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排序方式: 共有2549条查询结果,搜索用时 15 毫秒
51.
Shingo Hirano Masaru Yoshinaka Ken Hirota Osamu Yamaguchi 《Journal of the American Ceramic Society》1996,79(1):171-176
In the ZrO2 -Cr2 O3 system, metastable t -ZrO2 solid solutions containing up to 11 mol% Cr2 O3 crystallize at low temperatures from amorphous materials prepared by the hydrazine method. The lattice parameter c decreases linearly from 0.5149 to 0.5077 nm with increased Cr2 O3 content, whereas the lattice parameter a is a constant value ( a = 0.5077 nm) regardless of the starting composition. At higher temperatures, transformation (decomposition) of the solid solutions proceeds in the following way: t (ss)→ t (ss) + m + Cr2 O3 → m + Cr2 O3 . Above 11 mol% Cr2 O3 addition, c-ZrO2 phases are formed in the presence of Cr2 O3 . The t -ZrO2 solid solution powders have been characterized for particle size, shape, and surface area. They consist of very fine particles (15–30 nm) showing thin platelike morphology. Dense ZrO2 (3Y)-Cr2 O3 composite ceramics (∼99.7% of theoretical) with an average grain size of 0.3 μm have been fabricated by hot isostatic pressing for 2 h at 1400°C and 196 MPa. Their fracture toughness increases with increased Cr2 O3 content. The highest K Ic value of 9.5 MPa·;m1/2 is achieved in the composite ceramics containing 10 mol% Cr2 O3 . 相似文献
52.
Although the electroless plating method is known to be an effective method for obtaining fine wiring in particular, 1 mol hydrogen gas is generated during 1 mol Cu deposition, and voids are generated in the wiring when electroless Cu plating is applied to fine wiring. To avoid the hydrogen evolution, the possibility of performing electroless Cu plating was confirmed using an inexpensive FeII compound as a reducing agent. The bath contains CuSO4, FeSO4, NaCl, ethylenediamine, sodium citrate, polyethylene glycol (PEG), and 2,2′-bipyridine. Under optimal conditions, over 1.7 μm of copper deposit with a smooth surface was obtained after 3 h of plating, which did not contain iron as an impurity. The electrical resistivity of the copper film is about 3-4 μΩ cm corresponding to that of electroplated copper films. 相似文献
53.
Norihiro Moriyama Yuta Kawano Qing Wang Ryota Inoue Meng Guo Makoto Yokoji Hiroki Nagasawa Masakoto Kanezashi Toshinori Tsuru 《American Institute of Chemical Engineers》2021,67(7):e17223
Pervaporation (PV) is a membrane technology that holds great promise for industrial applications. To better understand the PV mechanism, PV dehydrations of various types of organic solvents (methanol, ethanol, iso-propanol, tert-butanol, and acetone) were performed on five types of organosilica and two types of silicon carbide-based membranes, all with different pore sizes. Water permeance was dependent on the types of organic aqueous solutions, which suggested that organic solvents penetrated the pores and hindered the permeation of water. In addition, water permeance of various types of membranes in PV was well correlated with hydrogen permeance in single-gas permeation. Furthermore, a clear correlation was obtained between the permeance ratio in PV and that in single-gas permeation, which was confirmed via the modified-gas translation model. These correlations make it possible to use single-gas permeation properties to predict PV performance. 相似文献
54.
Daiji Noda Makoto Tanaka Kazuma Shimada Wataru Yashiro Atsushi Momose Tadashi Hattori 《Microsystem Technologies》2008,14(9-11):1311-1315
X-ray imaging is a very important technology in the fields of medical, biological, inspection, material science, etc. However, it is not enough to get the clear X-ray imaging with low absorbance. We have produced a diffraction gratings for obtaining high resolution X-ray phase imaging, such as X-ray Talbot interferometer. In this X-ray Talbot interferometer, diffraction gratings were required to have a fine, high accuracy, high aspect ratio structure. Then, we succeeded to fabricate a high aspect ratio diffraction grating with a pitch of 8 μm and small area using a deep X-ray lithography technique. We discuss that the diffraction gratings having a narrow pitch and an large effective area to obtain imaging size of practical use in medical application. If the pitch of diffraction gratings were narrow, it is expected high resolution imaging for X-ray Talbot interferometer. We succeeded and fabricated the diffraction grating with pitch of 5.3 μm, Au height of 28 μm and an effective area of 60 × 60 mm2. 相似文献
55.
Naoki Sakamoto Mitsuru Higashimori Toshio Tsuji Makoto Kaneko 《Intelligent Service Robotics》2009,2(1):53-60
This paper discusses an optimum design approach on robotic food handling by considering the characteristics of viscoelasticity
of object. We pick up a traditional Japanese food, “Norimaki” as a typical example with the viscoelastic characteristics.
We first show that the dynamic characteristics of Norimaki can be expressed by utilizing the Burger model. After testing the
parameter sensitivity, we show an example of the optimum design for determining the combination of the hand stiffness and
the operating velocity. We further show that the resultant plastic deformation can be formulated with the exact solution. 相似文献
56.
H. Watanabe K. Hirota O. Yamaguchi S. Inamura H. Miyamoto N. Shiokawa K. Tsuji 《Journal of Materials Science》1994,29(14):3719-3723
In compositions having ZrO2/Y2O3=(74.25–71.25)/(0.75–3.75) (mol% ratio) with 25 mol% Al2O3, metastable t-ZrO2 solid solutions crystallize at 780° to 860°C from amorphous materials prepared by the simultaneous hydrolysis of zirconium, yttrium and aluminium acetylacetonates. Hot isostatic pressing has been performed for 1 h at 1130 and 1230°C under 196 MPa using their powders. Two kinds of material are fabricated: (i) perfect ZrO2 solid-solution ceramics and (ii) composites of ZrO2 solid solution and -Al2O3. Their mechanical properties are examined, in connection with microstructures and t/m ZrO2 ratios. Composites with a homogeneous dispersed -Al2O3 derived from solid-solution ceramics result in a remarkable increase of strength. 相似文献
57.
58.
Y Hirota 《Canadian Metallurgical Quarterly》1996,43(11):946-953
The prevention of influenza continues to be a major public health concern, and a program of vaccination has been promoted, especially to high-risk individuals such as the elderly. In addition, concerted efforts are being expended in many developed countries in order to better cope with the next influenza pandemic. These efforts include enhancing influenza virus surveillance, improving vaccine production and its delivery systems, centralizing vaccine distribution and establishing priorities, etc. In Japan, on the other hand, influenza is only considered a minor illness, and thus little attention has been give to measures against influenza. To disseminate information on recent international trends in influenza control to Japanese public health specialists, I herein outline the recommendations made at two recent international meetings: "Pandemic Influenza: Confronting a Reemergent Threat" held in the u.s., at Bethesda, Maryland, in December 1995; and "The 7th European Meeting of Influenza and Its Prevention" held in Berlin. Germany, in September 1993. Since a routine system capable of responding adequately to annual epidemics is considered to be the best defense against a pandemic, I also describe the present state of influenza control in other countries to contrast it with that in Japan: the target groups for special vaccination programs recommended by the U.S. Advisory Committee on Immunization Practices; the recommendations for influenza vaccination and reimbursement for the vaccination of recommended groups in developed countries: and influenza vaccine distribution in Japan and the U.S., 1980-1994. At present in Japan, the efficacy of the currently used inactivated vaccine is regarded as either very low or none at all. There is also no official national recommendations as to what groups should be targeted for active immunization, nor any system for vaccination reimbursement. Public health specialists in Japan, therefore need to fully understand Japan's peculiar situation and, as a result, better recognize the importance of influenza and its prevention. 相似文献
59.
Parametric interpolation has been widely used in CNC machining because of its advantages over the traditional linear or circular interpolation. Many researchers focused on this field and have made great progress in the specific one, NURBS curve interpolation. These works greatly improved the CNC machining with constant feedrate, confined chord error and limited acceleration/deceleration. However, during CNC machining process, mechanical shocks to machine tool caused by the undesired acceleration/deceleration profile will dramatically deteriorate the surface accuracy and quality of the machined parts. This is, in most occasions, very harmful to machine tools. In this paper, an accurate adaptive NURBS curve interpolator is proposed with consideration of acceleration–deceleration control. The proposed design effectively reduces the machining shocks by constraining the machine tool jerk dynamically. Meanwhile, the constant feedrate is maintained during most time of machining process, and thus high accuracy is achieved while the feedrate profile is greatly smoothed. In order to deal with the sudden change of the acceleration/deceleration around the corner with large curvature, a real-time flexible acceleration/deceleration control scheme is introduced to adjust the feedrate correspondingly. Case study has been taken to verify the feasibility and advantages of the proposed design. 相似文献
60.
Makoto Kanazawa 《Journal of Logic, Language and Information》2010,19(2):137-161
Second-order abstract categorial grammars (de Groote in Association for computational linguistics, 39th annual meeting and 10th conference of the European chapter,
proceedings of the conference, pp. 148–155, 2001) and hyperedge replacement grammars (Bauderon and Courcelle in Math Syst Theory 20:83–127, 1987; Habel and Kreowski in STACS 87: 4th Annual symposium on theoretical
aspects of computer science. Lecture notes in computer science, vol 247, Springer, Berlin, pp 207–219, 1987) are two natural
ways of generalizing “context-free” grammar formalisms for string and tree languages. It is known that the string generating
power of both formalisms is equivalent to (non-erasing) multiple context-free grammars (Seki et al. in Theor Comput Sci 88:191–229, 1991) or linear context-free rewriting systems (Weir in Characterizing mildly context-sensitive grammar formalisms, University of Pennsylvania, 1988). In this paper, we
give a simple, direct proof of the fact that second-order ACGs are simulated by hyperedge replacement grammars, which implies
that the string and tree generating power of the former is included in that of the latter. The normal form for tree-generating
hyperedge replacement grammars given by Engelfriet and Maneth (Graph transformation. Lecture notes in computer science, vol
1764. Springer, Berlin, pp 15–29, 2000) can then be used to show that the tree generating power of second-order ACGs is exactly
the same as that of hyperedge replacement grammars. 相似文献