The oxidative coupling of methane on alkali- and alkaline earth-phosphate catalysts

The oxidative coupling of methane has been tested over alkali- and alkaline earth-phosphate catalysts at 700 and 775 °C with and without the introduction of a small quantity of tetrachloromethane (TCM) to the feedstream. In general, the conversion of methane was enhanced by the addition of TCM but the effect on selectivity was dependent on the catalyst being examined. The selectivity to C₂ and higher hydrocarbons and that to oxidation products have been shown to have a dependence on the cation radius/charge ratio.     

Prediction model of surface residual stress within a machined surface by combining two orthogonal plane models

The variation of surface residual stress within a machined surface layer caused by face turning was studied. The size of the tool’s corner radius and the feed rate affect residual stress. A process model using the finite element method is proposed and the mechanical effects of the corner radius and feed rate on a machined surface were discussed. When a tool with a small corner radius is used, surface residual stress perpendicular to the cutting direction becomes compression stress. As well, surface residual stress changes from tension to compression as the feed rate decreases. The process model consists of an orthogonal cutting simulation and an indentation-like simulation of a corner radius into a work piece surface. The simulated results show quantitative agreement with the residual stress measured experimentally. The integrity of the machined surface will be controlled more efficiently if the cutting conditions during finishing are determined with the proper consideration of the surface generating process.     

Development of low thermal expansion superalloy

Alloy 903 and Alloy 909 are well-known Fe-Co-Ni-Al-Ti-Nb alloys with controlled low thermal expan-sion, but they have some properties that can be improved. To improve stress-accelerated grain boundary oxidation embrittlement of Alloy 903 and instability of theγ phase of alloy 909, two new alloys with good stress-rupture ductility, high creep-rupture strength, high tensile strength at high temperature, and good controlled thermal expansion were developed. These property improvements were accomplished by the combination of optimizing the Fe-Co-Ni ratio of the matrix and stabilizing theγ phase with the addition of aluminum.     

An Advanced Oscillation Mixing Method for Improving the Cooling Uniformity in Quenching

In quenching, the cooling uniformity is most important to diminish distortion occurring on work pieces. As a trial to accomplish uniform cooling, therefore, there exist various mixing methods of a quenchant and the quenchant circulation with an external pump has so far been the well accepted mixing method. However, this study proposes an advanced oscillation mixing method that can improve more the cooling uniformity in quenching. The proposed method includes a stirrer in oscillating motion, so that the simultaneous oscillating and mixing movements of the stirrer are considered to provide efecfively the uniform cooling characteristics for the quenchant. In comparison with the case of the circulation pump mixing, the investigation using the oscillation mixing method has demonstrated the following two experimental facts:(1) the short vapor blanket stage caused by the quick breakage of the oil vapor blanket and (2) the reduced variation of the quenching distortion.     

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).     

Chain-reaction solution update in MOEA/D and its effects on multi- and many-objective optimization

MOEA/D is one of the promising evolutionary algorithms for multi- and many-objective optimization. To improve the search performance of MOEA/D, this work focuses on the solution update method in the conventional MOEA/D and proposes its alternative, the chain-reaction solution update. The proposed method is designed to maintain and improve the variable (genetic) diversity in the population by avoiding duplication of solutions in the population. In addition, the proposed method determines the order of existing solutions to be updated depending on the location of each offspring in the objective space. Furthermore, when an existing solution in the population is replaced by a new offspring, the proposed method tries to reutilize the existing solution for other search directions by recursively performing the proposed chain-reaction update procedure. This work uses discrete knapsack and continuous WFG4 problems with 2–8 objectives. Experimental results using knapsack problems show the proposed chain-reaction update contributes to improving the search performance of MOEA/D by enhancing the diversity of solutions in the objective space. In addition, experimental results using WFG4 problems show that the search performance of MOEA/D can be further improved using the proposed method.     

Unitary equivalent classes of one-dimensional quantum walks

This study investigates unitary equivalent classes of one-dimensional quantum walks. We prove that one-dimensional quantum walks are unitary equivalent to quantum walks of Ambainis type and that translation-invariant one-dimensional quantum walks are Szegedy walks. We also present a necessary and sufficient condition for a one-dimensional quantum walk to be a Szegedy walk.     

Repeatedly foldable AMOLED display

In this study, a 5.9‐inch foldable active‐matrix organic light emitting diode (AMOLED) display was developed. A folding test was performed repeatedly. The display survived the folding test (100,000 folds) with a curvature radius of 2 mm. To protect an organic light emitting diode (OLED) against moisture, inorganic passivation layers are provided on the upper and lower sides of the flexible display. Using our transfer technology, high density passivation layers can be obtained. The measured water vapor transmission rate of the layer is 7 × 10^?6 g/m²?day or less, which improves OLED reliability. With these techniques, we have developed a book‐type display, which is repeatedly foldable like a book, and a tri‐fold display including a display area, which is foldable in three.     

Variable space diversity, crossover and mutation in MOEA solving many-objective knapsack problems

In this work, we analyze variable space diversity of Pareto optimal solutions (POS) and study the effectiveness of crossover and mutation operators in evolutionary many-objective optimization. First we examine the diversity of variables in the true POS on many-objective 0/1 knapsack problems with up to 20 items (bits), showing that variables in POS become noticeably diverse as we increase the number of objectives. We also verify the effectiveness of conventional two-point and uniform crossovers, Local Recombination that selects mating parents based on proximity in objective space, and two-point and uniform crossover operators which Controls the maximum number of Crossed Genes (CCG). We use NSGA-II, SPEA2, IBEA _??+? and MSOPS, which adopt different selection methods, and many-objective 0/1 knapsack problems with $n=\{100,250,500,750,\mbox{1,000}\}$ items (bits) and m?=?{2,4,6,8,10} objectives to verify the search performance of each crossover operator. Simulation results reveal that Local Recombination and CCG operators significantly improve search performance especially for NSGA-II and MSOPS, which have high diversity of genes in the population. Also, results show that CCG operators achieve higher search performance than Local Recombination for m?≥?4 objectives and that their effectiveness becomes larger as the number of objectives m increases. In addition, the contribution of CCG and mutation operators for the solutions search is analyzed and discussed.