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검색결과 719건 처리시간 0.052초

Determination of Urban Surface Aerodynamic Characteristics Using Marquardt Method

  • Zhang, Ning;Jiang, Weimei;Gao, Zhiqiu;Hu, Fei;Peng, Zhen
    • Wind and Structures
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    • 제12권3호
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    • pp.281-283
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    • 2009
  • Marquardt method is used to estimate the aerodynamic parameters in urban area of Beijing City, China, including displacement length (d), roughness length ($z_0$) and friction velocity (u*) and drag coefficient. The surface drag coefficient defined as the ratio between friction velocity and mean wind speed is 0.125 in our research, which is close to typical urban area value. The averaged d and $z_0$ are 1.2 m and 7.6 m. d and $z_0$ change with direction because of the surface heterogeneity over urban surface and reach their maximum values at S-SW sector, this tendency agrees with the surface rough element distribution around the observation tower.

Study on the space frame structures incorporated with magnetorheological dampers

  • Xu, Fei-Hong;Xu, Zhao-Dong;Zhang, Xiang-Cheng
    • Smart Structures and Systems
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    • 제19권3호
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    • pp.279-288
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    • 2017
  • Magnetorheological damper has received significant attention in recent years due to the reason that it can offer adaptability of active control devices without requiring the associated large power sources. In this paper, performance tests on a MR damper are carried out under different currents, excitation amplitudes and frequencies, the damping characteristics and energy dissipation capacity of the MR damper are analyzed. Elasto-plastic dynamic analysis on a space frame structure incorporated with MR dampers is conducted, and numerical analysis results show that MR dampers can significantly mitigate the structural vibration responses. Finally, the genetic algorithm with the improved binary crossover and mutation technique is adopted to optimize the arrangement of MR dampers. Numerical results show that dynamic responses of the optimal controlled structure are mitigated more effectively.

Genetic Reprogramming after Somatic Cell cloning

  • Tian, X.Cindy;Xu, Jie;Xue, Fei;Kubota, Chikara;Du, Fuliang;Yang, Xiangzhong
    • 한국수정란이식학회:학술대회논문집
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    • 한국수정란이식학회 2002년도 국제심포지엄
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    • pp.43-55
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    • 2002
  • Cloning by nuclear transfer in mammals using somatic cells has enormous potential applications. However, somatic cloning has been inefficient in all species in which NT is successful. High abortion and fetal death rates have been observed. These developmental defects have been attributed to incomplete nuclear reprogramming by the somatic cloning process. In this review, we will discuss studies conducted in our labs to understand the nuclear reprogramming process.

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IEC 61850 기반의 OCR IED에 대한 적합성 시험방안 (Conformance Testing for IEC 61850 based OCR IED)

  • 위페이;임성정;최면송;이승재
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 제39회 하계학술대회
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    • pp.19-20
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    • 2008
  • IEC 61850 is a new approach international standard which is applicable to Substation Automation System (SAS) and defines the communication between intelligent electric devices (IEDs) in the substation and the related system requirements. It already has a significant impact on the development of different devices or systems used in substation. Conformance claims and the establishment of their validity are important parts of the acceptance of systems and equipment. This paper introduces the conformance testing, mapping of IEC 61850 services and MMS services, and in case study part it gives the example of testing OCR IED.

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Expression of PGDH Correlates with Cell Growth in Both Esophageal Squamous Cell Carcinoma and Adenocarcinoma

  • Yang, Guo-Tao;Wang, Juan;Xu, Tong-Zhen;Sun, Xue-Fei;Luan, Zi-Ying
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권3호
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    • pp.997-1000
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    • 2015
  • Esophageal cancer represents the fourth most common gastrointestinal cancer and generally confers a poor prognosis. Prostaglandin-producing cyclo-oxygenase has been implicated in the pathogenesis of esophageal cancer growth. Here we report that prostaglandin dehydrogenase, the major enzyme responsible for prostaglandin degradation, is significantly reduced in expression in esophageal cancer in comparison to normal esophageal tissue. Reconstitution of PGDH expression in esophageal cancer cells suppresses cancer cell growth, at least in part through preventing cell proliferation and promoting cell apoptosis. The tumor suppressive role of PGDH applies equally to both squamous cell carcinoma and adenocarcinoma, which enriches our understanding of the pathogenesis of esophageal cancer and may provide an important therapeutic target.

Predicting Media Credibility in China: The Influence of Weibo Use

  • Shen, Fei;Zhang, Hongzhong
    • Asian Journal for Public Opinion Research
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    • 제1권4호
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    • pp.234-248
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    • 2014
  • A telephone survey was conducted in a metropolitan city in 2012 to examine people's credibility ratings of different media outlets, in particular, Weibo - one of the most popular social media platforms in China. Our findings suggest: First, people place more trust in traditional news media than in online sources by a significant margin. Second, demographic influences on media trust seem to be minimal. Only age and gender were related to some credibility measures. Third, Weibo use was not related to one's credibility perception toward traditional media but interestingly, Weibo use showed different impacts on people's evaluation of Weibo's credibility. Commenting frequency was negatively related to one's trust in Weibo, while retweeting frequency was positively related to one's trust in Weibo.

A New Variational Level Set Evolving Algorithm for Image Segmentation

  • Fei, Yang;Park, Jong-Won
    • Journal of Information Processing Systems
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    • 제5권1호
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    • pp.1-4
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    • 2009
  • Level set methods are the numerical techniques for tracking interfaces and shapes. They have been successfully used in image segmentation. A new variational level set evolving algorithm without re-initialization is presented in this paper. It consists of an internal energy term that penalizes deviations of the level set function from a signed distance function, and an external energy term that drives the motion of the zero level set toward the desired image feature. This algorithm can be easily implemented using a simple finite difference scheme. Meanwhile, not only can the initial contour can be shown anywhere in the image, but the interior contours can also be automatically detected.

Impact of Malaysia's Capital Market and Determinants on Economic Growth

  • Ali, Md. Arphan;Fei, Yap Su
    • The Journal of Asian Finance, Economics and Business
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    • 제3권2호
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    • pp.5-11
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    • 2016
  • This study investigates the impact of Malaysia's capital market and other key determinants on Economic Growth from the period of 1988 to 2012. The key determinants studied are foreign direct investment and real interest rate. This study also examines the long run and short run relationship between the economic growth and capital market, foreign direct investment, and real interest rate by using bound testing cointegration of Autoregressive Distributed Lag (ARDL) and Error Correction Model (ECM) version of ARDL model. The empirical results of the study suggest that there is long- run cointegration among the capital market, foreign direct investment, real Interest rate and economic growth. The result also suggests that capital market and real interest rate have positive impact on economic growth in the short run and long run. Foreign direct investment does not show positive impact on economic growth in the short run but it does in the long run.

STRUCTURAL AND SPECTRAL PROPERTIES OF k-QUASI-*-PARANORMAL OPERATORS

  • ZUO, FEI;ZUO, HONGLIANG
    • Korean Journal of Mathematics
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    • 제23권2호
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    • pp.249-257
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    • 2015
  • For a positive integer k, an operator T is said to be k-quasi-*-paranormal if ${\parallel}T^{k+2}x{\parallel}{\parallel}T^kx{\parallel}{\geq}{\parallel}T^*T^kx{\parallel}^2$ for all x $\in$ H, which is a generalization of *-paranormal operator. In this paper, we give a necessary and sufficient condition for T to be a k-quasi-*-paranormal operator. We also prove that the spectrum is continuous on the class of all k-quasi-*-paranormal operators.

Reduction of Peak-to-Average Power Ratio of Multicarrier Modulation Signals with Adaptive Companding Scheme

  • Hou, Jun;Zhao, Xiangmo;Hui, Fei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제10권7호
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    • pp.3117-3130
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    • 2016
  • High peak-to-average power ratio (PAPR) of transmitted signals is a major drawback in Multicarrier modulation (MCM) systems. Companding transform is a well-known method to reduce the PAPR without restrictions on system parameters such as the number of subcarriers, frame format and constellation type. In this paper, a novel adaptive companding scheme, mainly focuses on compressing the large signals into the desirable distribution, is proposed to reduce the PAPR with low implementation complexity. In addition, formulas to calculate its PAPR and bit error rate (BER) performance are also derived. Simulation results confirm that the proposed scheme can achieve an effective tradeoff between PAPR reduction and BER performance by carefully choosing the companding parameter.