Fault-tolerant switched reluctance motor drive using adaptive fuzzy logic controller

An adaptive fuzzy controller has been designed to develop a high-performance fault-tolerant switched reluctance motor (SRM) drive. The fuzzy controller continuously adapts its properties to regulate the machine torque as desired by the drive system even under fault conditions. The adaptation of the fuzzy membership functions results in extended conduction period and increased peak current of the healthy phases to deliver the commanded torque, as much as possible. The adaptive fuzzy controller provides smooth torque output with minimum ripple, even under fault conditions, yielding a high-performance SRM drive with fault-tolerant capability.     

Overexpression, purification and characterization of Dictyostelium calcineurin A

We examined the mechanical properties of bone in ovariectomized rats treated with tiludronate. 186 Sprague-Dawley (SD) rats, 6 months of age, were assigned to 13 groups and were maintained for 3-9 months after surgery. Ovariectomy (ovx) groups were given tiludronate orally at the respective doses of 0 (vehicle), 12.5 (low), 25 (medium), and 50 (high) mg/kg body weight daily for 3 months beginning 3 months after surgery. Rats were killed at 0 (start), 3, 6, and 9 months. Whereas bone mineral density (BMD) values of the midfemur did not increase after ovx, the values in the sham-operated groups increased age-dependently. Bending moment to failure of the femur in the sham group was larger than that of the ovx control group at 9 months. In the ovx control groups, the ultimate compressive load values of the third lumbar body were reduced compared with those in the sham groups at 3 months and thereafter. Although serum osteocalcin levels were decreased in the medium- and high-dose tiludronate groups, both serum PTH and 1,25(OH)2D levels were increased only in the high-dose group. Femoral BMD, mechanical properties, and the cortical bone area were increased by the high dose at 9 months. Lumbar ultimate compressive load and the circumscribing cortical shell area in the high-dose group were increased at 6 months and thereafter. The trabecular number values were maintained at 6 and 9 months by the high dose. These data demonstrate that tiludronate administration increased the mechanical properties of bone by preserving the age-dependent increases in the cortical bone mass and three-dimensional structure of trabecular bone. These effects seemed to be due to reduced bone turnover by the agent.     

Tuning the stator resistance of induction motors using artificialneural network

Tuning the stator resistance of induction motors is very important, especially when it is used to implement direct torque control (DTC) in which the stator resistance is a main parameter. In this paper, an artificial network (ANN) is used to accomplish tuning of the stator resistance of an induction motor. The parallel recursive prediction error and backpropagation training algorithms were used in training the neural network for the simulation and experimental results, respectively. The neural network used to tune the stator resistance was trained on-line, making the DTC strategy more robust and accurate. Simulation results are presented for three different neural-network configurations showing the efficiency of the tuning process. Experimental results were obtained for one of the three neural-network configurations. Both simulation and experimental results showed that the ANN have tuned the stator resistance in the controller to track actual resistance of the machine     

Weibull parameters for wind speed distribution in Saudi Arabia

The shape and scale parameters of a Weibull density distribution function are calculated for 10 locations in Saudi Arabia. The daily mean wind speed data from 1970 to mid-1990 are used for this purpose. It is found that the numerical values of the shape parameter vary between 1.7 and 2.7, whereas the value of the scale parameter is found to vary between 3 and 6. It is also concluded from this study that wind data are very well represented by the Weibull distribution function.     

Acute toxicity of synthetic Gymnodinium breve toxin metabolite and its analogues in mice

Accidental and operative trauma are able to induce a systemic reaction of the organism characterized by fever, leukocytosis, catabolism, and an activation of the coagulation system. Interleukin-6 (IL-6) has been found to be an important mediator of this acute-phase response. In this study the influence of elective craniotomy on IL-6 plasma levels was evaluated. Blood samples were obtained from 20 patients undergoing elective craniotomy for vascular or tumorous diseases of the brain. IL-6 increased significantly (p < 0.05) from the pre-operative (0(0-5.4) pg/ml) to the intraoperative (180 min after beginning of surgery) time-point (10.6 (0-18.5) pg/ml). The maximum was reached on the first postoperative morning (13.9(4.3-45.0) pg/ml). Interleukin-10 (IL-10) is an anti-inflammatory cytokine which suppresses IL-6 synthesis in vitro in various cell lines. IL-10 plasma concentrations showed no alterations throughout the study period. Epinephrine plasma concentrations increased significantly from pre-operative values (15 (0-74) pg/ml) to the postoperative time-point (57(9-459) pg/ml). A 4.5-fold increase (p < 0.05) of norepinephrine plasma concentrations was found when comparing the data obtained 60 min after beginning of surgery with the data of the first postoperative morning. In monocytes, which are a major source of plasma IL-6, an elevation of intracellular cAMP stimulates the IL-6 synthesis. The postoperative maximum of IL-6 in plasma could be due to a release of catecholamines. In conclusion this study demonstrated an elevation of IL-6 plasma concentrations during and after elective craniotomy. Increased plasma catecholamine concentrations as well as a damage in the blood-brain barrier due to the surgical trauma with a spill-over of IL-6 from brain tissue into plasma could have contributed to this result.     

Nutritional issues and therapy in inflammatory bowel disease

The molecular motions of D-alpha-galacturonic acid monohydrate (GA) and its derivative methyl-alpha-D-galacturonic acid methyl ester monohydrate (MGAM) in the solid state have been studied using 1H NMR. Both protonated and deuterium exchanged samples have been used. Spin-lattice relaxation times in the laboratory and rotating frames as well as second moments have been measured over the temperature range 90-370 K. Analysis of results has shown that in GA spin-lattice relaxation is chiefly by hydroxyl groups and water of crystallization. In MGAM, methyl groups dominate spin-lattice relaxation in the laboratory frame at the low temperature. Hydroxyl groups and water of crystallization contribute to the spin-lattice relaxation in the laboratory frame in the high temperature region. In the rotating frame motion of hydroxyl groups and water of crystallization provide the main relaxation pathway. Changes in the static second moment with temperature can be reasonably well predicted using values of correlation time and motionally averaged second moments obtained by fitting the spin-lattice relaxation data. 13C CPMAS spectra for GA and MGAM are also described.     

Free vibration analysis of orthotropic plates by the initial value method

A modified method of the classical initial value technique is presented for the free vibration analysis of rectangular orthotropic plates. The method employs finite difference operators in one direction and uses integration in the other direction. The solutions are superimposed to satisfy the boundary conditions. A detailed discussion of the method is given. A comparative study is presented of the initial value method and other numerical methods. Three examples that show the accuracy of the method are presented.