Current Issue : April - June Volume : 2012 Issue Number : 2 Articles : 4 Articles
A unique direct driven permanent magnet synchronous generator has been designed and constructed. Results from simulations as\nwell as from the first experimental tests are presented. The generator has been specifically designed to be directly driven by a vertical\naxis wind turbine and has an unusually low reactance. Generators for wind turbines with full variable speed should maintain a\nhigh efficiency for the whole operational regime. Furthermore, for this application, requirements are placed on high generator\ntorque capability for the whole operational regime. These issues are elaborated in the paper and studied through simulations.\nIt is shown that the generator fulfils the expectations. An electrical control can effectively substitute a mechanical pitch control.\nFurthermore, results from measurements of magnetic flux density in the airgap and no load voltage coincide with simulations.\nThe electromagnetic simulations of the generator are performed by using an electromagnetic model solved in a finite element\nenvironment....
Power reduction in CMOS platforms is essential for any application technology.\nThis is a direct result of both lateral scalingââ?¬â?smaller features at higher density, and\nvertical scalingââ?¬â?shallower junctions and thinner layers. For achieving this power\nreduction, solutions based on process-device and process-integration improvements, on\ncareful layout modification as well as on circuit design are in use. However, the drawbacks\nof these solutions, in terms of greater manufacturing complexity (and higher cost) and\nspeed degradation, call for ââ?¬Å?optimizedââ?¬Â solutions. This paper reviews the issues associated\nwith transistor scaling and related solutions for leakage and power reduction in terms of\ntopological design rules and layout optimization for digital and analog transistors. For\nstandard cells and SRAMs cells, leakage aware layout optimization techniques considering\ntransistor configuration, stressors, line-edge-roughness and more are presented. Finally,\ndifferent techniques for leakage and power reduction at the circuit level are discussed....
While Moore�s law scaling continues to double transistor density every\r\ntechnology generation, new design challenges are introduced. One of these challenges is\r\nvariation, resulting in deviations in the behavior of transistors, most importantly in switching\r\ndelays. These exaggerated delays widen the gap between the average and the worst case\r\nbehavior of a circuit. Conventionally, circuits are designed to accommodate the worst case\r\ndelay and are therefore becoming very limited in their performance advantages. Thus,\r\nallowing for an average case oriented design is a promising solution, maintaining the pace of\r\nperformance improvement over future generations. However, to maintain correctness, such\r\nan approach will require on the fly mechanisms to prevent, detect, and resolve violations.\r\nThis paper explores such mechanisms, allowing the improvement of circuit performance\r\nunder intensifying variations. We present speculative error detection techniques along with\r\nrecovery mechanisms. We continue by discussing their ability to operate under extreme\r\nvariations including sub-threshold operation. While the main focus of this survey is on circuit approaches, for its completeness, we discuss higher-level, architectural and algorithmic\r\ntechniques as well....
Transcutaneous energy transmission (TET) is the most promising noninvasive method for supplying driving energy to a\r\ntotally implantable artificial heart. Induction-heating (IH) cookers generate a magnetic flux, and if a cooker is operated near\r\na transcutaneous transformer, the magnetic flux generated will link with its external and internal coils. This will affect the\r\nperformance of the TET and the artificial heart system. In this paper, we present the design and development of a coil to be\r\nused for a magnetic immunity test, and we detail the investigation of the magnetic immunity of a transcutaneous transformer.\r\nThe experimental coil, with five turns like a solenoid, was able to generate a uniform magnetic field in the necessary bandwidth.\r\nA magnetic-field immunity examination of the TET system was performed using this coil, and the system was confirmed to have\r\nsufficient immunity to the magnetic field generated as a result of the conventional operation of induction-heating cooker....
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