Study of drive system for linear induction motor using magnetic energy recovery switch

This paper proposes a power supply suitable for driving linear induction motors. The power supply consists of a voltage source inverter (VSI) and a magnetic energy recovery switch (MERS). Circuit configuration and operation principles of the power supply are described. Power factor correction by MERS can increase the output power. Technical advantages of using MERS compared with increasing the rated voltage of VSI are discussed. Some experiments with a linear induction motor were conducted. The results confirm that MERS can reduce the capacity of the VSI or increase the output with the same VSI capacity. The number of devices and magnitude of losses are evaluated on a large‐scale drive system. A half‐bridge type of MERS is provided and discussed. The half‐bridge MERS mitigates disadvantages of using MERS. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(4): 65–74, 2009; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20832     

Measurement and calculation of neutron densities in BWR high burn-up fuels

A neutron-scanning device was developed for measuring accurate neutron densities of BWR high burn-up fuels up to 65 GWd tU⁻¹. Characteristic test of this device was done with a ²⁵²Cf source and adopted to measure axial distributions of neutron densities of BWR spent fuels with various enrichments (2.0–3.4%), which had been irradiated up to 60 GWd tU⁻¹ at Fukushima Daini Nuclear Power Station Unit 2(2F-2). We found the measured neutron densities were proportional to about fourth power of the corresponding burn-up values. The neutron densities calculated by the ORIGEN2.1 code and various cross section libraries showed good agreements with the measured ones in profile and absolute value except for BWR-UE file mainly based on ENDF/B-IV. The BS240J32 library based on JENDL3.2 was the best among the investigated libraries.     

Low Temperature Magnetization of Two Dimensional 3He on Three Layers of HD Preplated Graphite

We have measured the low temperature magnetization of submonolayer ³He on three layers of HD preplated graphite. NMR measurement has been performed by progressively adding ⁴He to the system, to prevent ³He atoms from being trapped in substrate heterogeneities and to change the areal density of ³He. The exchange constant (J) is found to have a similar density dependence to that for two layers of HD preplated one. The magnetization in the antiferromagnetic region increases gradually down to 100 K and shows no evidence corresponding to a spin gap.     

Observations of xenon gas-treated barley cells in solution by atomic force microscopy

Barley cells cut from a sprout were exposed to either air or high-pressure xenon gas for 3 days and the surface of those cells was observed by atomic force microscopy (AFM) to examine the effect of the gas treatment. This method enabled the direct observation of the fresh surface of the barley cells in solution at high resolution. The cuticle layer was preserved on the primary cell wall of 0.48 MPa xenon gas-treated barley cells, while air-treated barley cells lost the cuticle layer from the primary cell wall. These findings indicate that the high-pressure xenon gas treatment is effective to preserve the cuticle layer attached to the primary cell wall. AFM is a powerful tool for the observation of the surface structure of living plant cells in solution.     

Characterization of natural resin shellac by reactive pyrolysis-gas chromatography in the presence of organic alkali

A method to determine chemical composition of natural resin shellac was developed on the basis of reactive pyrolysis-gas chromatography (Py-GC) in the presence of an organic alkali, tetramethylammonium hydroxide ((CH(3))(4)NOH, TMAH). Py-GC using 25% TMAH aqueous solution enabled the highly sensitive determination of terpenic acids, aleuritic acid, several minor fatty acids, and the wax components of shellac as their methyl derivatives on the resulting pyrograms with less than 2.0% relative standard deviations without using any cumbersome pretreatment. The observed average distributions of each resin acid component determined by reactive Py-GC for shellac samples from India and Thailand showed that the average ratios among terpenic acids, aleuritic acid, and the other fatty acids were about 53:34:14 for Indian shellac and 51:35:14 for Thailand shellac, respectively, suggesting a slightly significant difference. However, clearer discrimination of the shellac samples from the two different growing places was attainable by applying principal component analysis for the mole percent distributions of all the acidic components determined by reactive Py-GC.     

Cautionary observations on preparing and interpreting brain images using molecular biology-based staining techniques

Though molecular biology-based visualization techniques such as antibody staining, in situ hybridization, and induction of reporter gene expression have become routine procedures for analyzing the structures of the brain, precautions to prevent misinterpretation have not always been taken when preparing and interpreting images. For example, sigmoidal development of the chemical processes in staining might exaggerate the specificity of a label. Or, adjustment of exposure for bright fluorescent signals might result in overlooking weak signals. Furthermore, documentation of a staining pattern is affected easily by recognized organized features in the image while other parts interpreted as "disorganized" may be ignored or discounted. Also, a higher intensity of a label per cell can often be confused with a higher percentage of labeled cells among a population. The quality, and hence interpretability, of the three-dimensional reconstruction with confocal microscopy can be affected by the attenuation of fluorescence during the scan, the refraction between the immersion and mounting media, and the choice of the reconstruction algorithm. Additionally, visualization of neurons with the induced expression of reporter genes can suffer because of the low specificity and low ubiquity of the expression drivers. The morphology and even the number of labeled cells can differ considerably depending on the reporters and antibodies used for detection. These aspects might affect the reliability of the experiments that involves induced expression of effector genes to perturb cellular functions. Examples of these potential pitfalls are discussed here using staining of Drosophila brain.     

Molecular simulation for adsorption of chlorinated hydrocarbon in zeolites

Equilibrium and isosteric heat of adsorption for the system of chloroform and USY-type zeolite were studied. The USY-type zeolite (PQ Co., SiO₂/Al₂O₃=70) was used both as a pure crystalline powder and as granulated particles with binder. Chloroform was reagent grade. The adsorption equilibria were measured using a gravimetric method and were expressed as isotherms. A chromatographic method (i.e. pulse response of chloroform through the USY column with helium carrier) was used to get the initial slope of the isotherms. In the simulation, the GCMC method was used to calculate amounts adsorbed for various conditions. FF parameters were confidently applied. And modified structure model was effective for simulation. This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between August 19 and 21, 1999.