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Qiusheng Li

Bio: Qiusheng Li is an academic researcher from City University of Hong Kong. The author has contributed to research in topics: Wind speed & Wind tunnel. The author has an hindex of 47, co-authored 429 publications receiving 8830 citations. Previous affiliations of Qiusheng Li include Chinese Ministry of Education & Guangzhou University.


Papers
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Journal ArticleDOI
TL;DR: It is proved that it is possible to separate a shear plate as two independent shear beams for free-vibration analysis and the function for describing the distribution of mass of each step plate can be selected as an arbitrary one.
Abstract: A new exact approach for free-vibration analysis of multistep nonuniform orthotropic shear plates with line spring supports and line masses is presented. The governing differential equation for free vibrations of an orthotropic shear plate with variably distributed mass and stiffness is established. It is proved that it is possible to separate a shear plate as two independent shear beams for free-vibration analysis. The jkth natural frequency of a shear plate is equal to the square root of the square sum of the jth natural frequency of a shear beam and the kth natural frequency of another shear beam. The jkth mode shape of the shear plate is the product of the jth mode shape of a shear beam and the kth mode shape of another shear beam. In this paper, the function for describing the distribution of mass of each step plate can be selected as an arbitrary one, and the distribution of shear stiffness is expressed as a functional relation with the mass distribution, and vice versa. The exact solutions of one-step shear plates with varying cross section are obtained first for eight cases. Then, the derived exact solutions are used to establish the frequency equation of a multistep nonuniform orthotropic shear plate with spring supports and line masses using the transfer matrix method and the recurrence method developed in this paper. The numerical example shows that the calculated results are in good agreement with the experimental data, and the proposed procedure is an exact and efficient method.

8 citations

Journal ArticleDOI
TL;DR: In this article, a number of squall line passages over the Pearl River Delta (PRD) are documented for the first time based on the wind data collected by a 356 m-high meteorological tower with high temporal resolution (10 Hz).
Abstract: A number of squall line passages over the Pearl River Delta (PRD) are documented for the first time based on the wind data collected by a 356 m-high meteorological tower with high temporal resolution (10 Hz). The mean wind and turbulence characteristics are studied based on a sample of six cases. The mean wind profile is consistent with the international standard for wind engineering, but the turbulence intensity profile has quite significant deviations. Moreover, the energy spectrum of the fluctuating wind is found to be consistent with the −5/3 law, as expected in the inertial subrange. For the purpose of wind gust nowcasting, the performance of a nowcasting algorithm based on upper air wind and thermodynamic profiles is examined using the limited dataset. The results highlight that the mean wind gust estimates are sufficient to nowcast the surface wind gust as measured by the anemometers, but for an extreme squall line case, the maximum wind gust estimates would be useful. The information in this paper is believed to be useful for wind engineering applications and weather nowcasting for wind gusts associated with subtropical squall lines, and, to the best of the authors’ knowledge, this is the first study of its kind for the PRD region.

8 citations

Journal ArticleDOI
TL;DR: In this article, a Kalman filtering-based inverse method for identification of wind forces on supertall buildings is proposed, which allows simultaneously estimating the wind loads and entire wind-induced responses of a supertall building using only a limited set of measurements.
Abstract: A Kalman filtering–based inverse method for identification of wind forces on supertall buildings is proposed. The new approach allows simultaneously estimating the wind loads and entire wind-induced responses of a supertall building using only a limited set of measurements. The effectiveness and good accuracy of the proposed algorithm are validated with experimental results. The wind loads acting on a supertall building are estimated based on the wind-induced responses determined from wind-tunnel testing. The stability of the proposed algorithm is evaluated. The effects of several key factors such as measurement noise, errors of structural modal parameters, and covariance matrix of noise on the identification accuracy are examined and discussed using the L-curve method. Finally, the identified wind loads on the supertall building based on field-measured displacements were compared with the wind-tunnel testing results to further verify the effectiveness of the inverse technique.

8 citations

Journal ArticleDOI
TL;DR: In this paper, the stability of non-uniform columns under the combined action of concentrated and variably distributed forces is solved analytically, and a new exact approach, which combines the exact solutions of one-step columns and the transfer matrix method, is presented for the non-conservative stability analysis of multi-step noniform columns.

8 citations

01 Apr 2016
TL;DR: In this article, the 3D S-wave structure of the Taiwan Strait was derived from a joint Chinese and Taiwanese 3D ambient noise tomography study, where the authors showed a thinning of the crust beneath the rift basins where, locally, thin highvelocity layers suggest the presence of intrusive bodies.
Abstract: Rifting along southeastern Eurasia in the Late Cenozoic led to the formation of a magma-poor rifted margin facing the South China Sea to the southeast and the Philippine Sea to the east. Further rifting along the outer part of the margin during the Middle to Late Miocene was accompanied by an extensive episode of intraplate flood volcanism that formed the Penghu Archipelago. Previous geophysical studies in the area of the Strait have focused primarily on the shallow structures of the rift basins and the depth to the Moho. In this study we present the regional-scale 3D S-wave structure of the Taiwan Strait that is derived from a joint Chinese and Taiwanese 3D ambient noise tomography study. The S-wave model shows a thinning of the crust beneath the rift basins where, locally, thin high-velocity layers suggest the presence of intrusive bodies. The rift basin and the foreland basin along the west coast of Taiwan are imaged as low velocity zones with thicknesses between 5 and 10 km, and extending eastward beneath the Taiwan mountain belt. In the upper 10 km of the crust, the basaltic rocks of the Penghu Archipelago are imaged as a high velocity zone that, with depth, becomes a relatively low velocity zone. We interpret this low velocity zone in the lower crust and upper mantle beneath the Penghu Archipelago to image a thermal anomaly related to the still cooling magma feeding system and the melt reservoir area that fed the flood basalts at the surface.

8 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Book ChapterDOI
11 Dec 2012

1,704 citations

Journal ArticleDOI

1,604 citations

01 Mar 1995
TL;DR: This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series and results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages.
Abstract: : This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency metric, and a classifier independent saliency metric are developed and tested. Ruck's saliency metric, the decision boundary based saliency metric, and the classifier independent saliency metric are compared for a data set consisting of the RSI and Stochastics indicators as well as delayed closing price values. The decision based metric and the Ruck metric results are similar, but the classifier independent metric agrees with neither of the other metrics. The nine most salient features, determined by the decision boundary based metric, are used to train a neural network and the results are presented and compared to other published results. (AN)

1,545 citations