Vol. 44 No. 3 (2012)

A C- algebra is the algebraic form of the 3-valued conditional logic, which was introduced by F. Guzman and C.C. Squier in 1990. In this paper, some equivalent conditions for a C- algebra to become a boolean algebra in terms of congruences are given. It is proved that the set of all central elements B(A) is isomorphic to the Boolean algebra S(A) B of all C-algebras Sa, where a  B(A). It is also proved that B(A) is isomorphic to the Boolean algebra R(A) B of all C-algebras Aa, where a B(A).

Suppose that a time series model is fitted. It is likely that the fitted model is not the true model. In other words, the model has been misspecified. In this paper, we consider the prediction interval problem in the case of a misspecified first-order autoregressive or AR(1) model. We have calculated the coverage probability of an upper one-step-ahead prediction interval for both properly specified and misspecified models through Monte Carlo simulation. It was found that dealing with prediction interval for misspecified model is complicated: the distribution of a future observation…

The magnetic states of Cobalt ions in magnetic thermoelectric materials of Bi1.5Pb0.5Ca2-zYzCo2O8 (z = 0, 0.1, 0.2, and 0.3) have been studied from the structural (X-ray diffraction) and magnetic susceptibility data. The misfit structure was revealed from refinement of the XRD data, with reduction of the lattice parameters while increasing the Y doping content. Compared with the (Bi,Pb)2Sr2Co2O8 parent compound system, the lattice parameter c was reduced significantly, while the misfit degree remained almost the same. The analysis of the magnetic data shows that the Cobalt ions are coupled…

In this paper, we study the instability properties of solutions of a kind of functional differential equations of the fifth order with constant delay. Using the Lyapunov-Krasovskii functional approach, we obtain certain sufficient conditions to guarantee that the zero solution of the equation is unstable.

Phase transformation of rice husk ash in the synthesis of ZSM-5 without organic template at various crystallization times has been studied. Zeolite has been synthesized using the hydrothermal method at 175 °C with molar ratio 10Na2O: 100SiO2: 2Al2O3: 1800H2O with addition of silicalite-1 as seed. Solids were characterized using X-ray diffraction (XRD), infrared (IR) spectroscopy and scanning electron microscopy (SEM) techniques. Analysis of the results of XRD and IR spectroscopy indicated that ZSM-5 crystalstarted to form at 12 h of crystallization time, reaching high crystallinity after 24…

A series of tris(β-diketonato)zirconium(IV) complexes was immobilized into a synthetic clay structure of Taeniolite by an ion-exchange method to generate organic/inorganic hybrid compounds. The hybrid compound served as a good catalyst for ring-opening reactions of methyl, ethyl, and dimethyl oxiranes with various alcohols to generate primary alkoxy alcohols in appreciable selectivity. This method describes a technique to immobilize cationic zirconium complexes without losing selectivity.

The governing equations describing methane oxidation in a reverse flow reactor are given by a set of convective-diffusion equations with a nonlinear reaction term, where temperature and methane conversion are dependent variables. In this study, the process is assumed to be a one-dimensional pseudohomogeneous model and takes place with a certain reaction rate in which thewhole process ofthereactor is still workable. Thus, the reaction rate can proceed at a fixed temperature. Under these conditions, we can restrict ourselves to solving the equations for the conversion only. From the available…

A polymer electrolyte membrane widely used in PEMFCs and DMFCs is a perfluorosulfonated membrane (the Nafion membrane). This perfluorosulfonated membrane material exhibits good chemical stability and proton conductivity, but it is very expensive and difficult to recycle. There is a high methanol crossover in DMFCs that causes a decrease in efficiency and performance of the fuel cell, so that a polymer electrolyte membrane with a low methanol crossover is needed as a substitute for the Nafion membrane. One of the materials that can be used as a polymer electrolyte membrane is the polyblends…