Study on the Development of Corrosion Resistant Overlay Welding Materials and Construction Techniques for Boiler Furnaces

広島大学(Hiroshima University)博士(工学)Doctor of Engineeringdoctora

The Period and the Distribution of the Fibonacci-like Sequence Under Various Moduli

We reduce the Fibonacci sequence mod m for a natural number m, and denote it by F (mod m ). We are going to introduce the properties of the period and distribution of F (mod m). That is, how frequently each residue is expected to appear within a single period. These are well known themes of the research of the Fibonacci sequence, and many remarkable facts have been discovered. After that we are going to study the properties of period and distribution of a Fibonacci-like sequence that the authors introduced in article in the previous issue of Undergraduate Math Journal. This Fibonacci-like sequence also has many interesting properties, and the authors could prove an interesting theorem in this article. Some of properties are very difficult to prove, and hence we are going to present some predictions and calculations by computers

Effect of Ammonia or Nitric Acid Treatment on Surface Structure, in vitro Apatite Formation, and Visible-Light Photocatalytic Activity of Bioactive Titanium Metal

Ti metal treated with NaOH, NH4OH, and heat and then soaked in simulated body fluid (SBF) showed in vitro apatite formation whereas that treated with NaOH, HNO3, and heat and then soaked in SBF did not. The anatase TiO2 precipitate and/or the fine network structure formed on the surface of the Ti metal treated with NaOH, NH4OH, and heat and then soaked in SBF might be responsible for the formation of apatite on the surface of the metal. The NaOH, NH4OH, and heat treatments might produce nitrogen-doped TiO2 on the surface of the Ti metal, and the concentration of methylene blue (MB) in the Ti metal sample treated with NaOH, NH4OH, and heat decreased more than in the untreated and NaOH- and heat-treated ones. This preliminary result suggests that Ti metal treated with NaOH, NH4OH, and heat has the potential to show photocatalytic activity under visible light

A Study on the Fatigue Characteristics of Polymethylmetacrylate Adherends

In this paper we describe an experimental study. Reported in this article are tensile fatigue characteristics of polymethylmetacrylate and its bonded material in relation to wave form of load, loading velocity and notch effect. In experiments, heat cured acrylic resin was used for base material, while heat cured and self-cured polymethylmetacrylate (Denture Acrylic SHOFU "Bio" Resin) were used as Adhesives. As a result of the research of test and experiments, it is found that; 1) Fatigue limits of the bonded materials using heat cured and self-cured P.M.M.A. are approximately 2/3 and 1/3 of that of the base material. 225 2) Two-fold property of S-N curve can be seen with dental P.M.M.A., and such property is partly attributable to temperature rise of the test piece. Fatigue limit drops as test velocity increases, and such drop is again partly attributably to temperature rise of the material. 3) Effect of notch is observed and it is noted that the notch causes deterioration in endurance limit by about 1/4

A Study on the Fatigue Characteristics of Polymethylmetacrylate Adherends

In this paper we describe an experimental study. Reported in this article are tensile fatigue characteristics of polymethylmetacrylate and its bonded material in relation to wave form of load, loading velocity and notch effect. In experiments, heat cured acrylic resin was used for base material, while heat cured and self-cured polymethylmetacrylate (Denture Acrylic SHOFU "Bio" Resin) were used as Adhesives. As a result of the research of test and experiments, it is found that; 1) Fatigue limits of the bonded materials using heat cured and self-cured P.M.M.A. are approximately 2/3 and 1/3 of that of the base material. 225 2) Two-fold property of S-N curve can be seen with dental P.M.M.A., and such property is partly attributable to temperature rise of the test piece. Fatigue limit drops as test velocity increases, and such drop is again partly attributably to temperature rise of the material. 3) Effect of notch is observed and it is noted that the notch causes deterioration in endurance limit by about 1/4

Phase diagram of ice polymorphs under negative pressure considering the limits of mechanical stability

Thermodynamic and mechanical stabilities of various ultralow-density ices are examined using computer simulations to construct the phase diagram of ice under negative pressure. Some ultralow-density ices, which were predicted to be thermodynamically metastable under negative pressures on the basis of the quasi-harmonic approximation, can exist only in a narrow pressure range at very low temperatures because they are mechanically fragile due to the large distortion in the hydrogen bonding network. By contrast, relatively dense ices such as ice Ih and ice XVI withstand large negative pressure. Consequently, various ices appear one after another in the phase diagram. The phase diagram of ice under negative pressure exhibits a different complexity from that of positive pressure because of the mechanical instability