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검색결과 1,358건 처리시간 0.038초

Investigation on vortex-induced vibration of a suspension bridge using section and full aeroelastic wind tunnel tests

  • Sun, Yanguo;Li, Mingshui;Liao, Haili
    • Wind and Structures
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    • 제17권6호
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    • pp.565-587
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    • 2013
  • Obvious vortex induced vibration (VIV) was observed during section model wind tunnel tests for a single main cable suspension bridge. An optimized section configuration was found for mitigating excessive amplitude of vibration which is much larger than the one prescribed by Chinese code. In order to verify the maximum amplitude of VIV for optimized girder, a full bridge aeroelastic model wind tunnel test was carried out. The differences between section and full aeroelastic model testing results were discussed. The maximum amplitude derived from section model tests was first interpreted into prototype with a linear VIV approach by considering partial or imperfect correlation of vortex-induced aerodynamic force along span based on Scanlan's semi-empirical linear model. A good consistency between section model and full bridge model was found only by considering the correlation of vortex-induced force along span.

Electromagnetic Environment of Transmission Line Based on Full Parameter Online Estimation

  • Sun, Zidan;Zhou, Xiaofeng;Liang, Likai;Mo, Yang
    • Journal of Information Processing Systems
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    • 제16권2호
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    • pp.394-405
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    • 2020
  • The parameters of transmission lines have an influence on the electromagnetic environment surrounding the line. This paper proposes a method based on phasor measurement unit (PMU) and supervisory control and data acquisition (SCADA) to achieve online estimation of transmission line full parameters, such as resistance, reactance and susceptance. The proposed full parameter estimation method is compared with the traditional method of estimating resistance independently based on SCADA system. Then, the electromagnetic environment is analyzed based on the different parameter estimation methods. The example results illustrate that online estimation of transmission line full parameters is more accurate in the analysis of electromagnetic environment, which further confirms its necessity and significance in engineering application.

HID-lamp용 Full-Bridge 전자식 안정기의 손실 특성 규명 (Examination of Loss Characteristics of Full-Bridge Electronic Ballast for HID Lamps)

  • 박종연;정동열;이혁순
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 하계학술대회 논문집 D
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    • pp.2537-2540
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    • 2001
  • The purpose of this study is to examine the calculated method of loss characteristics of full-bridge eletronic ballast for 250Watt HID lamps by approximated modeling. These lamps have the most emit effiency and color rendering. Especially, the majority of losses appear to the MOSFET do full-bridge, L of output terminal and driver IC, besides losses occur to the R in the ballast. These losses cause heating and breakage of MOSFET. When HID-lamp arrivals the steady-state, loss of ballast is measured 9% and analyzed value is 8% approximately. Accordingly it is not too much to say that greater part of losses is examined.

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A METHOD FOR DETERMINING MAGNETIC HELICITY OF SOLAR ACTIVE REGIONS FROM SOHO/MDI MAGNETO GRAMS

  • CHAE JONGCHUL;JEONG HYEWON
    • 천문학회지
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    • 제38권2호
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    • pp.295-298
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    • 2005
  • Recently a big progress has been made on the measurements of magnetic helicity of solar active regions based on photospheric magnetograms . In this paper, we present the details of Chae's method of determining the rate of helicity transfer using line-of-sight magnetograms such as taken by SORO /MDI. The method is specifically applied to full-disk magnetograms that are routinely taken at 96-minute cadence.

Difference, not Differentiation: The Thingness of Language in Sun Yung Shin's Skirt Full of Black

  • Shin, Haerin
    • 영어영문학
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    • 제64권3호
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    • pp.329-345
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    • 2018
  • Sun Yung Shin's poetry collection Skirt Full of Black (2007) brings the author's personal history as a Korean female adoptee to bear upon poetic language in daring formal experiments, instantiating the liminal state of being shuttled across borders to land in an in-between state of marginalization. Other Korean American poets have also drawn on the experience of transnational adoption and racialization explore the literary potential of English to materialize haunting memories or the untranslatable yet persistent echoes of a lost home that gestures across linguistic boundaries, as seen in the case of Lee Herrick or Jennifer Kwon Dobbs. Shin however dismantles the referential foundation of English as a language she was transplanted into through formal transgressions such as frazzled syntax, atypical typography, decontextualized punctuation marks, and phonetic and visual play. The power to signify and thereby differentiate one entity or meaning from another dissipates in the cacophonic feast of signs in Skirt Full of Black; the word fragments of identificatory markers that turn racialized, gendered, and culturally contained subjects into exotic things lose the power to define them as such, and instead become alterities by departing from the conventional meaning-making dynamics of language. Expanding on the avant-garde legacy of Korean American poets Theresa Hak Kyung Cha and Myung Mi Kim to delve further into the liminal space between Korean and American, referential and representational, or spoken and written words, Shin carves out a space for discreteness that does not subscribe to the hierarchical ontology of differential value assignment.

A Novel Perceptual Hashing for Color Images Using a Full Quaternion Representation

  • Xing, Xiaomei;Zhu, Yuesheng;Mo, Zhiwei;Sun, Ziqiang;Liu, Zhen
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제9권12호
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    • pp.5058-5072
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    • 2015
  • Quaternions have been commonly employed in color image processing, but when the existing pure quaternion representation for color images is used in perceptual hashing, it would degrade the robustness performance since it is sensitive to image manipulations. To improve the robustness in color image perceptual hashing, in this paper a full quaternion representation for color images is proposed by introducing the local image luminance variances. Based on this new representation, a novel Full Quaternion Discrete Cosine Transform (FQDCT)-based hashing is proposed, in which the Quaternion Discrete Cosine Transform (QDCT) is applied to the pseudo-randomly selected regions of the novel full quaternion image to construct two feature matrices. A new hash value in binary is generated from these two matrices. Our experimental results have validated the robustness improvement brought by the proposed full quaternion representation and demonstrated that better performance can be achieved in the proposed FQDCT-based hashing than that in other notable quaternion-based hashing schemes in terms of robustness and discriminability.

Power allocation for full-duplex NOMA relaying based underlay D2D communications

  • Li, Song;Li, Shuo;Sun, Yanjing
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제13권1호
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    • pp.16-33
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    • 2019
  • In this paper, a full-duplex NOMA relaying based underlay device-to-device (D2D) communication scheme is proposed, in which D2D transmitter assists cellular downlink transmission as a full-duplex relay. Specifically, D2D transmitter receives signals from base station and transmits the superposition signals to D2D receiver and cellular user in NOMA scheme simultaneously. Furthermore, we investigate the power allocation under the proposed scheme, aiming to maximize D2D link's achievable transmit rate under cellular link's transmit rate constraint and total power constraint. To tackle the power allocation problem, we first propose a power allocation method based on linear fractional programming. In addition, we derive closed-form expressions of the optimal transmit power for base station and D2D transmitter. Simulation results show that the performance of two solutions matches well and the proposed full-duplex NOMA relaying based underlay D2D communication scheme outperforms existing full-duplex relaying based D2D communication scheme.

Comparison of light-induced degradation and regeneration in P-type monocrystalline full aluminum back surface field and passivated emitter rear cells

  • Cho, Eunhwan;Rohatgi, Ajeet;Ok, Young-Woo
    • Current Applied Physics
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    • 제18권12호
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    • pp.1600-1604
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    • 2018
  • This paper reports on a systematic and quantitative assessment of light induced degradation (LID) and regeneration in full Al-BSF and passivated emitter rear contact cells (PERC) along with the fundamental understanding of the difference between the two. After LID, PERC cells showed a much greater loss in cell efficiency than full Al-BSF cells (~0.9% vs ~0.6%) because the degradation in bulk lifetime also erodes the benefit of superior BSRV in PERC cells. Three main regeneration conditions involving the combination of heat and light ($75^{\circ}C/1\;Sun/48h$, $130^{\circ}C/2\;Suns/1.5h$ and $200^{\circ}C/3\;Suns/30s$) were implemented to eliminate LID loss due to BO defects. Low temperature/long time ($75^{\circ}C/48h$) and high temperature/short time ($200^{\circ}C/30s$) regeneration process was unable to reach 100% stabilization. The intermediate temperature/time ($130^{\circ}C/1.5h$) generation achieved nearly full recovery and stabilization (over 99%) for both full Al-BSF and PERC cells. We discussed the effect of temperature, time and suns in regeneration mechanism for two cells.

Design of Integrated Magnetic Transformer for ZVS Phase Shift Full Bridge Converter

  • Li, Xin-Lan;Jang, Eun-Sung;Shin, Yong-Whan;Won, Jae-Sun;Kim, Jong-Sun;Oh, Dong-Seong;Shin, Hwi-Beom
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2008년도 하계학술대회 논문집
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    • pp.40-42
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    • 2008
  • This integrated magnetic (IM) transformer is proposed for a phase shifted full bridge (PSFB) converter with zero voltage switching (ZVS). In a new IM transformer, the transformer is located on the center leg of E-core and the output inductor is wound on two outer legs. The proposed circuit is analyzed electrically and magnetically. An E-core is redesigned and implemented. The proposed IM transformer is experimentally compared with the conventional one through a 1.2kW prototype converter.

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