Evidence of crossover phenomena in wind speed data

In this report, a systematic analysis of hourly wind speed data obtained from three potential wind generation sites (in North Dakota) is analyzed. The power spectra of the data exhibited a power-law decay characteristic of $1/f^{\alpha}$ processes with possible long-range correlations. Conventional analysis using Hurst exponent estimators proved to be inconclusive. Subsequent analysis using detrended fluctuation analysis (DFA) revealed a crossover in the scaling exponent ($\alpha$). At short time scales, a scaling exponent of $\alpha \sim 1.4$ indicated that the data resembled Brownian noise, whereas for larger time scales the data exhibited long range correlations ($\alpha \sim 0.7$). The scaling exponents obtained were similar across the three locations. Our findings suggest the possibility of multiple scaling exponents characteristic of multifractal signals

A Multifractal Description of Wind Speed Records

In this paper, a systematic analysis of hourly wind speed data obtained from four potential wind generation sites in North Dakota is conducted. The power spectra of the data exhibited a power law decay characteristic of $1/f^{\alpha}$ processes with possible long range correlations. The temporal scaling properties of the records were studied using multifractal detrended fluctuation analysis {\em MFDFA}. It is seen that the records at all four locations exhibit similar scaling behavior which is also reflected in the multifractal spectrum determined under the assumption of a binomial multiplicative cascade model

Separation of Scandium and Calcium by Liquid-Liquid Extraction using Tri-N-Butyl Phosphate as Solvent

Equilibrium data have been obtained for the systems Ca(N03)2- HNO3- TBP- H20 and Sc(N03)3- Ca(N03)2- HNO3- TBP- H20 over a wide range of concentration of the metal nitrates in the aqueous solution. Equilibrium acid concentration was used as a parameter for the equilibrium curves. For the system Sc(N03)3- Ca(NO3)2- HNO3- TBP- H20 the distribution coefficients of scandium and calcium decreased with increasing acidity of the aqueous phase. The distribution coefficient of scandium was largely dependent on the calcium concentration in the aqueous phase rather than the scandium concentration as a result of the salting-out effect of calcium nitrate. The separation factor of scandium with respect to calcium was in the range 11 - 295 depending on the total metal nitrate concentration in the aqueous phase and the acidity of the aqueous phase. It was also observed that the separation factor was not a function of the ratio of scandium to calcium in the aqueous phase. The solvent TBP was found to be highly selective for scandium than for calcium

Minimizing the effect of sinusoidal trends in detrended fluctuation analysis

The detrended fluctuation analysis (DFA) [Peng et al., 1994] and its extensions (MF-DFA) [Kantelhardt et al., 2002] have been used extensively to determine possible long-range correlations in self-affine signals. While the DFA has been claimed to be a superior technique, recent reports have indicated its susceptibility to trends in the data. In this report, a smoothing filter is proposed to minimize the effect of sinusoidal trends and distortion in the log-log plots obtained by DFA and MF-DFA techniques

Trends and Challenges in Electric Vehicle Motor Drivelines - A Review

Considering the need to optimize electric vehicle performance and the impact of efficient driveline configurations in achieving this, a brief study has been conducted. The drivelines of electric vehicles (EV) are critically examined in this survey. Also, promising motor topologies for usage in electric vehicles are presented. Additionally, the benefits and drawbacks of each kind of electric motor are examined from a system viewpoint. The majority of commercially available EV are powered by a permanent magnet motor or single induction type motors and a standard mechanical differential driveline. Considering these, a holistic review has been performed by including driveline configurations and different battery types. The authors suggest that motors be evaluated and contrasted using a standardized driving cycle

HYPOLIPIDEMIC POTENTIAL OF METHANOLIC EXTRACT OF GRACILARIA CORTICATA ON STREPTOZOTOCIN-INDUCED DIABETIC RATS

ABSTRACTObjectives: Diabetes mellitus is associated with profound alterations in the levels of plasma lipids and the lipoprotein profile. Herbs and herbal drugpreparations find wide use in alleviating the complications of uncontrolled diabetes owing to their low cost and lesser side effects. This study wasaimed at establishing the hypolipidemic effect of methanolic extract of sea weed Gracilaria corticata on streptozotocin (STZ)-induced diabetic rats.Methods: STZ-induced Wistar male albino rats were administered with methanolic extract of Gracilaria corticata (MGC) at a dosage of 100 mg/kgBW/day per orally for 45 days. Glibenclamide (600 μg/kg BW/day) administered rats served as standard drug control. Animals were sacrificed on46th day, biochemical parameters associated with lipid metabolism were analyzed in blood and tissue samples, statistical significance determined.Results: Elevated levels of total cholesterol, triglycerides, and free fatty acids were observed in the plasma and tissues of diabetic rats as compared toMGC and glibenclamide treated groups. The diabetic rats also had elevated levels of low-density lipoprotein (LDL-C) and very low-density lipoprotein(VLDL-C) and decreased levels of high-density lipoprotein (HDL-C) while the MGC and glibenclamide treated rats showed near normal levels of theseindices.Conclusion: This study establishes the hypolipidemic potential of MGC in STZ-induced diabetic rats.Keywords: Gracilaria corticata, Diabetes mellitus, Hypolipidemic, Streptozotocin

Multifractal fluctuations in the survival probability of an open quantum system

We predict a multifractal behaviour of transport in the deep quantum regime for the opened $\delta-$kicked rotor model. Our analysis focuses on intermediate and large scale correlations in the transport signal and generalizes previously found parametric {\em mono}-fractal fluctuations in the quantum survival probability on small scales.Comment: 8 pages, 3 figures, 2 tables. Physica A, accepted 200

Minimizing the effect of trends on detrended fluctuation analysis of long-range correlated noise

Detrended fluctuation analysis (DFA) has been proposed as a robust technique to determine possible long-range correlations in power-law processes [1]. However, recent studies have reported the susceptibility of DFA to trends [2] which give rise to spurious crossovers and prevent reliable estimation of the scaling exponents. Inspired by these reports, we propose a technique based on singular value-decomposition (SVD) of the trajectory matrix to minimize the effect of linear, power-law, periodic and also quasi-periodic trends superimposed on long-range correlated power-law noise. The effectiveness of the technique is demonstrated on publicly available data sets [2].Comment: 15 pages, 13 Figure