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.     

Effect of TiB2 and Boron Additions on the Stability of Wurtzite-Type Boron Nitride at High Temperatures and Pressures

Shock-synthesized wurtzite-type BN(w-BN) and mixtures of w-BN–TiB₂ and w-BN–ß were treated at high temperatures and pressures. The effect of TiB₂ and boron additions on the transformation of w-BN to zinc blende-type BN(z-BN) was studied at 1000° to 2200°C and 55 to 68 kbars. The formation region of z-BN was shifted toward higher temperatures by TiB₂ additions and toward lower temperatures by boron additions.     

Dependence of Vacuum Electrical Breakdown Field and Field Enhancement Factor on the Number of Apertures Drilled in Small Electrodes

Dark current based on field emission current is considered to be a factor causing the vacuum electrical breakdown between multiaperture acceleration grids in the JT‐60 negative ion source. In this paper, we focus on field enhancement factor, which is a key parameter of field emission from the electrode. Vacuum breakdown testing for small‐sized electrodes simulating the multiaperture acceleration grids of the negative ion source was performed. We found the field enhancement factor and breakdown field for multiaperture electrodes, and we investigated the dependence of each parameter on the number of apertures. The results revealed that an increase in the average field enhancement factor after the end of conditioning resulting from an increase in the number of apertures led to a decrease in the dielectric strength of the multiaperture electrodes.     

Magnetorefractive Effect for Co/Ru Multilayer Film with Antiferromagnetic Interlayer Exchange Coupling

The spin‐dependent scattering of conduction electron in metallic magnetic multilayers was investigated to reveal the optical properties which corresponded to the magnetization state. From the measurement of magnetorefractive effect in antiferro‐magnetically exchange coupled Co/Ru multilayers, it was found that (1) the transmittance varied around 1% at wavelength of 1550 nm during the parallel/antiparallel spin alignment changes, (2) as a result of number of repetition and Co thickness for the multilayers, transmittance difference between the parallel and antiparallel spin alignment states had trade‐off relationship with the magnitude of transmittance, and (3) asymmetric Co/Ru/Co stacking structure brought different interlayer exchange coupling fields in each layer, which resulted in magnetic field sensitive transmittance.     

資源環境の保全をめざした二次副産材を導入するコンクリ一ト材料の発展的利用に関する研究

日本では,21世紀半ばに人工の固体物質の代表である解体コンクリート塊の排出量がピークを迎えると同時に,最終処分が困難になる状況が想定されていることから,コンクリート材料の完全資源型の利活用要求はより一層高まるといえる.本研究は,副産微粉,再生骨材などの二次副産材を積極的に混和し,同一産地*種類型の調合条件のもとで,コンクリートの物性改善,資源有効利活用を目的としたコンクリートを製造し,その基礎的物性の評価と環境影響評価を行い,環境保全に資するコンクリート材料の発展的利用のあり方を検討した.     

SYSTEM TRANSFORMATIONS AND ADAPTIVE SYSTEMS

The purpose of this paper is to formulate the concept of system transformation and the concept of adaptive system in the framework of general systems theory, and to characterize both concepts as well as mutual relationships between them from a qualitative viewpoint.

We define a system transformation as a mapping on the class of all systems under consideration in a general and unified manner, and especially consider the variety of system behavior under parallel, cascade, and feedback transformation for linear functional time systems. We introduce the notion of open system in terms of system transformation. We then formulate class controllability and adaptability of an open system under system transformation, and characterize them in terms of basic system properties. In particular, we obtain a necessary and sufficient condition under which an open system is adaptive.     

Consideration of Stretchable Dry Electrodes for Smart Shirts Aimed for Biological Signal Monitoring

Dry electrodes of a smart shirt for measuring biological signals were prepared by the additive printing method using a stretchable conductive paste with Ag fillers loading. Interfacial impedance between the electrode and skin depended on the contact pressure of electrode and the moisture of stratum corneum. When moisture of stratum corneum was more than 30%, ECG could be measured using the stretchable electrodes printed on a compression shirt. However, noise signal in the ECG signal increased when the moisture of stratum corneum was less than 30%. To solve this problem, we propose to use additional electrodes made of an electrically conductive kneaded rubber.     

Phase Equilibrium in the System CrO2-Cr2O3

The CrO₂-Cr, O₃ equilibrium curve has been determined up to 35 kbars and 1400° C with a piston-cylinder apparatus. The phases were determined by magnetic, X-ray, and microscopic examination. The phase boundary can be represented by a straight line log P versus 1/T plot, where log P = 5.3 - 1400/ T. These results can be extrapolated to agree reasonably well with the results of previous investigations using gas pressure techniques.     

A GENERAL APPROACH TO THE CHARACTERIZATION OF CHANGES IN SYSTEM BEHAVIOUR BY OUTPUT FEEDBACK

The purpose of this paper is to formulate in a general and unified manner the change of system behaviour produced by output feedback and then to clarify from a qualitative point of view its general structure and meaning.

In this paper feedback is defined as a system transformation on the class of general linear systems represented by input-output relations. As a measure indicating the degree of how the behaviour of a system S?X×Y changes under feedback transformation three classes of systems are introduced for S and their system theoretic meaning is considered in a general setting. Furthermore, a variety problem of several structured systems under feedback transformation is investigated by characterizing these classes in terms of basic system concepts.     

ESTIMATION OF DAILY INTAKE OF FOUR KINDS OF TRIHALOMETHANE BY JAPANESE HOUSEWIVES

Duplicate portions of the daily meals consumed by 30 housewives were collected for 3 consecutive days in the cities of Nagoya and Yokohama in Japan.
Meals were analyzed for chloroform, bromodichloromethane (BDCM), chlorodibromomethane (CDBM) and bromoform by using a purge-trap procedure. The average concentration (and the range) of these four kinds of trihalomethane in each of the 24 h duplicate meals were, chloroform 19.6±18.1 ppb(n.d.-106.8 ppb), BDCM 0.3±0.3 ppb(n.d.-1.7 ppb), CDBM 0.1±0.2 ppb(n.d.-0.6 ppb) and bromoform 0.5±1.3 ppb(n.d.-8.1 ppb).
The mean daily dietary intake of the four kinds of trihalomethane by housewives were, chloroform 40.0±25.4 μg, BDCM 0.6±0.5 μg, CDBM 0.3±0.3 μg and bromoform 0.9±1.3 μg.