Current Issue : January - March Volume : 2012 Issue Number : 1 Articles : 6 Articles
Prediction of stage-discharge relation or a rating curve is of immense importance for reliable planning, design, and management of most of the water resources projects. Measurement of discharge in a river is a time-consuming, expensive, and difficult process, and the conventional approach of regression analysis of stage-discharge relation does not provide encouraging results especially during the floods. Therefore, the present study is aimed at the application of soft computing techniques such as back propagation feed forward neural network-based algorithm for modelling stage-discharge relation. A data set of discharge-measuring station located on an Indian river has been used for analysis in the present study. A multilinear regression model was also employed on the same data in order to compare the performance of the results. The performance of each model has been compared by calculating correlation coefficient and root mean square error for the used data set. The outcome of the study suggests that the back propagation feed forward ANN works quite well for the data sets and produced promising results in comparison to the linear regression technique....
It is difficult to incorporate multidimensional effect of the ground motion in the design and response analysis of structures. The motion trajectory in the corresponding multi-dimensional space results in time variant principal axes of the motion and defies any meaningful definition of directionality of the motion. However, it is desirable to consider the directionality of the ground motion in assessing the seismic damageability of bridges which are one of the most vulnerable components of highway transportation systems. This paper presents a practice-oriented procedure in which the structure can be designed to ensure the safety under single or a pair of independent orthogonal ground motions traveling horizontally with an arbitrary direction to structural axis. This procedure uses nonlinear time history analysis and accounts for the effect of directionality in the form of fragility curves. The word directionality used here is different from ââ?¬Å?directivityââ?¬Â used in seismology to mean a specific characteristic of seismic fault movement....
The objective of this study was to determine the effects of finishes applied to polyester fibers on the properties of asphalt binders and mastics. Asphalt binders were mixed with finishes that were extracted from the fibers, and mastics were also made with binder and fibers (with and without finish) to isolate the effects of the finish. The results indicated that crude source plays a significant role in how the fiber finish affects the binders and mastics. Additionally different finishes had different effects on binder properties. The major finding of this study is that different polyester fibers, even from the same manufacturer, may not necessarily perform the same in an asphalt mixture. It is important to use fibers that are compatible with the particular asphalt binder that is being used because of the significance of the binder source on the interaction between the finish and the binder....
Some recent advances of a recently developed structural health assessment procedure proposed by the research team at the University of Arizona, commonly known as generalized iterative least-squares extended Kalman filter with unknown input (GILS-EKF-UI) are presented. The procedure is a finite elements-based time-domain system-identification technique. It can assess structural health at the element level using only limited number of noise-contaminated responses. With the help of examples, it is demonstrated that the structure can be excited by multiple loadings simultaneously. The method can identify defects in various stages of degradation in single or multiple members and also relatively less severe defect. The defective element(s) need not be in the substructure, but the defect detection capability increases if the defect spot is close to the substructure. Two alternatives are suggested to locate defect spot more accurately within a defective element. The paper advances several areas of GILS-EKF-UI to assess health of large structural systems....
The goal of sustainable construction is to reduce the environmental impact of a constructed facility over its lifetime. Concrete is the main material used in construction in the Gulf Cooperation Council (GCC). Therefore, it makes economic and environmental sense to use recycled materials in the making of new concrete for different applications. The objectives of this study are to summarize published research on the use of recycled concrete aggregates in new concrete mixes and examine its implementation in construction and industry in the GCC region. The study showed that while there is reasonable research on recycled concrete, the practical implementation in the region greatly lacks behind, especially due to the lack of economic viability and awareness of such applications at the current time....
A plane, turbulent, nonbuoyant, vertical jet in shallow water is simulated numerically using a three-dimensional computation model employing standard k-e and renormalized group k-e turbulent closure schemes. Existing data of mean and turbulent flow quantities, measured using laser Doppler velocimeter, are used to assess the two turbulent closure schemes. Comparisons between the measured and simulated flow field data are made in the free jet region, within the zone of surface impingement, and in the zone of horizontal jets at the surface. The results show that the standard k-e scheme performs equally well and in some areas better than the more complicated renormalized group k-e scheme in simulating the mean and turbulent flow quantities in this case....
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