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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 121-123 (Mar. 2007), p. 1375-1378 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Ultrahigh-Quality microcavity with whispering-gallery-mode (WGM) is a new kind ofresonator with high quality. The evanescent wave of WGM plays an important role in surfaceenhanced Raman scattering (SERS). In this paper we study the relationship between couplingcoefficient and evanescent wave of the WGM and the coupling character difference between themicrosphere and the microstadium. Based on the finite-difference time-domain (FDTD), wecalculate the coupling coefficient of different substances (water, C2H5OH, CHCL3, olive oil, C6H6and CS2) with different dielectric constant and the mode volume ratio of the evanescent wave inmicrosphere and microstadium of the above substances in near field. The results show that (1) themode volume ratio of evanescent wave will decrease with the increasing of the coupling coefficient;(2) the microstadium has a higher coupling coefficient than the sphere one
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 50 (Oct. 2006), p. 75-82 
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: Hot pressing is an effective way to densify powder compacts, especially during theinclusion of a second phase, such as particles, whiskers or fibers. In the present study, SiC/SiC andC/SiC composites were prepared by hot pressing via liquid phase sintering. Nano-SiC powder wasused for matrix formation with sintering additives. The effects of preparation conditions such assintering temperature, pressure and matrix composition, on the microstructural evolution andmechanical behaviors were discussed. Using micro-SiC powder and nano-SiC powder for matrixformation, the interaction between fiber and matrix was characterized. Because the matrixcompositions can be easily modified in the CMC-processing from powders by hot pressing, theSiC-BN matrix was also studied in the present experiment. The inclusion of BN can either improvethe machinability or provide oxidation resistance to the composite. BN was derived through an in-situreaction between boron acid and urea by hot-pressing. Boric acid and urea were solved into theethanol and mixed with nano-SiC particles, and then infiltrated into the fiber bundles. Correlationsamong microstructures, properties and compositions will be discussed
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 1257-1259 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Chopped fiber and a hybrid reinforcement of chopped and continuous fibers were used forfabricating SiC/SiC composites. Under the selected sintering pressure, the composite sintered at lowertemperature (1820°C) had lower density. Increasing temperature to 1850°C, the density of the compositereached at a higher level. However, pores still existed and mainly distributed in the areas the fibersaccumulated, especially inside of the fiber bundles. Densely sintered matrix still could be found in thecomposite sintered at 1820°C, 15 MPa. In the areas with the fibers accumulated, matrix was relativelyweak so that the cracks were easily propagated leading to the delamination during bending test. Whencontinuous fiber was included into the chopped fiber reinforced composite, a hybrid reinforcingmechanism was obtained. This kind of composite had obviously improved toughness and strength. On thefracture surface, the pulled out fibers that were perpendicular to the fracture surface were increased
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 326-328 (Dec. 2006), p. 1797-1800 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The mechanical properties of rock under high temperature, high geostress and high porepressure are the basic and important information to assess the safety of underground engineering inwest China. Based on the environmental conditions of the west route of south-to-north watertransfer project in west China, a series of triaxial tests at confining pressures (0 to 60MPa) andtemperatures (25°C to 70°C) as well as pore pressure (0 to 10MPa) have been conducted for asandstone. It is reported that under the temperatures varying from 25°C to 70°C, the strength of therock increases with the increment of confining pressure, while the deformation modulus of the rockdoesn’t change distinctly with the increment of confining pressures. It is also indicated under thetemperatures condition in the experiments, when the confining pressure is lower than 40MPa, thestrength of the rock increases with the increment of temperature, whereas when the confiningpressure is higher than 40MPa, the strength of rock tend to decrease with increment of temperature.It is further shown that the strength decreases with increasing pore pressure, and the decreasingrates tend to decrease with the increment of confining pressures
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 334-335 (Mar. 2007), p. 1045-1048 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Continuous carbon fiber-reinforced silicon carbide (Cf/SiC) composite was fabricated byhot-pressing, via liquid phase sintering. Sintering conditions strongly affect the densification process,and therefore dominate the mechanical properties and fracture behavior. The composites under thelower sintering temperature behaves less densified matrix and it demonstrates a relatively weakfiber/matrix bonding allowing the longer fibers pull-out. Increasing sintering temperature couldaccelerate the densified matrix and make fiber/matrix bonding stronger. In this case, the shorter fiberspull-out was predominant fracture behavior and it could improve mechanical properties
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 1307-1309 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: To obtain high performance ceramic matrix composites (CMCs), fiber coatings are oftenfabricated as the interphase between fiber and matrix. The SiC coating was synthesized at lowtemperature and reduced pressure in the present experiment. SiC was derived from a gaseousmethyltrichlorosilane (MTS)/H2 precursor by chemical vapor infiltration (CVI). The thickness of thecoating was inspected by SEM. The correlation between the coating thickness and the depositingconditions, i.e. the deposition temperature, the pressure, the deposition time per pulse and the pulsenumber were investigated. Based on these work, the C/SiC double-layer coating was fabricated
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 340-341 (June 2007), p. 1151-1156 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The mechanical properties of rock under high temperature and high geostress are thebasic and important information to assess the safety of underground engineering. Based on theenvironmental conditions of the west route of south-to-north water transfer project in westernChina, experiments are conducted for a sandstone. The experiments are conducted in stress path ofhydrostate, pure shear, and conventional triaxial compression at the temperature of 25°C, 50°C and70°C. The change of strength and average moduli of the rock with temperatures are studied. Bycycle loading and unloading tests, elastic and plastic deformation of the rock are decomposed, it isshown that the plastic deformations of the rock are clearly changed with temperature, while theelastic deformation of the rock seems to be unaffected by the temperature. Moreover, based on theassociated plastic flow rule, a constitutive law considering temperature is proposed for thesandstone
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 1379-1382 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Because of its excellent environmental resistance and cold-working capacity, beta titaniumalloy Ti-15-3 has attracted more and more attention in aerospace manufacture industry. Another betatitanium alloy, Ti-29-13, has been recently developed for biomedical implant materials. Themechanical properties of three alloys including two β and one α+β are presented, particularly thecharacteristic of β alloy differing from that of α+β alloy. The high temperature deformation behaviorsof two alloys are also presented. Excellent formability of Ti-15-3 highlights the metal sheetapplication in commercial and military airplane. Band structure in Ti-29-13 has been found.Thermalmechanical processing is carried out to reduce the band structure and improve the elongation
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica solida Sinica 4 (1991), S. 369-379 
    ISSN: 0894-9166
    Keywords: dynamic plastic response ; Lee's extremum principle ; evolutionary mode ; large deflection ; portal frame
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An approximate method based on Lee's extremum principle is introduced to study the large deflections of dynamically loaded plastic structures. As an example, the evolutionary mode of an impulsively loaded rigid-perfectly plastic portal frame is determined and then compared with the experimental results [8] and with the large deflection complete solution obtained previously [9]. It is found that the evolutionary modal solution may approach the complete solution if the modes are appropriately chosen.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Division of spermatogonial stem cells produces daughter cells that either maintain their stem cell identity or undergo differentiation to form mature sperm. The Sertoli cell, the only somatic cell within seminiferous tubules, provides the stem cell niche through physical support and expression ...
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