Codes based on BCK-algebras

The notion of a BCK-valued function on a set is introduced, and related properties are investigated. Codes generated by BCK-valued functions are established.     

Aluminum assisted electrodeposition of europium in LiCl-KCl molten salt

Cyclic voltammetry (CV), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were employed to investigate the electrodeposition of Eu and Al in an LiCl-KCl eutectic melt containing Eu²⁺ and Al³⁺ at 450 °C. In order to deposit a pure Eu and Al alloy, the stoichiometrically lower concentration of Al³⁺ than that of Eu²⁺ and Al wires as a counter electrode was introduced into the bath of LiCl-KCl melt for the electrodeposition. The electrodeposition takes place at a potential more negative than −1.95 V vs. Ag|Ag⁺ while the deposit is oxidized at more positive potential than −1.92 V. Two new reduction peaks and an anodic peak on a W working electrode were observed at −2.39 V, −2.42 V, and −2.1 V, vs. Ag|Ag⁺, respectively, suggesting that the potential window of the Al system in LiCl-KCl melt can be extended to −2.43 V vs. Ag|Ag⁺. The EDS analysis indicated that AlEu can be deposited at the potential more negative than −2.37 V.     

The electrochemical behavior of an enzyme biosensor electrode using an oxyfluorinated pitch-based carbon

A glucose sensor electrode was prepared by thermally treating a pitch-based carbon material. Oxyfluorination was used to modify the surface of the prepared carbon to induce the formation of hydrophilic functional groups. A glucose oxidase enzyme was effectively loaded onto the surface of the oxyfluorinated carbon and was more sensitive in glucose sensing because of the effects of the improved interfacial affinity between the electrode and the glucose oxidase. The introduced hydrophilic functional groups were examined using XPS analysis. In current–voltage measurements, a higher current was observed in the samples prepared with a higher oxygen content. In addition, a clear redox peak was observed in the surface modified samples. These results can be attributed to efficient electrical resistance measurement by easy electron transfer during glucose sensing. An efficient glucose sensor electrode was prepared using pitch-based carbon, which has beneficial electrical properties, and oxyfluorination, which improves the surface interface.     

CO oxidation from syngas (CO and H<Subscript>2</Subscript>) using nanoporous Pt/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst

The concept of “waste-to-wealth” is spreading awareness to prevent global warming and recycle the restrictive resources. To contribute towards sustainable development, hydrogen energy is obtained from syngas (CO and H₂) generated from waste gasification, followed by CO oxidation and CO₂ removal. In H₂ generation, it is key to produce more purified H₂ from syngas using heterogeneous catalysts. In this respect, we prepared Pt/Al₂O₃ catalyst with nanoporous structure using precipitation method, and compared its catalytic activity with commercial alumina (Degussa). Based on the results of XRD and TEM, it was found that metal particles did not aggregate on the alumina surface and showed high dispersion. Optimum condition for CO conversion was 1.5 wt% Pt loaded on Al₂O₃ support, and pure hydrogen was obtained after removal of CO₂ gas.     

Performance improvement by metal deposition at the cathode active site in solid oxide fuel cells

In this study, the performance improvement of the SOFC single cell and its underlying mechanism was investigated. Furthermore, an application of the identified electrochemical mechanism is proposed and tested experimentally. The deposition of Platinum (Pt) at electrochemically active sites for the oxygen reduction reaction is determined to be responsible for the improved performance. Pt migration from a current collector to the cathode active sites originates from the oxygen partial pressure difference between current collector and triple phase boundary, and the electrochemical reduction reaction. It is supported by the confirmation of Pt particles at the cathode active sites by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and calculations of the thermodynamic equilibrium partial pressure values. In addition, correlation of the initial performance change and the quantities of Pt deposition are investigated. This selective Pt deposition mechanism at the active sites is applied to the LSCF cathode, as well.     

Effect of Mo contents on corrosion behaviors of welded duplex stainless steel

The corrosion behaviour and change of the phase fraction in welded 24Cr Duplex stainless steel was investigated for different chemical composition ranges of Mo contents. Filler metal was produced by fixing the contents of Cr, Ni, N, and Mn while adjusting the Mo content to 0.5, 1.4, 2.5, 3.5 wt%. The δ-ferrite fraction was observed to increase as the content of Mo increased. A polarisation test conducted in a salt solution, indicated the pitting corrosion potential increased continuously to 3.5 wt% Mo, while the corrosion potential changed most between 0.5 and 1.41 wt% Mo. The location of the pitting corrosion in 0.5 wt% Mo steel was randomly distributed, but it occurred selectively at the grain boundary between the γ- and δ-ferrite phases in 1.4, 2.5 and 3.5 wt% Mo steel. Energy dispersive X-ray spectroscopy mapping analysis showed that areas deficient in Cr, Mo, and Ni occurred around the grain boundary of the γ- and δ-ferrite phases. Non-metallic inclusions are thought to act as initiation points for the pitting corrosion that occurs in the salt solution initially as a result of the potential difference between the matrix structure and the incoherent inclusions.     

An approach to feature‐based software construction for enhancing maintainability

While the way we build software affects significantly its maintenance in terms of the effort and cost, the experience level of the maintainer in a software acquirers' organization is also one of concern. In this context, often the maintainer is the user of the system. Unfortunately, it is quite possible to lose the trustworthiness of the software due to the inexperience of the maintainer, especially when the maintainer is without the help of the original developers. One remedy for providing security against the effects of the maintainer's software modifications is to restrict the access to software parts (modules) relative to the experience level of the maintainers. For such a remedy to be successful, the software should be constructed in such a way that its parts under maintenance affect others as little as possible. We propose an approach to software construction aligning the dependencies among software parts in one direction so that they are allocated to maintainers based on their experience level. Our approach decomposes the software into parts based on functionality and orders the parts by essentiality, which indicates how difficult it is to change each part. Then, we align the dependencies in such a way that the less essential functionality is dependent on the more essential functionality. Consequently, any modification on less essential functionality does not affect the essential functionalities. To demonstrate the feasibility of our proposed approach, we applied it to a military application and found that the constructed software enables us to confine maintainers' activity within a limited working area, and thus the software is safer against maintainers' modification. Copyright © 2006 John Wiley & Sons, Ltd.     

Analysis of pricing strategies for e-business companies providing information goods and services

In this paper, we introduce a mathematical model to analyze pricing and service quality strategies for e-business companies providing information services to customers. The basic strategy considered in this paper is that a monopolistic e-business company provides free services to try to earn a profit by developing premium goods or services to market created by their free goods or services. It is a kind of versioning strategy where lower quality versions of information goods are provided free. And a direct network effect was also considered. And we tried to find the profit maximizing strategies for monopolistic e-business companies. As a result, the optimal quality and price for the premium goods or services can be obtained at the same level of the intensity of the direct network effect. And the exact term related with the network externality is derived and insights are demonstrated through numerical explorations.     

Structural evolution in Fe ion implanted Si upon thermal annealing

We have performed high-dose Fe ion implantation into Si and characterized ion-beam-induced microstructures as well as annealing-induced ones using transmission electron microscopy (TEM) and grazing-incidence X-ray diffraction (GIXRD). Single crystals of Si(1 0 0) substrate were irradiated at 623 K with 120 keV Fe⁺ ions to a fluence of 4 × 10¹⁷ cm⁻². The irradiated samples were then annealed in a vacuum furnace at temperatures ranging from 773 K to 1073 K. Cross-sectional TEM observations and GIXRD measurements revealed that a layered structure is formed in the as-implanted specimen with ε-FeSi, β-FeSi₂ and damaged Si, as component layers. A continuous β-FeSi₂ layer was formed on the topmost layer of the Si substrate after thermal annealing.