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Potentiality of Oxygenated Fuels on Soot-Free Diesel Combustion
Takaaki Kitamura,Takayuki Ito,Jiro Senda,Hajime Fujimoto 한국자동차공학회 2001 한국자동차공학회 Symposium Vol.- No.-
Fuel/air equivalence ratio '??' and temperature 'T' have a significant effect on the quality of particulate formation. In other words, it is probable that smokeless diesel combustion is realized if ?? and T inside the burning plume could be controlled based on the dependence of those on soot formation. The purpose of this work is to extract smokeless ?? - T conditions for various kinds of fuels, including paraffinic hydrocarbon, aromatic hydrocarbon, and oxygenated hydrocarbon, and to discuss a possibility of smokeless diesel combustion avoiding a soot formation region on ?? - T diagram. Sooting ?? - T map, which shows the tendency to generate soot particles as a function of ?? and T, was made using a detailed soot formation model. The model was based on a combination of a detailed reaction mechanism to calculate the gas phase chemistry and a detailed kinetic soot model based on the method of moments. It was found that smokeless ?? - T condition becomes more widespread especially for oxygenated fuels, due to the notable reduc-tion of both acetylene and PAHs. As a result of this work, a new concept for diesel combustion has been developed that utilizes the smokeless nature of oxygenated fuels.
( Hiroki Kitamura ),( Takayuki Shimaoka ),( Fumitake Takahashi ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-
Immobilization effect of chelate treatment was investigated using leaching experiments. Chemical forms of immobilized heavy metals in chelate treated municipal solid waste incineration (MSWI) fly ash were also investigated. Leaching experiments showed that heavy metals in chelate-treated MSWI fly ash are immobilized except for Cu. Some of Cu was incorporated into crystal structure of ettringite generated by chelate treatment. However, immobilization effect by ettringite might be limited. Chemical forms of heavy metals in chelate-treated MSWI fly ash seems to be oxides, sulfate or chlorides. Heavy metal particle sizes are several ten μm scale and concentrated spots of heavy metals were not mostly observed. Therefore, heavy metals seem to be distributed widely and tenuously on fly ash particle.
Xu, Tao,Shimada, Takahiro,Wang, Jie,Kitamura, Takayuki Techno-Press 2017 Coupled systems mechanics Vol.6 No.1
This work employed density functional theory to investigate the structural and ferroelectric properties of the Ruddlesden-Popper (RP) phase of lead titanate, $Pb_2TiO_4$, as well as its phase transitions with epitaxial strain. A wealth of novel structural instabilities, which are absent in the host $PbTiO_3$ material, were identified in the RP phase through phonon soft-mode analysis. Our calculations showed that the ground state of $Pb_2TiO_4$ is antiferroelectric, distinct from the dominant ferroelectric phase in the corresponding host material. In addition, applied epitaxial strain was found to play a key role in the interactions among the instabilities. The induction of a sequence of antiferroelectric and antiferrodistortive (AFD) phase transitions by epitaxial strain was demonstrated, in which the ferroic instability and AFD distortion were cooperative rather than competitive, as is the case in the host $PbTiO_3$. The RP phase in conjunction with strain engineering thus represents a new approach to creating ferroic orders and modifying the interplay among structural instabilities in the same constituent materials, enabling us to tailor the functionality of perovskite oxides for novel device applications.
Xu, Tao,Shimada, Takahiro,Wang, Jie,Kitamura, Takayuki 테크노프레스 2016 Multiscale and multiphysics mechanics Vol.1 No.3
This work employed density functional theory to investigate the structural and ferroelectric properties of the Ruddlesden-Popper (RP) phase of lead titanate, $Pb_2TiO_4$, as well as its phase transitions with epitaxial strain. A wealth of novel structural instabilities, which are absent in the host $PbTiO_3$ material, were identified in the RP phase through phonon soft-mode analysis. Our calculations showed that the ground state of $Pb_2TiO_4$ is antiferroelectric, distinct from the dominant ferroelectric phase in the corresponding host material. In addition, applied epitaxial strain was found to play a key role in the interactions among the instabilities. The induction of a sequence of antiferroelectric and antiferrodistortive (AFD) phase transitions by epitaxial strain was demonstrated, in which the ferroic instability and AFD distortion were cooperative rather than competitive, as is the case in the host $PbTiO_3$. The RP phase in conjunction with strain engineering thus represents a new approach to creating ferroic orders and modifying the interplay among structural instabilities in the same constituent materials, enabling us to tailor the functionality of perovskite oxides for novel device applications.
Group Velocity Matched Second Harmonic Generation in Periodically Poled Potassium Niobate
차명식,유난이,Sunao Kurimura,Kenji Kitamura,Satoshi Ashihara,Takayuki Ohta,Tsutomu Shimura,Kazuo Kuroda,Oc-Teob Jeon 부산대학교 유전체물성연구소 2004 유전체 논문집 Vol.3 No.
We investigated the group velocity matched second harmonic generarion in periodically poled potassium niobate. The QPM wavelength bandwidth was 38 nm around 1520 nm at 35℃ in 14.4㎛ QPM period with 10.5 mm interaction length. We also observed ultra-fast pulse used type-ⅠSHG conversion efficiency. The SHG conversion efficiency of the PPKN crystal was about 3 times that of type-Ⅰ SHG in PPMgLN.
Asynchronous cracking with dissimilar paths in multilayer graphene
Jang, Bongkyun,Kim, Byungwoon,Kim, Jae-Hyun,Lee, Hak-Joo,Sumigawa, Takashi,Kitamura, Takayuki The Royal Society of Chemistry 2017 Nanoscale Vol.9 No.44
<P>Multilayer graphene consists of a stack of single-atomic-thick monolayer graphene sheets bound with π-π interactions and is a fascinating model material opening up a new field of fracture mechanics. In this study, fracture behavior of single-crystalline multilayer graphene was investigated using an<I>in situ</I>mode I fracture test under a scanning electron microscope, and abnormal crack propagation in multilayer graphene was identified for the first time. The fracture toughness of graphene was determined from the measured load-displacement curves and the realistic finite element modelling of specimen geometries. Nonlinear fracture behavior of the multilayer graphene is discussed based on nonlinear elastic fracture mechanics.<I>In situ</I>scanning electron microscope images obtained during the fracture test showed asynchronous crack propagation along independent paths, causing interlayer shear stress and slippages. We also found that energy dissipation by interlayer slippages between the graphene layers is the reason for the enhanced fracture toughness of multilayer graphene. The asynchronous cracking with independent paths is a unique cracking and toughening mechanism for single-crystalline multilayer graphene, which is not observed for the monolayer graphene. This could provide a useful insight for the design and development of graphene-based composite materials for structural applications.</P>