Feature extraction using problem localization

Feature extraction is considered as a mean-quare estimation of the Bayes risk vector. The problem is simplified by partitioning the distribution space into local subregions and performing a linear estimation in each subregion. A modified clustering algorithm is used to fimd the partitioning which minimizes the mean-square error.     

Structural and hydration properties of amorphous tricalcium silicate

Mechanical milling was carried out to synthesize amorphous tricalcium silicate (Ca₃SiO₅) sample, where Ca₃SiO₅ is the most principal component of Portland cement. The partial phase transformation from the crystalline to the amorphous state was observed by X-ray and neutron diffractions. Moreover, it was found that the structural distortion on the Ca-O correlation exists in the milled Ca₃SiO₅. The hydration of the milled Ca₃SiO₅ with D₂O proceeds as follows: the formation of hydration products such as Ca(OD)₂ rapidly occurs in the early hydration stage, and then proceeds slowly after about 15 h. The induction time for the hydration of the milled Ca₃SiO₅ is approximately one half shorter than that for the hydration of the unmilled one. This result means that the mechanical milling brings about the chemical activity of Ca₃SiO₅ for hydration, and may be particularly useful for increasing the reactivity in the early hydration stage.     

Three-dimensional space charge observation of ion migration in a metal-base printed circuit board

Internal space charge measurement has been mainly applied to investigate insulating materials used in RV apparatus, such as HVDC cables. We have observed the space charge profiles to monitor copper ion migration occurring in an insulation layer of a metal-base printed circuit board and found that the space charge distribution along the thickness direction corresponds to the progress of ion migration in insulation. The migration, however, can proceed in any direction in the specimen simultaneously; therefore, it should be measured in three dimensions. We measured metal-base epoxy resin insulated printed circuit boards by a newly developed three-dimensional pulsed electroacoustic method. The results show that the space charge density varies in the lateral direction when ion migration occurs in the specimen.     

Pulsed electro-acoustic technique applied to in-situ measurement of charge distribution in electron-irradiated polymers

Dielectric materials are frequently used in satellite structures for substantial savings in weight. Their dielectric nature and the effect of different forms of radiation encountered in space combine to accumulate electrical charges resulting in the occurrence of electrostatic discharges which cause harmful interference with the electronic parts of the satellite, leading to its malfunction or to a total loss of equipment control. Therefore, the behavior of dielectrics under irradiation must be investigated before being used in space. A pulsed electroacoustic (PEA) device was mounted in an irradiation chamber to monitor the spatial distribution of electrons implanted into polymer films during electronic irradiation. Internal charge accumulation was clearly identified. Penetration depth versus energy was double checked by comparing PEA with surface potential data.     

Structural approach to nanoscience: a case study of complex and cluster formation in ZnBr2–ZnCl2 melts

Although the melt structure of glass-forming ZnCl₂ has so far been well studied, there exists quite little information on the structural change due to anion-substitution. In the present work, the short-range structure of ZnCl₂–ZnBr₂ mixture melts was analyzed systematically by time-of-flight pulsed neutron diffraction techniques, Raman spectroscopy, molecular orbital calculations, and molecular dynamics simulations. According to radial distribution analysis, it was found that there were tetrahedral structural units of ligand-substituted [ZnCl_nBr_4−n]²⁻ (n=0–4) in these melts, not implying the simple mixing of [ZnCl₄]²⁻ and [ZnBr₄]²⁻ units. Further detailed estimation indicated that the ligand-substituted complex anions were linked with each other by sharing a common anion.     

A novel bistable reflective display using quick‐response liquid powder

Abstract— We have developed new powder materials that exhibit liquid behavior, which can lead to the realization of novel bistable and reflective displays having paper‐white appearance, high contrast, and quick response. Two types of display were demonstrated, one had 160 × 160 array of pixels and the other had 320 × 320 in a 3.1‐in.‐diagonal viewable image size corresponding to 66 and 132 dpi, respectively. These displays were driven by passive‐matrix addressing. The displays showed a reflectivity of more than 41%, a contrast more than 1:10, and a pixel response time of less than 0.2 msec. The seven‐segment display for use in clocks was also demonstrated.     

Inhibition of char deposition using a particle bed in heating section of supercritical water gasification

Supercritical water gasification (SCWG) has attracted attention as a technology for utilizing wet biomass. We used a fluidized bed of alumina particles to prevent blockage of a SCWG reactor. A glucose solution was heated in the reactor with and without fluidized alumina particles. In the absence of alumina particles, char particles formed homogeneously in the reactor, but the use of a fluidized bed resulted in accumulation of char particles at the reactor’s exit rather than inside the reactor. Therefore, the fluidized bed was effective at preventing blockage of the reactor. However, the alumina particles did not remove deposits from the reactor’s walls. Instead, the fluidized bed caused larger char particles to form, preventing their adhesion to the reactor’s wall.     

Preparation of Polymer-Based Nanocomposites Composed of Sustainable Organo-Modified Needlelike Nanoparticles and Their Particle Dispersion States in the Matrix

Polymer-based nanohybrid materials were created using sustainable sepiolite clay composed from ubiquitous elements. Although sepiolite is generally recognized as a fibrous natural clay mineral, it turned out to be an acicular microcrystal because of the organo-modification of the outermost surface. Surface modification was performed using phosphonic acid derivatives containing hydrocarbon chains or fluorocarbon chains. Formation of a bidentate bond enhanced the desorption temperature and made nanocomposite preparation possible by melt compounding with polymers having a high melting point. As a result of organo-modification, amphiphilic sepiolite was obtained, and nanodispersion in an organic solvent was achieved. This technology was useful for detailed evaluation of sepiolite morphology. The nanocomposite of crystalline polymers/organo-modified sepiolites achieved uniform dispersion of these nanofillers in the matrix polymer. The introduction of 1 wt% nanofillers did not impair the transparency of the matrix polymer. As a result, a lamellae structure of the polymer developed, the crystallinity increased, and the mechanical properties improved. In addition, the crystallization temperature was improved, indicating that organo-modified sepiolites may act as a nucleating agent. It was found that sepiolite nanofiller with a highly aggregated tendency can achieve a well-nanodispersed state, even in phase-separable fluoropolymers, by applying fluorocarbon modification. POLYM. ENG. SCI., 60:541–552, 2020. © 2019 Society of Plastics Engineers     

Chemical reaction kinetics dataset of Cs-I-B-Mo-O-H system for evaluation of fission product chemistry under LWR severe accident conditions

In order to improve LWR source term under severe accident conditions, the first version of a fission product chemistry database named ‘ECUME’ was developed. The ECUME is intended to include several datasets of major chemical reactions and their effective kinetic constants for representative severe accident sequences. It is expected that the ECUME can serve as a fundamental basis from which fission product chemical models can be elaborated for use in the severe accident analysis codes. The implemented chemical reactions in the first version were those for representative gas species in Cs-I-B-Mo-O-H system from 300 to 3000 K. The chemical reaction kinetic constants were evaluated from either literature data or calculated values using ab-initio calculations. The sample chemical reaction calculation using the presently constructed dataset showed meaningful kinetics effects at 1000 K. Comparison of the chemical equilibrium compositions by using the dataset with those by chemical equilibrium calculations has shown rather good consistency for the representative Cs-I-B-Mo-O-H species. From these results, it was concluded that the present dataset should be useful to evaluate fission product chemistry in Cs-I-B-Mo-O-H system under LWR severe accident conditions, where kinetics effects should be considered.