Advanced research of the impact of rotor bars anisotropic conductivity on starting torque of an induction motor with a die-cast copper cage

The paper deals with an optimal design of an induction motor with a die-cast copper cage rotor characterized by an anisotropic layer in the upper part of the rotor bars. 1D FEM optimization of an explosion-proof induction motor with a die-cast copper rotor with overall parameters of a commercial induction motor with a die-cast aluminum rotor (180 kW, 1140 V, 1500 rpm) is made with the help of numeric computations. In the paper, the design features and experimental results are given. It is shown that induction motors with a special "starting" layer placed in the upper part the diecast copper rotor bar have maximum value of starting torque for relative conductivity factors ranging from 0.3 to 0.5. The basic performance data obtained in both bench and service tests of a prototype 210kW induction motor are in close agreement with analytical data.Изложены результаты исследований влияния анизотропии проводимости стержней ротора на пусковой момент асинхронного двигателя, стендовых и эксплуатационных испытаний взрывозащищенного двигателя типа 2ЭКВ3,5-210 мощностью 210 кВт с литой анизотропной медной обмоткой ротора

Effect of Contour Shape of Nervous System Electromagnetic Stimulation Coils on the Induced Electrical Field Distribution

BACKGROUND: Electromagnetic stimulation of the nervous system has the advantage of reduced discomfort in activating nerves. For brain structures stimulation, it has become a clinically accepted modality. Coil designs usually consider factors such as optimization of induced power, focussing, field shape etc. In this study we are attempting to find the effect of the coil contour shape on the electrical field distribution for magnetic stimulation. METHOD AND RESULTS: We use the maximum of the induced electric field stimulation in the region of interest as the optimization criterion. This choice required the application of the calculus of variation, with the contour perimeter taken as a pre-set condition. Four types of coils are studied and compared: circular, square, triangular and an 'optimally' shaped contour. The latter yields higher values of the induced electrical field in depths up to about 30 mm, but for depths around 100 mm, the circular shape has a slight advantage. The validity of the model results was checked by experimental measurements in a tank with saline solution, where differences of about 12% were found. In view the accuracy limitations of the computational and measurement methods used, such differences are considered acceptable. CONCLUSION: We applied an optimization approach, using the calculus of variation, which allows to obtain a coil contour shape corresponding to a selected criterion. In this case, the optimal contour showed higher intensities for a longer line along the depth-axis. The method allows modifying the induced field structure and focussing the field to a selected zone or line

Variable Mode Control Systems for a Tethered Aircraft With Ducted Wind Energy Generators

As the world\u27s needs for cleaner, carbon-free energy sources grows, it is inevitable that we look to wind power as a viable solution to humanity\u27s demand for electricity. Implementing some of the best features developed and tested by the pioneers of high-altitude wind power research, we introduce a new concept of a tethered wind energy conversion system, called Hawkeye, that is able to harvest the extreme power of jet stream wind. Hawkeye is an aircraft that operates in a nearly static configuration during high-speed wind at high altitudes. In this paper, we analyze the motion of the Hawkeye aircraft and present an innovative, sliding mode control algorithm that enables Hawkeye to operate in an optimal way

Rhabdomyolisys as a Cause of Acute Renal Injury

Rhabdomyolysis (RM) is defined as striate muscle-cell damage with disintegration of skeletal muscles and release of intracellular constituents to the circulation, with or without subsequent kidney injury. RM is one of the leading causes of acute kidney injury and is associated with substantial morbidity. The major signs of acute kidney injury in rhabdomyolysis are: pain, weakness and swelling of the injured muscle or muscle groups and myoglobinuria with reddish discoloration of the urine and decrease in urine output to anuria. The authors describe three cases of rhabdomyolysis with acute renal injury and discuss the current knowledge on the etiopathogenesis, clinical manifestations, diagnosis and treatment of this condition