Current waveform control of a high‐power‐factor rectifier circuit for harmonic suppression of voltage and current in a distribution system

This paper presents the input current waveform control of the rectifier circuit which realizes simultaneously the high input power factor and the harmonics suppression of the receiving‐end voltage and the source current under the distorted receiving‐end voltage. The proposed input current waveform includes the harmonic components which are in phase with the receiving‐end voltage harmonics. The control parameter in the proposed waveform is designed by examining the characteristics of both the harmonic suppression effect in the distribution system and the input power factor of the rectifier circuit. The effectiveness of the proposed current waveform has been confirmed experimentally. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(4): 62–71, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10046     

Formula-based approach of statistical tests for peri-stimulus time histograms

We introduce formula-based approaches for statistical tests regarding peri-stimulus time histograms (PSTHs) in cases when a conditioning stimulus was triggered by a motor-unit discharge with a constant delay time. The individual bin test and the cumulative sum test have recently been reported as methods for the quantitative analysis of PSTHs in the evaluation of human neural projections. These tests calculate confidence intervals using simulated point processes on the discharge of a motor unit, but require a significant amount of calculation time for the point process simulation. In order to overcome such a disadvantage in practical use, we provide a statistical formulization of the two above-mentioned tests using a combination theory. In general, the time required for calculating confidence intervals using these formula-based approaches was 2-13 times faster than when using the previous approaches. Unlike the previous ones, these formula-based approaches do not need to judge that a simulation process converges to the substationary state, and calculate an ideal distribution of statistical noise on the histogram, thereby providing high accuracy. We conclude that the formula-based approaches increase reliability and are sufficiently sophisticated for practical use.     

A novel type hypertriglyceridemia observed in FLS mice

The unique inborn hypertriglyceridemia seen in FLS (fatty liver Shionogi) mice was relieved by the administration of purified apolipoprotein (apo) C-II. Lipoprotein lipase (LPL) and its cofactor, apoC-II, play a pivotal role in VLDL metabolism. Therefore, we investigated the genetic background involved in this hypertriglyceridemia. Plasma levels of TG and total cholesterol as well as LPL activity were measured in male FLS mice and C57/BL6J mice. Agarose gel electrophoresis and fast protein liquid chromatography were used to analyze the lipoprotein profile. A cross experiment was done to determine the genetic background of hypertriglyceridemia observed in FLS mice. cDNA sequences of apoC-II and apoC-III of FLS mice were determined. Preα-lipoprotein was the predominant lipoprotein class in FLS mouse plasma. LPL activity remained in the range observed in C57/BL6J mice, and purified apoC-II transiently relieved FLS mice from hypertriglyceridemia. Preα-lipoproteinemia was inherited in an autosomal recessive manner. ApoC-III appeared to be a causal factor for this unique hypertriglyceridemia. Microsatellite analysis, however, revealed that the responsible chromosome was not 7; rather, apoC-III mapped onto chromosome 9. Therefore, we suggest apoC-III as a candidate causative factor for the hypertriglyceridemia observed in FLS mice because an excessive amount of apoC-III attenuates LPL activity in vivo and in vitro.     

Micro behavior at the notch tip during load increasing in brittle fracture beyond general yield

The micro behavior near the notch tip during load increasing was studied by using both plastic replication and optical microscope on mild steel specimen until the final stage of general yielding fracture at low temperature. Results show that a microcrack has already initiated at lower yield point, and the overall path of crack propagation appears to smear out such microcracks by the main crack starting from the notch root. Further, the ferrite grain size dependence of the brittle fracture stress and the temperature characteristics of the number of grains containing microcracks initiated prior to fracture are similar to that in unnotched (uncracked) ones established in the literature. Further, the effects of ferrite grain size and temperature on the crack tip opening displacement (CTOD) have been studied experimentally. The usefulness of the comparative study on cracked and uncracked specimens is discussed.

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Résumé Le comportement microscopique au voisinage de l'extrémité d'une entaille soumise à une charge croissante a été étudié en utilisant à la fois des répliques plastiques et un microscope optique sur des éprouvettes d'acier doux et ce jusqu'au stade final de la rupture par glissement généralisé à basse température. Les résultats montrent qu'une microfissure s'est déjà déclenchée au point de limite élastique inférieure et que le parcours général de la propagation de cette fissure apparait suivre de telles microfissures au départ d'une fissure principale démarrant à la pointe de l'entaille. On montre en outre que la liaison entre le grain ferritique et la tension de rupture fragile ainsi que les caractéristiques à la température du nombre de grains comportant des microfissures amorcées avant le rupture sont similaires aux relations constatées dans le cas d'éprouvettes non fissurées et non entaillées, dans la littérature. De plus, les effets du grain ferritique et de la temperature sur le déplacement d'ouverture de l'extrémité d'une fissure (COD) ont été étudiés expérimentalement. L'utilité de l'étude comparative sur des éprouvettes fissurées et non fissurées est discutée.

     

Flame retardancy effects of halogenated phosphates on poly(ethylene terephthalate) fabric

A Chemical research on the flame retardancy effect of halogenated phosphates on poly(ethylene terephathalate) fabric was carried out by thermogravimetry, infrared spectral analysis, and mass spectrometry. The following conclusions were drawn: (1) The flame retardancy effect of halogenated phosphates such as tris(2,3-dibromopropyl) phosphate is due to altering the pyrolysis reaction of polyester by aldol condensation. (2) The probability that liberated halogen compounds from the phosphates act as radical acceptors in a flame zone may be low. (3) Incorporation of halogen elements into phosphates appear to depress evaporation of phosphates, which act as acidic catalysts in aldol condensation from the condensed phase.     

Characteristics of alpha-glucosidase production from recombinant Aspergillus oryzae by membrane-surface liquid culture in comparison with various cultivation methods

alpha-Glucosidase was produced using recombinant Aspergillus oryzae by membrane-surface liquid culture (MSLC), a method previously developed by the authors and the results compared with other methods, including shaking flask culture (SFC), agar-plate culture (APC), culture on urethane sponge supports (USC), and liquid surface culture (LSC) to determine possible reasons for the advantageous features of MSLC. When yeast extract was used as a nitrogen source, the amount of enzyme produced by MSLC was 5 or more times higher than those for SFC and LSC, but similar to that using APC. Enzyme production in USC was slightly lower than in MSLC and APC. Cell growth was similar irrespective of the cultivation method used. When NaNO3, a typical inorganic nitrogen source was used, enzyme production in all the cultures was lower than that using yeast extract. However, even using NaNO3, the amount of the enzyme produced by MSLC was 8 to 20 times higher than those by SFC, APC, USC, and LSC. Although cell growth using NaNO3 was similar to that for yeast extract in MSLC, it was markedly decreased in SFC, APC, and LSC. The reason for the difference in enzyme productivity for various cultivation methods using yeast extract and NaNO3 as a nitrogen source is discussed, on the basis of the experimental findings. The role of the oxygen transfer effect and gene expression levels in enzyme production were also examined.     

Bioadhesive characteristics of chitosan microspheres to the mucosa of rat small intestine

Chitosan (Chi) microspheres were examined in vitro and in vivo in terms of their bioadhesive characteristics to the mucosa of rat small intestine. Chi was labeled with fluorescein isothiocyanate (FITC), and the microspheres (FTC-MS) were prepared by the dry-in-oil method using the obtained fluorescein thiocarbamyl-chitosan (FTC-Chi). FTC-MS with a mean diameter of 27 μm and size distribution of a few micrometers to several tens of micrometers was used for the bioadhesion experiment. FTC-MS exhibited a tendency to adhere to each part of the small intestine to a greater extent than dissolved FTC-Chi, and the ratio of adhering FTC-MS increased as the amount of added FTC-MS decreased. FTC-MS showed slower transit following intraduodenal injection than oral administration. Following the intraduodenal injection of FTC-MS, more than half remained in the upper or middle part of the small intestine for over 8 h. Further, insulin-containing chitosan microspheres with a mean diameter of 20 μm and size distribution of 5 μm to 45 μm were checked in situ for drug absorption, but intraduodenal or intraileal application hardly gave any decrease in plasma glucose level at a very high dose. The present chitosan microsphere system showed good adhesion to the intestinal mucosa, but scarcely facilitated absorption of insulin.