岡山大学工学部 Acta Medica Okayama 0475-0071 19 1 1984 Evaluation of Three Flow Injection Analysis Methods for the Determination of Chemical Oxygen Demand 53 62 EN /10.18926/15789 Three methods for determining chemical oxygen demand (COD) by means of flow injection analysis (FIA) with potassium permanganate, potassium dichromate, or cerium(IV) sulfate as oxidant, developed in this laboratory, are described from the point of view of their operating properties. The permanganate method is the most sensitive and common, but forms manganese(IV) oxide precipitate which blocks the FIA lines and connectors. Addition of phosphoric acid in the reagent system is, however, effective to some extent in order to avoid blocking the flow system. The dichromate method is the most workable and stable, but produces toxic wastes containing chromium(VI). The cerium method is the most probable because cerium(IV) is the strongest oxidant of the three and less poisonous. The last method with cerium(IV) sulfate is therefore recommendable to apply to the continuous monitoring of COD in many situation. No potential conflict of interest relevant to this article was reported.

岡山大学工学部 Acta Medica Okayama 0475-0071 19 1 1984 Preparation and Dielectric Properties of [Ba, Ca] TiO(3)-Al(2)O(3)-SiO(2) Glass-Ceramics 45 51 EN 10.18926/15787 Succeeding to 60(Ba,Sr)TiO(3)-10A1(2)O(3)-30SiO(2)glassceramics reported in our previous paper, another type of ferroelectric glass-ceramics was elaborated by the controlled growth of Ba(l-x)Ca(x)TiO(3) crystal particles in the glass system 60 (Ba(l-y)Ca(y)) TiO(3)-10Al(2)O(3)-30SiO(2) (0.0<y<0.25) in molar basis. Analysis of crystal phases by X-ray diffraction revealed that Ca content in the crystal phase of Ba(l-x)Ca(x)TiO(3) increased with increasing amount of CaO in glass up to y=0.125, and the composition of Ba(l-x)Ca(x)TiO(3) solid solution was restricted by x=0.225. Curie points(Tc) of the present glasscceramics were independent of the composition of Ba(l-x)Ca(x)TiO(3), however temperature coefficients of Σ were lowered by the addition of increasing amount of CaO. Frequency dependencies of dielectric constant and loss tangent were examined in the frequency range from 1 k to 1 M Hz. No potential conflict of interest relevant to this article was reported.

岡山大学工学部 Acta Medica Okayama 0475-0071 19 1 1984 Error Analysis of Band Matrix Method 33 44 EN /10.18926/15785 Numerical error in the solution of the band matrix method based on the elimination method in single precision is investigated theoretically and experimentally, and the behaviour of the truncation error and the roundoff error is clarified. Some important suggestions for the useful application of the band solver are proposed by using the results of above error analysis. No potential conflict of interest relevant to this article was reported.

岡山大学工学部 Acta Medica Okayama 0475-0071 19 1 1984 Pore Water Pressure in Sand Bed under Oscillating Water Pressure 13 32 EN /10.18926/15783 In this paper the theoretical method to analyse the pore water pressures in the sand bed under the oscillating water pressure is developed. In the former researchs the validity of the theoretical treatment for the one-dimensional problem has been verified. However, the one-dimensional treatment is not sufficient to obtain the precise informations concerning the many practical problems. From this point of view, in this study, we derive the fundamental equations for the general three-dimensional sand layer under the oscillating water pressure. The validity of this theoretical method is verified by experiments for the twodimensional problems. No potential conflict of interest relevant to this article was reported.

岡山大学工学部 Acta Medica Okayama 0475-0071 19 1 1984 On the Bremsstranlung in High-Density Plasmas 1 12 EN /10.18926/15781 Emission and absorption coefficients of bremsstrahlung by high-temperature partially degenerate electrons are calculated for high-density plasmas where Coulomb coupling between ions is not weak. It is shown that the ion correlation substantially reduces these coefficients. No potential conflict of interest relevant to this article was reported.