Perlites, naturally occurring phenomena of Okushiri Island, can be divided into the following three types by their petrographic features: A. massive type. B. pumiceous type. C. flow-textured type. They are very similar to each other in petrochemical character. Perlites from Okushiri contain large quantities of microlite, crystallite and small amounts of phenocrysts which consist of oligoclase, quartz and biotite. Based on X-ray spectrographical analysis and optical examination it can be deduced that the microlite essentially consists of oligoclase, albite and cristobalite with small amounts of biotite and quartz. A comparison study of Okushiri perlites to microlite indicates that perlite is less crystalline in structure than microlite. Okushiri perlites and those from other parts of Japan, although poor in CaO content, are rich in alkalies, especiallyin K2O and when plotted against the ternary eutectic point on the Q-Or-(Ab+An) triangular diagram devised by Bowen and Vogt. Also, the (Fe2O3+FeO)-(Na2O+K2O)-MgO triangular plot indicates that perlites concentrate near the apex (Na2O+K2O) listed in Kuno's hypersthenic rock series. Okushiri perlites are easily transformed into natural glass by heating and rapid cooling into a solid state. Thus producing a glass of high alkalies and silica similar to magma which has undergone the same physical transformations. As founded by differential thermal and thermogravimetric analyses, the H2O content was gradually dehydrated.
This paper examines the vibration characteristics of rectangular, symmetric composite sandwich plates and the layup optimization of their top and bottom laminated FRP composite faces. The honeycomb core is modeled as a thick plate whose transverse shear deformation is taken into consideraion based on a higher-order shear deformation theory, and the top and bottom laminated FRP composite faces are modeled as a very thin sheet. A two-dimensional finite element method is developed using an eight-node isoparametric element. First, the fundamental frequency of the composite sandwich plate is discussed in the subspace of four in-plane lamination parameters of the laminated FRP composite face. Next, the layup optimization of the laminated FRP composite face for maximizing the fundamental frequency of the composite sandwich plate is performed by a nonlinear mathematical programming method, and the optimum laminate configuration of the laminated FRP composite face is determined.
A numerical method for solving the unsteady two-dimensional incompressible flows through a cascade of the diagonal turbomachine is developed by using a discrete vortex method, based on the previous paper. In the discrete vortex method, "point vortices" are not singularities in the existing method but ones introduced only as calculating points on the Lagrangian coordinates. By the method a reasonably smooth distribution of vorticity on the Eulerian mesh can be obtained using relatively a few point vortices. The present method is applicable to an unsteady cascade flow in the water turbine runner subjected to the wakes from the guide vanes in which the distribution of vorticities is complicated.
