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The possibility of making short-term prediction of rainfall is studied by investigating the existence of chaotic behavior in the rainfall data series. The minimum number of variables essential and the number of variables sufficient to model the dynamics of the rainfall process are identified. The behavior of rainfall over different record lengths is studied. The effects of the data size and the delay time on the correlation dimension estimate are also analyzed. Daily rainfall data of different record lengths from each of six stations in Singapore are analyzed. The correlation dimension method, the inverse approach of the nonlinear prediction method, and the method of surrogate data (to detect nonlinearity) are used in the analysis. The results indicate that the rainfall data exhibit nonlinear behavior and possibly low-dimensional chaos, which imply that short-term prediction based on nonlinear dynamics might be possible. The minimum number of variables essential is identified as 3 and the number of variables sufficient lies in the range between 11 and 18. The results also indicate that the attractor dimensions of data of longer record lengths are greater than that of data of shorter record lengths. The study suggests that a minimum of ϳ1,500 data points is required for the computation of the correlation dimension. Recommendation on the selection of the delay time is also provided. 1 Res. Scholar,

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SUMMARYA new structural system for earthquake resistant steel structures is investigated in this paper. This new framing system, called the knee-brace-frame (KBF), is a braced frame with diagonal braces connected to ductile knee members. The diagonal braces provide the lateral stiffness, whereas the knee anchors yield in flexure to dissipate energy during severe seismic excitation. To assess the inelastic characteristics of the KBF, a large scale model of a KBF was tested using the pseudodynamic test procedure. The experimental results are compared with analytical results obtained from a DRAIN-2D model. It is found that, with an appropriate design of knee anchors, the KBF can be made to be ductile to dissipate energy during severe seismic excitation.

This paper focuses on the investigation of the existence of chaotic behavior in the Singapore rainfall data. The procedure for the determination of the minimum number of variables essential and the number of variables sufficient to model the dynamics of the rainfall process was studied. An analysis of the rainfall behavior of different time periods was also conducted. The correlation dimension was used as a basis for discriminating stochastic and chaotic behaviors. Daily rainfall records for durations of 30, 20, 10, 5, 4, 3, 2, and 1 years from six stations were analyzed. The delay time for the phase‐space reconstruction was computed using the autocorrelation function approach. The results provide positive evidence of the existence of chaotic behavior in the daily rainfall data. The minimum number of variables essential to model the dynamics of the rainfall process was identified to be 3 while the number of variables sufficient to model the dynamics of the rainfall process ranges from 11 to 18. The results also suggest that the attractor dimensions of rainfall data of longer time periods are higher than that of shorter time periods. The study suggests a minimum number of 1500 data points required for the computation of the correlation dimension of the rainfall data.

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