Contribution to Power Maximization of an Asynchronous Wind Electric Water Pumping System Using Single Input Fuzzy Logic Controller & Modified Enhanced Perturb and Observe

This paper investigates the efficiency of an original approach for Maximum Power Point Tracking (MPPT) algorithm applied to a Wind Electric Water Pumping System (WEWPS). The studied model is developed under Matlab/Sim-ulink software and consists of an asynchronous wind turbine, a Static Var Com-pensator (SVC) and a centrifugal water pump driven by a three phase Induction Motor (IM). The proposed control technique seeks to improve water flow rate by exploring the maximum amount of electrical power produced by the asynchro-nous wind turbine in a wide range of wind speed. Theoretical analysis as well as simulation results have shown that the highest electrical power rate depends on the value of the produced voltage which can be controlled by the SVC using single input fuzzy logic regulator. Modified Enhanced Perturb and Observe (MEPO) algorithm is then used in this application to calculate the optimal value of the voltage reference that ensure maximum electric power extraction and hence maximal water flow rate. Moreover, a comparison have been made with the conventional P&O algorithm to prove the superior performance of the proposed approach which does neither require to measure wind speed nor to know the WEWPS parameters

Vitamin D and skeletal health in infancy and childhood

During growth, severe vitamin D deficiency in childhood can result in symptomatic hypocalcaemia and rickets. Despite the suggestion from some studies of a secular increase in the incidence of rickets, this observation may be driven more by changes in population demographics than a true alteration to age, sex and ethnicity-specific incidence rates; indeed, rickets remains uncommon overall and is rarely seen in fair-skinned children. Additionally, the impact of less severe vitamin D deficiency and insufficiency has received much interest in recent years, and in this review, we consider the evidence relating vitamin D status to fracture risk and bone mineral density (BMD) in childhood and adolescence. We conclude that there is insufficient evidence to support the suggestion that low serum 25-hydroxyvitamin D [25(OH)D] increases childhood fracture risk. Overall, the relationship between 25(OH)D and BMD is inconsistent across studies and across skeletal sites within the same study; however, there is evidence to suggest that vitamin D supplementation in children with the lowest levels of 25(OH)D might improve BMD. High-quality randomised trials are now required to confirm this benefit.<br/