Evaluation Method for Flow Accelerated Corrosion of Components by Corrosion Analysis Coupled with Flow Dynamics Analysis

The troubles of major components and structural materials in nuclear power plants have often been caused by flow-induced vibration, corrosion, and their overlapping effects. In order to establish safe and reliable plant operation, it is required to forecast future troubles based on combined analyses of flow dynamics and corrosion and prevent them at very early stages. Corrosion analysis models have been combined with three-dimensional flow dynamics and heat transfer analysis models to evaluate corrosion damage (e.g., stress corrosion cracking [SCC] and flow-accelerated corrosion [FAC]) of major components and structural materials.

The models are divided into the following two parts. First is a prediction model of future trouble on materials. The distribution of oxidant concentrations along the flow path are obtained by solving water radiolysis reactions in the boiling water reactor primary cooling water and hydrazine and oxygen reactions in pressurized water reactor secondary cooling water. Then, the distribution of electrochemical corrosion potential (ECP) along the flow path is obtained by oxidant concentration based on a mixed potential model. Higher ECP enhances the possibility of SCC, while lower ECP accelerates FAC. Second is an evaluation model of wall thinning caused by FAC. At the location with a higher possibility for FAC occurrence, a trend of wall thinning is evaluated, and the lifetime is estimated for preventive maintenance.     

Stereological Analysis of Nonspherical Particles in Solid Metal

We review in this article the stereological theory of particles and perform stereological analysis of nonspherical TiB₂ particles dispersed in solid aluminum. The two-dimensional (2D) particle size distribution (PSD) obtained from a projected area (PSDP) of TiB₂ powder and the three-dimensional (3D) PSD based on the volume of particles were independently measured by optical microscopy and the electrical sensing zone method, respectively. The results obtained by the two methods were compared by transforming between them, using a fitted fractal dimension for the particles. The probability mass function of the cross-sectional areas (CSAs) of single nonspherical particles was measured by sectioning 3D reconstructions of particles obtained from a series of X-ray micro-CT images. The transformation from 3D PSD to 2D PSD according to the CSA (PSDC) was performed based on the stereological model. The inverse problem for the transformation from the 2D PSDC to 3D PSD is discussed.     

Amidated amino acids are prominent additives for preventing heat-induced aggregation of lysozyme

An additive that is highly effective in small amounts for controlling protein inactivation and aggregation has long been demanded. In this paper we show amidated amino acids as new potent additives. In the presence of 100 mM amidated amino acids, e.g., Ala, Arg, Asn, Met, and Val, the heat-induced inactivation and aggregation of lysozyme at pH 7.1 are one order of magnitude slower than those in the absence of additives. Although a high Arg concentration (>1 M) has been used to prevent aggregation among amino acids, it is worth mentioning that above amidated amino acids can prevent aggregation at submolar concentrations. The data obtained suggest the importance of amino and amide groups rather than the guanidium group as an aggregation suppressor.     

Directional alignment of FeCo crystallites in Si/NiFe/Ru/FeCoB multilayer with high anisotropy field above 500 Oe

In-plane magnetic anisotropy and crystal structure of FeCoB layer on Si/NiFe/Ru underlayer were investigated by using X-Ray Diffraction (XRD) measurement. A pole-figure measurement of XRD showed directionally tilted alignment of FeCo crystallites in Si/NiFe/Ru/FeCoB multilayered film with high in-plane anisotropy field H(k) but no directional alignment was found in FeCoB single layered film. The higher H(k) appeared in the Si/NiFe/Ru/FeCoB multilayered configuration with the thicker FeCoB layer. Since Ru crystallites in a multiunderlayer configuration exhibited no directional alignment, the surface structure of underlayer should be no main reason for the directional alignment of FeCo crystallites deposited on it. The dependence of hickness of FeCoB layer in Si/NiFe/Ru/FeCoB film on H(k) indicated that the in-plane magnetic anisotropy is caused by not only the structure of Ru underlayer but also oblique incidence effect of sputtered particles, which is attained in configuration of Facing Targets Sputtering (FTS) system. From these experimental results, remarkably high H(k) of 540 Oe was obtained.     

A novel framework based on a data-driven approach for modelling the behaviour of organisms in chemical plume tracing

We propose a data-driven approach for modelling an organism''s behaviour instead of conventional model-based strategies in chemical plume tracing (CPT). CPT models based on this approach show promise in faithfully reproducing organisms’ CPT behaviour. To construct the data-driven CPT model, a training dataset of the odour stimuli input toward the organism is needed, along with an output of the organism’s CPT behaviour. To this end, we constructed a measurement system comprising an array of alcohol sensors for the measurement of the input and a camera for tracking the output in a real scenario. Then, we determined a transfer function describing the input–output relationship as a stochastic process by applying Gaussian process regression, and established the data-driven CPT model based on measurements of the organism’s CPT behaviour. Through CPT experiments in simulations and a real environment, we evaluated the performance of the data-driven CPT model and compared its success rate with those obtained from conventional model-based strategies. As a result, the proposed data-driven CPT model demonstrated a better success rate than those obtained from conventional model-based strategies. Moreover, we considered that the data-driven CPT model could reflect the aspect of an organism’s adaptability that modulated its behaviour with respect to the surrounding environment. However, these useful results came from the CPT experiments conducted in simple settings of simulations and a real environment. If making the condition of the CPT experiments more complex, we confirmed that the data-driven CPT model would be less effective for locating an odour source. In this way, this paper not only poses major contributions toward the development of a novel framework based on a data-driven approach for modelling an organism’s CPT behaviour, but also displays a research limitation of a data-driven approach at this stage.     

A proposal of a procedure to estimate a standard line for contactless estimation of a solar cell voltage in a module using modulated light

It is important to measure the operating voltage of a cell sealed in a photovoltaic module as well as well-known faults such as abnormal hot spots observed by thermography or a dark part in electroluminescence distribution on the module for detecting a fault module. This paper proposes a method that radiating modulated light toward a cell and extracting the synchronized signal from the module output by phase detector can estimate the operating voltage quantitatively by using a standard line predicted by shading the module partially.     

Effect of admixture on hydration of cement, adsorptive behavior of admixture and fluidity and setting of fresh cement paste

The adsorptive behavior of admixtures and the hydration of cement in the presence of admixtures were examined and the relationships of them with the physical properties of fresh cement paste including fluidity, variation of fluidity with time and setting time were discussed with the quantitative determination of organic admixture adsorbed on the cement, and with the observation and determination of the surface microstructure and composition of polished clinker dipped in aqueous solution containing a specified quantity of admixture by advanced method of surface analysis.

In order to prepare the same fluidity of fresh cement paste, mortar and concrete, the required amount of an easily adsorbed admixture is larger than that of a hard adsorbed one. An admixture having a functional group producing a complex salt with Ca²⁺ decreases the concentration of Ca²⁺ in liquid phase at early age and delays the saturation of Ca²⁺, which influences the morphology of hydrate produced, causes fluidity loss with time and delays the setting time of cement. The microstructural and compositional estimations of the adsorption layer of admixture on the surface of clinker minerals by in-lens FESEM, ESCA-imaging, AES and AFM indicates that the admixture is partially adsorbed to the interstitial phase in a thick layer, forming characteristic three dimensional surface structure.     

Effect of Different Filler Contents and Printing Directions on the Mechanical Properties for Photopolymer Resins

Photopolymer resins are widely used in the production of dental prostheses, but their mechanical properties require improvement. We evaluated the effects of different zirconia filler contents and printing directions on the mechanical properties of photopolymer resin. Three-dimensional (3D) printing was used to fabricate specimens using composite photopolymers with 0 (control), 3, 5, and 10 wt.% zirconia filler. Two printing directions for fabricating rectangular specimens (25 mm × 2 mm × 2 mm) and disk-shaped specimens (φ10 mm × 2 mm) were used, 0° and 90°. Three-point bending tests were performed to determine the flexural strengths and moduli of the specimens. The Vickers hardness test was performed to determine the hardness of the specimens. Tukey’s multiple comparison tests were performed on the average values of the flexural strengths, elastic moduli, and Vickers hardness after one-way ANOVA (α = 0.05). The flexural strengths and elastic moduli at 0° from high to low were in the order of 0, 3, 10, and 5 wt.%, and those at 90° were in the order of 3, 0, 10, and 5 wt.% (p < 0.05). For 5 and 10 wt.%, no significant differences were observed in mechanical properties at 0° and 90° (p < 0.05). The Vickers hardness values at 0° and 90° from low to high were in the order of 0, 3, 5, and 10 wt.% (p < 0.05). Within the limits of this study, the optimal zirconia filler content in the photopolymer resin for 3D printing was 0 wt.% at 0° and 3 wt.% at 90°.     

Synthesis of ordered mesoporous carbon films, powders, and fibers by direct triblock-copolymer-templating method using an ethanol/water system

Morphology control of ordered mesoporous carbon was performed using an organic-organic interaction approach. Mesoporous carbons were synthesized from a resorcinol-phloroglucinol/formaldehyde polymer and triblock copolymer Pluronic F127 in ethanol-water solutions of different molar ratios. A face-centered orthorhombic Fmmm structure was formed in the film prepared by dip-coating method. A three-dimensional wormhole-like mesostructure was formed during powder preparation at EtOH/water molar ratios ranging from 0.5 to 1.25. When the molar ratio was further increased to 2.5, a hexagonal p6mm structure was obtained. The pore size of the mesoporous carbon powders increases with increasing EtOH/water molar ratio. A dual-templating approach was demonstrated to prepare mesoporous carbon nanofibers. Anodic aluminum oxide membranes were used as a hard template. A mesostructure with a short-range order was formed and oriented along the surface in different directions. The structural order became distorted in the interior region.