Electrical Conduction in β-Bi2O3 Doped with Sb2O3

Electrical conduction in tetragonal β-Bi₂O₃ doped with Sb₂O₃ was investigated by measuring electrical conductivity, ionic transference number, and Seebeck coefficient. The β-Bi₂O₃ doped with 1 to 10 mol% Sb₂O₃ was stable up to 600°C and showed an oxygen ionic and electronic mixed conduction, where the electron conduction was predominant at low oxygen pressures. The oxygen-ion conductivity showed a maximum at 4 mol% Sb₂O₃, whereas the activation energy for the ionic conduction remained unchanged for 4 to 10 mol% Sb₂O₃-doped specimens. These results were interpreted in terms of the oxygen vacancy concentration and the distortion of the tetragonal structure. The electron conductivity and its oxygen pressure dependence decreased with increasing Sb₂O₃ content. The fact that Sb⁵⁺ is partially reduced by excess electrons in heavily doped β specimens at low oxygen pressures is explained.     

Gas Sensing Characteristics of Porous ZnO and Pt/ZnO Ceramics

Changes in resistivity and chemical changes in reducing gases were measured for porous zinc oxide ceramics with and without a platinum catalyst at 300° and 400°C to examine the gas sensing mechanism and the effect of platinum additions. Reducing gases were oxidized to CO₂ and Hz₂ on the sensor surfaces. Platinum addition promoted the oxidation of reducing gases but did not lead to an increase in the resistivity change at 400°C. The reaction sequences for the gas sensing process are proposed, taking into account partially oxidized intermediates of hydrocarbons and oxidation on platinum without an electron transfer process.     

Dependence of Grain-Boundary Resistivity on Grain-Boundary Density in Yttria-Stabilized Zirconia

The dependence of grain-boundary resistivity and resistance per square centimeter of grain-boundary surface on grain-boundary density (D) in yttria-stabilized zirconia was investigated using reported data. The grain-boundary resistivity increased with increasing D in the high-D region but was independent of D in the low-D region. These results were interpreted in terms of intrinsic effects such as lattice irregularity and extrinsic effects such as impurity segregation.     

Optimization of weakly coupled subsystems by a two-level method

A two-level method to find the optimal control of a linear system is presented. We consider that the system is composed of coupled subsystems. And we solve two decoupled first-level problems and one coordinating second-level problem iteratively. When the system can be decoupled into weakly coupled subsystems, the solution fast converges to the optimal.     

Novel active-R synthesis of a driving-point impedance

A novel active-R synthesis baaed on the single-pole rolloff characteristics of operational amplifiers is described. Various types of driving-point impedance, such as an inductance, frequency-dependent negative-resistance and frequency-dependent negative-inductance are systematically derived by the suitable choice of the amplifier transfer function. It is shown by experiments that the inductance simulator presents reliable high frequency performance.     

The Effect of Annelation on the Colour of 1, 4-Disubstituted Benzoanthraquinone Disperse Dyes

The visible spectra of a series of 1,4-disubstituted benzoanthraquinone dyes in benzene solution has been measured. The position of the absorption maxima of the dyes has been found to be well correlated with a mean ionization potential of the substituent groups. An annelation of anthraquinone dyes in the position of 2, 3 or 6, 7produced a small hypsochromic shift, while 5,6-annelation produced a large bathochromic shift. The additive properties on the absorption maximum of dibenzoanthraquinone dyes were also observed.     

Power generation scheduling by neural network

A new method for solving a power generation scheduling problem in an electric power system is presented. The objective is to determine the hourly start-up/ shut-down schedules of all generators so that forecasted hourly power demands per day may be met and total operating costs, the sum of setup and fuel costs for a given day, may be minimized. The problem may be formulated as a large-scale combinatorial optimization problem which includes 0-1 variables representing the start-up/shut-down of generators and continuous variables representing the power outputs. Determination of an optimalsolution within practical time limits is consequently difficult. Until now, the lagrangian relaxation method has been studied as it appeared to be the most practical method for obtaining an approximate solution to the problem. The efficiency of this method, however, depends on how the Lagrange multipliers are determined. Here, it is proposed that the Lagrange multipliers be estimated by utilizing the neural network and results determined from examination of the possibility of applying the backpropagation algorithm to pattern recognitions which presume the relationship between power demand pattern and Lagrange multipliers are reported. Through numerical experiments, it was established that the Lagrange multipliers, estimated by the neural network, are applicable to the problem.     

Window functions obtained by convolution integrals of rectangular windows

The rectangular, triangular, and Parzen windows, which have been defined independently of each other, are obtained by repeating convolution integrals of the rectangular window with itself. They are extended to make a series of window functions. This series has the advantage that the sidelobe fall-off is variable though it has the disadvantage that the mainlobe band-width for the same highest sidelobe level is 1–1·3 times those of the gaussian, Kaiser, Dolph–Chebyshev or Blackman–Harris windows. Moreover, this series has a desirable mainlobe bandwidth of 0·85–1 times that of cos^x x windows for the same highest sidelobe level and sidelobe fall-off. Thus, this series is useful in designing window functions whose mainlobe bandwidth is in between that of the gaussian or Kaiser windows and that of cos^x x windows and whose sidelobe fall-off is as good as that of the cos^x x windows.     

Electrical Conduction in Sintered α-Sb2O4

Electrical conductivity and thermoelectric power were measured on sintered α-Sb₂O₄ at 250° to 780°C. Oxygen partial pressure dependence of the conductivity and sign of the Seebeck coefficient showed α-Sb₂O₄ to be a p -type semiconductor above 600°C in the oxygen pressure range of lo⁵ to 10² Pa. A hopping conduction was proposed from very small hole mobility with an activation energy of 18 kJ/mol.     

Optimization of linear systems with integral control for time-weighted quadratic performance indices

The necessary conditions to be satisfied by the feedback control constructed by available variables, minimizing time-weighted quadratic performance indices for linear systems incorporating integral action, are developed using the parameter optimization technique. To remove the dependence of the solution on a reference input and an external disturbance, a performance index based on the statistical expectation and a minimax solution are considered. An algorithm based on a gradient technique is given to solve the necessary conditions of the minimax solution. Numerical examples are given to illustrate the effect of a time-weighted performance index on the transient response of the output, and they show that the integral-square-time-square error performance index is acceptable for a reference input.