Effect of CNTs on Activation Volume and Mobile Dislocation Exhaustion Rate of CNTs/Al under Compression Loading

In this study, stress relaxation compression tests were performed to investigate the strain rate sensitivity, activation volume and mobile dislocations in carbon nanotubes/aluminum (CNTs/Al) composites. The results reveal that, with the addition of CNTs, the strain rate sensitivity of CNTs/Al increased. Meanwhile, a smaller V^* of CNTs/Al compared with pure Al was attributed mainly to the CNT-Al interfaces and partly to the increased forest dislocations cutting activities in grain interior, which was related to the tendency of short ranges order formation during plastic deformation. The incorporation of CNTs also improved the dislocation storage capability and reduced the dislocation velocity, leading to a lower mobile dislocation exhaustion rate.     

Comparison Study on Additive Manufacturing (AM) and Powder Metallurgy (PM) AlSi10Mg Alloys

The microstructural and mechanical properties of AlSi10Mg alloys fabricated by additive manufacturing (AM) and powder metallurgy (PM) routes were investigated and compared. The microstructures were examined by scanning electron microscopy assisted with electron-dispersive spectroscopy. The crystalline features were studied by x-ray diffraction and electron backscatter diffraction. Room-temperature tensile tests and Vickers hardness measurements were performed to characterize the mechanical properties. It was found that the AM alloy had coarser Al grains but much finer Si precipitates compared with the PM alloy. Consequently, the AM alloy showed more than 100% increment in strength and hardness compared with the PM alloy due to the presence of ultrafine forms of Si, while exhibiting moderate ductility.     

Fabrication of magnesium based composites reinforced with carbon nanotubes having superior mechanical properties

Magnesium (Mg) composite reinforced with carbon nanotubes (CNTs) having superior mechanical properties was fabricated using both pure Mg and AZ61 Mg alloy matrix in this study. The composites were produced via powder metallurgy route containing wet process using isopropyl alcohol (IPA) based zwitterionic surfactant solution with unbundled CNTs. The produced composites were evaluated with tensile test and Vickers hardness test and analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD). As a result, only with AZ61 Mg alloy matrix, tensile strength of the composite was improved. In situ formed Al₂MgC₂ compounds at the interface between Mg matrix and CNTs effectively reinforced the interfacial bonding and enabled tensile loading transfer from the Mg matrix to nanotubes. Furthermore, it was clarified that the microstructures and grain orientations of the composite matrix were not significantly influenced by CNT addition.     

The texture and anisotropy of hot extruded magnesium alloys fabricated via rapid solidification powder metallurgy

Rapid solidification magnesium alloy powders produced by spinning water atomization process were hot extruded into rectangular bars, from which tensile and compression samples have been cut at 0°, 45° and 90° angles from the extrusion direction to study their anisotropy. Electron back-scattered diffraction analysis has been used to investigate the texture evolution during the extrusion process. Texture parameters like the Schmid factor and the intensity of (0 0 0 1) basal plane in the pole figure have been evaluated and correlated to the mechanical properties. Results have shown that the extruded rods exhibited high strength and relatively less anisotropy compared to other previously reported values for wrought magnesium alloys. Tensile and compression yield stresses have shown very similar values to each other at all loading directions. This limited anisotropy could be linked to both the fine grained and inter-metallic-compound-dispersed microstructure of the extruded alloys. Dynamic recrystallization behavior during hot extrusion has also been investigated in the present study.     

Proposal of cause–effect pattern library for realizing sustainable businesses

Sustainable business design has gained growing interest in recent years. However, it is often difficult to clarify which business activities actually contribute to (or violate) the sustainability of the earth due to high complexity of environmental and economical system of our society. In order to help a business to generate sustainable business ideas handling this complexity in a systematic and comprehensive manner, this paper proposes a method to formulate a wide variety of causalities in our society into a cause–effect pattern library and illustrates how to use it for design and planning of sustainable businesses.     

Investigation of direct load management scheme with consideration of end‐user comfort

A direct load management scheme with two‐way communication, with consideration of end‐user comfort, is proposed. First, the control algorithm is developed and the data required to be transmitted between system operator and controllable loads are identified. Then, the actions of controllable air conditioners and the power adjustment of dispersed generators to eliminate overloads in a substation transformer are simulated. The results indicate that the proposed load management technique performs effectively to reduce overloads on the transformer while maintaining energy consumption in each load, and the performance is improved by coordination with the output of dispersed generators. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(3): 19–28, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21139     

Design of new catalysts for ecological high-quality transportation fuels by combinatorial computational chemistry and tight-binding quantum chemical molecular dynamics approaches

Recently, we introduced a concept of combinatorial chemistry to computational chemistry and proposed a new method called “combinatorial computational chemistry”, which enables us to perform a theoretical high-throughput screening of catalysts. In the present paper, we reviewed our recent application of our combinatorial computational chemistry approach to the design of new catalysts for high-quality transportation fuels. By using our combinatorial computational chemistry techniques, we succeeded to predict new catalysts for methanol synthesis and Fischer–Tropsch synthesis. Moreover, we have succeeded in the development of chemical reaction dynamics simulator based on our original tight-binding quantum chemical molecular dynamics method. This program realizes more than 5000 times acceleration compared to the regular first-principles molecular dynamics method. Electronic- and atomic-level information on the catalytic reaction dynamics at reaction temperatures significantly contributes the catalyst design and development. Hence, we also summarized our recent applications of the above quantum chemical molecular dynamics method to the clarification of the methanol synthesis dynamics in this review.     

Applications of in-line oxygen monitoring to a rapid thermal processing tool: diagnosing gas flow dynamics and silicidation processes

Two types of application of real-time oxygen monitoring on a production-type rapid thermal processor (RTP) are reported. Diagnosing of gas flow dynamics in an RTP chamber is described by using a tracer technique. Deviation from plug flow, which decreases purge efficiency, was observed as a function of gas flow rate. Purge design is performed on the basis of the gas flow dynamics, and the efficiency of several purge patterns was comparatively studied. Monitoring of a typical two-step RTP process for silicidation of Ti or Co was then demonstrated. Both adsorption and desorption were found to take place during annealing. Oxygen desorbs first at lower temperature (during temperature ramp) and then starts to adsorb at higher temperature. A few monolayers of oxygen is adsorbed to Ti during annealing, while less oxygen is adsorbed during Co RTP.     

Synthesis of Dense Lead Titanate Ceramics with Submicrometer Grains by Spark Plasma Sintering

Dense PbTiO₃ ceramics consisting of submicrometer-sized grains were prepared using the spark-plasma-sintering (SPS) method. Hydrothermally prepared PbTiO₃ (0.1 μm) was used as a starting powder. The powder was densified to ≳98% of the theoretical X-ray density by the SPS process. The average grain size of the spark-plasma-sintered ceramics (SPS ceramics) was ≲1 μm, even after sintering at 900°–1100°C, because of the short sintering period (1–3 min). The measured permittivity of the SPS ceramics showed almost no frequency dependence over the range 10¹–10⁶ Hz, mainly because pores were absent from the ceramics. The coercive field of the SPS ceramics was somewhat higher than that of conventionally sintered ceramics, which could be attributed to the small-grained microstructures of the SPS ceramics.     

Inter-laboratory validation studies of biological method for determination of streptomycin in royal jelly

Inter-laboratory validation studies were conducted in 6 laboratories to validate the biological method for determination of streptomycin in royal jelly. Streptomycin spiked at the level of 0.2 and 1.0 ppm was analyzed. Mean recoveries were 89 and 96%, reproducibility relative standard deviations (RSD(R)) were 15.0 and 14.0%, HORRAT(R) values were 0.7 and 0.9. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 113 and 99%, RSD(R) were 15.0 and 10.4%, and HORRAT(R) values were 0.8 and 0.6. The determination limit was 0.1 ppm. These results show that this method has good performance.