Effects of microstructure and environment on room-temperature tensile properties of B2-type polycrystalline CoTi intermetallic compound

Room-temperature tensile property and fracture mode of B2-type polycrystalline CoTi intermetallic compound was studied as functions of microstructure and environment. Using a hot-rolled CoTi sheet, various microstructures were prepared by different heat treatments and pre-straining. Tensile elongation as well as ultimate tensile strength (UTS) of specimens deformed in vacuum (i.e. intrinsic tensile elongation and strength) depended on microstructure. The hot-rolled and recovered specimens showed higher elongation and tensile strength than the fully-annealed and aged specimens. Also, the pre-strained specimen showed the improved elongation and UTS in comparison with the fully-annealed specimen. On the other hand, tensile elongation and UTS of the specimens deformed in air were lower than those of the specimens deformed in vacuum, irrespective of microstructure. The extent of embrittlement was lower in the hot-rolled, recovered and pre-strained specimens than in the fully-annealed and aged specimens. SEM observation for the hot-rolled and recovered specimens showed that the quasi-cleavage fracture mode was dominant irrespective of testing environment. However, the fully-annealed, aged and pre-strained specimens consisting of recrystallized grains exhibited quasi-cleavage fracture mode mixed with intergranular fracture mode. The results showed that not only the intrinsic room-temperature tensile properties but also the environmental embrittlement of CoTi intermetallic compound depended upon lattice defects (such as dislocations and vacancies) in addition to grain size and morphology.     

爱知县淑德大学8号楼

在有较大高差台地的校园园区内排列鳞次栉比的校舍,建筑物之间诸多大小不等的室外围合空间是整个校园空间的主要特征。将教室、食堂之间的空间为活泼好动的学生营造成最具活力的“舞台”,在这个“舞台”上由室内外一体化的缓坡、大台阶、廊桥等各要素从一层到三层构成连续的断面,不管哪一层的人们都能感受到其他各层活动的情况,是充满“动感”的空间。建筑物宽18m,长92m,形状非常细长,横向由6m和12m两种柱距组成,长向由4m的柱距均分构成连续的架构,这个模数使不同用途和大小的空间(24～336m2)都能获得良好的开间一进深比例,4m跨度的构架单元…     

Stability robustness for linear state space models - a Lyapunov mapping approach

Some Pythagorean-like conditions for the existence of a common Lyapunov solution for two given matrices are presented. These conditions are set on the Lyapunov mappings associated with given matrices. The key is the semipositiveness of linear mappings defined on symmetric matrices. From the viewpoint of the existence of a common Lyapunov solution, some known stability robustness results are reviewed and refined.     

日本式公寓——丰富而小的空间

一、日本式公寓的历史 1923年，关东大地震袭击了日本。在关东地区，包括东京和其他外围城市在内的大量建筑和住宅都在地震中倒塌。木结构住宅遭到了破坏性的损害。1924年，“同润会”成立，其目标是建造抗震效果更好的钢筋混凝土建筑。1926年，“同润会”建成了他们的第一栋钢筋混凝土公寓，而他们的最后一个作品完成于1934年。图1是位于代官山的一个同润会公寓。它的建筑面积约为30m^2，包括两个榻榻米房间。     

Activity tests of various catalysts for hydrocracking of coal by means of high pressure differential thermal analysis

The activities of fourteen kinds of catalysts for the hydrocracking of Taiheiyo coal were examined by a high pressure differential thermal analytical method. Exothermic peaks appeared at low temperatures (420–430°C) when MoO₃TiO₂, NiY zeolite and CoY zeolite were used as catalysts, indicating that these catalysts are highly active compared with other catalysts including MoO₃CoOAl₂O₃. The qualitative analysis of gas and liquid products revealed that MoO₃TiO₂ and CoY are good catalysts for the liquefaction reaction. The hydrogenation ability of the catalyst is concluded to be more important than its acidic property.     

爱知县淑德大学9号楼

这座建筑是大学的语言教育中心,设有500台计算机、影像和音响系统,主要用于语言教学、留学生教学及国际交流活动。作为建筑“外皮”的性能,设计满足以下三点要求:①充分考虑减少计算机显示器的光反射,营造照度对比小的均质柔和的光环境。②在影像放映时,光环境可渐变调节。③适度的外墙散热功能。教室分别布置在南北两侧,南面的波纹玻璃和合成树脂板材形成双层表皮,中间设计有可调控百叶,能根据日照的入射角度调节;夏季可排热,冬季则可让阳光照射进室内,从而既可获得柔和均质的采光效果又可对热负载进行有效的控制。在建筑北侧满铺的玻璃砖…     

PROGRESSIVE HYDROTREATMENT OF HOKKAIDO COALS (JAPAN)

Hokkaido coals were subjected to benzene extraction and non-catalytic hydrotreatment, alternatively, under progressive increase of temperature from 200 to 400 °C. For Taiheiyo coal the aliphatic materials in the hydrogen-rich part of the coal were converted to benzene soluble products at lower temperatures. With the increasing reaction temperature, aromaticity of the benzene solubles increased gradually. On the other hand, for Ohyubari coal, the structure of the benzene solubles were essentially the same for products obtained under all temperatures. Also, in the case of Taiheiyo coal (C : 76.9 %) the plastic state was not observed up to 400 °C, but for Ohyubari coal (C : 85.6 %) the onset of the plastic state was evident. It was assumed that there was an intimate relationship between the occurrence of plastic state and the structural uniformity of coal.     

Magnetic-field-induced non-linear effects of Josephson coupled superconductor Bi2Sr2CaCu2O8+δ

The dc current-voltage (I-V) relation along the c-axis of single crystalline Bi₂Sr₂CaCu₂O_8+δ has been measured in magnetic fields parallel and perpendicular to the c-axis. In zero field a clear and sharp jump with large hysteresis in theI-V curve was observed, indicative of the dc-Josephson effect. In magnetic field below a characteristic fieldB ^*≈0.4 T (at T=0 K) parallel to the c-axis the magnetic field suppresses the hysteresis and reduces the critical currentI _c drastically, whereas aboveB ^* theI-V curve becomes broad and featureless behavior. The characteristic field scaleB ^* can be interpreted as an energy scale of the Josephson coupling between superconducting layers in Bi₂Sr₂CaCu₂O_8+δ and is argued with emphasis on the correlation length of pancake vortices in this system.     

Ceramic capillary splices for optical fibres

A simple technique for splicing optical fibres is reported. The technique utilises a self-aligning ceramic capillary with inner dimensions slightly larger than the optical fibre. An average loss of below 0.1 dB is obtained for splices in graded-index and single-mode fibres with a 50 and 10 ?m core diameter, respectively.