Performance evaluation of fuzzy rule-based classification systems obtained by multi-objective genetic algorithms

In this paper, we examine the classification performance of fuzzy if-then rules selected by a GA-based multi-objective rule selection method. This rule selection method can be applied to high-dimensional pattern classification problems with many continuous attributes by restricting the number of antecedent conditions of each candidate fuzzy if-then rule. As candidate rules, we only use fuzzy if-then rules with a small number of antecedent conditions. Thus it is easy for human users to understand each rule selected by our method. Our rule selection method has two objectives: to minimize the number of selected fuzzy if-then rules and to maximize the number of correctly classified patterns. In our multi-objective fuzzy rule selection problem, there exist several solutions (i.e., several rule sets) called “non-dominated solutions” because two conflicting objectives are considered. In this paper, we examine the performance of our GA-based rule selection method by computer simulations on a real-world pattern classification problem with many continuous attributes. First we examine the classification performance of our method for training patterns by computer simulations. Next we examine the generalization ability for test patterns. We show that a fuzzy rule-based classification system with an appropriate number of rules has high generalization ability.     

Scalability of hybrid programming for a CFD code on the Earth Simulator

The Earth Simulator (ES) is an SMP cluster system. There are two types of parallel programming models available on the ES. One is a flat programming model, in which a parallel program is implemented by MPI interfaces only, both within an SMP node and among nodes. The other is a hybrid programming model, in which a parallel program is written by using thread programming within an SMP node and MPI programming among nodes simultaneously. It is generally known that it is difficult to obtain the same high level of performance using the hybrid programming model as can be achieved with the flat programming model.

In this paper, we have evaluated scalability of the code for direct numerical simulation of the Navier–Stokes equations on the ES. The hybrid programming model achieves the sustained performance of 346.9 Gflop/s, while the flat programming model achieves 296.4 Gflop/s with 16 PNs of the ES for a DNS problem size of 256³. For small scale problems, however, the hybrid programming model is not as efficient because of microtasking overhead. It is shown that there is an advantage for the hybrid programming model on the ES for the larger size problems.     

Thermal behaviour and particle size evaluation of primary clusters in a water-based magnetic fluid

This paper reports the experimental research on thermal behaviour and particle size evaluation of primary clusters of ferromagnetic nano-particles in a water-based magnetic fluid. The magnetic fluids are suspensions of ultra fine particles coated with a molecular layer of dispersant in a liquid carrier such as water or kerosene. The particles are coated with single- or double-layer of surfactant to achieve stable dispersion. Numerous experimental studies have indicated the existence of the primary cluster of ferromagnetic nano-particles in a water-based magnetic fluid. The purpose of this research is to evaluate the particle size of the primary clusters by applying the Einstein's equation for Brownian motion assuming that the primary cluster has a spherical-shape. The thermal behaviour of ferromagnetic nano-particles in magnetic fluids is investigated through the micro visualization using the optical darkfield microscope system and particle tracking velocimetry data processing system. Real-time visualization of the Brownian motion of primary clusters in a water-based magnetic fluid was carried out. The experimental results clarified that the primary cluster size depends upon the concentration of the ferromagnetic nano-particle in the magnetic fluid.     

The Atmospheric Scanning Electron Microscope with open sample space observes dynamic phenomena in liquid or gas

Although conventional electron microscopy (EM) requires samples to be in vacuum, most chemical and physical reactions occur in liquid or gas. The Atmospheric Scanning Electron Microscope (ASEM) can observe dynamic phenomena in liquid or gas under atmospheric pressure in real time. An electron-permeable window made of pressure-resistant 100 nm-thick silicon nitride (SiN) film, set into the bottom of the open ASEM sample dish, allows an electron beam to be projected from underneath the sample. A detector positioned below captures backscattered electrons. Using the ASEM, we observed the radiation-induced self-organization process of particles, as well as phenomena accompanying volume change, including evaporation-induced crystallization. Using the electrochemical ASEM dish, we observed tree-like electrochemical depositions on the cathode. In silver nitrate solution, we observed silver depositions near the cathode forming incidental internal voids. The heated ASEM dish allowed observation of patterns of contrast in melting and solidifying solder. Finally, to demonstrate its applicability for monitoring and control of industrial processes, silver paste and solder paste were examined at high throughput. High resolution, imaging speed, flexibility, adaptability, and ease of use facilitate the observation of previously difficult-to-image phenomena, and make the ASEM applicable to various fields.     

Lower Irritation Potential of Laureth‐3 Carboxylate Amino Acid Salt

Sodium laureth sulfate and amino acid type surfactants have been categorized as low‐skin irritation chemicals based on results of previous skin irritation tests. However, detergent‐induced skin irritation still occurs. Detergents with a low‐skin irritation effect are required, since the number of cosmetics for sensitive skin has increased. Therefore, an in vitro method of testing the safety of cosmetics for sensitive skin is required. Skin irritation by anionic surfactants was investigated to determine the effect of laureth‐3 carboxylate (polyoxyethylene lauryl carboxymethyl ether) amino acid salt on skin irritation. In addition, sodium laureth sulfate and amino acid type surfactants, regarded as low‐irritation surfactants, were also tested for skin irritation. The skin irritation effect of laureth‐3 carboxylate lysine salt (Surfactant 1 ), sodium laureth sulfate (Surfactant 2 ), and sodium N‐lauroyl glutamate (Surfactant 3 ) were investigated using a reconstructed human cultured epidermal model, LabCyte EPI‐MODEL24 6D. Cell viabilities of cultured epidermal cells exposed to Surfactant 1 (5.0 % aq.), Surfactant 2 , and Surfactant 3 were 82.0, 45.0 and 19.1 %, respectively. There were significant differences in cell viability upon exposure to 5.0 % aqueous test solutions of the three test chemicals. The results of the current investigation indicate that Surfactant 1 has a low skin‐irritation effect.     

Anomalous oxide scale formation under exposure of sodium containing gases for solid oxide fuel cell alloy interconnects

Reactivity of oxide scale on Fe-Cr alloy with Na-containing gases was examined to estimate the stability against sodium (Na): vapors of NaCl and Na₂SO₄ exposures with air flow at 1073 K. The identified reaction phases were Cr-Mn spinel, Cr₂O₃, and alloy from the X-ray diffraction of surface with no Na-reaction products. However, the protective oxide scales (Mn-Cr spinel and Cr₂O₃ layers) on the Fe-Cr alloy were partially decomposed by reacting with Na to form Na-compounds inside the oxide scale/alloy interfaces. In some parts, anomalous oxide scales were found around the oxide scale/Fe-Cr alloy interfaces, with forming Na-rich compounds: the compounds were distributed inner parts of oxide scales around oxide scale/alloy interfaces. The stability of oxide scales and degradation were discussed based on the observed distribution of elements.     

Microstructural analysis of the stir zone of Al alloy produced by friction stir spot welding

The present study applied friction spot joining (FSJ), which was recently developed as a lap joining technique of Al alloys, to two sheets of Al alloy 6061, 1 mm in thickness, and then examined the microstructural feature in the weld. The weld had the nugget-shaped stir zone around the exit hole of the probe, and the stir zone exhibited the equiaxed grain structure having finer grain size than that of the base material. The crystallographic texture analysis using electron backscattered diffraction method suggested that the material movement occurred along the rotating direction of the welding tool in the wide region including the stir zone. In the periphery of the nugget-shaped stir zone, which was characterized as the region having the finer grain size than that of the stir zone interior, any inclusions and precipitates were not found in the SEM scale. The weld was softened around the weld centre. The softening could be explained by dissolution and/or growth of the strengthening precipitates due to thermal cycle of FSJ.     

Determination of sucralose in foods by HPLC using pre-column derivatization

The development of a sensitive pre-column derivatization high-performance liquid chromatography (HPLC) method for determination of sucralose is reported. Sucralose is converted into a strongly ultraviolet (UV)-absorbing derivative, possessing strong absorption at 260 nm, by treatment with p-nitrobenzoyl chloride (PNBCl). Homogenized samples were dialyzed and washed with a Bond Elut ENV cartridge, then the eluate was evaporated to dryness and the residue was derivatized. Subsequently, the sucralose derivative was purified with hexane-ethyl actate (9:1) in a silica cartridge, and then the sucralose derivative was eluted with acetone. HPLC was performed on a phenyl column, using acetonitrile-water (73:27) as a mobile phase with UV detection (260 nm). The calibration curve was linear in the range of 1 microgram/mL to 50 micrograms/mL of sucralose. The recoveries of sucralose from eight kinds of foods spiked at the levels of 0.20 and 0.05 g/kg of sucralose were more than 76.2% with SD values in the range from 0.90% to 4.31%. The quantitative limit of the developed method was 0.005 g/kg for sucralose in samples.