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191.
Yasuyuki Shirai Hideki Tatsumoto Masahiro Shiotsu Koichi Hata Hiroaki Kobayashi Yoshihiro Naruo Yoshifumi Inatani 《低温学》2010,50(6-7):410-416
Heat transfer from a flat plate facing upward immersed in a liquid hydrogen pool was measured for the pressures from atmospheric to 1.1 MPa. The flat plate heater used was 10 mm in width, 100 mm in length and 0.1 mm in thickness. Critical heat fluxes (CHFs) in saturated boiling increased with the increase in pressure up to around 0.3 MPa and then decreased with further pressure increase. The CHFs under subcooled condition at each pressure increased with the increase in sub-cooling. Discussions were made on the experimental results by comparing with those of the other cryogenic liquids and also the Kutateladze’s equations under saturated and subcooled conditions. The experimental CHFs were much smaller than the Kutateladze’s equation for higher pressure up to critical. The heater surface temperature was found to reach the critical temperature before the occurrence of hydrodynamic instability and jump to the film boiling regime at the lower heat flux in the higher pressure range. It was suggested that the CHFs are determined not by the heat flux but by the temperature in the higher pressure range. 相似文献
192.
N. Sakoda K. Shindo K. Motomura K. Shinzato M. Kohno Y. Takata M. Fujii 《International Journal of Thermophysics》2012,33(1):6-21
A measurement method for PVT properties of high-temperature and high-pressure gases was developed by simplifying the Burnett
method and revising the data acquisition procedure. Instead of a differential pressure transducer, which is traditionally
used, an absolute pressure transducer is used in the present method, and the measurement of pressure becomes easier. However,
the absolute pressure transducer is placed outside the constant temperature bath because of the difficulty of its use in high-temperature
surroundings, and some parts with different temperatures from the sample vessels exist as dead space. The present method takes
into account the effect of the dead space in the data acquisition procedure. Nitrogen was measured in the temperature range
from 353 K to 473 K and at pressures up to 100 MPa to determine the apparatus constants, and then, hydrogen was measured at
473 K and up to 100 MPa. The determined densities are in agreement within uncertainties of 0.07% to 0.24% (k = 2), both with the latest equation of state and existing measured data. 相似文献
193.
Hiroshi Takamatsu Hikaru Yamashiro Nobuo Takata Hiroshi Honda 《International Journal of Refrigeration》2003,26(6):79
Heat and mass transfer in a falling film vertical in-tube absorber was studied experimentally with LiBr aqueous solution. The presented results include the effect of solution flow rate, solution subcooling and cooling water temperature on the absorption in a smooth copper tube 16.05 mm I.D. and 400 mm long. The experimental data in the previous report for a 1200-mm-long tube was also re-examined and compared. It was demonstrated by the observation of the flow in the tube that the break down of the liquid film into rivulets leads to deterioration of heat and mass transfer at lower film Reynolds number or in longer tubes. An attempt to evaluate physically acceptable heat and mass transfer coefficients that are defined with estimated temperature and concentration at the vapor–liquid interface was also presented. 相似文献
194.
Positive temperature coefficient of resistivity (PTCR) materials have become very important components, and among these materials
barium titanate compounds make up the most important group. When properly processed these compounds show a high PTCR at the
Curie temperature (the transition temperature from the ferroelectric tetragonal phase to the paraelectric cube phase). In
the first half of this paper literature related to the resistivity-temperature behaviour is discussed. As explained by the
well established Heywang model, the PTCR effect is caused by trapped electrons at the grain boundaries. From reviewing experimental
results in the literature it is clear that the PTCR effect can not be explained by assuming only one kind of electron trap.
It is concluded that as well as barium vacancies, adsorbed oxygen as 3d-elements can act as electron traps. In the second
half of this paper, the influence of the processing parameters on the PTCR related properties is discussed. Special emphasis
is placed on the phenomenon that the conductivity and grain size decrease abruptly with increasing donor concentration above
∼ 0.3 at%. Several models explaining this phenomenon are discussed and apparent discrepancies in experimental data are explained. 相似文献
195.
Yasuyuki Kaneno Wataru Soga Hiroshi Tsuda Takayuki Takasugi 《Journal of Materials Science》2008,43(2):748-758
Dual two-phase intermetallic alloys composed of geometrically close-packed (GCP) structures of Ni3Al (L12) and Ni3V (D022) containing Nb were investigated in terms of microstructural evolution during low-temperature annealing (aging) and the related
mechanical properties. The eutectoid region, i.e. the prior Al phase (Ni solid solution) is composed of the lamellar-like
structure consisting of Ni3Al (L12) and Ni3V (D022) even at an early aging stage, and then coarsen with increasing aging time. The lamellar-like structure tend to align along
direction and on {001} plane in the prior A1 phase (or the L12 phase). In a wide range of temperature, the dual two-phase intermetallic alloys showed high yield and tensile strength, and
also reasonable tensile ductility, accompanied with ductile fracture mode. The observed mechanical properties were less sensitive
to the microstructural evolution during low-temperature annealing (aging), meaning that the present dual two-phase intermetallic
alloy is promising for a new type of high-temperature structural material. 相似文献
196.
Yanai N Kitayama K Hijikata Y Sato H Matsuda R Kubota Y Takata M Mizuno M Uemura T Kitagawa S 《Nature materials》2011,10(10):787-793
The development of a new methodology for visualizing and detecting gases is imperative for various applications. Here, we report a novel strategy in which gas molecules are detected by signals from a reporter guest that can read out a host structural transformation. A composite between a flexible porous coordination polymer and fluorescent reporter distyrylbenzene (DSB) selectively adsorbed CO? over other atmospheric gases. This adsorption induced a host transformation, which was accompanied by conformational variations of the included DSB. This read-out process resulted in a critical change in DSB fluorescence at a specific threshold pressure. The composite shows different fluorescence responses to CO? and acetylene, compounds that have similar physicochemical properties. Our system showed, for the first time, that fluorescent molecules can detect gases without any chemical interaction or energy transfer. The host-guest coupled transformations play a pivotal role in converting the gas adsorption events into detectable output signals. 相似文献
197.
Unno Y 《Applied optics》2011,50(3):271-281
Theoretical modeling of a slit-scan-type aerial image measurement sensor used for optical lithography is presented. Slit transmission properties are fully represented by the slit transfer function in terms of incident and scattering angles of light, which is then incorporated into the scheme of a partially coherent imaging formula to obtain an expression for image profiles measured by slit scanning. As an exemplary case, we analyze the influence of a 100 nm width slit used in an ArF lithography system. To understand the mechanism of image profile changes by slit transmission, we focus on frequency transfer characteristics of sinusoidal patterns. 相似文献
198.
199.
Kiyoshi Mizuuchi Kanryu Inoue Yasuyuki Agari Toru Nagaoka Masami Sugioka Motohiro Tanaka Takashi Takeuchi Jun-ichi Tani Masakazu Kawahara Yukio Makino Mikio Ito 《Composites Part B》2012,43(4):2012-2019
Silicon carbide (SiC)-particle-dispersed-aluminum (Al) matrix composites were fabricated in a unique fabrication method, where the powder mixture of SiC, pure Al and Al–5mass% Si alloy was uniquely designed to form continuous solid–liquid co-existent state during spark plasma sintering (SPS) process. Composites fabricated in such a way can be well consolidated by heating during SPS processing in a temperature range between 798 K and 876 K for a heating duration of 1.56 ks. Microstructures of the composites thus fabricated were examined by scanning electron microscopy and no reaction was detected at the interface between the SiC particle and the Al matrix. The relative packing density of the Al–matrix composite containing SiC was higher than 99% in a volume fraction range of SiC between 40% and 55%. Thermal conductivity of the composite increased with increasing the SiC content in the composite at a SiC fraction range between 40 vol.% and 50 vol.%. The highest thermal conductivity was obtained for Al–50 vol.% SiC composite and reached 252 W/mK. The coefficient of thermal expansion of the composites falls in the upper line of Kerner’s model, indicating strong bonding between the SiC particle and the Al matrix in the composite. 相似文献
200.
Makoto Sasaki Motoki Inoue Yasuyuki Katada Yuuki Nishida Akiyoshi Taniguchi Sachiko Hiromoto Tetsushi Taguchi 《Science and Technology of Advanced Materials》2012,13(6)
Calcium phosphate was formed on nickel-free high-nitrogen stainless steel (HNS) by chemical solution deposition. The calcium phosphate deposition was enhanced by glutamic acid covalently immobilized on the surface of HNS with trisuccinimidyl citrate as a linker. X-ray diffraction patterns and Fourier transform infrared spectra showed that the material deposited on glutamic acid-immobilized HNS within 24 h was low-crystallinity calcium-deficient carbonate-containing hydroxyapatite (HAp). The biological activity of the resulting HAp-coated HNS was investigated by using a human osteoblast-like MG-63 cell culture. The HAp-coated HNS stimulated the alkaline-phosphate activity of the MG-63 culture after 7 days. Therefore, HAp-coated HNS is suitable for orthopedic devices and soft tissue adhesion materials. 相似文献