Effects of cononsolvency on gelation of poly(vinyl alcohol) in mixed solvents of dimethyl sulfoxide and water

We studied the rates of gelation and phase separation of poly(vinyl alcohol) (PVA) solutions in mixtures of dimethyl sulfoxide (DMSO) and water at 25 °C and found that both the rates show a maximum at a volume fraction of DMSO φ_DMSO=0.60 while gelation was not observed either in pure DMSO or pure water, suggesting that water-DMSO is a cononsolvent system for PVA. On the basis of the data by Cowie [Can J Chem 36 (1961) 2240] we concluded that the 1:2 stable complex between one DMSO molecule and two water molecules is the main cause of this cononsolvency.     

Measurement of self-diffusion coefficients in Li ionic conductors by using the short-lived radiotracer of 8Li

For the effective use of short-lived radioactive beams, soon to be available at the Tokai Radioactive Ion Accelerator Complex, the authors have developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound βLiAl using an α-emitting radiotracer of ⁸Li (T_1/2=0.84 s). It was found that the time-dependent yields of the α particles from the diffusing ⁸Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in βLiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects (i.e., the existence of the atomic vacancies of Li and the defects in Ga sites that are replaced by Li).     

Design of moving magnet type pickup actuator using inserted coil

Recently, the demand of the information storage devices with large storage capacity such as Blu-ray Disc and high-definition television is increased. In keeping with this trend, the optical storage devices are also required to have high data transfer rate and large storage capacity. To satisfy these requirements, the actuator for optical disc drive should have a high servo bandwidth to compensate the vibration of optical disc. The servo bandwidth is limited by some flexible modes of the actuator, thus it is essential to make these frequencies of flexible modes to high frequency region. The frequency of flexible mode depends on materials and shape. Stiff materials and simple shape is useful to increase the frequency of flexible mode. In this paper, we suggested a moving magnet type actuator having flexible modes which are happened at high frequency region. Generally, the moving magnet type actuator has an advantage to increase the frequency of flexible mode because the moving magnet type actuator has simple structure and the Young’s modulus of magnet is high. However, large moving mass and inefficiency of Electromagnetic (EM) circuit cut down driving sensitivities of actuator. To improve driving sensitivities, we designed the model with the closed EM circuit for tracking actuation. The design of experiments (DOE) procedure is applied to get proper design parameters and the variable metric method (VMM) which is a technique of optimization is used to improve driving sensitivity. The lens holder is also improved based on the optimization result of EM circuit. And to make up for the low efficiency of EM circuit, the thermal stability is checked on condition that the input current is very high. At last, the final design of moving magnet type actuator is suggested and it is verified that the driving performance and the structural stiffness of the final design is sufficient.     

Logic circuit synthesis using Prolog

This paper briefly reviews the current use of CAD in logic design, and then describes an expert system used to synthesize logic circuits. Specialized knowledge dealing with standard TTL ICs is written in Prolog and AGE, and the results are compared.     

Decoupling properties of singular LQ regulation problem

Some properties of a limiting solution derived from a standard LQ regulator problem are discussed in the case where the input weighting matrix tends to zero, for a discrete time system. The explicit limiting solution is given in some literature. It is shown that the limiting solution is closely connected with a disturbance decoupling problem. Moreover it is pointed out that the limiting feedback gain with the help of feedforward gain constructs the decoupled system with the maximum number of blocks.     

An order acceptance strategy under limited engineering man-hours for cost estimation in Engineering–Procurement–Construction projects

Accurate cost estimation is essential for any Engineering–Procurement–Construction (EPC) contractor accepting profitable projects because the project price is determined prior to receiving the contract. Therefore the contractor needs to ensure engineering man-hours (MH) in order to estimate project costs accurately as well as carry out the accepted orders. In this paper, we develop MH based order acceptance strategies and investigate their effects on the total expected profit through a long-term operation in EPC projects under a competitive bidding situation. To this end we build a simulation model describing relations among the volume of MH for cost estimation, accepted orders, revenues, and profits in EPC projects. Using our model, we show that the strategy, which maintains the appropriate balance of MH for cost estimation and project execution under the variability of accepted orders with competitive bidding situations, improves the total expected profit in EPC projects.     

Syntheses of Spinon Thermal Conductivity Materials in Sr–Cu–O System by Glass‐Ceramics Technique

We have synthesized spinon thermal conductivity materials in Sr–Cu–O system by glass‐ceramics technique. The materials are promising for active control of thermal energy in microelectronic devices because of high and anisotropic thermal conduction, its controllability, and electric insulation. Nevertheless, research on these materials has been limited to that concerning theoretical perspectives and investigation of physical properties using large single crystals. In this study, we adopt glass‐ceramics technique to synthesize these materials: We prepared melt‐quenched multicomponent oxides including SrO and CuO, and checked its glass‐forming ability and crystallization behaviors by heating. As a result, we have found that SrCuO₂ and Sr₁₄Cu₂₄O₄₁, known as the spinon thermal conductivity materials, are synthesized using SrO–CuO–?Li₂O–?Al₂O₃?–Ga₂O₃ system. This synthesis process for the system will provide practical application of the spinon thermal conductivity materials.     

Friction-induced ultra-fine and nanocrystalline structures on metal surfaces in dry sliding

Sliding friction tests of pin-on-disc type were carried out for carbon steel, pure iron and pure copper, and the microstructure and hardness near the sliding surfaces were investigated in detail. It was found that patchy transfer layers with ultra-fine (<200 nm) structures were produced on the disc surfaces. Nanocrystalline grains of 30–50 nm were identified for carbon steel, and submicron sized grains of 100–150 nm were observed in pure copper. The thicknesses of the ultra-fine structures were in the range of 10–50 μm, depending on the specimen material, sliding speed and applied load. The hardness near the sliding surface of pure iron was increased compared with the matrix. It was suggested that the hardening was due to the very fine structure formed by severe plastic deformation, but not due to phase transformation caused by thermal effects.     

Corrosion characteristics of reduced activation ferritic steel, JLF-1 (8.92Cr–2W) in molten salts Flibe and Flinak

Static corrosion tests were performed in molten salts, LiF–BeF₂ (Flibe) and LiF–NaF–KF (Flinak), at 500 °C and 600 °C for 1000 h. The purpose is to investigate the corrosion characteristics of reduced activation ferritic steels, JLF-1 (8.92Cr–2W) in the fluids. The concentration of hydrogen fluoride (HF) in the fluids was measured by slurry pH titration method before and after the exposure. The HF concentration determined the fluoridation potential. The corrosion was mainly caused by dissolution of Fe and Cr into the fluids due to fluoridation and/or electrochemical corrosion. Carbon on the surface might be dissolved into the fluids due to the corrosion, and this resulted to the decrease of carbide on the surface. The corrosion depth of the JLF-1 specimen, which was obtained from the weight losses, was 0.637 μm in Flibe at 600 °C and 6.73 μm in Flinak at 600 °C.