Fuzzy Logic Controller for grid connected Wind Energy Conversion System

The use of renewable power sources, like wind power, has been increased recently due to climatic changes caused by fossil fuels and fast depletion of fossil fuels. This has lead to the tremendous increase in the interconnection of wind turbines to power system grid. This interconnection on a large number in to grid causes problems such as power quality, maintaining system voltage, reactive power compensation, control of grid frequency and aspects of power system grid stability. In this proposed scheme, a fuzzy logic based controller is employed for a STATCOM to improve the power quality. The proposed control scheme supplies the required reactive power to the system and thus relieves the source, leading to Unity Power Factor (UPF) at the source and also it injects currents to reduce total harmonic distortion (THD) to satisfy IEC standard. For extracting the reference currents, an instantaneous reactive power theory based control algorithm is employed. To determine the effectiveness of the proposed fuzzy logic controller, a comparative analysis is also performed with a PI controller and the results have been presented

Partial Characterization of α-Amylase from Germinating Little Millets (Panicum sumatrense)

α-Amylase, a starch splitting enzyme, was purified to homogeneity from little millet (Panicum sumatrense L. Roth ex Roem. et Schult.) cotyledons excised from 3-day-old seedlings by successive chromatography on DEAE-cellulose and Sephadex G-150. Purification achieved was 10.15 fold from the crude extract with a yield of 29% giving a final specific activity of 1001U/mg protein. SDS-PAGE showed a molecular weight of 46 kDa for the enzyme. The enzyme was characterized in terms of pH optimum and stability, temperature optimum and stability, activation energy, Km and Vmax. The enzyme displayed optimum activity at pH 5.0 and 50°C with an apparent Km value of 1.6 mg for soluble starch as substrate and Vmax 1388 units/ min/mg protein. The energy of activation (Ea) for the enzyme-catalyzed reaction was 9.7 kcal./mole. Significant enhancement in the enzyme activity was observed in the presence of metal ions like Ca2+ and Ba2+ while metal ions such as Fe2+, Hg2+ and  Al3+ completely inactivated the enzyme. Incubation of the enzyme with 10mM EDTA for 30 min at 45°C results in complete loss of activity. Key words: α-Amylase, Little millet, Characterization, Panicum sumatrense Usha B et al. Partial Characterization of α-Amylase from Germinating Little Millets (Panicum sumatrense). J Phytol 3/1 (2011) 01-08

Alterations in Serum SOD and CAT Levels in Patients with Breast Cancer

Breast cancers are potentially life-threatening malignancies in women. Development of cancer produces oxidative stress, which increases with disease progression. Hence, studies on antioxidants may be the most promising area of research for this clinical menace. We analysed serum superoxide dismutase (SOD), catalase (CAT) in women with breast cancer. The changes in the levels of serum superoxide dismutase and catalase are measured in breast cancer patients to assess the oxidative stress. A significant increase in the level of superoxide dismutase and a lower catalase activity was observed in all the three categories of breast cancer patients compared to normal individuals. The results suggested that high ROS production supports the oxidative stress in breast cancer. So, the treatment with antioxidants in the initial stages of the disease may be useful as secondary therapy

Clinical Evaluation of Oxidative Stress in Women with Breast Cancer

Breast cancers are potentially life-threatening malignancies in women. Development of cancer produces oxidative stress, which increases with disease progression. Hence, studies on antioxidants may be the most promising area of research for this clinical menace. We analysed serum Uric acid (UA) and Bilirubin (BR) in women with breast cancer. The changes in the levels of serum uric acid and bilirubin are measured in breast cancer patients to assess the oxidative stress. A significant increase in the levels of uric acid and an insignificant increase in the levels of bilirubin was observed in all the three categories of breast cancer patients compared to normal individuals. The results suggested that high ROS production supports the oxidative stress in breast cancer. So, the treatment with antioxidants in the initial stages of the disease may be useful as secondary therapy

Role of coupling delay in oscillatory activity in autonomous networks of excitable neurons with dissipation

We study numerically the effects of time delay in networks of delay-coupled excitable FitzHugh Nagumo systems with dissipation. The generation of periodic self-sustained oscillations and its threshold are analyzed depending on the dissipation of a single neuron, the delay time, and random initial conditions. The peculiarities of spatiotemporal dynamics of time-delayed bidirectional ring-structured FitzHugh-Nagumo neuronal systems are investigated in cases of local and nonlocal coupling topology between the nodes, and a first-order nonequilibrium phase transition to synchrony is established. It is shown that the emergence of oscillatory activity in delay-coupled FitzHugh-Nagumo neurons is observed for smaller values of the coupling strength as the dissipation parameter decreases. This can provide the possibility of controlling the spatiotemporal behavior of the considered neuronal networks. The observed effects are quantified by plotting distributions of the maximal Lyapunov exponent and the global order parameter in terms of delay and coupling strength.Comment: 14 pages, 17 figure