High-performance tantalum oxide capacitors fabricated by a novelreoxidation scheme

High-performance tantalum oxide capacitors with excellent reliability that were developed by a two-step oxidation scheme are discussed. An anodic reoxidation process is applied to the reactively sputter-deposited tantalum oxide films to make the densified oxide structure. The electrical and physical properties as well as the reliability of these two-step oxidized sputtered/anodized tantalum oxide films are shown to be much superior to those of conventional tantalum oxide films prepared by either anodization or sputtering alone. Capacitors made of the sputtered/anodized tantalum oxide film have greatly improved electrical properties and better reliability than anodized or sputtered tantalum oxide capacitors and are very useful for applications to high-capacity storage capacitors in future high-density VLSI memories     

Effect of the nitrogen inducing agents on the corrosion behavior of AlON-Al2O3 coatings prepared by electrolytic plasma processing on an Al6061 alloy

The electrolytic plasma processing method was used to prepare AlON-Al₂O₃ oxide coatings on an Al6061 alloy at room temperature in 15 min at a hybrid voltage with various nitrogen inducing agents. The nitrogen inducing effects were studied by X-ray diffractometer and scanning electron microscopy. The corrosion behavior of the coating was evaluated by electrochemical tests in a 3.5 wt% NaCl solution under static conditions by open circuit potential and potentiodynamic polarization. The results show that NaNO₂ is a suitable steady nitrogen inducing agent for preparing a uniform and dense AlON-Al₂O₃ coating on the Al6061 alloy to protect the substrate.     

Sm-doped CaTiO3 phosphor: Synthesis, structure, and photoluminescent properties

Photoluminescent properties of samarium-doped calcium titanate for near ultra-violet excitation were studied. CaTiO₃:Sm³⁺ phosphor was synthesized by using the solid-state reaction method. The structure and properties of the phosphor were characterized by using X-ray diffractometer, scanning electron microscope, UV-visible spectrophotometer, high-resolution secondary ion mass spectrometer, and X-ray photoelectron spectrometer. The photoluminescent properties were studied by taking excitation and emission spectra. A strong red-orange luminescence corresponding to ⁴G_5/2 → ⁶H_7/2 transition of Sm³⁺ for near ultra-violet excitation was observed. It was found that CaTiO₃:Sm³⁺ was a red-orange emitting phosphor and had higher efficiency for the operation with near ultra-violet excitation.     

Temperature oscillations in methanol partial oxidation reactor for the production of hydrogen

Methanol partial oxidation (POX) is a well-known reforming reaction for the production of hydrogen from methanol. Since POX is relatively fast and highly exothermic, this reforming method will be efficient for the fast startup and load-following operation. However, POX generates hot spots around catalyst and even oscillations in the reactor temperature. These should be relieved for longer operations of the reactor without catalyst degradations. For this, temperature oscillations in a POX reactor are investigated experimentally. Various patterns of temperature oscillations according to feed flow rates of reactants and reactor temperatures are obtained. The bifurcation phenomena from regular oscillations to chaotic oscillations are found as the methanol flow rate increases. These experimental results can be used for theoretical analyses of oscillations and for designing safe reforming reactors.     

Carbon fiber coating with silver using intervening Au/Pd nanoparticle films produced using a spark discharge

A low roughness conductive silver film on a fiber substrate was fabricated via a catalytic surface activation (needed to initiate electroless silver deposition) with spark produced gold aerosol nanoparticles. Gold had a similar lattice parameter with silver in crystallinity and thus a crystallographic misfit between gold activated substrate and silver was minimized during the deposition, resulting in formation of a flat silver film. Properties were compared with those obtained with palladium aerosol activation, the gold activation enhanced thin-metallic film properties in surface root-mean-square roughness (nm: 8, gold vs 44, palladium) and electrical resistivity (μΩ cm: 64, gold vs 498, palladium) at 88 mg/g (silver/substrate) in deposition amount.     

An experimental study on the effect of tow variations on compressive characteristics of plain weave carbon/epoxy composites under compressions

The effect of tow deformation on the static and fatigue characteristics of fabric composites under compression was investigated by experimental approach. Sheared specimens made of plain weave carbon/epoxy prepregs were prepared using a picture frame rig and the shear angles were 0°, 16°, 26°, 34°, 46°. To verify the effect of the tow variations of the fabric composites on compressive characteristics, the unidirectional composite specimens composed of the same fibre and matrix system with the same stacking sequences as the fabric composites were prepared for comparison. The static compressive test results showed that the static compressive strength of sheared fabric specimens was lower than that of the unidirectional specimens with the same stacking angle. On the other hand, the fatigue test results showed that fatigue life of sheared fabric specimens was higher than that of the unidirectional specimens for mild shear deformation cases. It was proved that these results were fully affected by the tow deformation caused by the shear deformation of the fabric specimens. The compression–compression fatigue behaviours of sheared fabric specimens were verified by appropriate unit-cell models.     

Study of microcellular injection-molded polypropylene/waste ground rubber tire powder blend

Microcellular polypropylene/waste ground rubber tire powder blend processing was performed on an injection-molding machine with a chemical foaming agent. The molded samples produced based on the design of experiments (DOE) matrices were subjected to tensile testing and scanning electron microscope (SEM) analyses. Molding conditions and waste ground rubber tire (WGRT) powder have been found to have profound effects on the cell structures and mechanical properties of polypropylene (PP) and waste ground rubber tire powder composite samples. The result shows that microcellular PP/WGRT blend samples exhibit smaller cell size and higher cell density compare with polypropylene resin. Among the molding parameters studied, chemical foaming agent weight percentage has the most significant effect on cell size, cell density, and tensile strength. The results also suggest that tensile strength of microcellular PP/WGRT composites is sensitive to weight reduction, and skin thickness.     

Optimal job scheduling in grid computing using efficient binary artificial bee colony optimization

The artificial bee colony has the advantage of employing fewer control parameters compared with other population-based optimization algorithms. In this paper a binary artificial bee colony (BABC) algorithm is developed for binary integer job scheduling problems in grid computing. We further propose an efficient binary artificial bee colony extension of BABC that incorporates a flexible ranking strategy (FRS) to improve the balance between exploration and exploitation. The FRS is introduced to generate and use new solutions for diversified search in early generations and to speed up convergence in latter generations. Two variants are introduced to minimize the makepsan. In the first a fixed number of best solutions is employed with the FRS while in the second the number of the best solutions is reduced with each new generation. Simulation results for benchmark job scheduling problems show that the performance of our proposed methods is better than those alternatives such as genetic algorithms, simulated annealing and particle swarm optimization.