Effect of temperature and surface roughness on the wettability of boron nitride by molten Al

Reactive wetting of hexagonal BN by molten Al at 1073–1273 K was studied using an improved sessile drop method. The temperature and substrate surface roughness have a remarkable effect on the wetting behavior. Reasons for the large discrepancy in the final contact angles reported in the literature were addressed.     

Finite‐dimensional approximate modeling with error bounds of flexible vibrating systems based on partial eigenstructures

An approach to control‐oriented uncertainty modeling is presented for a class of elastic vibrating systems such as flexible structures, beams and strings, described by partial differential equations. Uncertainty bounding techniques are developed using the upper and lower bounds of the unknown eigenparameters. The result forms a basis for a finite‐dimensional controller design in which closed loop stability and performance are guaranteed. A feasible set of systems is defined of all systems governed by a class of differential equations with certain norm bounds of the unknown input and output operators and with partially known bounds of the eigenparameters. Then the perturbation magnitude covering the feasible set is evaluated in the frequency domain where a standard truncated modal model is chosen as the nominal one. An upper bound to the truncated error magnitude which is calculated by linear programming is proposed. It is demonstrated that all the parameters formulating a feasible set are derived by finite element analysis for a flexible beam example, and feasibility of the proposed scheme is also illustrated by numerical bounding results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(2): 36–44, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20272     

Characteristics of the optical resonator composed of the nonlinear directional coupler

This paper describes a simple method of analysis of an optical resonator composed of a nonlinear directional coupler. Assuming the coupler is made in semiconductor‐doped glass by the K⁺‐ion diffused technique, the transmission and reflection characteristics are calculated and demonstrated. The parameter dependence of the bistability appearing in the transmitted and reflected light is also presented. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(3): 1–10, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20036     

Intergranular stress corrosion cracking behavior of niobium-added Type 308 stainless steel weld overlay metal in a simulated BWR environment

Type 308 stainless steel weld metal as an internal cladding of reactor pressure vessels for boiling water reactors is subject to postweld heat treatment during fabrication and can suffer sensitization depending on carbon and ferrite contents. This sensitization can be avoided by using niobium-added Type 308 weld metal (specified as Type 308 NbL) which was developed for one-layer overlay welding application. In the present study, stress corrosion cracking (SCC) behavior of heat-treated Types 308 and 308NbL weld metals in oxygenated high temperature pure water was evaluated by slow strain rate test and U-bend tests with and without crevice. Every test showed that Type 308NbL weld metals were highly resistant to SCC compared to ordinary Type 308 weld metals. In single U-bend test, one-layer overlay weld metals of Type 308NbL produced by electroslag welding process using wide strip electrodes were crack free over 23,000 h. The U-bend test data of ordinary Type 308 weld metals were successfully analyzed by an SCC reaction model. Using this analysis, the SCC life margin for Type 308NbL over ordinary Type 308 weld metals, expressed as a ratio of respective times to SCC initiation, was estimated to be about 36.     

Intergranular stress corrosion cracking behavior of types 308 and 316 stainless steel weld metals in a simulated boiling water reactor environment

The sensitization behavior of types 308 and 316 stainless steel weld metals as internal overlays for reactor pressure vessels (RPVs) was studied with respect to the effects of postweld heat treatment (PWHT) at about 600 °C during RPV fabrication and low-temperature aging during operation. For the study, a criterion for the rate of intergranular corrosion (IGC) for detecting the susceptibility to intergranular stress corrosion cracking (IGSCC) in high-temperature oxygenated pure water was established by quantitatively evaluating the results from a modified ASTM A262E test. A criterion for expecting satisfactory resistance to IGSCC was found to be an IGC rate of about 1 μm/h. Type 308 weld metal can be sensitized as indicated by an IGC rate >1 μm/h, and can be healed, as indicated by an IGC rate <1 μm/h, depending on the length of PWHT. However, this healed weld metal can be resensitized by exposing it to 500 °C×24 h; in this condition, it shows a relatively high susceptibility to IGSCC. On the contrary, type 316 weld metal was almost immune to sensitization under the same heat treatments. By transmission electron microscopy (TEM), its excellent resistance was attributable to carbon fixation by molybdenum carbide precipitation within ferrite phases during PWHT. Reheat embrittlement of type 316 weld metal was also examined.     

Novel charge neutralization techniques applicable to wide current range of FIB processing in FIB-SEM combined system

FIB-induced charging is one of the most critical issues for achieving successful circuit modifications of LSI. We have developed novel charge neutralization techniques applicable to a wide current range (from pico to nanoampere-order) of FIB processing in a FIB-SEM combined system. The method utilizes a 500 eV focused electron beam instead of an electron shower, and also a combination of microprobing and FIB-assisted deposition to make a current path from FIB processing point to the grounded microprobe. The effects of our techniques on charge neutralization capability were investigated using electrically erasable-programmable read-only memory devices and n-MOS transistors. For the low FIB current condition of less than 500 pA, it is found that the focused electron beam prevents threshold voltage shifts of both irradiated and neighboring transistors, and that the ratio of electron to ion beam currents is a key parameter to achieving effective charge neutralization. We also demonstrated that the combined method of microprobing and FIB-assisted deposition prevents parameter shifts of transistors even for high-current (nanoampere-order) FIB irradiation. Moreover, we evaluated the upper-limit resistance of the current path formed by FIB-assisted carbon deposition to prevent charging induced by a given FIB current.     

Characterization of structure of single particles from various automobile engines under steady-state conditions

The effective density ρ_eff of particles emitted from various types of automobile engines was measured using a differential mobility analyzer (DMA)–aerosol particle mass analyzer method, and their morphology was investigated via transmission electron microscopy analysis. The measured exhaust particles were particles emitted from diesel engines (DEs), gasoline direct injection spark ignition (DISI) engines, gasoline port fuel injection (PFI) engines, and liquefied petroleum gas (LPG) engines. ρ_eff and the morphology of the particles were measured after classification with the DMA, and six electrical mobility diameters D_m ranging from 30 to 300 nm were selected. ρ_eff was found to decrease as D_m increased for all particles. A morphological study showed that DE and DISI particles were mainly agglomerates and PFI and LPG particles were mainly nonagglomerates. Numbers and diameters of the primary particles in the agglomerates showed no systematic differences between DE and DISI particles at a given D_m. Rather, the primary particle diameter d_p increased with increasing D_m of the agglomerates; the empirical relationship between the two diameters was found to be d_p = 8.498ln(D_m) – 12.781 for DE and DISI particles. The core (elemental carbon) diameters in the primary particles of the DE particles increased as D_m increased and were estimated to range from 8.5 nm for D_m = 70 nm to 22.1 nm for D_m = 300 nm. Although the primary particle diameter and core diameter depend on D_m, the organic coating (shell) thickness, which ranged from 5.1 to 7.4 nm, was found to be independent of D_m.

Copyright © 2016 American Association for Aerosol Research     

Distributed power flow loss minimization control for future grid

In this paper, a novel decentralized algorithm is proposed to minimize power flow loss in a large‐scale future grid connecting with many real‐time‐distributed generation systems by which power flows bi‐directionally. The DC‐power loss at each link is defined as the product of resistance and the square of current that can be considered as a quadratic flow cost. We employ the notion of tie‐sets that reduces the complexity of the power flow loss problem by dividing a power network into a set of loops that forms a linear vector space on which the power loss problem can be formulated as a convex optimization problem. As finding a solution in each tie‐set enables global optimization, we realize parallel computing within a system of independent tie‐sets by integrating autonomous agents. Simulation results demonstrate the minimization of the power loss on every link by iteratively optimized power flows and show the superiority against the traditional centralized optimization scheme. Copyright © 2014 John Wiley & Sons, Ltd.     

IR Practical Extinction Coefficients of Water in Alkali Lime Silicate Glasses Determined by Nuclear Reaction Analysis

Infrared spectroscopy (IR) is widely used to determine the water concentration in glasses, whereas determination of the IR practical extinction coefficient is necessary to deduce the absolute water concentration of glasses on the basis of Beer–Lambert law. From the nuclear reaction analysis data, the IR practical extinction coefficients of water were successfully determined for the alkali lime silicate glasses with different levels of sodium/potassium cation (Na/K) ratio. The two‐band method is well‐known to be useful for the determination of the water concentration in some alkali lime silicate glasses. It is proved here that the two‐band method is not applicable to the variety of composition for alkali lime silicate and soda lime aluminosilicate glasses, whereas it is valid for the similar composition of soda lime silicate glasses [SLS: Composition (in mol%) 16Na₂O·10CaO·74SiO₂]. The single‐band procedure with the IR practical extinction coefficient is crucial for the determination of the precise water concentration in the wide variety of glass composition although the determination of the IR practical extinction coefficient is troublesome. It also appears that the ion radius of alkali affects the IR practical extinction coefficient and the chemical state of OH group in glasses.