A compensation method for the end effect of a linear induction motor

For the end effect of a linear induction motor (LIM), the authors propose a new concept that the end effect can be compensated for only by the supply of secondary current synchronized with the current of the LIM in front of the entry end of the LIM, without considering the flux density distribution in the LIM primary region. As a concrete method to supply the secondary current in front of the LIM, the authors propose the rotator with rare‐earth‐type permanent magnets which has a strong flux density without ohmic loss, and does not cause the power factor problem even for the influence of end effect. The results of analytical study on the numerical example of LIM designed for subways are as follows. This method can make the flux density and thrust density distribution in the LIM primary region almost entirely agree with those of the case without end effects. This method can compensate for the thrust, power factor, and efficiency of the LIM at the rated speed to coincide with the characteristics without end effect. There is no problem in the slip characteristic curves of the LIM with the compensator, although the compensator only rotates synchronizing with the frequency of the LIM. The effect of compensation becomes large in the lower slip. The force to rotate the compensator is very small in the suitable design. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(3): 58–67, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10132     

Facial identification system based on a high‐speed matching algorithm for isodensity lines

In this paper, a high‐speed personal identification system which is adaptable for slant faces is presented. In the proposed method, the 25 facial images which are taken with different angles are registered in the database as reference images. The similarity of an input image is first examined between all registered images and the three facial images, which are similar to the input image, are then extracted as the candidate facial images. The isodensity map, which is expected to have the maximum similarity to the input image, is created by the interpolation between two candidate images and the input facial image is judged identical or not with the interpolated images. A template matching is adopted to obtain a similarity between two isodensity lines. In general, template matching requires a lot of time to obtain maximum similarity, while on the other hand it is very simple to use. To reduce the processing time for the matching efficiently, the techniques which are suited for the line pictures and the Sequential Similarity Detection Algorithm (SSDA) are adopted. Computer simulation using 50 people shows an accuracy of 95.2% correct discrimination. In addition, processing time is reduced to approximately 1/12. From the experimental results, the prospects of using this method are very encouraging. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(4): 31–41, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10147     

Fabrication of a spiral microcoil using a 3D-LIGA process

LIGA processes have been developed generally in the 2.5D world. We introduced techniques of 3D X-ray lithography and worm injection molding with a unscrewing release mechanism, and succeeded in the development to three dimensions of LIGA process. We called this technology 3D-LIGA process, and came to be able to fabricate the plastic molded product with a spiral microstructure. Furthermore, we succeeded in the trial production of a spiral microcoil using 3D-LIGA process and metallization technique combining flat and smooth electroplating with a leveling agent and an isotropic chemical etching. The diameter of this microcoil was 0.5 mm and the length was 1 mm. The width of the Cu coil line was 10 μm, and the pitch was 20 μm. Moreover, we measured characteristics of this microcoil as an inductor. The inductance and the quality factor at the frequency of 1 GHz were 91 nH and 5.8, respectively. This is the first time successful fabrication of an electric device with a 3D form like a spiral microcoil using the 3D-LIGA process has been achieved.     

Generation of triplet and cation-radical bacteriochlorophyll a in carotenoidless LH1 and LH2 antenna complexes from Rhodobacter sphaeroides

The LH1 antenna complex and a native form of the LH2 complex were isolated from the carotenoidless R26 and R26.1 mutants of Rhodobacter sphaeroides by the use of a new detergent, sucrose monocholate. One-color, pump-and-probe transient Raman spectroscopy of these complexes using 351 nm, approximately 50 ps pulses showed the generation of the triplet state of bacteriochlorophyll a (BChl a), whereas measurements using 355 nm, approximately 12 ns pulses showed the generation of BChl a cation radical. Subpicosecond to nanosecond time-resolved absorption spectroscopy using 388 nm, 200 fs pulses for excitation showed rapid (<1 ps) generation of the triplet state and fast decay (<10 ps) of the singlet state of BChl a. Microsecond absorption spectroscopy confirmed the generation of BChl a cation radical. EPR spectroscopy using 532 nm, approximately 5 ns pulses for excitation established the generation of BChl a cation radical. The EPR line width suggested that the unpaired electron is shared by two BChl a molecules. In LH1, the yield of BChl a cation radical per complex was estimated to be about 80% of that in the reaction center, and in LH2 about 50%. Thus, rapid generation of the triplet state, and its subsequent transformation into the cation-radical state of BChl a have been shown to be intrinsic properties of B870 and B850 BChl a assembly in the carotenoidless LH1 and LH2 antenna complexes. In the case of the carotenoid-containing LH2 complex, the triplet states of BChl a and carotenoid (spheroidene) were generated immediately after excitation, but the triplet-state BChl a was quenched efficiently by the carotenoid so that no BChl a cation radical was generated. Thus, the photoprotective function of the carotenoid in this antenna complex is shown.     

High-performance bismuth-telluride compounds with highly stable thermoelectric figure of merit

The p-type (Bi_0.25Sb_0.75)₂Te₃ ingot doped with 8 wt% excess Te alone and the n-type Bi₂ (Te_0.94Se_0.06)₃ ingot codoped with 0.068 wt% I and 0.017 wt% Te were grown by the Bridgman method and annealed at 673 K for 5 h in a hydrogen stream. The electrical resistivity ρ, Seebeck coefficient α and thermal conductivity κ before and after annealing were measured at 298 K, so that the annealing degraded significantly ZT of the p-type specimen but enhanced remarkably that of the n-type one. The temperature dependences of ρ, α and κ of the as-grown p-type and annealed n-type specimens with higher ZT were investigated in the temperature range from 200 to 360 K. As a result, ZT values of the as-grown p-type and annealed n-type specimens have a broad peak and reached great values of 1.19 and 1.13 at approximately 320 K, respectively. The present materials were thus found to be far superior to any other bismuth-telluride compound in the thermal stability of energy conversion efficiency in addition to the high performance.     

Effect of crystalline quality of diamond film to the propagation loss of surface acoustic wave devices

Diamond films with various crystal qualities were grown by chemical vapor deposition on silicon wafers. Their crystallinity was characterized by Raman scattering and electron backscattering diffraction. By fabricating a device structure for surface acoustic wave (SAW) using these diamond films, the propagation loss was measured at 1.8 GHz and compared with the crystallinity. It was found that the propagation loss was lowered in relatively degraded films having small crystallites, a narrow distribution in the diamond crystallite size, and preferential grain orientation. This experiment clarifies diamond film characteristics required for high-frequency applications in SAW filters.     

Strictly anaerobic halophiles isolated from canned Swedish fermented herrings (Surströmming)

Strictly anaerobic halophiles were isolated from canned Swedish fermented herrings (Surstr?mming). All isolates were phenotypically uniform with some exceptions and were identified as the genus Haloanaerobium and assigned to either Haloanaerobium praevalens or Haloanaerobiuim alcaliphilum. A comparative analysis of 16S rDNA sequences revealed that the representative strain S-8 of the isolates was identical to that of Haloanaerobium praevalens DSM 2228T. Furthermore, this strain exhibited high levels (> 80%) of DNA-DNA homology with Haloanaerobium praevalens DSM 2228T. This is a novel report of halophilic anaerobes isolated from a food product. Such anaerobes may contribute to the intense flavor and the swollen can characteristics of Swedish fermented herring.     

Cytochrome P450rm of Rhodotorula functions in the beta-ketoadipate pathway for dissimilation of L-phenylalanine

The physiological function of a microsomal cytochrome P450, P450rm, from Rhodotorula minuta was determined. We obtained a mutant, 5-286, which has a point mutation in the P450rm gene, resulting in loss of the activities of the isobutene-forming enzyme and benzoate 4-hydroxylase and the ability to grow on medium containing L-phenylalanine as the sole carbon source. Mutant 5-286 spontaneously reverted to the wild-type at a frequency of approximately 10(-9)-10(-10). These results indicate that P450rm functions in the dissimilation pathway starting from L-phenylalanine.     

Surface tension of molten silicon measured by the electromagnetic levitation method under microgravity

The surface tension of molten silicon was measured using the electromagnetic levitation method under microgravity. The atmosphere was Ar-3 pct H₂ purified by Pt asbestos and magnesium perchlorate. The partial oxygen pressure is estimated to be less than 1.1 × 10⁻¹⁴ Pa. The spherical droplet shape was controlled by changing the current ratio between a quadrupole coil and a dipole coil. The surface tension of molten silicon can be expressed by the equation