Comparative Study of DC Breakdown and Space Charge Characteristics of Insulation Paper Impregnated with Natural Ester and Mineral Oil

Hao, Jian,Zou, Run-Hao,Liao, Rui-Jin,Yang, Li-Jun,Liao, Qiang,Zhu, Meng-Zhao The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

Natural ester is a suitable substitute for mineral oil and has been widely used in AC transformer in many countries. In order to further application of natural ester in direct current (DC) equipment, it is needed to investigate its long term insulation property under DC condition. In this paper, a thermal ageing experiment was conducted for both mineral oil-paper and natural ester-paper insulation. The DC breakdown and space charge characteristics of insulation paper impregnated with natural ester and mineral oil was compared. Results show that the resistivity of the paper immersed in natural ester and mineral oil both increase as the ageing goes on. While insulation paper impregnated with natural ester has higher resistivity and DC breakdown voltage than the paper impregnated with mineral oil. The DC breakdown voltage for the oil impregnated insulation paper being DC pre-stressing is higher than that without pre-stressing. The average DC breakdown field strength difference between the test with pre-stressing and without pre-stressing clearly shows that there is an apparent enhancement effect for the homo-charge injection on the DC breakdown.

Chord rotation demand for effective catenary action of RC beams under gravitational loadings

Meng-Hao Tsai 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.2

Many experimental and analytical studies have been conducted with beam-column subassemblages composed of a two-span beam to investigate the progressive collapse resistance of RC frames. Most study results reveal a strength-decreased transition phase in the nonlinear static load-deflection curve, which may induce dynamic snap-through response and increase the chord rotation demand for effective catenary action (ECA). In this study, the nonlinear static response is idealized as a piecewise linear curve and analytical pseudo-static response is derived for each linearized region to investigate the rotation demands for the ECA of the two-span RC beams. With analytical parameters determined from several published test results, numerical analysis results indicate that the rotation demand of 0.20 rad recommended in the design guidelines does not always guarantee the ECA. A higher rotation demand may be induced for the two-span beams designed with smaller span-to-depth ratios and it is better to use their peak arch resistance (PAR) as the collapse strength. A tensile reinforcement ratio not greater than 1.0% and a span-to-depth ratio not less than 7.0 are suggested for the two-span RC beams bridging the removed column if the ECA is expected for the collapse resistance. Also, complementary pseudo-static analysis is advised to verify the ECA under realistic dynamic column loss even though the static PAR is recovered in the nonlinear static response. A practical empirical formula is provided to estimate an approximate rotation demand for the ECA.

Control of thermoacoustic instability of liquid-spray flame with porous sound absorber

Hao Zhou,Hao Fang,Dongliang Wei,Zihua Liu,Zhaowen Wang,Hanxiao Meng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

A kind of porous sound absorber was studied to control the thermoacoustic oscillation of liquid mist flame, which combined natural fibrous materials and perforated plate. It could optimize the sound absorption characteristics of fibrous materials by adding perforated plate and air cavity. The influences of the interlayer and back cavity depth of two kinds of fibrous materials with the mass of 20, 30, 40 g were investigated experimentally in an impedance tube and applied to control the oscillating ethanol flame. The results showed that the best depth of interlayer and back cavity were 20 cm and 30 cm, respectively. The addition of two kinds of fiber sandwich structures could reduce the amplitude of the sound pressure oscillation in the combustion chamber by 89.2 % and 92.6 %, as well as 88.0 % and 91.2 % in the plenum chamber, meanwhile, restrained the flame heat release fluctuation by 73 %. It was proved that the porous sound absorber could act as a damp in the acoustic transmission path and suppress the sound source.

Column-loss response of RC beam-column sub-assemblages with different bar-cutoff patterns

Meng-Hao Tsai,Jun-Kai Lu,Bo-Hong Huang 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.6

Static loading tests were carried out in this study to investigate the effect of bar cutoff on the resistance of RC beam-column sub-assemblages under column loss. Two specimens were designed withcontinuous main reinforcement. Four others were designed with different types of bar cutoff in the mid-span and/or the beam-end regions. Compressive arch and tensile catenary responses of the specimens under gravitational loading were compared. Test results indicated that those specimens with approximately equal moment strength at the beam ends had similar peak loading resistance in the compressive arch phase but varied resistance degradation in the transition phase because of bar cutoff. The compressive bars terminated at one-third span could help to mitigate the degradation although they had minor contribution to the catenary action. Among those cutoff patterns, the K-type cutoff presented the best strength enhancement. It revealedthat it is better to extend the steel bars beyond the mid-span before cutoff for the two-span beams bridgingover a column vulnerable to sudden failure. For general cutoff patterns dominated by gravitational and seismic designs, they may be appropriately modified to minimize the influence of bar cutoff on the progressive collapse resistance.

Column-loss response of RC beam-column sub-assemblages with different bar-cutoff patterns

Tsai, Meng-Hao,Lua, Jun-Kai,Huang, Bo-Hong Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.6

Static loading tests were carried out in this study to investigate the effect of bar cutoff on the resistance of RC beam-column sub-assemblages under column loss. Two specimens were designed with continuous main reinforcement. Four others were designed with different types of bar cutoff in the mid-span and/or the beam-end regions. Compressive arch and tensile catenary responses of the specimens under gravitational loading were compared. Test results indicated that those specimens with approximately equal moment strength at the beam ends had similar peak loading resistance in the compressive arch phase but varied resistance degradation in the transition phase because of bar cutoff. The compressive bars terminated at one-third span could help to mitigate the degradation although they had minor contribution to the catenary action. Among those cutoff patterns, the K-type cutoff presented the best strength enhancement. It revealed that it is better to extend the steel bars beyond the mid-span before cutoff for the two-span beams bridging over a column vulnerable to sudden failure. For general cutoff patterns dominated by gravitational and seismic designs, they may be appropriately modified to minimize the influence of bar cutoff on the progressive collapse resistance.

Comparative Study of DC Breakdown and Space Charge Characteristics of Insulation Paper Impregnated with Natural Ester and Mineral Oil

Jian Hao,Run-Hao Zou,Rui-Jin Liao,Li-Jun Yang,Qiang Liao,Meng-Zhao Zhu 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

Natural ester is a suitable substitute for mineral oil and has been widely used in AC transformer in many countries. In order to further application of natural ester in direct current (DC) equipment, it is needed to investigate its long term insulation property under DC condition. In this paper, a thermal ageing experiment was conducted for both mineral oil-paper and natural ester-paper insulation. The DC breakdown and space charge characteristics of insulation paper impregnated with natural ester and mineral oil was compared. Results show that the resistivity of the paper immersed in natural ester and mineral oil both increase as the ageing goes on. While insulation paper impregnated with natural ester has higher resistivity and DC breakdown voltage than the paper impregnated with mineral oil. The DC breakdown voltage for the oil impregnated insulation paper being DC prestressing is higher than that without pre-stressing. The average DC breakdown field strength difference between the test with pre-stressing and without pre-stressing clearly shows that there is an apparent enhancement effect for the homo-charge injection on the DC breakdown.

Molecular simulation of adsorption of NO and CO2 mixtures by a Cu-BTC metal organic framework

Guanghao Meng,Xuedan Song,Min Ji,Juanyuan Hao,Yantao Shi,Suzhen Ren,Jieshan Qiu,Ce Hao 한국물리학회 2015 Current Applied Physics Vol.15 No.9

Environmental problems due to the discharge of gases, including NO and CO2, in addition, diseases caused by improper concentration of NO and CO2 in vivo must be resolved. In this study, Grand canonical Monte Carlo (GCMC) simulations are combined with density functional theory (DFT) to calculate the adsorption of NO and CO2 from a dual-component mixture to the Cu-BTC metal organic framework. The results show that the adsorption isotherms for various molar ratios of the gaseous mixture followed a Langmuir distribution. At higher pressures more CO2 than NO was adsorbed by Cu-BTC, with NO showing a tendency to desorb. However, better results for adsorption of NO were observed at lower pressures. For the different pressure and molar ratios of the gaseous mixture examined, more CO2 than NO was always adsorbed. Compared with three-way catalysts, Cu-BTC offers benefits to adsorption of CO2 and NO from gaseous mixtures without increased durability problems.

A Nano-power Switched-capacitor Voltage Reference Using MOS Body Effect for Applications in Subthreshold LSI

Zhang, Hao,Huang, Meng-Shu,Zhang, Yi-Meng,Yoshihara, Tsutomu The Institute of Electronics and Information Engin 2014 Journal of semiconductor technology and science Vol.14 No.1

A nano-power CMOS voltage reference is proposed in this paper. Through a combination of switched-capacitor technology with the body effect in MOSFETs, the output voltage is defined as the difference between two gate-source voltages using only a single PMOS transistor operated in the subthreshold region, which has low sensitivity to the temperature and supply voltage. A low output, which breaks the threshold restriction, is produced without any subdivision of the components, and flexible trimming capability can be achieved with a composite transistor, such that the chip area is saved. The chip is implemented in $0.18{\mu}m$ standard CMOS technology. Measurements show that the output voltage is approximately 123.3 mV, the temperature coefficient is $17.6ppm/^{\circ}C$, and the line sensitivity is 0.15 %/V. When the supply voltage is 1 V, the supply current is less than 90 nA at room temperature. The area occupation is approximately $0.03mm^2$.

Research and Implementation of a Vertical Search Engine in the Financial Domain

Yue Hou-guang,ZhangLing,Meng Fan-jun,Songhong-hao 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.5

The exponential growth of the data on the web makes it difficult for web users to locate and obtain the interesting information. The general web search engines, such as Google, Baidu, reduce the degree of difficulty to some extent. The rise of vertical search engine provides a promising approach to address the big challenge. A Chinese vertical search engine is urgently needed to provide professional financial information retrieval service for related financial institutions and government agencies. Therefore, in this paper we investigate, design and implement a vertical search engine in the financial domain. Based onNutch plug-in mechanism, we provide and implement the details of a vertical search engine in the financial domain, especially in the finance domain focused crawler. Experimental results show that, the finance domain focused crawler based on Nutch plug-in mechanism has good performance and can satisfy practical requirements of medium search application, and the system runs well.

Injectable Cell Delivery Vehicle and Polymeric Conductive Constructs for Myocardial Tissue Engineering

Meng-Hsuan HSIEH,Congyu ZHANG,Song-Yi WU,Shu-Hong LI,Jun WU,Shi-Ming LIU,Hao-Ji WEI,Ren Ke LI,Hsing-Wen SUNG 한국생물공학회 2019 한국생물공학회 학술대회 Vol.2019 No.4