Quench protection tests of a cryocooler cooled 6 T NbTi superconducting magnet by an active power method

When a quench occurs in a superconducting magnet, excessive joule heating may damage the magnet. We have presented the quench protection system based on an active power method. Our previous quench protection tests have been carried out for small superconducting magnets whose self inductances are less than several hundred mH to verify principles of our proposed system. In this paper, we present experimental results of quench protection tests of a cryocooler cooled 6 T NbTi superconducting magnet (self inductance 15.5 H), which is a commercial size magnet made by Tamakawa Co., Ltd. We confirmed that our proposed system could inhibit the maximum temperature of the superconducting magnet (initial temperature 4.3 K) after the quench to less than about 44 K at operation magnetic field 5.5 T. Experimental results suggest that our proposed system is useful for practical used superconducting magnets.     

Intrabody three-dimensional position sensor for an ultrasound endoscope

To avoid or reduce the X-ray exposure in endoscopic examinations and therapy, as an alternative to the conventional two-dimensional X-ray fluoroscopy we are developing an intrabody navigation system that can directly measure and visualize the three-dimensional (3-D) position of the tip and the trace of an ultrasound endoscope. The proposed system can identify the 3-D location and direction of the endoscope probe inserted into the body to furnish endoscopic images. A marker transducer(s) placed on the surface of the body transmits ultrasound pulses, which are visualized as a marker synchronized to the scanning of the endoscope. The position (direction and distance of the marker transducer(s) outside the body relative to the scanning probe inside the body) of the marker is detected and measured in the scanned image of the ultrasound endoscope. Further, an optical localizer locates the marker transducer(s) with six degrees of freedom. Thus, the proposed method performs inside-body 3-D localization by utilizing the inherent image reconstruction function of the ultrasound endoscope, and is able to be used with currently available commercial ultrasound image scanners. The system may be envisaged as a kind of global positioning system for intrabody navigation.     

Wireless communications in the twenty-first century: a perspective

Wireless communications are expected to be the dominant mode of access technology in the next century. Besides voice, a new range of services such as multimedia, high-speed data, etc. are being offered for delivery over wireless networks. Mobility will be seamless, realizing the concept of persons being in contact anywhere, at any time. Two developments are likely to have a substantial impact on the mobile communications systems deployed in the twenty-first century: the adoption of International Mobile Telecommunications-2000 and wireless asynchronous transfer mode (ATM). They are two different but cooperative approaches to providing high-speed wireless access. The limitations of the radio-frequency spectrum and radio channel propagation impose special constraints on the technologies of systems to be deployed. To make future mobile systems globally acceptable, standardization efforts are underway in the International Telecommunications Union and the ATM Forum. This paper reviews the international standardization efforts, the challenges to the technologies imposed by the radio spectrum limitations, radio channel propagation-induced distortions, and possible solutions. Evolution, migration, and architecture issues also are discussed     

Tribo-Film Formation of Lubricant Additives on Cr-Plated Surface Sliding Against Nitrile–Butadiene Rubber

A Bowden and Leben type sliding tester was used with a base oil to evaluate four types of friction modifier additives—acid phosphate, hydrogen phosphite, acid phosphate amine salt, and amine—as a fundamental study on hydraulic fluid additives for sliding of nitrile–butadiene rubber on Cr-plated metal. Acid phosphate showed the lowest friction coefficient among the phosphorus acids. After the sliding test, the formation of tribo-films on the Cr-plated surface was investigated by Fourier transform infrared reflection absorption spectroscopy and a time-of-flight secondary ion mass spectrometer. The analytical results suggest that tribo-films formed by the phosphorus acids effectively reduced friction.     

Determination of vedaprofen in livestock products and seafoods by liquid chromatography-tandem mass spectrometry

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the trace residue determination of vedaprofen (VPF) in livestock products and seafoods. VPF was extracted from each sample with acidified acetone, and the crude extract was re-extracted with ethyl acetate and NaCl solution. Clean-up was performed using a weak anion exchange cartridge (Bond Elut DEA). The LC separation was performed on a C18 column using acetonitrile-0.0025 mol/L formic acid (3 : 2) as the mobile phase and MS was run in the negative ion electrospray ionization mode. The calibration curve was linear in the range of 0.001-0.1 μg/mL VPF. The mean recoveries from equine muscle, cattle muscle, cattle liver, cattle fat, salmon, eel, corbicula, milk, egg and buckwheat honey were 72-94%, and the relative standard deviations (RSDs) were 1.1-2.0%. Limits of quantitation (LOQs) ranged from 0.001 to 0.007 μg/g.     

Frequency domain discussions on PD signal propagation characteristics in GIS

The frequency dependency of PD signal propagation in GIS was investigated at an underground substation. Injecting dummy pulses into a GIS through its internal electrode, frequency spectra were measured by a spectrum analyzer at various points of the GIS. It is shown that this measurement is very reproducible and the signal propagation phenomena are independent of its direction. It is also clarified that the PD signal reduction phenomena are closely related with mode transfer from TEM to TE or TM. The major higher mode seems to be TE₁₁. Pulse waveforms were also measured with 65‐MHz bandpass filter. Their magnitudes are compared with the gain of the 65‐MHz component of the frequency spectra and good agreement is obtained. This implies the possibility of PD location by observing a frequency pattern with several bandpass filters. © 2000 Scripta Technica, Electr Eng Jpn 133(3): 9–17, 2000     

Low dose exposure diagnosis with a transXend detector aiming for iodine-marked cancer detection

The energy resolved computed tomography (CT), which had advantage over conventional CT (twofold higher CT value for iodine contrast agent and being free from beam hardening effect), was shown practical by employing the transXend detector: it measured X-rays as electric current and gave energy distribution of incident X-rays after analysis. This article shows a new application of the transXend detector for estimating the thicknesses of acrylic, iodine, and aluminum in a phantom. For this purpose, the responses of the segment detectors in the transXend detector are changed intentionally with inserting filters. With previously obtained two-dimensional maps for acrylic–iodine and acrylic–aluminum thicknesses, which are shown by the ratios of electric currents measured by the segment detectors, the thickness of materials on the path of the X-rays are obtained by a transmission measurement.     

Effect of chromatic components on facial skin whiteness

Although the color measurement of facial skin becomes more common in dermatology and cosmetics, little is known about the relationship between subjective color perception and colorimetric values in facial skin. In this study, the possible relationships among perceived whiteness and the metric lightness, chroma and hue angle of Japanese females' facial skin color were investigated. First, the perceived brightness of the facial skin of Japanese females was evaluated visually and compared with metric lightness, chroma and hue angle, and the effect of hue and chroma on the perceived brightness was discussed. Second, a psychophysical experiment on the whiteness of the facial images and synthesized skin color plate images was conducted for examining the effect of hue and chroma on the perceived whiteness more precisely and independently. The results of two experiments showed that in regard to the facial skin color of the Japanese female, metric lightness disagrees with perceived whiteness or brightness in a narrow lightness range. The reddish facial skin color appeared brighter or whiter than that of a yellowish one in high lightness regions, and the low‐chroma facial skin color appeared brighter or whiter than a high‐chroma one. However, in the color plate images, a change in perceived whiteness by hue could not be confirmed, and the change in perceived whiteness by chroma was weaker than that from facial images. These results indicated that a higher‐level process of face recognition affected whiteness perception, and the criterion of facial skin whiteness was determined by facial skin color distribution. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011;     

Multiplication and motility of Salmonella enterica serovars enteritidis, infantis, and montevideo in in vitro contamination models of eggs

The invasive ability of Salmonella enterica serovars Enteritidis, Infantis, and Montevideo in eggs was examined. Strains of these serovars originating from egg contents, laying chicken houses, and human patients were experimentally inoculated (0.1-ml dose containing 78 to 178 cells) onto the vitelline membrane of eggs collected from specific-pathogen-free chickens and incubated at 25 degrees C. The test strains were detected in 25 of 138 yolk contents by day 6, indicating the penetration of Salmonella organisms through the vitelline membrane. There were no significant differences in overall rates of penetration between serovars. The organisms were also detected in the albumen from 125 of 138 eggs tested by day 6. Growth to more than 10(6) CFU/ml was observed in 48 of the 125 albumen samples. An inoculum of 1000 Salmonella cells was added to 15 ml of albumen at the edge of a petri plate. A 10-mm-diameter cylindrical well, the bottom of which was sealed with a polycarbonate membrane with 3.0-microm pores, was filled with egg yolk and placed into the albumen at the center of the dish, which was maintained at 25 degrees C. Experiments were performed in triplicate with each strain. Salmonella organisms in all the albumen samples were detected by day 11. However, motility of the organisms toward the yolk was observed in only two dishes inoculated with the Salmonella Enteritidis strain from a human patient and in one dish inoculated with the Salmonella Infantis strain from liquid egg. The albumen samples obtained from the dishes inoculated with the Salmonella Enteritidis strain had high numbers of bacteria (>10(8) CFU/ml). The present study suggests that Salmonella organisms in egg albumen are unlikely to actively move toward the yolk, although depositionon or near the vitelline membrane can be advantageous for proliferation.