Striking effects of cobalt (III) nuclearity in fused salphen complexes on their electroconductivity and thin film transistor activity

Dinuclear and trinuclear cobalt (III) complexes were prepared using fused salphen ligands that have the same number of benzene rings along the major axis of the molecules. The two compounds were used as organic thin film formed on a glass or a SiO₂/n-Si substrate for investigating electronic conductivity and transistor characteristics, respectively. The conductivity of di- and trinuclear complexes were 8.5 × 10⁻⁵ and 5.8 × 10⁻³ S cm⁻¹, meaning that the increment of the nuclearity from two to three resulted in multiplication of 70 times. The thin film of the trinuclear complex showed a faint transistor activity, where the thin film act as n-type semiconductor. In contrast, the dinuclear complex did not afford a detectable response to the gate voltage.     

Transmission analysis of electromagnetic induction RFID system

The transmission characteristics of the electromagnetic induction RFID systems are greatly influenced by the distance between the primary and secondary antenna coils and by the materials used in their design. In this paper the induced current of the secondary antenna coil is calculated by the 3D finite element method when both the primary and secondary antenna coils are operated in resonant circuits. The influences of the analyzed parameters on the transmission characteristics are demonstrated. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(4): 38–45, 2010; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21019     

Testing for EGARCH Against Stochastic Volatility Models

Abstract. It is shown that the EGARCH model is the degenerate case of Danielsson's [Journal of Econometrics (1994) Vol. 61, pp. 375–400] stochastic volatility model where the disturbance of the transition equation of conditional volatility has zero variance. The Lagrange multiplier test statistic is obtained for the EGARCH model against the stochastic volatility model by expressing the degenerate density under the null hypothesis by the Dirac delta function. The finite sample performance of the test is studied in a small Monte Carlo experiment.     

Experimental proof of voltage‐current waveform sensor output of resin molded type for measurement of power factor and harmonics in general power distribution system

We have proposed a voltage‐current sensor of resin molded type for measurement of the power factor and harmonics. To understand the characteristics of the conventional prototype sensor and the problems of its practical use, we conducted a finite element analysis. Problems involving the cost and practical usage of the sensor were identified. Therefore, we have redesigned the prototype sensor, incorporating the current sensor designed on the basis of the FEM and a ready‐made voltage sensor. In this paper, we describe feasibility field experiments with the present sensor in a practical 6.6‐kV distribution system and show that the sensor can measure the power factor and harmonics of horizontal and vertical power line systems successfully. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(3): 1–10, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21213     

Formation of Continuous Pore Structures in Si–C–O Fibers by Adjusting the Melt Spinning Condition of a Polycarbosilane–Polysiloxane Polymer Blend

A polymer blend containing polycarbosilane (PCS) and 15 mass% of polyhydromethylsiloxane (H-oil) was prepared and the properties of the polymer melt were investigated in order to clarify the mechanisms of continuous pore formation. Melt viscosity decreased as the H-oil content increased. Moreover, the saturation of the plasticizer effect of H-oil on the viscosity and apparent turbidity of the melting polymer suggested that the compatibility of H-oil to PCS in melting was limited at 15 mass%. Gas chromatography data after heating showed that an amount of evolved hydrogen at 573 K was increased by 15 mass% of H-oil addition. The fibers formed by the melt-spun of the polymer blend at 578 K mainly possessed a single pore at the center of the fibers' cross section. On the other hand, the fibers melt-spun at 543 K usually included multiple pores, and the fibers melt-spun at 538 K included a number of tiny pores. It is proposed that the evolved hydrogen can be dissolved in the polymer melt, and the desaturation process of the dissolved gas during the fiber spinning with a sudden temperature reduction likely determined the size and location of pores in the fibers.     

Method of measuring oxygen diffusivity in microporous media

It is known that the mass transfer characteristics of gas diffusion layers (GDLs) are closely related to cell performance in PEFCs. In this study, a method for measuring oxygen diffusivity in microporous media by means of an oxygen sensor based on a galvanic cell has been developed. This method is expected to be useful for measuring oxygen diffusivity in microporous media in a wet condition. Oxygen diffusivity in two kinds of microporous GDL media was evaluated. Experimental results indicate that diffusivity in microporous media cannot be determined on the basis of porosity alone, but that it may be influenced by some other factor, such as tortuosity. Additionally, there are some GDL materials that exhibit anisotropic diffusivity.     

Phosphate Esters as Dispersants for the Cathodic Electrophoretic Deposition of Alumina Suspensions

The stability of alumina ethanol suspensions prepared with phosphate esters (PEs) having three different alkoxy functional groups (ethyl, butyl, and butoxyethyl) and the corresponding effects on the electrophoretic deposition characteristics were investigated. The mechanism of particle charging was characterized by measuring the suspension pH, conductivity, zeta-potential, and deposition yield under various experimental conditions. The highest stability was observed for the suspension prepared with the butoxyethyl acid phosphate though the zeta-potentials of the three suspensions were very similar. This was attributed to the steric repulsion of the alkoxy functional group. The PEs made the alumina particles positively charged which allowed the cathodic deposition to occur. The zeta-potential, deposition yield and green density were functions of the PE addition amount. The highest green density was obtained at the highest zeta-potential, however, the deposition rate for this PE amount was the lowest. The over-addition of PE caused decreases in the zeta potential and green density, but an increase in the adhesion of the deposit to a metal substrate. Thick deposits with smooth surfaces were obtained from the over-added PE suspension.