A time and wavelength division fiber loop distribution system with acousto-optic tunable filters

A time and wavelength division fiber loop distribution system with acousto-optic tunable filters is proposed. This system can provide a large number of 150 Mb/s HDTV channels with a reliable technology. A theoretical analysis by Gaussian beam approximation shows that one system can distribute 320 HDTV channels to 256 subscribers with a minimum wavelength spacing of 2 nm. An experimental 12 channel (4 time division × 3 wavelength division) system with a wavelength spacing of 20 nm in the 1.3 μm region demonstrates a data rate of 1.2 Gb/s with only ?4dB loss and ?20 dB crosstalk at the tunable filter. The experimental loss and crosstalk characteristics agree well with the theoretical analysis.     

Depth perception for moving images shown on a large LED display with an aperture grille

Abstract— A type of depth illusion created by the use of an aperture grille is reported. When viewing a moving target through multiple slits, a movement with depth is perceived, which was originally reported (see Ref. 11). The binocular delay is considered to cause a virtual disparity between both perspective images with apparent movement. By using an LED display with an aperture grille as a stereoscopic display, perceived distance caused by a binocular delay has been measured. The measured distance is compared with the perceived distance for stereoscopic still images shown on a stereoscopic LED panel. The comparison supported that the binocular delay is converted into binocular disparity. Furthermore, pair‐comparison tests were conducted to investigate depth impressions. It was found that use of an aperture grille improves depth impression for a movie that was taken with a laterally moving camera.     

Characterization of neutron field in the experimental fast reactor JOYO for fuel and structural material irradiation test

The experimental fast reactor JOYO has been operated as an irradiation test facility for fast reactor fuel and structural material since 1983 with its MK-II core. During this time, an extensive study was conducted to characterize the neutron field in order to assure the accuracy and reliability of neutron fluence. Neutron flux for a given irradiation test was calculated using a core management code system based on three-dimensional diffusion theory. It was then corrected with the adjusted neutron spectrum by means of the multiple foil activation method. The neutron fluence calculation accuracy in the fuel region was evaluated within a 5% error by comparing the burn-up of spent fuel with the measured values, which had been obtained from their post-irradiation examination. At positions away from the fuel region, the neutron flux distribution was calculated using a two-dimensional transport code. A Monte Carlo code was also used to analyze the detailed neutron flux distribution within an irradiation test subassembly that had a heterogeneous internal structure. With the neutron flux results various irradiation parameters, such as displacement per atom (dpa) and helium production, could be evaluated. A helium accumulation fluence monitor has been developed to measure not only neutron fluence but also helium production. Neutron flux and fluence obtained from the core management calculations were compiled as a database for users’ convenience together with related irradiation information and fuel subassembly material compositions. These data are expected to be widely used in the post-irradiation analysis of fuel and structural material.     

High‐efficiency UV LEDs and RGB white LEDs for lighting and LCD backlights

Abstract— Progress in the development of blue light‐emitting diodes and yellow phosphor has led to the realization of solid‐state lighting. The development was followed by improvement in the luminous efficacy of ultraviolet light‐emitting diodes (UV‐LEDs). By using near‐UV‐LEDs (n‐UV‐LEDs) excited light for red, green, and blue (RGB) phosphors, a new type of solid‐state lighting was realized. An innovative method for increasing the efficiency of LEDs by using a silicon nitride layer as the active layer and piling them up to a nano‐sized level with nano‐sized holes has been developed.     

Cooperative relaxation processes in polymers

The basic mode of relaxation in polymer molecules involves the rotation of a conformer, with a time scale of the order of picoseconds. This fast relaxation process, however, cannot take place easily in the condensed state crowded by densely packed conformers, necessitating the intermolecular cooperativity among them. The domain of cooperativity grows at lower temperatures, towards the infinite size at the Kauzman zero entropy temperature, though the system deviates from the equilibrium as the glass transition intervenes at about 50°C above that temperature. From the temperature dependence of the domain size, the well-known Vogel equation is derived, which we consider is the basic origin of the empirical WLF and free volume equations. The molar volume is a crucial factor in determining molar free volume. The molecular weight of a conformer with a density correction, therefore, can be used as a parameter in determining the T_g of liquids and amorphous polymers. A larger size conformer means a higher glass transition temperature. A conformer at the chain end, on the other hand, has a higher enthalpy, i.e., a smaller effective size for that conformer. If a conformer is reacted trifunctionally, the resulting conformer is a combination of the two conformers and T_g increases, but a further addition of another conformer to that branch point reduces the average size of the conformers, so T_g decreases. The model for cooperative relaxation can be directly applied to predicting T_gs from the chemical structure of polymers, the kinetics and T_gs of thermosets during the crosslinking reaction, the distribution of relaxation times from the domain size distribution at a given temperature, the dynamics of the physical aging process, and other complex behaviors of polymers and liquids near the glass transition temperature. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 77–93, 1997     

A shell type superconducting transformer for experiments using Nb3Sn superconducting cables

A shell-type superconducting transformer was developed for experiments using Nb₃Sn superconducting cables. The designed capacity is 667 kVA (single phase), the voltage is 440/220 V, the current is 1515/3030 A and the percent impedance is 16 percent. Main features of the transformer are as follows: (1) Magnetic field in superconducting coils is decreased by increasing the number of high and low coil groups. (2) Large-scale superconducting cables are not needed when the number of high and low coil groups is increased. (3) Epoxy impregnated coils are used to withstand an electromagnetic force at 120 Hz. The Nb₃Sn basic strand was manufactured by the internal tin diffusion process. The cable consists of seven insulated subcables, and the subcable consists of seven strands. The primary (HV) coil of the transformer was excited, in which the secondary (LV) coil was shortened. The primary current reached 1618 A_rms without quenching, and the reached capacity corresponds to 712 KA. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (3): 13–21, 1997     

阳极极化状态下铁电极的交流阻抗

研究了铁电极在中性Na_2SO_4溶液中恒电位阳极极化下。和在不同pH的H_2SO_4/Na_2SO_4溶液中腐蚀电位下的交流阻抗特性。当pH>3.5时,铁电极的界面电容急剧增大至10~3μF/cm~2数量级。而铁电极在中性Na_2SO_4溶液中的界面电容为铁电极上覆盖的Fe(OH)2的电容。通过恒电位阳极极化状态铁电极的高频和低频部份的阻抗特性分析,建立了阳极极化状态铁电极的等效电路。用交流阻抗计算了极化电流密度,其值与同样条件下测得的稳态电流密度相等,说明阳极极化状态下交流阻抗测定的适用性。     

Synergistic cytotoxicity induced by α-solanine and α-chaconine

α-Solanine and α-chaconine are well-known potato toxins, but the mechanism of the synergistic cytotoxic effect of these alkaloids has been little clarified. This study confirmed their synergistic cytotoxic effects on C6 rat glioma cells by three different cell viability tests, namely WST-1 (water-soluble tetrazolium) assay sensitive to intracellular NADH concentration, menadione-catalysed chemiluminescent assay depending on both NAD(P)H concentration and NAD(P)H:quinone reductase activity, and LDH (lactate dehydrogenase) assay sensitive to the release of LDH from damaged cells. The maximum cytotoxic effect was observed at a ratio of 1:1 between α-solanine and α-chaconine at micromolar concentrations. The cytotoxic effects of these alkaloids were observed immediately after incubation and were constant after 30 min, suggesting that rapid damage of plasma membrane causes the lethal disorder of metabolism.     

Identification and determination of unknown chemicals in crops by dual-column GC system equipped with MS and ECD

A dual-column GC system equipped with MS and ECD, using two identical columns (HP-1701), one connected to the MS and one to the ECD, has been developed. The carrier gas flow rate was adjusted to give the same retention time of each peak in both columns. Unknown peaks were detected and identified in 7 samples of crops using this system. It was confirmed that the unknown peaks were 5 pesticides, i.e., bromopropylate and others. The recoveries and CV of bromopropylate from spinach and Komatsuna were good. The results of determination of bromopropylate by both MS and ECD were the same. Unknown chemicals can be easily identified using GC equipped with MS and ECD, and this system should be useful in the field of food hygiene.