Finite difference implementation of distributed parameter filters

The numerical problems associated with the full three-dimensional (spatial) distributed parameter filters demand a novel technique that maintains accuracy and efficiency for the complex partial differential Riccati equation governing the filter variance. The filters can be successfully implemented by using numerical operators that can, in various ways, be factored. Use of the finite difference method having this property increases the accuracy and efficiency of the implementation.

This paper outlines a time-splitting technique for the numerical implementation of distributed parameter filters. The paper provides rationales to the square root and U-D factorizations of the distributed parameter filter by means of the time-splitting finite difference method.     

Influences of interfacial bonding strength and scatter of fibre strength on tensile behaviour of unidirectional metal matrix composites

The influences of interfacial bonding strength and scatter of strength of fibres on tensile behaviour of unidirectional metal matrix composites, whose matrix has low yield stress in comparison to the strength of fibres, were studied using the Monte-Carlo simulation technique using two-dimensional model composites. The following results were found. The strength of composites increases with increasing bonding strength, especially when the bonding strength exceeds the shear yield stress of the matrix and then remains nearly constant. The strength of composites is very sensitive to bonding strength when the scatter of fibre strength is large, but not when it is small. The fracture mode varies from non-cumulative to cumulative with increasing scatter of fibre strength for both cases of weak and strong interfacial bondings. The fracture surface becomes irregular when bonding strength becomes low and scatter of fibre strength becomes large. The applicability of the Rosen and Zweben models and the rule of mixtures to predict the strength of composites was examined.     

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.     

Enhancement of the photocatalytic reactivity of TiO2 nano-particles by a simple mechanical blending with hydrophobic mordenite (MOR) zeolite

The photocatalytic oxidation of gaseous acetaldehyde with O₂ on commercial TiO₂ nano-particles could be successfully enhanced by a simple mechanical blending with a high-silica mordenite (MOR) zeolite, the surface of which showed high hydrophobic properties. When the TiO₂ nano-particles of ca. 5–20 wt% were mixed with the MOR zeolite powders in an agate mortar for only 5 min, the blended TiO₂/MOR samples showed higher photocatalytic reactivity as compared to the pure TiO₂ nano-particles. Since the high-silica zeolite powders are highly transparent in UV light regions, the incident UV light is effectively irradiated onto the whole part of the TiO₂ nano-particles without any loss of light intensity. Furthermore, the siliceous MOR zeolite powders effectively adsorb the gaseous acetaldehyde molecules and supply them onto the surfaces of the blended TiO₂ nano-particles, resulting in an enhancement of the photocatalytic reactivity.     

Liquid-fuel combustion in a narrow tube using an electrospray technique

This study experimentally investigated the possibility of stable burning conditions of liquid fuel inside a narrow tube using an electrospray technique without external heating or a catalyst. The mixture of 30% volume ethanol and 70% volume n-heptane was used as a liquid fuel atomized by the electrospray method with single capillary-ring extractor-mesh collector electrode configuration placed inside a quartz glass tube with an inner diameter of 3.5 mm. A stable flame was established inside the narrow tube without wall wetting within a certain range of equivalence ratio for a fuel flow rate of 1 mL/h. This study confirmed that the role of the mesh as the collector was very important in establishing a stable flame inside the narrow tube. If the fuel flow rate was sufficiently large, wall wetting occurred and eventually stable burning stopped.     

Photo-catalytic heat mirror with a thick titanium dioxide layer

Some of the heat mirrors, which have high transmittance in the visible region and high reflectance in the infrared, consist of three thin titanium compound stacked films, TiO₂/TiN/TiO₂ on glass substrate. TiO₂ is known to have excellent photo-catalytic properties and the top layer may be expected to work as a photo-catalyst as well as the anti-reflection coating. However, strong thickness dependence of the photo-catalytic properties has been reported and the optimum thickness of the top layer for the heat mirror was too thin for the photo-catalytic properties for decomposition of acetaldehyde gas. In this report, we show a possibility to realize a multi-functional heat mirror which shows the photo-catalytic and heat mirror effects simultaneously by optical calculation and preliminary experiments. We found top TiO₂ thickness of 350–400 nm or about 1170 nm showed high heat mirror performance. This thickness was enough to show the photo-catalytic properties.     

Oxygen Potential Analysis to Evaluate Irradiation Behavior in MOX and MA-Bearing MOX Fuels

Oxygen potentials of oxide nuclear fuels are important thermodynamic data in development of nuclear fuel technologies. Minor actinide bearing MOX （mixed oxide） fuels have been developed as sodium cooled fast reactor fuels. Content of Am which is one of the minor actinide elements causes oxygen potentialto increase. The effects of the oxygen potential increase on the irradiation behavior were evaluated. Profiles of temperature and O/M （oxygen-to-metal） ratio in the pellets were evaluated to better understand the irradiation behavior. From these data, local oxygen potential in the radial direction of the pellets was calculated, and was compared with free energy of compounds composed of fission products. Based on this comparison, it was concluded that Cs2MoO4 was likely formed at pellet periphery of （U07Pu03）O1.98 and （U0.66Pu03Amoo16Npo.016）Ol.976 The extent of cladding tube inner surface oxidation was predicted by using the calculated oxygen potential. No significant difference between irradiation behaviors of （Uo.7Puo3）O2_x and （U0.66PUo 3Amo.016Npo.016）O2.x pellets was confirmed.