Fabrication of vertically aligned single-walled carbon nanotubes in atmospheric pressure non-thermal plasma CVD

A fabrication technique of high-purity vertically aligned single-walled carbon nanotubes (VA-SWCNTs) using atmospheric pressure plasma enhanced chemical vapor deposition is presented. Although densely mono-dispersed Fe-Co catalysts of a few nanometers is primarily responsible for VA-SWCNT growth, carbon precipitation was virtually absent in the thermal CVD regime at 700 °C. On the other hand, high-purity VA-SWCNTs without measurable defects were grown at 4 μm min⁻¹ by applying atmospheric pressure radio-frequency discharge (APRFD) which has been previously developed for this purpose. The results proved that cathodic ion sheath adjacent to the substrates, where a large potential drop exists, also plays an essential role for the controlled growth of SWCNTs, while ion damage to the VA-SWCNTs is inherently avoided due to high collision frequency among molecules in atmospheric pressure. Operation regime of APRFD and tentative reaction mechanisms for VA-SWCNT growth are discussed along with optical emission spectroscopy of near substrate region.     

An energy trading system with consideration of CO2 emissions

Abatement of CO₂ emission is one of the most important issues in the 21st century regarding preservation of the earth environment. This paper addresses a utility operations planning problem for distributed energy management systems (DEMSs), where we are to obtain optimal plans that minimize both costs and CO₂ emissions. A DEMS consists of multiple entities that seek their own economic profits. In this paper, we give a mathematical formulation of the utility operations planning problem for each entity, and propose an energy trading market, which utlizes a multi‐attribute auction protocol in order to deal with both a price and a CO₂ emission rate. Experimental results show that collaboration among entities through the market provides a more profitable plan for each entity and abatement of CO₂ emission is also achieved. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 54–63, 2008; Published online in Wiley InterScience ( www.interscience.wiley. com ). DOI 10.1002/eej.20418     

Preparation of novel porous solids from alumina-pillared fluorine micas by acid-treatment

New porous solids from alumina-pillared fluorine micas (APMs), which were obtained from synthetic Na-tetrasilicic fluorine mica [NaMg_2.5Si₄O₁₀F₂], were prepared by sulfuric acid-treatment under mild conditions at 25 °C. The products were investigated by XRD, ICP, SEM, TEM and N₂ adsorption–desorption isotherm at 77 K. XRD measurements indicated that the interlayer pillared structure having a large basal spacing collapsed during the early stages of the acid-treatment. ICP analyses indicated that Al³⁺ and Mg²⁺ ions were leached out from the pillared micas during the acid-treatment. The pore properties of the leached products were found to differ from those of the mother pillared micas: the acid leaching of the pillared micas leads to the formation of mesopores around 3.2 nm in diameter. The correlation between the change in pore properties and cation elution behavior suggests that the mesopore formation results from the leaching of Mg²⁺ ions from the octahedral sheet of the pillared micas. The leached products thus obtained retained the flaky morphology of the mother pillared micas. These results show that the mild acid-treatment using APMs provides a novel route for obtaining unique mesopore solids having the large particle sizes of the mother micas.     

Temperature-controlled triaxial compression/creep test device for thermodynamic properties of soft sedimentary rock and corresponding theoretical prediction

In deep geological disposal of high-level nuclear waste,one of the most important subjects is to estimate long-term stability and strength of host rock under high temperature conditions caused by radioactive decay of the waste.In this paper,some experimental researches on the thermo-mechanical characteristics of soft sedimentary rock have been presented.For this reason,a new temperature-controlled triaxial compression and creep test device,operated automatically by a computer-controlled system,whose control software has been developed by the authors,was developed to conduct the thermo-mechanical tests in different thermal loading paths,including an isothermal path.The new device is proved to be able to conduct typical thermo-mechanical element tests for soft rock.The test device and the related testing method were introduced in detail.Finally,some test results have been simulated with a thermo-elasto-viscoplastic model that was also developed by the authors.     

Oligoethylenes in high pressure polyethylene

Summary Series of several alkylated cycloheptanes were detected in some commercial samples of high pressure polyethylene. The structures of the alkylated cycloheptanes were found closely related to the chain transfer agents used in the polymerization process. A probable mechanism involving radical cyclization to cycloheptane structures was presented.     

Neutron cross section sensitivity analysis of UO2 and MOX core physics experiments on light water reactors

The perturbation theory based on the transport calculation has been applied to study sensitivity of neutron multiplication factors (k_eff's) to neutron cross sections used for the reactivity analysis of UO₂ and MOX core physics experiments on light water reactors. The studied cross sections were neutron capture, fission and elastic scattering cross sections, and a number of fission neutrons, ν. The obtained sensitivities were multiplied to relative differences in the cross sections between JENDL-4.0 and JENDL-3.3 in order to estimate the reactivity effects. The results show that the increase in k_eff, 0.3%Δk/kk′, from JENDL-3.3 to JENDL-4.0 for the UO₂ core is mainly attributed to the decreases in the capture cross sections of ²³⁸U. On the other hand, there are various contributions from the differences in the cross sections of U, Pu, and Am isotopes for the MOX cores. The major contributions to increase in k_eff are decreases in the capture cross sections of ²³⁸U,²³⁸Pu, ²³⁹Pu, and those to decrease in k_eff are decreases in ν of ²³⁹Pu and increases in the capture cross sections of²⁴¹Am. They compensate each other, and the difference in k_eff between JENDL-3.3 and JENDL-4.0 is less than 0.1%Δk/kk′ and relatively small.     

Applicability of angular flux discontinuity factor preserving region-wise leakage for integro-differential transport equation

In the current core analysis, spatial homogenization is utilized to reduce the computational time. The discontinuity factor (DF) is one of the effective correction factors to reduce spatial homogenization error. The DF in diffusion equation is widely used; on the other hand the DF in transport equation has not been put to practical use although several efforts have been carried out. In this paper, the angular flux discontinuity factor (AFDF) as the DF for the integro-differential transport equation (e.g., the discrete-ordinate method, the method of characteristics) is theoretically described and its applicability is discussed. The AFDF is used to preserve the region-wise neutron leakage at each spatial mesh and defined as a ratio of heterogeneous and homogeneous angular fluxes at the homogenized region surface. In a homogeneous calculation with the AFDF, the angular flux is discontinuous at the region surface. In this paper the applicability of the AFDF to fuel pin cell homogenization is verified for one-dimensional slab geometry. As a result of this verification, it is confirmed that the AFDF has the capability to reduce the spatial homogenization error of fuel pin cell homogenization.     

Analysis of annotations on documents for recycling of information

In order to make collaborative business activities fruitful, it is essential to know characteristics of organizations and persons in more details and to gather information relevant to the activities. In this paper, we describe a notion of “information recycling” that actualizes these requirements by analyzing documents. The key of recycling information is to utilize annotations on documents as clues for generating user profiles and for weighting contents in the context of the activities. We also propose a method of extracting annotations on paper documents just by pressing one button with the help of techniques of camera‐based document image analysis. Experimental results demonstrate that it is fundamentally capable of acquiring annotations on paper documents on the condition that their electronic versions without annotations are available for the processing. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 60–68, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20516     

Fabrication of dense β-calcium orthophosphate with submicrometer-sized grains and its high-temperature superplastic deformation

High-density β-calcium orthophosphate (β-Ca₃(PO₄)₂, also called β-tricalcium phosphate: β-TCP) ceramics with submicrometer-sized grains were fabricated using a pulse-current pressure firing route. The maximum relative density of the β-TCP compacts was 98.7% at 1050 °C and this was accompanied by a translucent appearance. The mean grain size of the β-TCP compacts increased slightly with temperature to reach 0.78 μm at 1000 °C. However, upon further increasing the firing temperature to 1050 °C the mean grain size increased significantly to 1.6 μm. The extent of plastic deformation during tensile testing was examined at temperatures between 900 and 1100 °C using a strain rate in the range 9.26 × 10⁻⁵ to 4.44 × 10⁻⁴ s⁻¹. The maximum tensile strain achieved was 145% for a test temperature of 1000 °C and strain rate of 1.48 × 10⁻⁴ s⁻¹ and this was attributed to the relatively high density and small grain size.