A novel strategy for microcomputer-based control of a single-phaseoutput cycloconverter

A novel control algorithm using a time process chart that is capable of accurate control of cycloconverters is developed. This algorithm is obtained by making a straight-line approximation in a newly contrived phase plane. In spite of its rather simple procedures, this algorithm is capable of highly accurate control that is comparable to that of the conventional analog scheme. A six-pulse noncirculating current-type cycloconverter is controlled with a small-scale interface and a high-speed control program. Experimental results confirm the validity and usefulness of the proposed method. As far as the processing time is concerned, this method could be used to control a system with a larger pulse number, such as a 12 or 24-pulse system     

Synthesis and hydrophilic property of polypropylene-graft-poly(polyethylene glycol-methacrylate) (PP-g-P(PEGMA))

Polypropylene-graft-poly(polyethylene glycol-methacrylate) (PP-g-P(PEGMA)), which is a hydrophobic-hydrophilic graft copolymer, was synthesized by a combination of an atom transfer radical polymerization (ATRP) of PEGMA with brominated polypropylene (PP-Br), which was synthesized from PP-OH prepared by metallocene-catalyzed copolymerization. Its structure was confirmed by ¹H NMR and GPC analyses. Transmission electron microscope (TEM) micrographs of PP-g-P(PEGMA) revealed the nanometer level microphase-separation morphology between the PP segment and the P(PEGMA) segment. The obtained PP-g-P(PEGMA) showed water-absorbing property as well as thermostability.     

Effects of welding residual stress on compressive behavior and ultimate strength of corroded plate

This study examined the effects of welding residual stress on the compressive behavior and the ultimate strength of the corroded plate. First, welding residual stress was obtained by the thermal elastic-plastic analysis. Then, the change of welding residual stress and the deflection due to the volume loss was investigated by using a newly developed program based on FEM. Finally, the effects of welding residual stress on the compressive behavior and the ultimate strength of the corroded plate were investigated by the elastic-plastic large deformation analysis. As results, the beginning point of the reduction of the initial stiffness with welding residual stress was earlier than that without welding residual stress. Such effect was observed significantly in the case that the volume was lost in the region which has compressive residual stress. Furthermore, the ultimate strength of the corroded plate was reduced by welding residual stress regardless of the plate length, the corroded regions and the reduction of the thickness. The effect of welding residual stress on the ultimate strength became small with the decrease of the thickness.     

Chained aggregation model with minimum truncation error

A reduced–order model for a multi–input single–output or a single–input multi–output continuous system is proposed. The model is especially suitable for the case where accuracy in the high-frequency region is important. It also satisfies basic conditions for reduced-order models, such as uniqueness, stability, and a simple calculation requirement. Chained aggregation with the minimization of truncation errors introduces an internal system representation characterized by a system matrix of Hessenberg form and a diagonalized covariance matrix.     

Study on environmental effect on fatigue and creep-fatigue strength of 316FR stainless steel in sodium at elevated temperature

Low-carbon 316 stainless steel with medium-nitrogen (316FR) is considered as the principal structural material for next generation fast breeder reactor (FBR) plants in Japan. The material strength standard and the creep-fatigue life evaluation method for 316FR have been developed. However, they are based on the results of material tests in air, while actual structural material will be used mainly in liquid sodium environment in the plants. In order to clarify the environmental effect, cyclic bending tests were carried out with and without hold time in sodium. Tested materials were 316FR and conventional 304 and 316 stainless steels. Weld metal of 316FR was also tested. As a result, it was found that fatigue and creep-fatigue lives of 316FR in sodium were larger than those in air and no explicit consideration of the environmental effect is necessary in design. It was also found that the life evaluation method based on the ductility exhaustion concept is applicable to creep-fatigue life assessment in sodium.     

Filter-embedded design and its applications to passive components

A design in which a filter is embedded in a fiber fixed on a substrate is proposed. It was successfully applied to the fabrication of low loss fiber optic components for a single-mode fiber transmission system. These components have a wide operational temperature range. The design is easily adapted to a multifilter or multifiber component. Filter embedding is achieved in two ways. One is to insert a thin filter chip in a slit which is machined into a fiber fixed on a substrate by a dicing saw (filter inserted type). The other is to evaporate a filter film directly on a fiber end face and butt this fiber to another fiber on a guide groove on a substrate (filter evaporated type)     

On the pseudo-freeness and the CDH assumption

The notion of pseudo-free group was first introduced by Hohenberger (Master’s thesis, EECS Dept., MIT, 2003). Rivest (TCC 2004. LNCS 2951, 505–521, 2004) formalized it and showed that several standard cryptographic assumptions hold on pseudo-free groups, such as the RSA assumption, the strong RSA assumption and the discrete logarithm assumption. Rivest (TCC 2004. LNCS 2951, 505–521, 2004) also proposed some variations of pseudo-free group, and those were formalized by Hirano and Tanaka (Research Reports, Series C: Computer Science, C-239, Tokyo Institute of Technology, 2007). In this paper, we study the relationships among such variations of pseudo-free group. We show that the pseudo-freeness implies the weak pseudo-freeness, and that the pseudo-freeness is equivalent to the pseudo-freeness with generalized exponential expressions. We also show that the computational Diffie-Hellman assumption holds on pseudo-free groups in a slightly varied form.     

Solvated structure of C60 nanowhiskers

This work characterizes the structure of C₆₀ nanowhiskers prepared by the liquid-liquid interfacial precipitation method in the C₆₀-saturated m-xylene and isopropyl alcohol system. Transmission electron microscopy and X-ray diffraction measurement show that the C₆₀ nanowhiskers had a hexagonal structure with cell dimensions a = 2.407 nm and c = 1.018 nm which is different from pristine C₆₀. The structure of the C₆₀ nanowhiskers in solution is different from that of the solvated structure reported for the C₆₀ nanotubes but similar to that reported for the C₆₀ bulk crystal solvated with m-xylene. X-ray diffraction analysis also showed a shift to fcc structure after solvent evaporation. The C₆₀ nanowhiskers prepared using toluene as solvent also showed a similar solvated structure, and a more rapid structural change into fcc upon drying was again observed.     

Fundamental study of high Q‐factor RF spiral inductor using carbonyl‐iron/epoxy composite magnetic core

In order to increase the Q‐factor of an RF spiral inductor used in the RF front‐end circuit of smartphone handsets, we introduced a carbonyl‐iron/epoxy composite magnetic core in the air‐core spiral inductor. The composite magnetic core, which was made by metal‐mask printing, consisted of carbonyl‐iron powder of 1.1 μm mean diameter and an epoxy resin matrix. We found that the 45 vol.% CIP composite magnetic core had a saturation magnetization of 0.9 T, relative permeability of ∼6, and loss tangent (tan δ) of ∼0.2 at 1 GHz. A two‐turn copper spiral inductor fabricated with the composite magnetic core filled only in the spacing between the conductor lines showed a clear Q‐factor increase of ∼29% compared to the air‐core spiral inductor at 1 GHz. Thus we obtained a substantial increase in the Q‐factor by the embedded composite magnetic core in the spacing between the conductor lines. The main reason for this is that the magnetic flux passing through the conductor lines was decreased by the magnetic core embedded in the spacing between conductor lines as a result of the magnetic flux passing mainly through the embedded magnetic core. Therefore, proximity effect is suppressed in the conductor line of the spiral coil. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Demand forecasting for production planning in remanufacturing

The International Journal of Advanced Manufacturing Technology - Remanufacturing is effective for energy and material savings; however, production planning and control in remanufacturing are more...