Tetragonal to monoclinic transformation and microstructural evolution in ZrO2–9.7 mol% MgO during cyclic heating and cooling

The tetragonal (t) to monoclinic (m) transformation behaviour and its relationship to microstructural evolution were investigated by means of dilatometry and transmission electron microscopy for ZrO2–9.7 mol% MgO during cyclic heating and cooling between room temperature and 1490 K. In the as-sintered specimens, fine oblate ellipsoidal t-phase precipitates, 20–50 nm in diameter and 100–200 nm long, were distributed in the cubic (c)-phase matrix. They were below a critical size for transformation and exhibited no transformation in the first three cycles. In the fourth and further cycles, transformation occurred in two distinct stages. A low-temperature stage appeared at 850–1000 K on heating and at 400–700 K on cooling, while a high-temperature stage appeared at 1350–1400 K on heating and at 1000–1200 K on cooling. With the increasing number of cycles, at first the size of low-temperature stages increased and then decreased above ten cycles accompanying the development of the high-temperature stage. During cyclic heating and cooling, coarsening of ellipsoidal precipitates and decomposition of c- and t-phases occurred. As a result of the decomposition, MgO particles and a new m-phase containing a very low concentration of MgO were produced. The coarsened ellipsoidal t-phase precipitates were responsible for the low-temperature stage. The new m- or t-phase containing very low MgO produced by the decomposition was responsible for the high-temperature stage.     

Interfacial structures and mechanical properties of steel–Ni and steel–Ti diffusion bonds

Static and fatigue shear tests of steel–Ni bonds and steel–Ti bonds were carried out to obtain the relations between the strengths and the bonding conditions. Ultrasonic measurements were also made to examine the relations between the strengths and the size of the bonded region (the estimated diameter). At the bonding interface of the steel–Ni bonds, no intermediate phase was observed. At the bonding interface of the steel–Ti bonds, a thin layer of intermetallic compound was formed at lower bonding temperatures but, at higher bonding temperatures, the interlayer melted and the bonding interface became rough. The intensity of the ultrasonic wave reflected from the bonding interface changed, depending on the state of the bonding interface. In shear tests of the steel–Ni and steel–Ti bonds, cracks propagated along the bonding interface, and the strength was proportional to the square of the estimated diameter. In fatigue tests, cracks propagated in the thickness direction of the plate and no relation was obtained between the fatigue life and the estimated diameter. Fatigue life distributions were represented by two- and three-parameter Weibull distributions. This revised version was published online in November 2006 with corrections to the Cover Date.     

Recrystallization and Phase Transformation in Reaction-Sintered Sic

Reaction-sintered Sic specimens prepared at ∼1500°C and heat-treated at ∼1850°C in the presence of molten silicon were examined by transmission electron microscopy. The β-Sic grains in as-prepared specimens grew to a large size when heat-treated in the presence of molten Si; the number of growth twins in such °-Sic crystals was very small. The boundary areas of α- and β-Sic crystals were microsyntactic, consisting of thin strips of α- and β-Sic after heat-treating. These changes were due mostly to thin lamellar growth of α-Sic into β-Sic grains along the basal plane. There is also a high density of similar growth of transformation twins in β-Sic crystals. The results provide clear evidence of in situ solid-state transformations in sic.     

日本铝材复合氧化膜涂层技术的现状

日本四周环海，必须考虑海盐微粒或者混有海沙的灰泥引起铝材的腐蚀问题，因此铝窗架的防腐性非常重要。复合涂层(阳极氧化膜层上加一层有机涂层)是日本建筑铝材表面处理的最普遍的处理方式。最初，阳极氧化膜的有机涂层是使用亮漆进行喷涂处理获得的。在这以后有两种处理方式，即TFS涂层和电泳涂层。这两种涂层方法都适于大规模生产，而且涂层均匀。由于电泳涂层工艺无需有机溶剂而保护了环境，从而成了主要的工艺。电泳涂层采用的主要树脂为溶于水的丙烯酸阴离子树脂，电泳涂层表面包括光面、白色表面以及无光表面。对于无光表面，目前主要采用一种分离式树脂法。现在开发的其他方法还包括在着色的氰化膜上采用着色树脂的有机复合涂层、含氟化物树脂的电泳涂层和高耐久性涂层。     

Novel Transmitting Power Control Method without Signal Communication for Wireless Power Transfer via Magnetic Resonance Coupling

Wireless power transfer (WPT) via magnetic resonance coupling has been widely studied for vehicle applications, particularly the stationary and dynamic charging of electric vehicles. Our research group previously proposed a wireless in‐wheel motor to improve the reliability and safety of in‐wheel motors. Transmit power control is necessary to achieve stable WPT. We proposed a control method that uses a feedforward controller on the primary side and a feedback controller on the secondary side. However, the control method may cause shortfalls in the transmission power owing to modeling error, coupling coefficient variation, and signal communication delay. In this paper, we propose a novel feedback control method for the primary side based on conversion ratio estimation. The effectiveness of the proposed method was verified by simulations and experiments on the load current control of a constant voltage load and load voltage control of a constant power load.     

Uncertain variance in an optimal linear system with white gain

For scalar quadratic optimal linear systems with a white gain coefficient, the influence of the uncertainty of the gain variance is analysed by means of elementary methods. First, the mean-square stability of the closed loop systems is analysed on the assumption that the controller is designed with an erroneous variance. It is shown that the use of an overestimated value of the variance less than a threshold value, which is infinite for the stable free systems, does not damage the stability of closed-loop systems. A relative underestimation error bound guaranteeing the stability of closed-loop systems is obtained. Secondly, performance of the controller designed with an erroneous variance is compared analytically with that of the certainty equivalence controller. An explicit relative overestimation error bound on the variance guaranteeing the superiority of the controller over the certainty equivalence controller is obtained.     

Economic Evaluation of Power System Flexibility by Commercial Air Conditioner Control with Large Penetration of Photovoltaic Generation

High penetration of intermittent renewable energy such as photovoltaic (PV) and wind power could cause shortage of power system flexibility. Demand response is expected to help supply ancillary service instead of the conventional power plant. Commercial air conditioners are a promising responsive load for demand response because they account for a large proportion of power consumption in the power system. We calculate a system operation cost and hourly operation pattern of each power plant by using the optimal power generation model considering flexibility supply from controlling commercial air conditioner. We obtained the following results as an effect of commercial air conditioner control. (1) The power generation of oil fired power plants decreases at peak time and annual fuel cost of oil fired plant is reduced by approximately 30% at most in Kanto area. (2) The percentage of rated operation mode of LNG combined cycle plants increases. (3) Curtailed energy rate of PV decreases because a power storage amount by pumped hydropower generation increases. (4) Required battery capacity to reduce PV curtailed amount decreased by combining battery energy storage system in case of high penetration of PV.     

改定JASS 5における再生骨材コンクリ一トの規定の概要

日本建築学会建築工事標準仕様書JASS 5鉄筋コンクリート工事が2009年2月に大改定された.今回の改定では、新技術の取込みはもとより、エコセメントや再生骨材コンクリートの節の新設などによる環境配慮への取組みの強化、かぶり厚さなどの規定の検査方法の充実、計画供用期間の級の超長期への対応や耐久性向上にかかわる乾燥収縮率*ヤング係数*許容ひび割れ幅などのコンクリートの品質基準の設定、調合強度の定め方の合理化を目指した構造体強度補正値(S値)の適用の拡大など、きわめて多岐にわたっている.また、水密コンクリートをはじめ特別な仕様のコンクリートについて、より実情に即した形で規定の充実が図られている.この報告は、そのうち、再生骨材コンクリートに関する規定について紹介する.     

Ethylene Absorbent to Maintain Quality of Lightly Processed Fruits and Vegetables

Ethylene had an undesirable effect on the quality of kiwifruits, bananas, broccoli, and spinach leaves that were prepared and stored as lightly processed products. A 2.or 20 ppm ethylene treatment hastened the softening of the pulp of kiwifruits and bananas held at 20°C. Use of charcoal with palladium chloride, as ethylene absorbent, prevented the accumulation of the ethylene and was effective in reducing the rate of softening in kiwifruits and bananas and of chlorophyll loss in spinach leaves, but not in broccoli.