A study of rotor configuration for IPMSM with concentrated winding considering the iron loss

This paper reports an IPMSM rotor configuration with a concentrated‐winding stator. The inductance of the concentrated winding is greater than that of the distributed winding and the flux density of the concentrated winding contains higher harmonic components. The result is higher winding losses than in the IPMSM with a distributed‐winding stator. We discuss three types of interior magnetic rotor with different saliency ratios. In the lower speed range, the highest‐saliency rotor is effective in decreasing the load current and copper losses. On the other hand, in the higher speed range, the higher‐saliency rotors result in greater iron losses and lower motor efficiency; in this range, the lower‐saliency rotor is effective in decreasing iron losses and increasing motor efficiency. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(4): 71–78, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10005     

Optical limitations to cell size reduction in IT-CCD image sensors

We have determined the practical limits of cell size reduction in interline-transfer charge-coupled device (IT-CCD) image sensors, which result from diffraction occurring at the aperture above the photodiode. We have found that image cell size cannot be reduced to a level for which aperture width would fall below about 0.2 μm. We have also found, however that image cells with greater than 0.2 μm aperture size are sensitive over the entire wavelength range of visible light, and that sensitivity can be increased by thinning the photoshield film     

Adaptive maximum-likelihood sequence estimation by means ofcombined equalization and decoding in fading environments

This paper proposes an adaptive maximum-likelihood sequence estimation (MLSE) by means of combined equalization and decoding, i.e., adaptive combined MLSE, which employs separate channel estimation for respective states in the Viterbi algorithm. First, an approximate metric including channel estimation is derived analytically for this proposed adaptive combined MLSE. Secondly, procedures to accomplish blind equalization are investigated for the proposed MLSE. Finally, its excellent BER performance on fast time-varying fading channels is confirmed by computer simulation, when the proposed MLSE operates as a blind equalizer     

An overvoltage self-protected thyristor with a structure to predictbreakover voltage

A new concept for an overvoltage self-protected thyristor was theoretically analyzed and the thyristor manufactured. Its breakover operation is basically a combination of punchthrough and avalanche phenomena. Temperature dependence of the original structure in this thyristor is 5% from 20 to 125°C. A second device which has a function to predict breakover voltage was also produced. The difference in temperature dependence of breakover voltage for both devices was investigated by an analytical model. Structures offering improved characteristics were proposed. The breakover voltage decrease of the developed structures at high temperature could be made equal to that of the original structure by a slight modification of the breakover region     

Cerebellar infarction with hydrocephalus caused by spontaneous extracranial vertebral artery dissection--case report

A 38-year-old male suffered sudden onset of rotational vertigo without headache. Consciousness disturbance developed on the 3rd day after the onset. Computed tomography showed cerebellar infarction with obstructive hydrocephalus. External ventricular drainage was performed. Angiography showed bilateral extracranial vertebral artery dissection. Antiplatelet therapy was given. Repeat angiography showed improvement of the dissection. His neurological deficits completely resolved. Vertebral artery dissections may cause both lateral medullary or cerebellar infarction and hydrocephalus due to the cerebellar infarction manifesting as various symptoms so careful evaluation and treatment are required.     

Blood flow patterns in the rat pancreas: a simulative demonstration by injection replication and scanning electron microscopy

Scanning electron microscopy of vascular casts prepared by arterial injections of intentionally reduced amounts of resin showed that in the rat pancreas, the casting medium fills blood capillaries in the endocrine islets more promptly than those in the exocrine lobules and secretory ducts. Furthermore, the exocrine lobules containing endocrine islets allowed a more rapid resin flow through the insulo-acinar portal route than those lobules lacking an islet. The capillaries of secretory ducts were the last portions to be filled with resin. Since the resin used in this study was as viscous as blood and injected under a physiological pressure, the microcirculatory patterns demonstrated by the present method reflect the physiological flow pattern of blood in the pancreas.     

Intramembrane structure of the sensory axon terminals in bullfrog muscle spindles

Much physiologic and morphologic research has been done into the sensory mechanism of the frog muscle spindle. However, no freeze-fracture study has described in detail the shape and intramembrane structure of the nonmyelinated sensory axon terminals of the frog muscle spindle. In this study, muscle spindles were isolated from the red part of bullfrog semitendinous muscles. Chemically fixed spindles were subjected to freeze fracturing. The sensory axon endings were reconstructed, and the size and density of intramembrane particles (IMPs) were measured along the sensory nerve endings. The axon terminals had four distinctive parts: parent trunks (>0.5 microm in diameter), primary branches (0.15-0.5 microm), terminal branches (<0.1 pm), and varicosities (0.02-0.5 microm). IMPs ranged from 5 nm to 21 nm in diameter and were present in the intramembrane space of the plasma membrane all throughout the nonmyelinated sensory nerve endings. Mean IMP sizes in the protoplasmic face (PF) and the external face (EF), respectively, were 8.1 nm and 8.4 nm in the parent trunks, 8.8 nm and 8.8 nm in the primary branches, 9.4 nm and 9.0 nm in the varicosities, and 8.7 nm and 8.7 nm in the terminal branches. Mean IMP size in the PF was smallest in the parent trunk and largest in the varicosity. Mean IMP densities (numbers of IMPs per microm2) in the PF and the EF, respectively, were 2,500 and 700 in the parent trunks, 2,200 and 500 in the primary branches, 1,700 and 400 in the varicosities, and 1,000 and 300 in the terminal branches. Density decreased with the tapering of the axon terminal, with IMPs distributed evenly in the PF and the EF. The characteristic intramembrane structure of sensory nerve endings is discussed.     

a-Si:H position-sensitive detector with striped metal electrodes

A novel dual-axis tetralateral position-sensitive detector (PSD) has been fabricated with a hydrogenated amorphous silicon (a-Si:H) p-i-n structure. The a-Si:H film for a photocurrent generator is formed by a plasma-enhanced chemical vapour deposition (PECVD) method. The PSD has striped metal electrodes formed by a chromium resistive layer on its photosensitive surface. It is confirmed from the experimental data that the PSD has very good linearity with the detected positions for both axes and that it can determine the positions of two or more incident light spots simultaneously if they illuminate different electrode stripes.