Quantitative risk assessment using a Japanese hydrogen refueling station model

Although hydrogen refueling stations (HRSs) are becoming widespread across Japan and are essential for the operation of fuel cell vehicles, they present potential hazards. A large number of accidents such as explosions or fires have been reported, rendering it necessary to conduct a number of qualitative and quantitative risk assessments for HRSs. Current safety codes and technical standards related to Japanese HRSs have been established based on the results of a qualitative risk assessment and quantitative effectiveness validation of safety measures over ten years ago. In the last decade, there has been much development in the technologies of the components or facilities used in domestic HRSs and much operational experience as well as knowledge to use hydrogen in HRSs safely have been gained through years of commercial operation. The purpose of the present study is to conduct a quantitative risk assessment (QRA) of the latest HRS model representing Japanese HRSs with the most current information and to identify the most significant scenarios that pose the greatest risks to the physical surroundings in the HRS model. The results of the QRA show that the risk contours of 10^?3 and 10^?4 per year were confined within the HRS boundaries, whereas the risk contours of 10^?5 and 10^?6 per year are still present outside the HRS. Comparing the breakdown of the individual risks (IRs) at the risk ranking points, we conclude that the risk of jet fire demonstrates the highest contribution to the risks at all of the risk ranking points and outside the station. To reduce these risks and confine the risk contour of 10^?6 per year within the HRS boundaries, it is necessary to consider risk mitigation measures for jet fires.     

Direct Observation of Pure Cu and Cu-Ag Anode Passivation in H2SO4-CuSO4 Aqueous Solution by Channel Flow Double Electrode and Optical Microscopy

Metallurgical and Materials Transactions B - The dissolution and passivation of pure Cu and Cu-5 wt pct Ag anodes in H2SO4-CuSO4 electrolyte were investigated by a direct...     

Mechanisms of orientational and photoelastic birefringence generation of methacrylates for the design of zero–zero‐birefringence polymers

The intrinsic birefringence Δn⁰ and photoelastic coefficient C of poly(methyl methacrylate), poly(2,2,2‐trifluroethyl methacrylate), poly(phenyl methacrylate), and poly(2,2,3,3,3‐pentafluorophenyl methacrylate) were determined. We categorized these methacrylate polymers into four birefringence‐types, even though their molecular structures differed only by the substituents on the side chains. Based on the results of Δn⁰ and C, novel polymers that exhibit neither orientational nor photoelastic birefringence, i.e., zero–zero‐birefringence polymers, were designed and synthesized by quaternary copolymerization system. Furthermore, we confirmed that the mechanisms of orientational birefringence and photoelastic birefringence generation were different in these methacrylate polymers. The conformation of the repeat unit of the polymers was nearly constant during the generation of orientational birefringence. In contrast, the conformation of the repeat unit of the polymers changed during the generation of photoelastic birefringence in the glassy state. These findings demonstrated the reasonability of evaluating orientational and photoelastic birefringence separately, as well as the adequacy of the classification of polymers into four birefringence‐types. Given these results and the fact that zero–zero‐birefringence polymers could be prepared successfully by four‐birefringence type monomers, we demonstrated the reasonability of the method for designing the zero–zero‐birefringence polymers. POLYM. ENG. SCI., 55:1330–1338, 2015. © 2015 Society of Plastics Engineers     

The method of double averaging: an approach for modeling power-factor-correction switching converters

This paper describes the modeling of power-factor-correction converters under average-current-mode control, which are widely used in switch-mode power supply applications. The objective is to identify stability boundaries in terms of major circuit parameters for facilitating design of such converters. The approach employs a double averaging procedure, which first applies the usual averaging over the switching period and subsequently applies generalized averaging over the mains period. The resulting model, after two averaging steps and application of a harmonic balance procedure, is nonlinear and capable of describing the low-frequency nonlinear dynamics of the system. The parameter ranges within which stable operation is guaranteed can be accurately and easily found using this model. Experimental measurements are provided for verification of the analytical results.     

Synthesis and photosensitivity of acryloylmorpholine copolymers with a pendant (meth)acryloyl group

We have developed new photopolymers that have superior waterproof properties and that can easily interact with polyfunctional acrylate compounds, thus serving as hydrophobic photocrosslinking reagents. Acryloylmorpholine monomers whose homopolymers were less moisture absorbing than the usual water‐soluble polymers but were still water soluble to a good degree, were copolymerized with other acryloyl monomers. We then introduced the photosensitive (meth)acryloyl group to side chains of the resulting polymers. Among six copolymers examined, the copolymers composed of acryloyl morpholine, hydroxyethyl acrylate, ethyl, or methyl methacrylate, and methacryloyl isocyanate were found to have nicely balanced hydrophilicity and waterproof properties, in addition to good compatibility with hydrophobic photocrosslinking reagents. The composite polymers thus obtained were confirmed to be promising photopolymers usable even in a highly humid environment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 684–692, 2003     

Prediction of spectral reflectance factor distribution of automotive paint finishes

It is necessary to determine the accurate reflectance of painted surfaces for the review of paint finishes by computer graphics (CG) before actual painting of the exterior color of automobiles, and for quality control during production and inspection processes. We have optimized a method for measuring reflectance by using a statistical technique. We have found that the reflectance of a painted surface is best measured at an incident angle of 60° and at five aspecular angles of 10°, 18°, 28°, 40°, and 90°. Our method makes it possible to accurately reproduce reflection characteristics of paint finishes containing special flake pigments, such as pearl mica. Also it was proved that our method can apply not only to solid and metallic coatings but to all painted surfaces. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 275–282, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20125     

New approach to environmentally benign epoxidation: the solid-phase-system using urea–H2O2 and recyclable dodecatungstate on apatite

On the basis of new concept using a solid disperse phase we have developed an efficient catalytic solid-phase-system for epoxidations of alkenes using urea–hydrogen peroxide (urea–H₂O₂) complex and cetylpyridinium dodecatungstate ((CetylPy)₁₀[H₂W₁₂O₄₂]) catalyst on fluorapatite (FAp). The recovered solid catalyst phase was reused to keep the catalytic activity after several times. In the conceptual idea it is a key point that in situ solid-phase-activation of the catalyst with urea–H₂O₂ proceeds to form microcrystals of the active species dispersed on the solid phase. The dispersion of the catalyst on FAp in the case of tungstic acid (H₂WO₄) was suggested by EPMA analysis. We proposed the peroxo type of species keeping the parent polyoxometalate framework as novel active species from FT-IR spectroscopic studies. FAp phase plays important roles of dispersing the active species on its surface to have high catalytic activity and of stabilizing the active species to lead to high reusability.     

Phenol novolac/poly(4- hydroxyphenylmaleimide) blend hardeners for DGEBA-type epoxy resin

Phenol novolac/poly (4-hydroxyphenylmaleimide) (PHPMI) blends were used as an epoxy resin hardener. The curing behavior of the above system and the thermal and mechanical properties of the cured epoxy resin were studied. It was not necessary to use a curing accelerator for this system, because PHPMI caused acceleration of the curing reaction. The curing mechanism of this system was investigated by using model compounds. Test pieces from the neat resins and the glass fiber reinforced resins were evaluated in terms of thermal and mechanical properties, respectively. It was found that heat resistance and mechanical properties were improved by increasing the amount of PHPMI in the hardener.     

Preparation and photoconduction of rapidly quenched films in the Bi2O31bM2O5 system (M=V,Nb and Ta)

The Bi₂O₃1bM₂O₅ films (M=V, Nb and Ta) were prepared by a rapid quenching technique using a twin-roller type equipment. Quenched film of pure Bi₂O₃ partially precipitated a tetragonal phase which differs from well-known β-Bi₂O₃ in structure. In every (Bi₂O₃)_0.975 (M₂O₅)_0.025 composition (2.5% M₂O₅), the tetragonal phase was obtained as single phase, and the tetragonality became greater than that of the pure Bi₂O₃. Beyond this composition, the tetragonality decreased to form δ-phase with a fcc structure with increasing the M₂O₅ content. The lowest V₂O₅ content forming a δ-phase was 5%, while a slight tetragonality still remained in the samples containing 10% Nb₂O₅ and 10% Ta₂O₅, respectively. From the measurement of the photoconductivities of the quenched films, it was proved that a photoconduction appeared in the tetragonal phase while no photoconductivity was observed in the cubic phase. The characteristic of the photoconduction was that a remarkable decrease in the resistivity was observed when a light of ca. 500 nm in wave length was irradiated on the films.