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.

Preparation and Characterization of a Novel Hyperbranched Poly(aryl ether ketone) Terminated with Cobalt Phthalocyanine to be Used for Oxidative Decomposition of 2,4,6-Trichlorophenol

Lei Lei,Yunhe Zhang,Xiujie Li,Jianxin Mu,Guibin Wang,Zhenhua Jiang,Shuling Zhang 한국고분자학회 2010 Macromolecular Research Vol.18 No.4

A novel hyperbranched poly(aryl ether ketone) terminated with cobalt phthalocyanine (CoPc-T-HPAEK)was prepared using 1,3,5-tris[4-(4-fluorobenzoyl) phenoxy] benzene (B3), as a ‘core’ molecule, 4,4'-(hexafluoroisopropylidene)diphenol (6F-BPA) as an A2 monomer, and cobalt phthalocyanine as an end-capping reagent. CoPc-THPAEK showed good solubility, thermal stability and catalytic activity in the oxidative decomposition of 2,4,6-trichlorophenol (TCP) under H2O2 or KHSO5. Moreover, the oxidative effect of KHSO5 was superior to that of H2O2,and the catalytic activity of CoPc-T-HPAEK was much higher than that of linear poly(aryl ether ketone) terminated with cobalt phthalocyanine (CoPc-T-LPAEK) and linear poly(aryl ether ketone) with a cobalt phthalocyanine pendant unit (CoPc-S-LPAEK).

Accuracy Analysis for 3D Model Measurement Based on Digital Close-range Photogrammetry Technique for the Deep Foundation Pit Deformation Monitoring

Lei-lei Guan,Yong-gui Chen,Rao-ping Liao 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

The deformation of deep foundation pits (DFP) may pose a huge potential threat to the safety of the bracing system and the surrounding environment. A large amount of deformation data facilitates the deformation prediction of DFP and the dynamic adjustment of the bracing scheme. This study proposes and validates a 3D modeling technique based on digital close-range photogrammetry, which can obtain sufficient deformation data and enhance the understanding of deformation patterns. Two typical sets of deformation experiments, namely the vertical deformation test and the horizontal deformation test, were conducted to examine the viability and accuracy of 3D model measurement. Furthermore, the factors affecting the accuracy of the measurement were discussed in detail. The results indicate that the measurement accuracy of 3D models can reach millimeter-level or even sub-millimeter level. The measurement accuracy is affected by the coupling of the pixel resolution of CCD, focal length, photographic distance, and photographic baseline. The increase in the pixel resolution of CCD and focal length improve the measurement accuracy of 3D model measurement, but increasing photographic distance shows the opposite trend. The ratio of photographic baseline to photographic distance (BDR) has a much greater effect on accuracy than other factors. The photographic distance with a resolution of less than 1.0mm and the BDR value of 0.6 − 1.8 are recommended. Based on the results, it is found that this technique can be adopted as an effective monitoring method in DFP deformation monitoring due to the high precision and labor-saving.

CHISELED NICKEL HYDROXIDE NANOPLATES GROWTH ON GRAPHENE SHEETS FOR LITHIUM ION BATTERIES

LEI-LEI TIAN,XIAN-YONG WEI,QUAN-CHAO ZHUANG,CHAO WU,RUI-LUN XIE,ZHI-MIN ZONG,YONG-LI CUI,SHI-GANG SUN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.6

The morphologies and structures of Ni(OH)2–graphene hybrid materials were tailored by using different mineralizers in this work. It was revealed that the synergic effects of the highly oxidized graphene sheets and the mineralizers played a crucial role in controlling the morphology and structure of the nanocomposites, and Na2CO3 is a very effective mineralizer for growing chiseled 2D nanoplates of Ni(OH)2 on graphene sheets. When produced with NaOH, fragmental Ni(OH)2 crystals with irregular shapes erratically decorated on graphene sheets. In contrast, chiseled Ni(OH)2 hexagonal nanoplates grown on graphene sheets were obtained when Na2CO3 was used as the mineralizer. These unique 2D–2D nanoarchitectures with higher contact area between the nanocrystals and graphene substrate can increase the interfacial interaction and then efficiently improve the structural stability of the composite material, thus exhibiting an enhanced Li storage capacity and excellent cycling performance of 562 mAh g-1 after the 36th cycle.

A Study on Kyaikkatha: An Early Urban Settlement in Lower Myanmar

( Lei Lei Win ) 부산외국어대학교 동남아지역원 2015 Suvannabhumi Vol.7 No.1

Sittaung-Thanlwin region in Lower Myanmar is an ecological niche for human settlement. Evidences of human activities in the region are seen through various archaeological sites or settlements along the coastal area between the rivers Sittaung and Thanlwin (Salween). In Lower Myanmar, scholar, U Aung Myint, discovered one major site Kyaikkatha and other small scale sites, namely, Sittaung, Kawhtin, Kadaikgyi, Kadaikkalay, Katkadit, Kelatha (little Zothoke), Ayetthama, Winka, Zothoke (big Zothoke), Lagonbyi (Sampannago), Wagaru, Laming and Ye in present day Mon State. In 1980, U Aung Myint undertook an exploration program at Kyaikkatha. After the exploration, an excavation team conducted systematic digging at Kyaikkatha in March 1986. Excavation continued occasionally at Kyaikkatha throughout the years between 1995 and 2000. It is known that Kyaikkatha, the old city, reveals a kind of monumental civilization exposing four religious structures (a stupa and three monasteries). This essay looks into the distribution of features within Kyaikkatha and infers on its social, political, and religious organization. This essay is also about a new discovery of an early urban settlement located at the apex of the Gulf of Muttama (Martaban) where a lost city of Suva..ahumi flourished in the ancient days. By means of aerial photographic observations, the site had been noticed recently, which was by followed some excavations. More systematic and detail surveying may be needed to know more about the site and its features for comparison to other similar settlements of through-out mainland South East Asia.

Wave propagation of graphene platelets reinforced metal foams circular plates

Lei-Lei Gan,Jia-Qin Xu,Gui-Lin She 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.5

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity- I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.

Validation of the C-Test amongst Chinese ESL Learners

Lei Lei 아시아영어교육학회 2008 The Journal of Asia TEFL Vol.5 No.2

Modeling and Analyzing Per-flow Throughput in IEEE 802.11 Multi-hop Ad Hoc Networks

( Lei Lei ),( Xinru Zhao ),( Shengsuo Cai ),( Xiaoqin Song ),( Ting Zhang ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.10

In this paper, we focus on the per-flow throughput analysis of IEEE 802.11 multi-hop ad hoc networks. The importance of an accurate saturation throughput model lies in establishing the theoretical foundation for effective protocol performance improvements. We argue that the challenge in modeling the per-flow throughput in IEEE 802.11 multi-hop ad hoc networks lies in the analysis of the freezing process and probability of collisions. We first classify collisions occurring in the whole transmission process into instantaneous collisions and persistent collisions. Then we present a four-dimensional Markov chain model based on the notion of the fixed length channel slot to model the Binary Exponential Backoff (BEB) algorithm performed by a tagged node. We further adopt a continuous time Markov model to analyze the freezing process. Through an iterative way, we derive the per-flow throughput of the network. Finally, we validate the accuracy of our model by comparing the analytical results with that obtained by simulations.

Sesquiterpenoids with Various Carbocyclic Skeletons from the Flowers of <i>Chrysanthemum indicum</i>

Liu, Lei-Lei,Ha, Thi Kim Quy,Ha, Wei,Oh, Won Keun,Yang, Jun-Li,Shi, Yan-Ping American Society of Pharmacognosy 2017 Journal of natural products Vol.80 No.2

<P>A phytochemical investigation of the flowers of Chrysanthemum indicum yielded sesquiterpenoids 1-25 with various carbocyclic skeletons, including 10 new (1-10) and 15 known (11-25) analogues. The structures were elucidated via their physical data, while the absolute configuration of compounds 6, 8, and 10 was assessed via electronic circular dichroism analysis. The evaluation of the effect of sesquiterpenoids on porcine epidemic diarrhea virus (PEDV) replication showed that compounds 1-5, 12, 14, 16, 17, 19, and 21 increased cell viability against cell death in PEDV-injected cells. Compounds 2, 12, and 17 were selected and investigated for their inhibition of proteins required for PEDV replication. Compounds 2 and 17 significantly reduced PEDV nucleocapsid and spike protein synthesis compared with azauridin as a positive control.</P>

吴昌硕篆书创作小考

刘磊磊(Lei-Lei Liu),袁暁鹏(Xiao-Peng Yuan) 한국서예학회 2023 서예학연구 Vol.42 No.-

오창석(吴昌硕)의 전서는 필법, 구성, 장법, 묵법, 필법 등의 기법이 선인과 판이하게 다른데, 전서의 새로운 모습을 만들어내는 데 성공하여 큰 성과를 거둔 배경에는 여러 가지 이유가 있을 것이다. 우선 비파(碑派)서법의 서학사상을 흡수하여 금석(金石)을 취하고 고풍스럽고 웅장한 예술양식을 추앙하였다. 둘째, 등석여(邓石如), 양기손(杨沂孙) 등의 명가를 충분히 학습하는 기초 위에서 ≪석고문(石鼓文)≫을 주요 법으로 삼는 동시에 다양한 서체를 참고하여 여러 예술을 융합하고 자신의 예술 실천을 지속적으로 풍부하게 한다. 특히, 개인 특색 있는 필기구를 사용하여 개인 스타일을 지속적으로 강화합니다. 수십 년의 노력을 통해 마침내 ‘이리(二李)’ 전서 외에 다른 필법을 개척하고 전서 예술의 또 다른 정점을 창조하여 후대의 서예 예술 발전에 심대한 영향을 미쳤습니다. Wu Changshuo's seal book is very different from its predecessors in the use of pen, structure, sealing, ink, writing rhythm and other techniques, successfully shaping the new face of seal writing, and achieving great achievements, the reasons behind it should be many, first of all, he absorbed the calligraphy ideas of the stele calligraphy, took the golden stone, and advocated the simple and strong artistic style. Secondly, on the basis of fully learning from famous artists such as Deng Shiru(邓石如) and Yang Yisun(杨沂孙), he took “Shiguwen”(石鼓文) as the main object, and at the same time drew on a variety of book styles, integrated multiple arts, and constantly enriched his artistic practice. Third, use a very personal writing instrument to constantly strengthen your personal style. Through decades of hard work, it finally opened up another way outside the “Er Li” seal book, creating another peak of seal book art, which had a far-reaching impact on the development of calligraphy art in later generations. 吴昌硕的篆书在用笔、结构、章法、墨法、书写节奏等技法上都迥异于前人,成功地塑造了篆书的新面貌,取得了巨大的成就,其背后的原因应该是多方面的,首先,他吸收了碑派书法的书学思想,取法金石,推崇古朴雄强的艺术风格。其次,在充分学习邓石如、杨沂孙等名家的基础上,以≪石鼓文≫为主要取法对象,同时借鉴多种书体,融合多门艺术,不断丰富自己的艺术实践。再次,采用极具个人特色的书写工具,不断强化个人风格。通过几十年的努力,最终于“二李”篆书之外另辟蹊径,创造了篆书艺术的又一座高峰,对后世书法艺术的发展产生了深远的影响。