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1.
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. 相似文献
2.
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. 相似文献
3.
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. 相似文献
4.
阿部道彦 《青岛理工大学学报》2009,30(4)
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. 相似文献
5.
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. 相似文献
6.
YOTARO NOSE TAKAO TSUJI TSUTOMU OYAMA TAKAHARU ITO KATSUYA ABE MASAHIRO MINAMI KAZUNARI ISHIBASHI 《Electrical Engineering in Japan》2017,198(4):51-62
It is of prime importance to maintain voltage profile within the proper range in distribution systems with a large amount of photovoltaics and electric vehicles (EVs). In particular, there is a possibility that line drop compensation (LDC) logic, which is utilized for the control of load ratio tap transformer (LRT) does not work properly when reverse power flow is included partially. Hence, in this paper, we have developed a new LRT control method based on the sensor information supposing that some section switchgears with sensors are introduced in the future distribution systems. Specifically, the extreme value of voltage profile is estimated by convergence calculation in the section between the section switchgear with sensor and LRT. Moreover, the voltage at the end node can be estimated by LDC method using sensor information of section switchgear. The proposed method was tested using a distribution system model and its effectiveness was shown. 相似文献
7.
8.
Cystatins are protein inhibitors of cysteine proteinases. Oryzacystatin I (OC-I) has been cloned and is apparently the first well-defined cystatin of plant origin (phytocystatin). Besides OC-I, various other phytocystatins occur in rice, corn, wheat and soybean. Phytocystatins have endogenous target enzymes whose expression is induced by gibberellin, and also exogenous target enzymes from viruses and insects. It is thus likely that phytocystatins are involved in the regulation of intracellular protein catabolism as well as in the defense from infection. Better understanding of this phenomenon and cloning of appropriate genes will facilitate the creation of transgenic crops with enhanced resistance to viruses and insects. 相似文献
9.
Gigacycle fatigue properties of 1800 MPa class spring steels 总被引:2,自引:0,他引:2
T. ABE Y. FURUYA S. MATSUOKA 《Fatigue & Fracture of Engineering Materials & Structures》2004,27(2):159-167
Fatigue tests up to 108 cycles were carried out for two spring steels (Heats A and D1) and one valve spring steel (Heat F) with tensile strength, σ B, of 1720, 1725 and 1764 MPa, respectively. The size and composition of inclusions in Heats Dl and F were controlled. The surface‐type fracture occurred at shorter lives below 106 cycles, while the fish‐eye‐type fracture occurred at longer lives. The fatigue limit, σ W, at 108 cycles was 640 MPa for Heats A and D1 and 700 MPa for Heat F. Al2O3 inclusions for Heat A and both TiN inclusions and matrix cracks, i.e. internal facets, for Heat F were observed at the fish‐eye‐type fracture sites, while only matrix cracks were observed for Heat Dl. ODA, i.e. optically dark area, which is considered to be related to hydrogen effects, were formed around Al2O3 and TiN inclusions. Fatigue tests were also conducted after specimens were heated up to 573 K in high vacuum of 2 × 10–6 Pa. The heat treatment eliminated matrix cracks for Heat D1 and the fatigue limit at 108 cycles recovered to the estimated value of 920 MPa from the equation σ w= 0.53 σ B for the surface fracture. These results suggest that inclusions control and hydrogen influence the gigacycle fatigue properties for these high strength steels. In addition, it is expected that the creation of a martensite structure with a high resistance to hydrogen effects in the inclusion‐controlled steel could achieve the higher fatigue limit estimated for the surface‐type fracture. 相似文献
10.
YOSHIHIRO ABE KOICHI KAWASHIMA SUGURU SUZUKI 《Journal of the American Ceramic Society》1981,64(4):206-209
Coloring and bleaching of reduced phosphate glasses in the systems K2 O-B2 Or Al2 O3 -P2 O5 and K2 O-Al2 O3 -P2 O5 , containing no silver halide, were studied. The as-cast glasses, which are colorless and transparent, become tinged with red when they are reheated at high temperatures for long times. The bleached specimens (PTC-RP glass) are obtained by heating at >600°C, then quenching. The PTC-RP glasses exhibit coloring phenomena by irradiation of light or by heating above 200°C; the colored glasses are again bleached thermally. Coloring of the glasses by heating is described in this paper in terms of phase change within the colloidal phosphorus formed in the glasses. The apparent activation energy for the thermocoloring is estimated to be ∼15×104 J/mol (35 kcal/mol). 相似文献