Influence of Microstructure and Mechanical Properties on Formability in High Strain Rate Rolled AZ31 Magnesium Alloy Sheets

Fubao Liu,Xiao Liu,Biwu Zhu,Hui Yang,Gang Xiao,Mingyue Hu 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

High strain-rate rolling (≥ 10 s−1) has been successfully employed to produce AZ31 magnesium alloy sheets to a high reductionof 82% with a fine grain structure in a single pass. The rolled sheets inevitably undertake various forming processessuch as press and deep forming in the fabrication stage. To investigate the formability, the Erichsen tests were carried out onhigh strain rate rolled AZ31 magnesium alloy sheets at room temperature. The relationship among mechanical properties,microstructure and formability were investigated. The crack behavior during Erichsen tests was also studied. It was foundthat the formability was related to the lowest in-plane tensile strengthen and dislocation density of initial microstructure. The competitive relationship between micro-crack and twinning/shear bands would also influence the formability of highstrain rate rolled magnesium alloy sheets. Deformed shear band with substaintial twins prohibits the crack extension andenhances strengthen of materials in front of crack tip.

"五四"何以失精神

劉慧軍 한국중국문화학회 2000 中國學論叢 Vol.9 No.-

5·4운동은 중국 역사상 위대한 사상변혁운동이다. 5·4운동이 제창한 "立人"사상은 당시뿐만 아니라 현재에 있어서도 중국문화의 발전과 변화에 중요한 의의를 지니고 있다. 그러나 여러 가지 원인 때문에 5·4정신은 잊혀졌다. 본고는 정치와 문화적 측면에서 5·4정신이 잊혀지게 된 원인을 검토한 바, 다음 3가지가 주된 원인으로 작용하였다고 분석하였다. 첫째, 중국전통문화의 뿌리가 확고하여 민주사상이 단시간 내에 확립될 수 없었다. 둘째, 정치의 막강한 흡인력이 신문화운동 발전에 영향을 미쳐 지식인이 문화적 사고를 포기하여, 중국의 사상계몽이 시작되자마자 중단되었다. 셋째, 5·4운동 후 권력자의 남용이 5·4정신을 잊혀지게 하는 중요한 원인이 되었다.

A Hausdorff Distance Based Image Registration Algorithm

Liu Hui,Zhang Zhichun,Wei Dong 보안공학연구지원센터(IJSIP) 2015 International Journal of Signal Processing, Image Vol.8 No.1

Hausdorff distance is a common image registration method that is based on the edge features in the image. Theoretically, using Hausdorff distance method, the rotation, scaling and translation factors of the image can be obtained by searching the four-dimensional space that includes one rotation factor, one scaling factor and two translation factors. However, each additional factor means that the dimension degree of searching space is increased one more. The searching speed will be greatly reduced with the increasing of dimension degree. This paper presents a new image registration algorithm that combines the Hausdorff distance with the angle transform. Using this method, the translation factors can be obtained by Hausdorff distance and the angle transform can be directly computed. There is three step for finishing the image registration through the new method. Firstly, discrete Canny edge detection is used on the image. Secondly, the linear features of the image is directly used to calculate the rotation angle parameter. Then Hausdorff distance is used searching in two-dimensional space for getting the translation parameters of the image. Simulation results verified the correctness and validity of the paper method.

Nickel hydroxide/chemical vapor deposition-grown graphene/nickel hydroxide/nickel foam hybrid electrode for high performance supercapacitors

Liu, Shude,Yin, Ying,San Hui, Kwan,Hui, Kwun Nam,Lee, Su Chan,Chan Jun, Seong Elsevier 2019 ELECTROCHIMICA ACTA Vol.297 No.-

<P><B>Abstract</B></P> <P>Rational design of electrode structures has been recognized as an effective strategy to improve the electrochemical performance of electrode materials. Herein, we demonstrate an integrated electrode in which nickel hydroxide (Ni(OH)<SUB>2</SUB>) nanosheets are deposited on both sides of chemical vapor deposition-grown graphene on Ni foam, which not only effectively optimizes electrical conductivity of Ni(OH)<SUB>2</SUB>, but also accommodates the structural deformation associated with the large volume change upon cycling. The synthesized Ni(OH)<SUB>2</SUB>/graphene/Ni(OH)<SUB>2</SUB>/Ni foam electrode exhibits a high specific capacity of 991 C g<SUP>−1</SUP> at a current density of 1 A g<SUP>−1</SUP>, which is higher than the theoretical specific capacity of additive sum of Ni(OH)<SUB>2</SUB> and graphene, and retains 95.4% of the initial capacity after 5000 cycles. A hybrid supercapacitor is constructed by using Ni(OH)<SUB>2</SUB>/graphene/Ni(OH)<SUB>2</SUB>/Ni foam as the positive electrode and activated carbon on Ni foam as the negative electrode, which achieves a maximum energy density of 49.5 W h kg<SUP>−1</SUP> at a power density of 750 W kg<SUP>−1</SUP>, and excellent cycling lifespans with 89.3% retention after 10000 cycles at 10 A g<SUP>−1</SUP>.</P>

Design of 3-electrode system for <i>in situ</i> monitoring direct methanol fuel cells during long-time running test at high temperature

Liu, Guicheng,Li, Xinyang,Wang, Hui,Liu, Xiuying,Chen, Ming,Woo, Jae Young,Kim, Ji Young,Wang, Xindong,Lee, Joong Kee Elsevier 2017 APPLIED ENERGY Vol.197 No.-

<P>To understand the effect mechanisms of long-time running and high operation temperature on performance of the direct methanol fuel cell (DMFC) more clearly and directly, in this paper, a new design of 3-electrode system with a solution-type salt bridge has been developed to distinguish the integral polarization into anodic and cathodic polarizations at various temperatures and explore the attenuation mechanism by in situ monitoring the potential of anode during long-time running process at 80 degrees C, for the first time. The results indicate that the optimized 3-electrode system consists of a standard calomel electrode (SCE) and a solution-type salt bridge placed in the anode hole filled by 0.5 mol L-1 H2SO4 solution. By utilization of the 3-electrode system, the effect mechanisms of the running temperature and time on electrochemical parameters of the DMFC have been found: (1) The increasing operation temperature improves cathodic performance more significantly than that of anode; (2) the attenuation of fuel cell performance mainly comes from that of anode during the 20-h running test at 80 degrees C, resulting from the sharp drop of electrochemical active surface area of anode. More important, the new 3-electrode system has simplified the detection equipment and reduced the operating difficulty in a practical application for DMFCs, resulting in its portability. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Genome-Wide Analysis of the Thioredoxin Gene Family in Gossypium hirsutum L. and the Role of the Atypical Thioredoxin Gene GhTRXL3-2 in Flowering

Liu Hui,Li Yunfei,Huang Xianzhong 한국식물학회 2021 Journal of Plant Biology Vol.64 No.5

Thioredoxin (TRX) is a highly conserved low-molecular-weight protein and a ubiquitous antioxidant enzyme that plays key role in the regulation of plant growth and development. Here, using the whole-genome sequence, we performed a systematic analysis for the TRX gene family in upland cotton (Gossypium hirsutum L.) and analyzed their structural characteristics, evolution, and expression profiles during growth and development. At least 86 GhTRX members, 40 typical and 46 atypical, were identified in the cotton genome, and they were unevenly distributed on the 26 chromosomes. Conserved domains and phylogenic tree construction classified the typical TRX gene family into seven subfamilies and the atypical TRX into nine subfamilies. An evolutionary analysis revealed that the TRX gene family underwent purification selection during evolution. In addition, an RNA-Seq analysis showed that, during vegetative and reproductive development, the differences in transcript abundance levels and organ-specific expression patterns suggest functional diversity. Biochemical assays demonstrated that the atypical TRX protein GhTRXL3-2 interacted with the cotton FLOWERING LOCUS T protein GhFT. The overexpression of GhTRXL3-2 in Arabidopsis thaliana resulted in early flowering compared with control plants. Additionally, the silencing of GhTRXL3-2 in cotton delayed maturation, suggesting that it has important roles in cotton’s flowering regulation. These results help clarify the evolution of the TRX genes and elucidate their biological functions in cotton flowering regulation.

Study on a stretchable, fiber-shaped, and TiO₂ nanowire array-based dye-sensitized solar cell with electrochemical impedance spectroscopy method

Liu, Guicheng,Wang, Hui,Wang, Manxiang,Liu, Wenbing,Anugrah Ardhi, Ryanda Enggar,Zou, Dechun,Lee, Joong Kee Elsevier 2018 ELECTROCHIMICA ACTA Vol.267 No.-

<P><B>Abstract</B></P> <P>A spring-like Ti@TiO<SUB>2</SUB> nanowire array wire has been introduced into a stretchable fiber-shaped dye-sensitized solar cell (FDSSC) as a photoanode to achieve high flexibility and elasticity in this paper. Given the TiO<SUB>2</SUB> layer, which was prepared by a hydrothermal reaction in the optimized NaOH concentration of 2.5 mol L<SUP>−1</SUP>, with a 1D structure and high adhesion between the TiO<SUB>2</SUB> nanowire array and the Ti wire substrate, the novel FDSSC still possesses photoelectric conversion efficiency retention rates of approximately 97.00% and 95.95% after bending to a radius of 1.0 cm and stretching to 100% strain, respectively. EIS result shows the degradation mechanism of the FDSSC photoelectric performance: the bending test leads to more terrible electron combination; the stretching operation increases the internal resistance and charge-transfer resistance at the counter electrode. Moreover, it's worth noting that, this is the first time to show a 100%-stretching degree in the FDSSC research field so far.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A fiber-shaped, stretchable, TiO<SUB>2</SUB> nanowire array-based DSSC was reported firstly. </LI> <LI> Using EIS analysis method to analyse effect of bending and stretching on FDSSC performance. </LI> <LI> Photoelectric conversion efficiency retention rate of 95.95% after stretching to 100% strain. </LI> <LI> High flexibility with 97.00% performance retention rate at bending radius of 1 cm. </LI> </UL> </P>

Synthesis of New Sulfonated Polyimide and Its Photo-Crosslinking for Polymer Electrolyte Membrane Fuel Cells

Hui Liu,Myong Hoon Lee,Jun Ho Lee 한국고분자학회 2009 Macromolecular Research Vol.17 No.10

Performance and applications of flow-guided sieve trays for distillation of highly viscous mixtures

Hui Liu,Qun Shen Li,Chun Ying Song,Hai Long Wu,Yi Qiu Qian 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6

With a particular focus on the distillation of highly viscous or self-polymerized mixtures, this study reports the hydrodynamic and mass transfer performance of two flow-guided sieve trays, including their pressure drop, entrainment, weeping and tray efficiency, obtained experimentally with an air-water/oxygen system in a Φ600 mm plexiglass column. The results show that the 8 mm hole flow-guided sieve tray tested shows better characteristics than the 7 mm flow-guided hole tray in terms of pressure drop and mass transfer. Then we present practical industrial examples of applications of the flow guided trays for distillation of viscous mixtures, i.e., the separation of vinyl acetate (VAC) from a polyvinyl acetate (PVAC) polymer solution with dynamic viscosity μ=50,000 mPas, the separation of highly unsaturated C5 mixtures by extractive distillation, and the distillation of thick, condensed and highly viscous fermentation mixtures made from fermented mash. It is demonstrated that flow-guided sieve trays with relatively large holes are an excellent candidate for distillation of mixtures with suspended solids, or concentrated/self-polymerized polymer solutions.

Multiple Sexual Partners as a Potential Independent Risk Factor for Cervical Cancer: a Meta-analysis of Epidemiological Studies

Liu, Zhi-Chang,Liu, Wei-Dong,Liu, Yan-Hui,Ye, Xiao-Hua,Chen, Si-Dong Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.9

It's known that having multiple sexual partners is one of the risk factors of human papillomavirus (HPV) infection which is a major cause of cervical cancer. However, it is not clear whether the number of sexual partners is an independent risk factor for cervical cancer. We identified relevant studies by searching the databases of MEDLINE, PubMed and ScienceDirect published in English from January 1980 to January 2014. We analyzed those studies by combining the study-specific odds ratios (ORs) using random-effects models. Forty-one studies were included in this meta-analysis. We observed that the number of sexual partners was associated with the occurrence of non-malignant cervical disease (OR=1.82, 95%CI 1.63-2.00) and invasive cervical carcinoma (OR=1.77, 95%CI 1.50-2.05). Subgroup analyses revealed that the association remained significant after controlling for HPV infection (OR=1.52, 95%CI 1.21-1.83 for non-malignant disease; OR=1.53, 95%CI 1.30-1.76 for invasive cervical carcinoma). We found that there was a non-linear relation of the number of sexual partners with both non-malignant cervical disease and invasive cervical carcinoma. The risk of both malignant and non-malignant disease is relatively stable in women with more than 4-7 sexual partners. Furthermore, the frequency-risk of disease remained significant after controlling for HPV infection.The study suggested that h aving multiple sexual partners, with or without HPV infection, is a potential risk factor of cervical cancer.