Study on Influences and Elimination of Test Temperature on PDC Characteristic Spectroscopy of Oil-Paper Insulation System

Liu, Xiao,Liao, Ruijin,Lv, Yandong,Liu, Jiefeng,Gao, Jun,Hao, Jian The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

Test temperature is an important factor affecting the measurement results of dielectric response of field power transformers. In order to better apply the polarization and depolarization current (PDC) to the condition monitoring of oil-paper insulation system in power transformers, the influences and elimination method of test temperature on PDC characteristic spectroscopy (PDC-CS) were investigated. Firstly, the experimental winding sample was measured by PDC method at different test temperatures, then the PDC-CS was obtained from the measurement results and its changing rules were discussed, which show that the PDC-CS appears a horizontal mobility with the rise of temperature. Based on the rules, the “time temperature shift technique” was introduced to eliminate the influence of test temperature. It is shown that the PDC-CS at different test temperatures can be converted to the same reference temperature coincident with each other.

Study on Influences and Elimination of Test Temperature on PDC Characteristic Spectroscopy of Oil-Paper Insulation System

Xiao Liu,Ruijin Liao,Yandong Lv,Jiefeng Liu,Jun Gao,Jian Hao 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

Test temperature is an important factor affecting the measurement results of dielectric response of field power transformers. In order to better apply the polarization and depolarization current (PDC) to the condition monitoring of oil-paper insulation system in power transformers, the influences and elimination method of test temperature on PDC characteristic spectroscopy (PDC-CS) were investigated. Firstly, the experimental winding sample was measured by PDC method at different test temperatures, then the PDC-CS was obtained from the measurement results and its changing rules were discussed, which show that the PDC-CS appears a horizontal mobility with the rise of temperature. Based on the rules, the “time temperature shift technique” was introduced to eliminate the influence of test temperature. It is shown that the PDC-CS at different test temperatures can be converted to the same reference temperature coincident with each other.

Aging Hardening and Precipitation Characteristics of Extruded Mg–9Al–0.8Zn–0.2Mn–0.3Ca–0.2Y Alloy

Fangce Liu,Yue Bi,Chao Wang,Jian Kang,Tong He,Yandong Liu,Guo Yuan 대한금속ᆞ재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

In this paper, high temperature hot rolling and weld simulations were performed in Al-killed and Ti-Zr-killed steels. Themicrostructure and impact toughness of the heat-affected zone (HAZ) of the two experimental steels were investigated, andthe ferrite transformation behavior in HAZ was also observed. The characteristic inclusions in the Ti-Zr-killed steel werestudied using electron probe microanalysis (EPMA) and electron backscatter diffraction (EBSD). The results suggested thatthe HAZ microstructure of the Al-killed steel consisted of coarse bainite ferrite (BF) and granular bainite (GB) packets. TheHAZ microstructure of Ti-Zr-killed steel was significantly refined and mainly contained fine acicular ferrite (AF) and BF. TheTi-Zr-O + MnS inclusions were 0.3–2.1 μm and could effectively promote the formation of AF after the weld simulations. MnS had a specific orientation relationship: {111}MnS║{0001}Ti-Zr-O, < 110 > MnS║ < 2 −1−1 0 > Ti-Zr-O with Ti-Zr-O inclusion,and its precipitation promoted the formation of the Mn-depleted zone (MDZ). AF formed around it. The formation of aninterlocked AF structure in the HAZ of the Ti-Zr-killed steel obviously increased the proportion of high angle grain boundaries(HAGBs) and refined the average effective grain size of the HAZ microstructure. Consequently, the impact toughnessof the Ti-Zr-killed steel had no deterioration, but the impact toughness of Al-killed steel had an obvious loss after the weldsimulation with a heat input of 70 kJ/cm. The impact absorption energy of HAZ of Ti-Zr-killed steel was improved from 6to 219 J compared to Al-killed steel.

Inclusion Characteristics and Acicular Ferrite Formation in the Simulated Heat-Affected Zone of Ti-Zr-Killed Low-Carbon Steel

Fangce Liu,Yue Bi,Chao Wang,Jian Kang,Tong He,Yandong Liu,Guo Yuan 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3

In this paper, high temperature hot rolling and weld simulations were performed in Al-killed and Ti-Zr-killed steels. Themicrostructure and impact toughness of the heat-affected zone (HAZ) of the two experimental steels were investigated, andthe ferrite transformation behavior in HAZ was also observed. The characteristic inclusions in the Ti-Zr-killed steel werestudied using electron probe microanalysis (EPMA) and electron backscatter diffraction (EBSD). The results suggested thatthe HAZ microstructure of the Al-killed steel consisted of coarse bainite ferrite (BF) and granular bainite (GB) packets. TheHAZ microstructure of Ti-Zr-killed steel was significantly refined and mainly contained fine acicular ferrite (AF) and BF. TheTi-Zr-O + MnS inclusions were 0.3–2.1 μm and could effectively promote the formation of AF after the weld simulations. MnS had a specific orientation relationship: {111}MnS║{0001}Ti-Zr-O, < 110 > MnS║ < 2 −1−1 0 > Ti-Zr-O with Ti-Zr-O inclusion,and its precipitation promoted the formation of the Mn-depleted zone (MDZ). AF formed around it. The formation of aninterlocked AF structure in the HAZ of the Ti-Zr-killed steel obviously increased the proportion of high angle grain boundaries(HAGBs) and refined the average effective grain size of the HAZ microstructure. Consequently, the impact toughnessof the Ti-Zr-killed steel had no deterioration, but the impact toughness of Al-killed steel had an obvious loss after the weldsimulation with a heat input of 70 kJ/cm. The impact absorption energy of HAZ of Ti-Zr-killed steel was improved from 6to 219 J compared to Al-killed steel.

Flexible Cu2O/Cu film self-powered photodetector for high visible light selection and fast response

Liu Yonghao,Zhao Dawei,Sun Ximing,Cui Feng,Zhang Shan,Shang Xue,Xuan Zhen,Xiao Juqing,Wang Jiapeng,Ren Yandong 한국물리학회 2024 Current Applied Physics Vol.58 No.-

Spectral selection is one of the key performance parameters for visible light photodetectors (VLPD). However, as the absorbing layer of the VLPD, the semiconductor has strong ultraviolet light absorption, leading to poor visible light selectivity of the VLPD. This work fabricated a flexible photovoltaic VLPD based on Cu2O/Cu Schottky junction by annealing Cu foil. Under zero bias, the Cu2O/Cu VLPD showed the responsivity of 14 mA/W, the response time of 1 ms, and the detectivity of 8.8 × 1011 Jones to 620 nm light. Moreover, the detection band of the device is in the range of 500–640 nm, indicating excellent visible light selectivity. Optical and electrical characterization shows that the high visible selectivity of the device is mainly attributed to the fact that the penetration depth of visible light in Cu2O film matches the position of the Cu2O/Cu Schottky junction. This, in turn, induces the effective separation of the photogenerated carriers excited by the visible light. In addition, the bend detection performance of the device is demonstrated. This work provides a reference for improving the spectral selectivity of visible photodetectors.

LncRNA MALAT1/MiR-145 Adjusts IL-1β-Induced Chondrocytes Viability and Cartilage Matrix Degradation by Regulating ADAMTS5 in Human Osteoarthritis

Chengyao Liu,Shan Ren,Shifeng Zhao,Yandong Wang 연세대학교의과대학 2019 Yonsei medical journal Vol.60 No.11

Purpose: Accumulating evidence suggests that microRNA-145 (miR-145) plays an important role in osteoarthritis (OA), which is achronic progressive joint disease. Long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) promotesmetastasis in cancers and functions as a sponge for miR-145. However, the role of MALAT1/miR-145 in OA pathogenesishas not yet been elucidated. Materials and Methods: The expression of MALAT1 and miR-145 was examined by quantitative real-time PCR; the interactionbetween miR-145, MALAT1 and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 5 was verified by luciferasereporter assay. Correlations among MALAT1, miR-145, and ADAMTS5 were analyzed by Spearman rank analysis. Chondrocytesviability and cartilage extracellular matrix (ECM) degradation were investigated with cell viability assay and Western blottinganalyzing expression of ADAMTS5, collagen type 2 alpha 1 (COL2A1), aggrecan (ACAN), and cartilage oligomeric matrix protein(COMP). Results: MALAT1 was upregulated, and miR-145 was downregulated in OA samples and IL-1β-induced chondrocytes. Mechanically,miR-145 could directly bind to MALAT1 and ADAMTS5. Moreover, miR-145 expression was negatively correlated withMALAT1 and ADAMTS5 expression in OA patients, whereas MALAT1 and ADAMTS5 expression was positively correlated. Functionally,overexpression of MALAT1 inhibited chondrocyte viability and promoted cartilage ECM degradation in IL-1β-inducedchondrocytes. In support thereof, MALAT1 silencing and miR-145 upregulation exerted the opposite effect in IL-1β-inducedchondrocytes. Moreover, the effect of MALAT1 was counteracted by miR-145 upregulation, and ADAMTS5 restoration couldabate miR-145 effects. Conclusion: An MALAT1/miR-145 axis contributes to ECM degradation in IL-1β-induced chondrocytes through targeting ADAMTS5,suggesting that MALAT1/miR-145/ADAMTS5 signaling may underlie human OA pathogenesis.

Light doubly charged Higgs boson via the $$WW^*$$ W W ∗ channel at LHC

Kang, Zhaofeng,Li, Jinmian,Li, Tianjun,Liu, Yandong,Ning, Guo-Zhu Springer-Verlag 2015 European Physical Journal C Vol.75 No.12

Effect of Sn Micro-Alloying on Recrystallization Nucleation and Growth Processes of Ferritic Stainless Steels

Tong He,Yang Bai,Xiuting Liu,Dan Guo,Yandong Liu 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.4

We investigated the Effect of Sn micro-alloying on recrystallization nucleation and growth processes of ferritic stainlesssteels. The as-received hot rolled sheets were cold rolled up to 80% reduction and then annealed at 740–880 °C for 5 min. The cold rolling and recrystallization microstructures and micro-textures of Sn-containing and Sn-free ferritic stainless steelswere all determined by electron backscatter diff raction. Our Results show that Sn micro-alloying has important Effects onrecrystallization nucleation and growth processes of ferritic stainless steels. Sn micro-alloying conduces to grain fragmentationin the deformation band, more fragmented grains are existed in Sn-containing cold rolled sheets, which provides moresites for recrystallization nucleation. Sn micro-alloying also promotes recrystallization process and inhibits the growth ofrecrystallized grains. The recrystallization nucleation and growth mechanism of Sn-containing and Sn-free ferritic stainlesssteels are both characterized by orientation nucleation and selective growth, but Sn micro-alloying promotes the formation ofγ-oriented grains. Furthermore, Sn micro-alloying contributes to the formation of Σ13b CSL boundaries and homogeneousγ-fi ber texture. Combining the results of microstructure and micro-texture, the formability of Sn-containing ferritic stainlesssteels will be improved to some extent.