Wavelet Bootstrap Multiple Linear Regression Based Hybrid Modeling for Daily River Discharge Forecasting

A new hybrid model, the wavelet–bootstrap–multiple linear regression (WBMLR) is proposed to explore the potential of wavelet analysis and bootstrap resampling techniques for daily discharge forecasting. The performance of the developed WBMLR model is also compared with five more models: multiple linear regression (MLR), artificial neural network (ANN), wavelet-based MLR (WMLR), wavelet-based ANN (WANN) and wavelet–bootstrap–ANN (WBANN) models. Seven years of discharge data from seven gauging stations in the middle reaches of Mahanadi river basin in India are applied in this study. Significant input vectors are decomposed into discrete wavelet components (DWCs) using discrete wavelet transformation (DWT) to generate wavelet sub time series that are used as inputs to the MLR and ANN models to develop the WMLR and WANN models, respectively. Effective wavelets are selected by considering several types of wavelets with different vanishing moments. WBMLR and WBANN models are developed as ensemble of different WMLR and WANN models, respectively, developed using different realizations of the training dataset generated using bootstrap resampling technique. The results show that the wavelet bootstrap hybrid models (i.e. WBMLR and WBANN) produce significantly better results than the traditional MLR and ANN models. Hybrid models based on MLR (WMLR, WBMLR) perform better than the ANN based hybrid models (WBANN, WANN). The WBMLR and WMLR models simulate the peak discharges better than the WBANN, WANN, MLR and ANN models, whereas the overall performance of WBMLR model is found to be more accurate and reliable than the remaining five models.     

An efficient BEM formulation for three-dimensional steady-state heat conduction analysis of composites

In this work, an efficient boundary element formulation has been presented for three-dimensional steady-state heat conduction analysis of fiber reinforced composites. The cylindrical shaped fibers in the three-dimensional composite matrix are represented by a system of curvilinear line elements with a prescribed diameter which facilitates efficient analysis and modeling together with the reduction in dimensionality of the problem. The variations in the temperature and flux fields in the circumferential direction of the fiber are represented in terms of a trigonometric shape function together with a linear or quadratic variation in the longitudinal direction. The resulting integrals are then treated semi-analytically which reduces the computational task significantly. The computational effort is further minimized by analytically substituting the fiber equations into the boundary integral equation of the material matrix with hole, resulting in a modified boundary integral equation of the composite matrix. An efficient assembly process of the resulting system equations is demonstrated together with several numerical examples to validate the proposed formulation. An example of application is also included.     

Biological applications of diamond electrodes; electrochemical studies of riboflavin

The electrochemical study of flavines is a challenge using many solid-state electrode materials, since pronounced adsorption effects are observed which have deleterious effects on the recorded observations. In the present work three distinctive types of diamond electrode are employed to measure electrochemical charge transfer to riboflavin. At nanodiamond, it is found that rapid charge-transfer kinetics are observed, between the electrode and an adsorbed layer of around 2 monolayers thickness which rapidly forms at the electrode surface. In contrast, high phase purity microcrystalline diamond electrodes, show little adsorption, enabling solution phase diffusion controlled electrochemistry to be observed. Studies of the pH dependence of the observed electrochemistry are presented, which show results comparable to those observed at dropping mercury electrodes, and electrochemical measurements in the presence of power ultrasound are also described.     

Effects of chronic vanadium pentoxide administration on L-ascorbic acid metabolism in rats: influence of L-ascorbic acid supplementation

1. Rats toxicated with vanadium pentoxide showed drastic retardation in growth rate and supplementation of L-ascorbic acid to these rats could not reverse this effect. The urinary excretion of L-ascorbic acid and D-glucuronic acid was decreased in the toxicated group of rats. 2. Considerable lowering of L-ascorbic acid content of the liver tissues of rats was observed under vanadium toxicated conditions. Supplementation of L-ascorbic acid to this group raised the tissue Vitamin C reserve considerably. 3. The normal histological patterns of the liver and kidney tissues of rats were severely disturbed under vanadium toxicated conditions. L-ascorbic acid supplementation to this group of rats showed marked signs of restoration in this respect. 4. Vanadium pentoxide treatment brought about a significant reduction in the biosynthetic capacity of L-ascorbic acid, along with an enhanced utilization of this vitamin. Subsequent supplementation of L-ascorbic acid to the toxicated group of rats was found to be effective in reversing these effects almost to the basal level.