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HCCI COMBUSTION CHARACTERISTICS DURING OPERATION ON DME AND METHANE FUELS
Y. TSUTSUMI,A. IIJIMA,K. YOSHIDA,H. SHOJI,J. T. LEE 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.6
The Homogeneous Charge Compression Ignition (HCCI) engine has attracted much interest because it can simultaneously achieve high efficiency and low emissions. However, the ignition timing is difficult to control because this engine has no physical ignition mechanism. In addition, combustion proceeds very rapidly because the premixed mixture ignites simultaneously at multiple locations in the cylinder, making it difficult to increase the operating load. In this study, an HCCI engine was operated using blended test fuels comprised of dimethyl ether (DME) and methane, each of which have different ignition characteristics. The effects of mixing ratios and absolute quantities of the two types of fuel on the ignition timing and rapidity of combustion were investigated. Cool flame reaction behavior, which significantly influences the ignition, was also analyzed in detail on the basis of in-cylinder spectroscopic measurements. The experimental results revealed that within the range of the experimental conditions used in this study, the quantity of DME supplied substantially influenced the ignition timing, whereas there was little observed effect from the quantity of methane supplied. Spectroscopic measurements of the behavior of a substance corresponding to HCHO also indicated that the quantity of DME supplied significantly influenced the cool flame behavior. However, the rapidity of combustion could not be controlled even by varying the mixing ratios of DME and methane. It was made clear that changes in the ignition timing substantially influence the rapidity of combustion.
Horie, K.,Yamashita, M.,Hayasaka, Y.,Katoh, Y.,Tsutsumi, Y.,Katsube, A.,Hidaka, H.,Kim, H.,Cho, M. Elsevier Scientific Pub. Co., etc.] 2010 Precambrian research Vol.183 No.1
U-Pb zircon geochronology of two Permo-Triassic granites (samples OT-52 and OT-272 with ages of 229+/-8Ma and 256+/-2Ma, respectively) in the Unazuki area, Hida Metamorphic Belt, southwest Japan, revealed the presence of Eoarchean to Paleoproterozoic inheritance. Inheritance is consistent with both samples showing low zircon saturation temperatures for their bulk compositions. In OT-52, dark in CL, low Th/U zircon domains have a mean <SUP>207</SUP>Pb/<SUP>206</SUP>Pb age of 1940+/-17Ma, which is consistent with an age of 1937+/-6Ma for anatexis in the Precambrian Busan gneiss complex in Korea. Eoarchaean inherited zircons with <SUP>207</SUP>Pb/<SUP>206</SUP>Pb ages from ca. 3750 to 3550Ma are common in OT-272 but are few in OT-52, suggesting a source from rocks with affinities to those in the Anshan area in the northeast China part of the North China Craton. On the other hand, a Hida Metamorphic Belt metasedimentary gneiss into which the granites were intruded contains ca. 1840, 1130, 580, 360, 285 and 250Ma zircons (Sano et al., 2000). These ages suggest that the Unazuki Mesozoic granites did not originate from proximal Hida Metamorphic Complex rocks, but instead from unrelated rocks obscured at depth. The predominance of Eoarchean to Paleoproterozoic age components, and the marked lack of 900-700Ma components suggest that the source was the (extended?) fringe of the North China Craton, rather than from Yangtze Craton crust. The Mesozoic evolution of Japan and its linkages to northeast Asia are discussed in the context of these results.
Sahu, B. B.,Yin, Y. Y.,Tsutsumi, T.,Hori, M.,Han, Jeon G. The Royal Society of Chemistry 2016 Physical Chemistry Chemical Physics Vol.18 No.18
<P>Control of the plasma densities and energies of the principal plasma species is crucial to induce modification of the plasma reactivity, chemistry, and film properties. This work presents a systematic and integrated approach to the low-temperature deposition of hydrogenated amorphous silicon nitride films looking into optimization and control of the plasma processes. Radiofrequency (RF) and ultrahigh frequency (UHF) power are combined to enhance significantly the nitrogen plasma and atomic-radical density to enforce their effect on film properties. This study presents an extensive investigation of the influence of combining radiofrequency (RF) and ultrahigh frequency (UHF) power as a power ratio (PR = RF : UHF), ranging from 4: 0 to 0: 4, on the compositional, structural, and optical properties of the synthesized films. The data reveal that DF power with a characteristic bi-Maxwellian electron energy distribution function (EEDF) is effectively useful for enhancing the ionization and dissociation of neutrals, which in turn helps in enabling high rate deposition with better film properties than that of SF operations. Utilizing DF PECVD, a wide-bandgap of similar to 3.5 eV with strong photoluminescence features can be achieved only by using a high-density plasma and high nitrogen atom density at room temperature. The present work also proposes the suitability of the DF PECVD approach for industrial applications.</P>