Development of the visible light communication device for swarm using nonlinear synchronization

This paper describes development of a visible light 4 Pulse position modulation (4PPM) data communication device for underwater swarms using a nonlinear synchronizing system. SWARM—a group robot that uses intelligence as a group—do as ants and bees, is expected to be useful for marine resource exploration. Specifically, numerous SWARMs will be grouped to explore marine resources efficiently. An important difficulty is the change in electronic circuit characteristics because of high water pressure in the deep sea. Development of small and simple underwater SWARM communication devices must eliminate this problem without using large pressure-proof containers. As described herein, we considered nonlinear synchronizing systems as effective because they can be synchronized even if system time constants differ. Such systems resemble the glow mechanism used by fireflies. They have individuality, but they flash synchronously when in a group. We developed a visible light communication device using this nonlinear synchronization system based on the firefly concept. Test results confirmed that they are synchronized even if a time constant difference exists between them. Furthermore, we achieved 4PPM data communication using the nonlinear synchronization signal as a communication clock.     

DIFFUSION COEFFICIENTS OF CARBON DIOXIDE WITHIN TYPE 13X ZEOLITE PARTICLES

The self-diffusion processes of CO₂ in a single particle of commercial type 13X zeolite have been studied by a new sorption rate method using a constant volume, variable pressure system. Experiments were carried out at 303.2 and 343.2 K. An inverse analysis of experimental uptake curves based on a macropore and micropore series diffusion model was performed to determine effective diffusion coefficients for both macropore and micropore diffusion simultaneously. Knudsen diffusion occurs within the macropore and the micropore diffusion coefficients having values of the order 10^-15-10^-14 m²/s, which are slightly greater than the previously reported micropore diffusion coefficients of type 5A zeolite crystals.     

The extraction of divalent cobalt,copper, zinc and cadmium from hydrochloric acid solutions by tri-n-butyl phosphate

The partition of divalent cobalt, copper, zinc and cadmium between hydrochloric acid solutions and solutions of tri-n-butyl phosphate (TBP) in benzene or kerosene has been investigated under different conditions. Further the absorption spectra of both the aqueous and organic phases have been studied, and the infrared spectra of the organic phases have been examined. It was found that the order of the extraction efficiency of TBP for divalent metalsis Zu > Cd > Cu > Co for [HCl]_aq < 8M and Zn > Cd > Co > Cu for [HCl]_aq > 8M.     

Characterization of a Large-Scale Nondoped YBa2Cu3O7−x Superconductor Prepared by Plastic Forming Without High-Pressure Molding

A slurry containing YBa₂Cu₃O_{7− x} particles and a fine YBa₂Cu₃(OH) _x colloid solution was prepared, and a large-scale bulk YBa₂Cu₃O_{7− x} superconductor (about 50 mm × 35 mm × 2 mm) was produced by plastic forming without high-pressure molding. The samples molded from the slurry were dried and then fired at 1223 K in air. X-ray diffraction data indicated that the samples had the characteristic orthorhombic YBa₂Cu₃O_{7− x} structure. Measurements of electrical resistance were carried out between 300 and 50 K by the standard four-probe DC electrical measurement. The samples began superconducting at an onset temperature around 92 K, and the full-transition temperature (critical temperature) ( T _c) was 88.7±1.4 K. The critical current density ( J _c) measured at 77 K was about 440 A/cm², the value of J _c was improved by the heat treatment under an oxygen atmosphere, and J _c=1.6 × 10³ A/cm² was observed. Under the magnetic field (B=1 T), the sample held its superconductivity, and demonstrated that this method can be used to produce the magnetic shielding used in magnetic resonance imaging diagnosis.     

Solute atmosphere around an edge dislocation in Al-based ternary alloys

We evaluated the solute atmosphere around a moving dislocation and the dragging stress due to the atmosphere in binary and ternary Al-based alloys in terms of a chemical potential gradient by modifying the method proposed by Yoshinaga et al. In ternary alloys, we analyzed formation of the complex solute atmosphere around a straight edge dislocation and the dragging stress in terms of a misfit parameter of a solute element (positive or negative) and an interaction parameter between solute elements (attractive or repulsive).     

Multiferroic nanocomposite fabrication via liquid phase using anodic alumina template

We report a novel and inexpensive fabrication process of multiferroic nanocomposite via liquid phase using an anodic alumina template. The sol-gel spin-coating technique was used to coat the template with ferrimagnetic CoFe₂O₄. By dissolving the template with NaOH aqueous solution, a unique nanotube array structure of CoFe₂O₄ was obtained. The CoFe₂O₄ nanotube arrays were filled with, and sandwiched in, ferroelectric BaTiO₃ layers by a sol-gel spin-coating method to obtain the composite. Its multiferroicity was confirmed by measuring the magnetic and dielectric hysteresis loops.     

An ESCA study of the Fe2+/Fe3+ ratio in passive films on iron-chromium alloys

X-ray photoelectron spectra of Fe $\text{2p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ electrons are measured for passive films on iron and FeCr alloys passivated for 1 h in 1M H₂SO₄ at + 100 and + 500 mV (s.c.e.). When chromium content of FeCr alloys increased to ca. 12 at.%, binding energy of Fe $\text{2p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ electrons from oxidized state shifted abruptly from ca. 710·3 to ca. 709·6 eV and no more change in binding energy was observed at high chromium content. This abrupt shift of binding energy is in accord with the fact that the Fe²⁺/Fe³⁺ ratio showed sharp increase at ca. 12 at.% chromium. This phenomenon can be attributed to the inhibition of oxidation of iron due to the change in film structure and properties.     

Relationship between Rice Flour Particle Sizes and Expansion Ratio of Pure Rice Bread

We examined a method to produce bread from crystalline rice flour without using thickening agents such as gluten, polysaccharide thickening, and amorphous rice flour. Rice grains were pulverized by a jet mill to produce flour. Samples of rice flours of various particle size distributions were prepared by using a size shifter. The degree of starch damage and the dynamic viscoelasticity of rice batter were measured in this work. We also baked bread of the flour of each size distribution to study processability for making bread. The batter made by the pulverized flour of rice particle size ranging from 75 to 106 μm had the highest expansion ratio and a good processability for baking breads compared to other particle size batters. The rice bread with high expansion ratio was produced by controlling particle size of crystalline rice flour without using thickening agents.