The eigenvalue problem for banded matrices

The generalized Lanczos method is used for the purpose of calculating frequencies and mode shapes for linearly elastic discretized structures where the energy-consistent stiffness and mass matrices are equally banded. This approach involves reduction of the problem to standard tridiagonal form without expanding the band width of either of the original arrays. Applications of the method to both vibrational and buckling analyses indicate its potential for conserving core storage when solving the eigenvalue problem on a digital computer.     

Doping effect of divalent cations on sintering of polycrystalline yttria

The sintering behavior of Y₂O₃ doped with 1 mol% of Ca²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Sr²⁺ or Zn²⁺ was investigated by pressureless sintering in air at a sintering temperature in the range 900–1600 °C. The sintering temperature required for full densification in Y₂O₃ was reduced by 100–400 °C by the cation doping, while undoped Y₂O₃ was densified at 1600 °C. The most effective dopant among the examined cations was Zn²⁺. The grain growth kinetics of undoped and cation-doped Y₂O₃ was described by the parabolic law. The grain boundary mobility of Y₂O₃ was accelerated by doping of the divalent cations. High-resolution transmission electron microscopy (HRTEM) observations and nano-probe X-ray energy dispersive spectroscopy (EDS) analyses confirmed that the dopant cations tended to segregate along the grain boundaries without forming amorphous layers. The improved sinterability of Y₂O₃ is probably related to the accelerated grain boundary diffusion owing to the grain boundary segregation of the dopant cations.     

Fabrication of Transparent Pb(Mg1/3Nb2/3)O3–PbTiO3 Based Ceramics by Conventional Sintering

Transparent 0.9Pb(Mg_1/3Nb_2/3)O₃–0.1PbTiO₃ (PMN‐PT) based ceramics were prepared by a conventional solid‐state synthesis without using a hot‐press method. The ceramics became transparent when they were sintered in an O₂ atmosphere. The optical transmission increased with decreasing diameter of the calcined powder, which was controlled by the size of zirconia ball‐milling media. Substitution of 3 mol% La for Pb in PMN‐PT further increased the optical transmission to 68% at the wavelength of 2000 nm, which was comparable to that of hot‐pressed Pb(Mg_1/3Nb_2/3)O₃‐PbTiO₃ based transparent ceramics.     

Characterization of Antifungal Metabolites Produced by Penicillium Species Isolated from Seeds of Picea glehnii

We screened the microorganisms that are present on the surface of Picea glehnii seeds and produced antifungal compounds against Pythium vexans, a fungus that causes damping-off. Four isolates of Penicillium species that produced patulin, citrinin, palitantin, and arthrographol, respectively, were identified from 149 different microorganisms screened. This study is the first step in an examination of the ecological interaction between host conifers and fungi located on the surface of their seeds.     

Pressure dependence of extraction behavior of plutonium(IV) and uranium(VI) from nitric acid solution to supercritical carbon dioxide containing tributylphosphate

Plutonium(IV) and uranium(VI) were extracted into supercritical CO₂ fluid phase (SF-CO₂) containing tributylphosphate (TBP) with equilibrium distribution ratios, D, e. g., D_Pu(IV) = 3.1 and D_U(IV) = 2.0, for the extraction of 2 × 10⁻³ M Pu(IV) and U(VI) from 3 M HNO₃ into SF-CO₂ containing 0.3 M TBP at 60 °C and 15 MPa. A simple linear relation between D and density of CO₂; long D = a log + b (a,b; constants), was observed, which was explained theoretically by the formulation of the extraction equilibrium taking into account the phase distribution behavior of extractant TBP and extracted species, i.e. Pu(IV)- and U(VI)-TBP complexes involved in the extraction reaction. The slopes a of the log D vs. log plots were −(1.6 ± 0.1) and −(2.7 ± 0.5) for the extraction of Pu(IV) and U(VI), respectively. The differences in D as well as the slope a between Pu(IV) and U(IV) make it possible to design the U and Pu separation method by which one can achieve an enhancement of the extraction efficiency and selectivity by tuning the operation pressure.     

An approach to higher damping capacity based on a control theory strategy

In order to compare the active damping (computer-controlled damping) via a control theory with the passive (material) damping, the vibration suppressing effect has been investigated by constructing a feedback control system. It consists of a cantilever beam (3×35×300 mm³), a sensor, an actuator and a feedback controller, which has been designed on the basis of the optimal regulator control theory. In a freely decaying vibration state, the active damping effect increases the vibration damping capacity (Q⁻¹) from 0.011 to 0.157 (almost 14.3 times). On the other hand, in a resonant state, the active damping reduces the resonant amplitude to about 1/12. The active damping corresponds to about 6.8 times the maximum damping observed in the ferromagnetic metal SIA.     

Study on the generation process of the discharge for color plasmadisplays based on observation by using an ultra-high-speed electroniccamera

Instead of the direct observation of ultraviolet rays of 147 nm emitted from Xe, light emission of 828 nm was observed first by using ultra-high-speed electronic camera system. The experimental results show that the ultraviolet rays of 147 nm emit above both cathodes and anodes simultaneously. The striation phenomena observed on anodes were analyzed