Contribution of metal vapor mass at periphery part of pulsed arc to electromagnetic force in weld pool

The arc welding has been used in various welding methods because it is inexpensive and high in strength after welding. However, it is a problem that accidents such as collapse of the bridge occur because of the welding defects. The welding of low cost and high productivity is required without the welding defects. The pulsed TIG welding is inexpensive and capable of high‐quality welding. The electromagnetic force contributing to penetration changes because the transient response of arc temperature and iron vapor generated from anode occurs. However, the analysis of pulsed TIG welding with metal vapor has been elucidated only metal vapor concentration near anode with transient phenomenon and heat flux. Thus, the theoretical elucidation of penetration depth with control factor has not been researched. In this paper, the contribution of metal vapor mass at the periphery part of pulsed arc to the electromagnetic force in the weld pool is elucidated. As a result, the iron vapor mass at periphery part decreased with increasing the frequency. The iron vapor was stagnated at axial center within one cycle. The electromagnetic force to the penetration depth direction in weld pool increased at axial center. Therefore, the metal vapor mass at periphery part plays an important role for the electromagnetic force increment at axial center.     

Improved quantum efficiency of Sr(Al,Si)5(O,N)7:Ce3+ by selection of Ce raw material

The luminescence properties of yellow-emitting Ce³⁺-doped Sr-containing sialon phosphor Sr(Al,Si)₅(O,N)₇:Ce³⁺ were notably improved by the Ce raw material selection. By changing the Ce raw material from oxides to nitrides or chlorides, the emission wavelength shifted to above 560 nm, which is beneficial for higher color rendering index white light-emitting diodes. This result from an increase in the covalency of the host crystal being associated with a decrease in the oxygen content. When Ce chloride was used, both the absorption and internal quantum efficiency increased, resulting in an increase in the external quantum efficiency up to 65%–72%. Inductively coupled plasma mass spectrometry, X-ray diffraction, and electron spin resonance measurements showed that the reason for the absorption increase is an increase in Ce³⁺ content and suppression of the generation of the second phase, and the reason for the increase in the internal quantum efficiency is a decrease in the host crystal absorption via suppression of anion vacancy generation. It was found that Ce chloride not only suppresses oxygen impurities but also acts as a flux that results in improved crystallinity.     

Characterization of pigmented granules in minocycline-induced cutaneous pigmentation: observations using fluorescence microscopy and high-performance liquid chromatography

Ambiguous abdominal situs, asplenia/polysplenia and severe cardiac malformations characterize heterotaxy in humans. These anomalies result from the inability of the developing embryo to establish normal left-right asymmetry. We have studied an interesting family in which the heterotaxy phenotype segregates as an X-linked recessive trait. In order to map the heterotaxy locus (HTX), we have analysed 39 family members using highly-polymorphic microsatellite markers from the X chromosome. One of these markers, DXS994, shows no recombination with the disease locus in 20 informative meioses. Linkage analysis results in a maximum lod score of 6.37. Current genetic and physical mapping data assign the order of loci in Xq24-q27.1 as cen-DXS1001-(DXS994, HTX)-DXS984-tel. These results establish the first mapping assignment of situs abnormalities in humans.     

Operation of superconducting fault current limiter using vacuum interrupter driven by electromagnetic repulsion force for commutating switch

Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315     

Boron removal by titanium addition in solidification refining of silicon with Si-Al melt

In order to effectively remove B from Si for its use in solar cells, a process involving B removal by solidification refining of Si using a Si-Al melt with Ti addition was investigated. For clarifying the effect of Ti addition on B removal from the Si-Al melt, TiB₂ solubilities in Si-64.6 at. pct Al melt at 1173 K and Si-60.0 at. pct Al melt at 1273 K were determined by measuring the equilibrium concentrations of B and Ti in the presence of TiB₂ precipitates. The small solubilities of TiB₂ in the Si-Al melt indicate the effective removal of B from the Si-Al melt by Ti addition. Further, solidification experiments of Si-Al alloys containing B by Ti addition were performed, and the effect of Ti addition on the solidification refining of Si with the Si-Al melt was successfully confirmed.     

Comparative studies on Ar and He closed-cycle MHD power plants combined with fossil fuel

Comparative studies on Ar and He closed-cycle MHD power plants combined with fossil fuel are performed. The sizes of a regenerative heat exchanger and a boiler are expected to be smaller for He than for Ar. The pressure loss of a working gas in a regenerative heat exchanger is reduced for He. The purification subsystem for He is expected to be more compact and economical than that for Ar; but a larger compressor is required for He than for Ar.     

Clinical features of primary and secondary atypical mycobacteriosis

A clinical investigation was carried out in 39 patients with atypical mycobacteriosis (AM). The patients at our hospital diagnosed as having AM during an 11-year period from 1981 to 1991 were reviewed in this study. The incidence of AM among all of mycobacterial infections has been increasing since 1988. The atypical mycobacteria detected included M. avium complex (MAC) in 79%, M. kansasii in 26%, and other organisms in 5%. Patients who had primary infection without underlying respiratory disease were compared with those who had secondary infection. In secondary infection, MAC was detected in the sputum of a high percentage of patients and was positive for more than 6 months despite therapy. Gamma globulin levels were also increased in patients with secondary infection. Cell mediated immunity was examined by the DNCB reaction and the detection of CD4- and CD8- positive T lymphocytes. The DNCB skin reaction was positive in 6 out of 26 patients with secondary infection. The percentage of CD8- positive T lymphocytes was higher in patients with secondary disease. Fischer's ratio (indicating the balance of plasma amino acids) was also examined as an index of the nutritional status. It was significantly lower in secondary infection compared with primary infection. Moreover, secondary infection was associated with a lower positive rate for the DNCB skin reaction and a lower Fischer's ratio when compared with pulmonary tuberculosis. Thus impairment of cell-mediated immunity, malnutrition, and a poor prognosis were significantly more common in secondary infection compared with primary infection.     

An image analyzing system using an artificial neural network forevaluating the parenchymal echo pattern of cirrhotic liver and chronichepatitis

To objectively evaluate the parenchymal echo pattern of cirrhotic liver and chronic hepatitis, the authors applied an image analyzing system (IAS) using a neural network. Autopsy specimens in a water tank (n=13) were used to examine the relationship between the diameter of the regenerative nodule and the coarse score (CS) calculated by IAS. CS was significantly correlated with the diameter of the regenerative nodule (p<0.0001, r=0.966). CS is considered to be useful for evaluating the coarseness of the parenchymal echo pattern     

Intelligent tutoring system for electric circuit exercising

An intelligent tutoring system called Circuit Exerciser is described. The system is designed to help university students learn more about electric circuits. It can formulate drill problems, solve them, and infer mistakes in a student's answer. It can also provide helpful comments to the students on how the mistake was made. The system shows the circuit of the presented problem on graphic displays and is student-friendly. The system architecture, pedagogical cycle, and execution of the system are presented