高功率因数三相软开关PWM变流器

本文提出一种三相软开关PWM变流器,它具有电路结构简单,开关次数较传统变流器少的特点,电路的开关切换是以单纯的ZVS方式进行的,从而可以减少开关损耗和抑制EMI。文章阐述了变流器输入功率因数为1和输出直流电压恒定的控制方法,通过改变调制信号的调制度a和相位角φ,不但可以使输入电流和相电压保持同相位,输入电流波形为正弦波,而且可以使输出直流电压保持恒定。     

Critical current test results of 13 T-46 kA Nb3Al cable-in-conduit conductor

In the framework of ITER-EDA, a 13 T-46 kA Nb₃Al conductor with stainless steel jacket has been developed in order to demonstrate applicability of an Nb₃Al conductor with react-and-wind technique to ITER-TF coils. Using a 3.5 m sample consisting of a pair of conductors with 0% and 0.4% bending strain, the critical current performances of the Nb₃Al conductors were studied to verify that the conductor achieves the expected performance and the bending strain of 0.4% does not originate degradation. The critical currents were measured at background magnetic fields of 7, 9, 10 and 11 T at temperatures from 6 to 9 K. The expected critical currents were evaluated taking into account the variation of the strain in the cross-section due to the bending strain as well as self-field and non-uniform current distribution as results of an imbalance in the joint resistance and inductances. The calculation results indicate that the current distribution is almost uniform and the experimental results showed good agreement with the expected critical currents. Accordingly, we can conclude that the fabrication process of this conductor is appropriate and the react-and-wind technique using the Nb₃Al conductor is applicable to ITER-TF coils. In addition, the critical current of the Nb₃Al conductor is expected to be 108 kA at 13 T and 4.5 K, resulting in a sufficient margin against the nominal current of 46 kA. Furthermore, it was found that the decrease in the critical current by thermal strain can be made small by applying the bending strain to the conductor so as to reduce the compressive strain at higher fields, i.e. inner side of the coil, in the conductor cross-section.     

ANALYSIS OF DIFFUSE PARENCHYMAL LIVER DISEASE BY LIVER SCINTIGRAMS: DIFFERENTIAL DIAGNOSIS USING FUZZY INFERENCE AND GENETIC ALGORITHM IN NUCLEAR MEDICINE

In nuclear medicine, diagnosis of diffuse parenchymal liver disease such as chronic hepatitis (CH) or liver cirrhosis (LC) is evaluated by size and distortion of the liver, distribution of radioactive tracer in the liver, size and activities of the tracer in the spleen, the degree of visualization of the bone marrow, etc. using colloid liver scintigraphy, It is not difficult to read a scintigram for a typical pattern; however in some cases it is difficult to distinguish between normal and CH or CH and LC visually. Therefore, we tried to use fuzzy inferences to perform differential diagnosis. Using fuzzy inference, differential diagnosis of LC could be performed up to 100%, but those of CH and Severe fibrosis (SF) could not be performed sufficiently. Therefore genetic algorithm was tried to determine the fuzzy rules. By combining genetic algorithm and fuzzy inference, CH, SF, and LC could be differentiated to the degree 70%, 60%, and 100%, respectively.     

A sinusoidal PAM-PWM inverter

A new strategy, using both PAM (pulse amplitude modulation) and PWM (pulsewidth modulation) in combination for a power inverter is described. The output waveforms in the proposed PAM-PWM inverter are investigated both theoretically and experimentally. The line-to-line voltage waveform includes the fundamental component and the sidebands of the carrier frequency. Lower-order harmonics are not included in the output waveform. The amplitude of the fundamental component increases 15 percent more than that of a conventional sine-wave inverter. Since each inverter arm does not operate during two-thirds of the period, the heat generated in the devices is reduced, i.e., the size of the inverter system can be minimized because of the reduction in the heat dissipating equipment.     

Inhibitory Potency of Plant Antinutrients towards the In Vitro Digestibility of Buckwheat Protein

The inhibitory potency of dietary fiber sources, tannins, phytate, and a protein protease inhibitor on the in vitro pepsin-pancreatin digestibility of protein was compared. The protein inhibitor exhibited the highest inhibitory capacity among the substances examined; and phytate the lowest. Our findings suggest that the inhibition of the digestion of dietary sources of plant proteins by such factors as fiber and tannins, in addition to the protein protease inhibitors, may also be taken into account.     

Purification and Properties of Carp Muscle Cathepsin D

A carp muscle cathepsin was purified as an electrophoretically homogeneous preparation. The preparation represented about 2,000-fold purification and about 4% yield against the crude extract. The activity against hemoglobin was maximal at pH 2.6—2.8 with 0.6M buffer and near 3.2 with 0.12M buffer and at 50°C. The molecular weight was found to be 41,000 and the isoelectric point to be pH 5.4. From the effect of various inhibitors on the enzyme activity, the enzyme was identified as cathepsin D under the classification of Barret. Carp muscle cathepsin D hydrolyzed myofibrils optimally at pH 3–4, but did not above pH 6.0. The participation of the enzyme in autolysis is very doubtful.     

Kooroo color: 90-day dietary toxicity study in F344 rats

A subchronic toxicity study on kooroo color was conducted using F344 rats of both genders. Kooroo color is an extract of yam root, Dioscorea matudai Hayata, of which the major components are known to be flavonoid pigments. Use of kooroo as a food color is permitted by the Food Sanitation Law in Japan, but the chronic toxicity has not been evaluated in the literature. Rats were fed the product of kooroo color (PKC) at doses of 0.5%, 1.50%, and 5.0% in basal powder diet, while control groups received PKC-free basal diet, for ninety days. A vehicle control given propylene glycol (PG) alone, at the same dosage that the 5.0% group received, was included, because PKC used in this study contained ca. 80 percent PG, used as an extractant during the manufacturing processes. Daily observation of general behavior, and weekly measurement of body weight as well as food consumption were performed. Hematological, serum biochemical and anatomopathological examinations were conducted at the end of administration. No abnormalities ascribable to the treatment with PKC or PG were noted in any examination in this study. Hence, dietary intake of 5.0% of PKC, i.e., 2,993 mg/kg/day for males, and 3,376 mg/kg/day for females, as a mean daily intake for 90 days, had no observable adverse effect in F344 rats. Therefore, kooroo color has no significant general toxicity, and its toxicity, if any, is of a very low order.     

Normal spectral emittance of a nickel metal surface with rectangular microcavities

Spectral control of thermal radiation emitted from rectangular microcavities (0.5×0.5×0.5µm³) was investigated through emission experiments at high temperatures. The microcavities were fabricated on a mirror‐finished Ni metal surface. Through measurement of the normal spectral emittance, the maximum emittance was obtained around a wavelength of 0.87µm, which was very close to that (0.894µm) estimated from the cavity resonance theory. The emittance reached a maximum value of 0.95, and then decreased drastically with increasing wavelength, from the cut‐off wavelength. For a longer wavelength range from 1.7µm, it was equal to the emittance of the mirror‐finished surface. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20248