Simultaneous measurement of liquid velocity and interface profiles of horizontal duct wavy flow by ultrasonic velocity profile meter

A simultaneous measurement of the liquid velocity and interface profiles was performed for stratified-smooth and wavy flows in a horizontal duct using a ultrasonic velocity profile (UVP) meter. The influences of the reflections of ultrasonic pulses at the gas–liquid interface and channel bottom were reduced by using an absorbent for the ultrasonic pulses on the duct bottom wall and optimization of the liquid level and time interval between pulses. For a smooth–stratified flow, good comparison was obtained with a velocity profile obtained by particle tracking velocimetry (PTV) for video pictures taken simultaneously at the UVP measurement. Polystyrene beads were used as the reflector and tracers respectively, for the UVP and PTV measurements. The velocity profiles measured for a wavy flow with periodically-generated interfacial waves agreed well with the theoretical prediction for solitary waves. Turbulence component appeared in the velocity profiles of both the smooth–stratified and wavy flows.     

Application of Highly Functional Ti-Oxide-Based Photocatalysts in Clean Technologies

Various Ti-oxide based photocatalysts such as the highly dispersed Ti-oxide species within zeolite frameworks, TiO₂ nano-particles hybridized with hydrophobic zeolite adsorbents as well as visible light responsive TiO₂ thin films have been successfully prepared. Characterization studies at the molecular level, such as X-ray absorption fine structure (XAFS) and photoluminescence (PL), revealed that the highly dispersed Ti-oxide species within the nano-spaces of zeolites possess a tetrahedral coordination and that they demonstrate unique and high performance for the photocatalytic decomposition of NOx and the photocatalytic reduction of CO₂ with H₂O. A high photocatalytic reactivity for the TiO₂ semiconducting photocatalysts could be achieved by blending them with hydrophobic siliceous zeolites which was equal to the performance of TiO₂ deposited with expensive Pt particles. The role of the siliceous zeolites can be described as a so-called “catch and release effect of organic compounds”, i.e., (i) the condensation of the reactants within the hydrophobic cavities of zeolites and; (ii) the efficient diffusion of the reactant onto the TiO₂ photocatalytic sites. Furthermore, a novel photocatalytic system which can convert abundant solar energy into renewable H₂ energy by the decomposition of H₂O into H₂ and O₂ can also be achieved by using visible light responsive TiO₂ thin film photocatalysts prepared by a RF-magnetron sputtering deposition method. The conversion efficiency of solar energy into H₂ energy may be estimated at ca. 0.1% from the initial rate of H₂ evolution.     

Morphologic Control of Pt Supported Titanate Nanotubes and Their Photocatalytic Property

Morphologic control of Pt supported titanate nanotubes was attempted by the hydrothermal hot-pressing (HHP) technique in order to improve the handleability as a photocatalyst. The bulk of Pt-nanocrystal supported titanate nanotubes was successfully fabricated without the H₂ reduction process by applying the HHP technique. The bulky Pt-nanocrystal supported titanate nanotubes possessed dense microstructures, significantly sharp distributions of mesopores, and high Brunauer–Emmett–Teller (BET) surface area. Furthermore, the bulky Pt-nanocrystal supported titanate nanotubes showed the photocatalytic degradation activities of 2-propanol aqueous solution under UV-light irradiation.     

Hardware‐oriented ant colony optimization and its application to dynamic route guidance problem

Ant colony optimization (ACO) is based on the behavior of food gathering of ants and it is a powerful search tool particularly when applying it to combinatorial optimization problems. However, ACO has the inherent problem of substantial processing time, because it requires a lot of repetitive calculations. In this article, we propose novel hardware‐oriented ACO (H‐ACO) to reduce processing time. H‐ACO adopts new integer arithmetic instead of conventional floating point arithmetic in the optimization process and it achieves high‐speed processing while keeping the quality of solutions. In addition, H‐ACO reduces the hardware resources, accelerates the clock frequency, and improves the latency, if it is implemented as a dedicated hardware. Furthermore, we also propose a new route guidance algorithm which combines H‐ACO with Dijkstra's algorithm and it can be applied to a dynamic route guidance problem. Experiments using actual map data demonstrate the validity of the proposed route guidance algorithm. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Preparation and electrochemical properties of pure lithium cobalt oxide films by electron cyclotron resonance sputtering

Positive Li–Co–O films for all-solid-state thin-film lithium batteries were prepared by electron cyclotron resonance (ECR) sputtering using Li_xCoO₂ targets (x = 1.0, 1.2, 1.7 and 2.0). The Li–Co–O films prepared using the x = 1.0, 1.2 and 1.7 targets contained a Co₃O₄ impurity phase with high-temperature phase LiCoO₂. The film prepared using the x = 2.0 target was found to contain only a pure LiCoO₂ phase by Raman spectrometry and the inductively coupled plasma/atomic emission spectrometry (ICP/AES) method, and a thin-film battery using this film exhibited good electrochemical properties as a result of the improved utilization of the positive film.     

Performance evaluation of membrane on catalyst module for hydrogen production from natural gas

We have been developing a hydrogen production module with a Pd-based membrane on catalyst (MOC) from natural gas. The MOC module is expected to be more compact and cheaper than the conventional hydrogen production module. To evaluate the hydrogen production performance of the MOC module and to clear the factor that dominates the effective hydrogen production, we compared the reforming performance of the catalytic support without hydrogen permeable membrane and the MOC module at various reaction conditions. As a result, it was cleared that hydrogen permeation through the membrane improves the methane conversion drastically in the MOC module by comparing with the support only module and changing the experimental conditions.     

Characterization of electrical properties and photosensitivity of SnS thin films prepared by the electrochemical deposition method

Using the electrochemical deposition (ECD) method, we prepared tin sulfide thin films, which are suitable for the absorption layer in solar cells because of its bandgap energy (1 eV). We first optimized pulse-form biasing for ECD by characterizing deposited samples with scanning electron microscope, Auger electron spectroscopy and X-ray diffraction measurements. Then, we investigated the electrical properties of deposited SnS thin films and the properties of contacts with several different metals. Furthermore, we observed the photoconductivity of the films by means of photoelectrochemical measurements. From these results, we confirmed that the SnS thin films show p-type conduction.     

Epitaxial p-type SiC as a self-driven photocathode for water splitting

Solar-to-hydrogen conversion efficiencies of water-splitting photochathodes using epitaxially grown p-type 4H-, 6H- and 3C-SiC were estimated in a two-electrode system without applying any external bias. By using electrode materials with small oxygen overpotentials as counter electrodes, the photocurrent became comparable to that observed in a three-electrode system with a suitable bias. Estimated efficiencies seem to depend on the bandgap of the SiC polytypes. For the 3C-SiC, the obtained efficiency was 0.38%, which is so far the highest value reported for SiC. We confirmed that the hydrogen volumes estimated from the photocurrent were almost the same as actual volumes observed by gas chromatography.     

Performance of plastic gear made of carbon fiber reinforced poly-ether-ether-ketone

A carbon fiber (CF) reinforced poly-ether-ether-ketone (PEEK) gear was prepared by injection molding, and its gear performance was evaluated. It was found that the wear process of the CF reinforced PEEK gear significantly varied depending on the test conditions, such as the kind of the partner gear combined and whether a lubricant exists on the engagement region or not. It was assumed that the existence of transfer film at the engagement region, the affinity between PEEK and CF, the compression modulus as well as surface hardness of the partner gear, and the characteristics of CF play a role of differentiation in the wear depth.     

Microwave-assisted desulfurization of NOx storage-reduction catalyst

The activity of NO_x storage-reduction (NSR) catalysts is greatly reduced by sulfur poisoning, caused by the SO₂ present in the exhaust stream. Desorption of sulfur species from poisoned NSR catalysts occurs at temperatures in excess of 600 °C using reducing atmospheres and conventional heating. In this work, microwave (MW) heating has been used to promote desulfurization of poisoned NSR catalysts. The experiments were carried out by heating the catalyst with MW radiation and using hydrogen as the reducing gas. Desorption of H₂S at 200 °C was observed. Desorption at even lower temperatures (150 °C) was observed when water was introduced to the system. In the presence of water, sulfur species desorbed as both H₂S and SO₂. An overall reduction of sulfur species of about 60% was obtained. The use of MW heating proves to be an efficient way to achieve regeneration of poisoned NSR catalysts.