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A reduced time-varying model for a long beam on elastic foundation under moving loads
Guiming Mei,Caijin Yang,Shulin Liang,Jiangwen Wang,Dong Zou,Weihua Zhang,Yunshi Zhao,Zhong Huang,Shuqi Song,Mengying Tan,Yao Cheng,Bingrong Miao 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.9
Dynamics of a long beam on the elastic foundation subjected to moving loads is studied in the present paper. The sliding window technique is used to dynamically truncate the long beam and a reduced time-varying beam system is obtained. The Hamilton’s principle is employed to establish the equations of motion of the reduced system. The variable separation method is adopted to solve dynamical responses of the reduced system. Examples of a long simply supported Timoshenko beam on the nonlinear foundation subjected to a single moving load and multiple loads are included. Numerical results of the reduced model compared with the ones obtained from the moving element model adapted in literature are carried out to show the validity and the good efficiency of the method proposed in the present paper.
Monitoring and Cause Analysis of Tread Abnormal Wear in a Metro Line
Heji Zhang,Guiming Mei,Hengyu Wang,Wenjian Wang,Zefeng Wen,Xuesong Jin 한국도시철도학회 2014 IJAR Vol.2 No.2
Abnormal wera of tread is a commonly seen problem in the operation of metro systems. It was found that abnormal wear of tread widely exists on vehicles in a line of Beijing metro. The two main types of abnormal wear are “w” shape wear and narrow grooves on tread. It was found that hardness of the tread is strongly correlated with abnormal wear. Monitoring was conducted to watch the growth of abnormal wear on tread surface. Monitoring results show that abnormal wear of tread disappeared after changing brake shoes. Analysis showed that hardness of brake shoes have a great effect on tread wear. The competition between the wear of wheel tread caused by brake shoes and rail head was discussed to explain the reason of commonly seen abnormal wear of tread in metro systems.
Strongly Consistent Identification for Stochastic Linear Errors-in-variables Systems
Dan Fan,Guiming Luo 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
Since the practical systems are very complicated and the survey signals are disturbed, it is necessary to build anti-interference adaptive algorithms for disturbed systems modeling. Real-time errors-in-variables (EIV) systems, in which both the output and the input variables are disturbed by noises, are widely used in signal processing, communications, and control engineering. The adaptive modeling for stochastic linear EIV systems is considered in this paper. A recursive estimation algorithm is proposed for identifying both the system parameters and the noise variance. Then the convergence of the new algorithm is analyzed and the rate of convergence is obtained. It is shown that the parameter estimation can converge to their true values. Numerical simulations are included to illustrate the efficiency of the new algorithm.
Heo, Jungwoo,Kim, Sangeun,Guim, Hwanuk,Jin, Hyung-Ha,Moon, Joonoh,Lee, Chang-Hoon,Shin, Chansun Elsevier 2018 Journal of Nuclear Materials Vol.512 No.-
<P><B>Abstract</B></P> <P>Radiation-induced hardening of newly developed Ti/Ta-added reduced activation ferritic-martensitic (RAFM) steel is evaluated by combining self-ion irradiation and cross-sectional micropillar compression tests. 500-nm micropillars were fabricated on a cross-section polished surface using argon ion beam at locations of the ion-irradiated and unirradiated layers. The compressed micropillars showed that the deformation mode and flow behavior were changed because of ion irradiation. The radiation-induced increase in yield strength was evaluated by considering the specimen size effects manifested in the micropillar compression tests. The evaluated radiation hardening of the Ti/Ta-added RAFM steel at the dose of ∼2 dpa was found to be comparable to that of the reference RAFM steel with a composition similar to Eurofer97. The size and the number density of radiation-induced dislocation loops are analyzed, and the difference between the two RAFM steels is discussed.</P>
Lee, So-Yeon,Guim, Hwan-Uk,Kim, Dong-Ik,Joo, Young-Chang,Shim, Cheol-Hwee,Ahn, Jae-Pyoung,Choi, In-Suk,Abbasi, Majid Elsevier 2017 Scripta materialia Vol.138 No.-
<P><B>Abstract</B></P> <P>Nanostructure of cupper thin film on polyimide flexible substrate is revealed by novel orientation imaging techniques. Copper and polyimide thicknesses play critical roles on what technique is successful in acquiring diffraction patterns while avoiding electron beam damage and blistering. Conventional electron backscattered diffraction as well as emerging higher resolution transmission orientation imaging were employed to resolve the grain structure. Spatial resolution is compared in terms of minimum detectable twin width. Experiments and simulations indicate that polyimide thicknesses below 1000nm allow the electrons to scape; resulting in acceptable reflective or transmission patterns and lack of blistering.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ting Huang,Zhongning Guo,Guiming Liang,Shunzhi Qiao,Pengcheng Cai,Zhixiang Zou 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8
The mask jet electrochemical deposition was used to deposit the large-scale micro cylinders array in this study. The effect of the pulse peak current density, pulse frequency, pulse duty cycle, injection pressure and scanning speed on the deposition characteristics (i.e. deposition height, surface roughness and surface quality of micro cylinders) have been investigated. The experiment results showed that the mean height and the surface roughness of micro cylinders increased form the peak current density. Moreover, due to a high pulse frequency provided a shorter pulse on-time, and significantly facilitating the renewal of the ion concentration in the electroforming fluid. A higher pulse frequency and larger duty cycle provide a better deposition characteristic. The injection pressure was found to have a significant effect on the height, the surface roughness and surface appearance of micro cylinders. Furthermore, when using higher scanning speed, the crystalline particles of the cast layer decrease, significantly decreasing the surface roughness. Based on discussed, the pulse current density of 12 A/dm 2 , a pulse frequency of 3000 Hz, a pulse duty cycle of 30 %, a jet inlet pressure of 80 kPa, a scanning speed of 8 mm/s and a number of scans of 100 is optimal parameters. Finally, by using these parameters, a large-area micro cylindrical array structures with a height of 22.53±2.46 μm and diameter of 205±3.21 μm were successfully fabricated. It can be concluded that the mask jet electrochemical deposition is a simple method to realize the electrodeposition of large-area array structures.
Gene expression analysis of “green tide” alga Ulva prolifera (Chlorophyta) in China
Shangang Jia,Xumin Wang,Guiming Liu,Dan Luo,Jing Zhang,Yan Liu,Xiangzhi Lin,Tao Liu 한국유전학회 2011 Genes & Genomics Vol.33 No.2
Ulva prolifera (Ulvophyceae, Chlorophyta) is the causative species of the annual “green tides” in the Bohai Gulf of Northern China. In order to gain some more insight into the transcriptome of this fast-growing species of algae, we acquired 6,203 high-quality expressed-sequence-tags (ESTs),which were clustered into 4,080 unique sequences (UniSeqs). Functional classification revealed that most of the acquired transcripts were related to metabolic and biosynthetic processes,nucleotide binding, and cell part that might contribute to the organism’s rapid growth. Using 39 EST pools, 28 mitochondria genomes, and 18 chloroplast genomes from algae and land plants, we constructed three phylogenetic trees. These trees provided evidence that U. prolifera was in a sister position to Ulva linza, and shared a similar chloroplast origin with Pseudendoclonium akinetum. The findings of this study will improve our knowledge of the transcriptome and taxonomic position of U. prolifera.
Abbasi, Majid,Dehghani, Morteza,Guim, Hwan-Uk,Kim, Dong-Ik Elsevier 2016 Acta materialia Vol.117 No.-
<P>An attempt has been made to investigate Fe-rich fragments and surrounding intermetallic compounds in aluminum-steel friction stir welds using conventional EBSD + EDS as well as advanced Transmission Kikuchi Diffraction (TKD). Results indicate that the fragments are covered by a layer of orthorhombic Al5Fe2. This layer is surrounded by a mixed region composed of sub-micrometer Al3Fe crystals in a matrix of Al nano grains. Employing high beam current TKD on electron-transparent samples enables investigation of sub-micrometer grains in the mixed region with a higher spatial resolution than conventional EBSD. As a result, nano-twinning in Al in the mixed region has been observed. Microstructural and texture results imply that Fe-rich fragments travel through the Al matrix under extreme shear forces, severely refining Al grains, and inducing nano-twinning. Due to extreme shear forces and Fe outward diffusion, fine steel fragments dissolve in the surroundings leading to the nucleation of nano Al3Fe crystals particularly along Al grain boundaries. Al3Fe crystals consume the Al matrix as they grow in size and fraction. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.</P>