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.

Dynamic responses of a 492‐m‐high tall building with active tuned mass damping system during a typhoon

Abstract: SUMMARY This paper presents observations on the dynamic properties and wind-induced response characteristics of a 492-m-high building installed with an active tuned mass damping (ATMD) system during a typhoon. Damping ratios, natural frequencies, and wind-induced vibrations of the super-tall building with/without the operation of the ATMD system are investigated. Field measurement results show that the ATMD system functioned efficiently for the suppression of the wind-induced vibrations of this super-tall building, and the building's acceleration responses were well confined within the range stipulated in the International Standards Organization for serviceability concerns. A modified time-weighted random decrement operator is proposed for estimation of damping ratio, which is able to provide more reasonable estimations than unmodified form under nonstationary conditions. In addition, extreme responses of this building under the typhoon are studied using the crossing method and the generalized extreme value model. The main objective of this study is to investigate the effectiveness of the ATMD system and the performance of the actively controlled high-rise structure under typhoon condition to assess the benefits gained from the application of the vibration control technique. Copyright © 2013 John Wiley & Sons, Ltd.

Field measurements of wind effects on the tallest building in Hong Kong

Abstract: Central Plaza has a height of approximately 374 m and is 78-storeys tall. It is the tallest structure in Hong Kong and was the highest reinforced-concrete building in the world when it was built several years ago. This paper describes some results obtained from the full-scale measurements of wind effects on Central Plaza. The field data such as wind speed, wind direction and acceleration responses have been measured during the close passage of several typhoons in recent years. Detailed analysis of the field data is conducted to investigate wind effects on the tall building. The full-scale measurements are compared with the wind tunnel results. The amplitude-dependent characteristics of damping that were obtained by using the random decrement technique are investigated on the basis of the field measurements. Copyright © 2003 John Wiley & Sons, Ltd.

I and i

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 …

Nonlinear Time Series Analysis.

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)