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Y. Shi,R. Zhao,C. Z. Jiang,X. J. Fan 한국진공학회(ASCT) 2002 Journal of Korean Vacuum Science & Technology Vol.6 No.2
The Si_(1-x)Ge_x/Si surface alloy (x = 0.3, 0.4 and 0.5), which are prepared by solid source MBE and have the SiGe epilayer thickness of 50Å, are annealed with different parameters. The surface structure analyses of the heterostructure samples are made on a triple-axis X-ray diffractometer in grazing incidence X-ray diffraction (GIXRD) geometry. It has been found that with different annealing time (1.5h, 18h, 64h) and annealing temperature (550℃, 750℃), the SiGe epilayer experienced different strain relaxation process, which was deduced from the GIXRD measurements of the in-plane (220) diffraction peak of Si(001) substrate and the relevant (220) surface diffraction of SiGe epilayer. The results show that the stress relieving and the lateral strain relaxation in the SiGe/Si heterostructure can be promoted by correct annealing, which is very helpful for the preparation of SiGe/Si strained superlattice with fine strain crystallization.
Magnetic Characteristics and Structure Studies of Mn-Implanted p-type GaN Films
Y. Shi,C. Z. Jiang,D. J. Fu,L. Lin,강태원,X. J. Fan 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
Wurtzite GaN ¯lms are grown by low-pressure MOCVD on (0001)-plane sapphire substrates. The GaN ¯lms have a total thickness of 4 ¹m with a surface Mg-doped p-type layer which has a thickness of 0.5 ¹m. 90-keV Mn+ ions are implanted into the GaN ¯lms at room temperature with doses ranging from 1 £ 1015 cm¡2 to 5 £ 1016 cm¡2. After an annealing step at about 800 ±C in °owing N2, the magnetism of the Mn-implanted GaN ¯lms is investigated by superconducting-quantum-interference device (SQUID). Despite the diamagnetic background of the undoped sample, the Mn-implanted GaN ¯lms show paramagnetism with dose of 1£1015 cm¡2 and ferromagnetism with a dose of 5 £ 1015 cm¡2 » 5 £ 1016 cm¡2. Combined with the structural characteristics given by X-ray diraction (XRD) and scanning electron microscopy (SEM), the magnetism of the Mn-implanted p-type GaN ¯lms is discussed.
Structural studies of $Mn^+$ implanted GaN film
Shi, Y.,Lin, L.,Jiang, C.Z.,Fan, X.J. The Korean Vacuum Society 2003 Applied Science and Convergence Technology Vol.12 No.1
Wurtzite GaN films are grown by low-pressure MOCVD on (0001)-plane sapphire substrates. The GaN films have a total thickness of 4 $\mu$m with a surface Mg-doped p-type layer, which has a thickness of 0.5 $\mu$m. 90k eV $Mn^{+}$ ions are implanted into the GaN films at room temperature with doses ranging from $1 \times10^{15}$ to $1 \times 10^{16}\textrm{cm}^{-2}$. After an annealing step at $770^{\circ}C$ in flowing $N_2$, the structural characteristics of the $Mn^{+}$ implanted GaN films are studied by X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) and atomic force microscopy (AFM). The structural and morphological changes brought about by $Mn^{+}$ implantation and annealing are characterized.
Structural studies of Mn+ implanted GaN film
Y. Shi,L. Lin,C. Z. Jiang,X. J. Fan 한국진공학회(ASCT) 2003 Applied Science and Convergence Technology Vol.12 No.S1
Wurtzite GaN films are grown by low-pressure MOCVD on (0001)-plane sapphire substrates. The GaN films have a total thickness of 4 ㎛ with a surface Mg-doped p-type layer, which has a thickness of 0.5 ㎛. 90k eV Mn^+ ions are implanted into the GaN films at room temperature with doses ranging from 1×10^(15) to 1×10^(16) ㎝-². After an annealing step at 770℃ in flowing N₂, the structural characteristics of the Mn^+ implanted GaN films are studied by X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) and atomic force microscopy (AFM). The structural and morphological changes brought about by Mn^+ implantation and annealing are characterized.
R&D Status of High-current Accelerators at IFP
J. J. Deng,J. S. Shi,W. P. Xie,L. W. Zhang,K. Z. Zhang,S. P. Feng,J. Li,M. Wang,Y. He,L. S. Xia,Z. Y. Dai,H. T. Li,L. Wen,S. F. Chen,X. Li,Q. G. Lai,M. H. Xia,Y. C. Guan,S. Y. Song,L. Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Zpinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 × 60 ns) to be built will be presented briefly.
Comparison of Axi-symmetric Single-Hole Nozzle with Multi-Hole Sac Nozzles
( M. C. Lai ),( Y. Zheng ),( X. Xie ),( K. Im ),( S. Moon ),( Z. Liu ),( J. Gao ),( J. Wang ),( J. M. Shi ),( R. E. Winsor ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-
It is well know that the internal flow field and nozzle geometry affect the spray behavior, but without high-speed microscopic visualization, it is difficult to characterize the spray structure in details. Single-hole Diesel injectors have been used in fundamental spray research, while most direct-injection engines use multi-hole nozzle to tailor the fuel spray to the combustion chamber geometry. Recent engine trends also use smaller orifice and higher injection pressure. This paper discussed the quasi-steady near-nozzle Diesel spray structures of an axisymmetric single-hole nozzle and a symmetric two-hole nozzle configuration, with a nominal nozzle size of 130 ㎛. Both nozzle holes originate from a sac of identical geometry, but different flow structure inside the nozzle cause significant difference in the observed flow structure near the nozzle exit. The ultrafast fast Phase-contrast X-ray images revealed unique surface and internal morphology of the fuel sprays that can be identified. The two-hole nozzle produces much more unstable jet structure under same injection conditions. The early wavelength developed in the jet is measured to be 30~80 ㎛, depending on the injection conditions. The differences between the nozzle configurations are investigated using CFD simulation. The results show that the three-dimensional fluid flow entering the two-hole nozzle generates stronger streamline curvature and stream-wise vortices which are by default absent in the axisymmetric single-hole nozzle. It also produces thicker shear layer and higher turbulence. The interactions of downwash entrance flow with turbulence potentially enhance the instability and produce wider spray cone angles. The number of holes also has interesting effects on the strength of the vortices and the downwash.
( D. Q. Zhang ),( C. Shi ),( J. Li ),( L. X. Gao ),( K. Y. Lee ) 한국부식방식학회 2017 Corrosion Science and Technology Vol.16 No.1
The corrosion behavior of a ferritic/martensitic steel T91 exposed to an aqueous solution containing chloride and sulfate ions is investigated depending on the stimulated all-volatile treatment (AVT) and under oxygenated treatment (OT) conditions. The corrosion of T91 steel under OT condition is severe, while the corrosion under AVT condition is not. The co-existence of chloride and sulfate ions has antagonistic effect on the corrosion of T91 steel in both AVT and OT conditions. Unlike to corrosion resistance in the aqueous solution, OT pretreatment provides T91 steel lower oxidation-resistance than VAT pretreatment. From scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis, the lower corrosion resistance in the aqueous solution by VAT conditions possibly is due to the formation of pits. In addition, the lower oxidation resistance of T91 steel pretreated by OT conditions is explained as follows: the cracks formed during the immersion under OT conditions accelerated peeling-off rate of the oxide film.
Investigation on the Weld Damage Behavior of Steel Beam-to-column Connection
X. Y. Liu,Y.Q. Wang,J. Xiong,Y.J. Shi 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.1
A large number of steel moment frames fractured at the welds of beam-to-column connections in earthquake. As the weld damage behavior is a crucial factor for aseismic performance of steel frame connections, 20 local welded connections representing beam-to-column connections were tested under monotonic and cyclic loads to study the weld damage behavior in this paper. The failure modes and deformation curves were recorded; the effects of material strength, load types, and beam geometries on the connection damage behavior were analyzed. Three damage evolution models were calibrated, the relation between weld damage and macro connection performance was established. The results indicate weld cracking and plate buckling are the main causes of the connection damage; the range of cyclic loads is the key factor affecting the weld damage level; the plastic strain based damage model illustrate the damage process with good accuracy. This study provide technical basis for the damage evaluation and fracture prevention of the welded steel beam-to-column connections.
MEACHANISM AND METHOD OF DPF REGENERATION BY OXYGEN RADICAL GENERATED BY NTP TECHNOLOGY
Y. X. SHI,Y. X. CAI,X. H. LI,Y. Y. CHEN,D. W. DING,W. TANG 한국자동차공학회 2014 International journal of automotive technology Vol.15 No.6
By using a self-designed non-thermal plasma (NTP) injection system, an experimental study of theregeneration of DPF was conducted at different temperatures, where oxygen as the gas source. The results revealed that PMcan be decomposed to generate CO and CO2 by these active substances O3, O which was generated through the dischargereaction of NTP reactor. With the increasing of test temperature, the mass of C1 (C in CO) shows a overall downward trendwhile the mass of C2 (C in CO2) and C12 (C1 and C2) increase firstly and then decrease. When the test temperature is 80oC, thebackpressure of DPF decreases fastest and the regenerative effect is remarkable. DPF can be regenerated by NTP technologywithout any catalyst at a lower temperature. Compared with the traditional regeneration method, the NTP technology has itssuperiority.