The yttrium effect on the corrosion resistance of CO2-laser processed MCrAlY coatings

To improve the corrosion resistance and to study the effect of yttrium in the behavior of coatings produced by thermal spraying MCrAlY (M=Ni, Co) powders, CO₂ laser processing was conducted. Three methods were used: (1) a combination of gas flame and plasma spraying in air followed by laser glazing in argon, (2) low-pressure plasma spraying (LPPS) and laser glazing in argon, and (3) LPPS and laser-gas (O₂) alloying. Laser glazing in argon of the MCrAlY coatings sprayed in air promoted formation of weakly adherent agglomerates of Al–Y oxides and an alumina-chromia solid solution. Glazing in argon atmosphere of LPPS CoNiCrAlY and NiCrAlY coatings caused the formation of nickel aluminides besides the formation of Y–Al compounds. Gas (O₂)-alloying of these coatings produces continuous and adherent (yttrium-containing) alumina and chromia layers. The effects of yttrium on the characteristics of the oxides formed in the coatings during laser glazing, laser-gas alloying, and high-temperature oxidation is discussed. This work also investigated the oxidation resistance of the laser-processed MCrAlY coatings in air and in the presence of 85 mol/o V₂O₅–Na₂SO₄ fused salt at 900°C.     

High-intensity multi-bunch beam generation by a photo-cathode RF gun

A multi-bunch photo-cathode RF gun system has been developed as an electron source for the production of intense quasi-monochromatic X-rays based on inverse Compton scattering. The desired multi-bunch beam is 100 bunches/pulse with a total charge of 500 nC and a bunch spacing of 2.8 ns. We modified the gun cavity of a ‘BNL-type IV’ RF gun to allow a CsTe cathode plug in the end plate. The system uses a four-dipole chicane beam line to allow the injection of laser light normal to the cathode surface. We compensate the gun cavity beam loading caused by the high-intensity multi-bunch electron beam by injecting the laser pulse before RF power has filled the cavity. We have achieved a total intensity of 220 nC in 100 bunches with a bunch-to-bunch energy spread under 1.3% (peak-to-peak). This paper concentrates on experiments to generate the high-intensity multi-bunch beam with compensation of the bunch-to-bunch energy spread due to heavy beam loading.     

Current steel forgings and their properties for steam generator of nuclear power plant

Current steel forgings used for the construction of steam generators (SGs) for a nuclear power plant (NPP) were introduced from the following three (3) features. (1) Integral type steel forgings such as (i) primary head integrated with nozzles, manways and supports, (ii) steam drum head integrated with nozzle and handhole, (iii) conical shell integrated with cylindrical sections and handholes, have been developed to enhance the structural integrity of the component and to make fabrication and inspection including in-service inspection easier. (2) The high strength steel such as SA508 Cl.3a has been adopted to decrease the weight of components, resulting in enhancement of aseismatic properties of SG. (3) Low Si SA508 Cl.3 steel with the addition of Al was investigated and was applied to a heavy thick tube sheet forging, to minimize the macro- and micro-segregations in the ingot.     

Degradation behavior of moduli in extruded pure magnesium during low- to giga-scale cyclic tension fatigue

The mechanical properties of extruded pure magnesium during cyclic tension fatigue in the low- to giga-scale regime at room temperature have been investigated using ultrasonic reflection methods with longitudinal and shear waves. The acoustic velocities and calculated Young’s and shear moduli decreased by a large percentage with an increase in the number of cycles in all cycle modes due to growth of grain boundary voids. The eventual degradation of the properties was largest during giga-cycle fatigue, in which the moduli decreased by ～9%. The elastic behavior depended on the drive stress and the number of cycles rather than on fatigue time. Longitudinal and shear wave propagation characteristics and investigations of a grain boundary before and after fatigue using electron backscatter diffraction based on field-emission scanning electron microscopy and focused ion beam transmission electron microscopy revealed that the largest boundary void gap width was less than several nanometers (almost closed). The Poisson’s ratio and bulk modulus were affected notably by the void gap, in which the threshold corresponds to the longitudinal wave amplitude. Other damage phase data were determined using scanning electron microscopy, Vickers hardness, and surface roughness tests under progressive fatigue; these results also indicated slight grain boundary degradation.     

Robust comprehension of natural language instructions by a domestic service robot

We present a method through which domestic service robots can comprehend natural language instructions. For each action type, a variety of natural language expressions can be used, for example, the instruction, ‘Go to the kitchen’ can also be expressed as ‘Move to the kitchen.’ We are of the view that natural language instructions are intuitive and, therefore, constitute one of the most user-friendly robot instruction methods. In this paper, we propose a method that enables robots to comprehend instructions spoken by a human user in his/her natural language. The proposed method combines action-type classification, which is based on a support vector machine, and slot extraction, which is based on conditional random fields, both of which are required in order for a robot to execute an action. Further, by considering the co-occurrence relationship between the action type and the slots along with the speech recognition score, the proposed method can avoid degradation of the robot’s comprehension accuracy in noisy environments, where inaccurate speech recognition can be problematic. We conducted experiments using a Japanese instruction data-set collected using a questionnaire-based survey. Experimental results show that the robot’s comprehension accuracy is higher in a noisy environment using our method than when using a baseline method with only a 1-best speech recognition result.     

Investigation of Precipitation Behavior in Age-Hardenable Cu-Ti Alloys by an Extraction-Based Approach

We investigated the precipitation processes in Cu-4 mol pct Ti alloy specimens aged at 723 K (450 °C), by means of X-ray diffraction and chemical analyses of the precipitates extracted from the parent alloy specimens. Aging-induced precipitate particles of a spinodally decomposed disorder, α′; those of a metastable order, β′-Cu₄Ti; and those of a stable order, β-Cu₄Ti, were continuously formed in the aged specimens. The extraction of the precipitate particles from the aged specimens by submergence in a nitric solution allowed for not only the structural analyses of the constituent precipitate phases but also the quantitative evaluation of their chemical compositions and volume fractions. Early during the aging process, the supersaturated Cu solid solution decomposes spinodally in a continuous manner, and an unstable disorder, α′, appears. Then, fine needle-shaped β′-Cu₄Ti particles, which have a Ti content of approximately 37.5 mol pct, form in the Cu matrix. During prolonged aging, coarse cellular components composed of the terminal Cu solid solution and stable β-Cu₄Ti particles which have a Ti content of 20.5 mol pct nucleate and grow, primarily in the grain boundaries, at the expense of the metastable β′-Cu₄Ti particles. The volume fraction of the β′-Cu₄Ti particles in the alloy reaches a maximum of approximately 1.7 pct after aging for 24 hours, while that of the β-Cu₄Ti particles increases steadily to more than 18 pct after 480 hours. The volume fraction of the fine β′-Cu₄Ti particles in the alloy specimens remained constant throughout the age-hardening, indicating that the hardening is primarily owing to the fine dispersion of the β′-Cu₄Ti particles and not because of the large volume fraction of coarse β-Cu₄Ti particles.     

Development of a new heterojunction structure (ACJ -HIT) and its application to polycrystalline silicon solar cells

A new solar cell structure named HIT (Heterojunction with Intrinsic Thin layer) has been developed based on new artificially constructed junction (ACJ) technology. In this structure a non-doped a-Si thin layer was inserted between the p(a-Si)/n(c-Si) heterojunction, improving the output characteristics and achieving a conversion efficiency of 18.1%. This structure was applied to cast polycrystalline silicon solar cells of a practical size. A high conversion efficeincy of 13.6% was obtained with a cell size of 10 cm × 10 cm using various technologies, including hydrogen plasma passivation.     

Collision response for deformable models based on hertz's contact theory

This paper presents an animation technique of collision response for deformable models defined as a spring-mass-damper system. Our approach is to calculate impulsive forces to prevent penetration of colliding objects by means of Hertz's contact theory. With this theory, contact duration and deformation in collision are obtained according to physical properties such as mass and elasticity. Animators, therefore, can represent the differences between materials such as rubber and steel in the sequence of collision animations with a few intuitive physical parameters. We also describe a deformation mapping technique which reduces the computational time of dynamic analysis and realizes the effect of global deformation.     

Analysis of Plasmalogen Species in Foodstuffs

Ethanolamine plasmalogen (PlsEtn), which is present at high levels in brains, is believed to be involved in neuronal protection. The present study was performed to search for PlsEtn resources in foodstuffs. The foodstuffs examined showed a wide range of PlsEtn contents from 5 to 549 μmol/100 g wet wt. The marine invertebrates, blue mussel, and ascidian had high PlsEtn contents (over 200 μmol/100 g wet wt). Profiling of the molecular species showed that the predominant fatty acids of PlsEtn species were 20:5 (EPA) and 22:6 (DHA) at the sn‐2 position of the glycerol moiety in marine foodstuffs, whereas major PlsEtn species in land foodstuffs were 20:4. Following quantitative analysis by multiple reaction monitoring, the ascidian viscera were shown to contain the highest levels of 18:0/20:5‐PlsEtn and 18:0/22:6‐PlsEtn (86 and 68 μmol/100 g wet wt, respectively). In order to evaluate a neuronal antiapoptotic effect of these PlsEtn species, human neuroblastoma SH‐SY5Y cells were treated with ethanolamine glycerophospholipid (EtnGpl), purified from the ascidian viscera, under serum starvation conditions. Extrinsic EtnGpl from ascidian viscera showed stronger suppression of cell death induced by serum starvation than with bovine brain EtnGpl. The EtnGpl from ascidian viscera strongly suppressed the activation of caspase 3. These results suggest that PlsEtn, especially that containing EPA and DHA, from marine foodstuffs is potentially useful for a therapeutic dietary supplement preventing neurodegenerative diseases, such as Alzheimer's disease (AD).