cha,You-Jin Jeon 제주대학교 해양과학연구소 2020 해양과환경연구소 연구논문집 Vol.44 No.-

Particulate matters (PM), the main contributor to air pollution, have become a serious issue that threatens human’s health. Skin is the largest organ in humans, as well as the primary organ exposed to PM. Overexposure of PM induces skin damage. Diphlorethohydroxycarmalol (DPHC), an algal polyphenol with the potential of skin protection, has been isolated from the edible brown seaweed Ishige okamurae. The purpose of the present study is to investigate the protective eect of DPHC against PM (ERM-CZ100)-induced skin damage in human dermal fibroblasts (HDF) cells. The results indicated that DPHC significantly and dose-dependently reduced intracellular reactive oxygen species generation in HDF cells. In addition, DPHC significantly induced collagen synthesis and inhibited collagenase activity in ERM-CZ100-stimulated HDF cells. Further study demonstrated that DPHC remarkably reduced the expression of human matrix metalloproteinases through regulation of nuclear factor kappa B, activator protein 1, and mitogen-activated protein kinases signaling pathways in ERM-CZ100-stimulated HDF cells. This study suggested that DPHC is a potential candidate to protect skins against PM-induced damage, and it could be used as an ingredient in pharmaceutical and cosmeceutical industries.

Single Line-to-ground Fault Location and Information Modeling Based on the Interaction between Intelligent Distribution Equipment

Wang, Lei,Luo, Wei,Weng, Liangjie,Hu, Yongbo,Li, Bing The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

In this paper, the fault line selection and location problems of single line-to-ground (SLG) fault in distribution network are addressed. Firstly, the adaptive filtering property for empirical mode decomposition is formulated. Then in view of the different characteristics showed by the intrinsic mode functions(IMF) under different fault inception angles obtained by empirical mode decomposition, the sign of peak value about the low-frequency IMF and the capacitance transient energy is chosen as the fault line selection criteria according to the different proportion occupied by the low-frequency components. Finally, the fault location is determined based upon the comparison result with adjacent fault passage indicators' (FPI) waveform on the strength of the interaction between the distribution terminal unit(DTU) and the FPI. Moreover, the logic nodes regarding to fault line selection and location are newly expanded according to IEC61850, which also provides reference to acquaint the DTU or FPI's function and monitoring. The simulation results validate the effectiveness of the proposed fault line selection and location methods.

Influence of equilibrium magnetic shear on the double tearing modes for different rational surface spacing

Wang Le,Zhao Qing,Sun Wen Yang,Wang Lei,Liu Xiao Wei,Li Zhen Guo 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.4

Based on the two-dimensional geometric model, the infuence of equilibrium magnetic shear on the double tearing modes for diferent rational surface spacing is numerically simulated. We fnd that when the spacing is small, the saturation time of unstable mode decreases with the increase of the equilibrium magnetic shear. With the spacing increases, the saturation time will gradually change from decreasing with the increase of the equilibrium magnetic shear to increasing with the increase of the equilibrium magnetic shear. When the spacing is large, the saturation time increases with the equilibrium magnetic shear.