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A simple model for the f?d transition of actinide and heavy lanthanide ions in crystals
Chang-Kui Duan,Michael F. Reid,Gang Ruan 한국물리학회 2006 Current Applied Physics Vol.6 No.3
The original simple model for 4f5d transitions [C.K. Duan, M.F. Reid, G.W. Burdick, Phys. Rev. B 6 (2002) 155108; C.K. Duan,M.F. Reid, J. Solid State Chem. 171 (2003) 299], which assumes a stronger exchange Coulomb interaction between 4forbitals and 5dorbitals than the 4fspinorbit interaction, is extended to the case where the eect of thef(4ffor heavy lanthanide and 5ffor actinidef5dspectra of heavy lanthanide and actinide ions in crystals.
Remote Sensing Image Fusion Based On IHS and Dual Tree Compactly Supported Shearlet Transform
Chang Duan,Qihong Huang,Xuegang Wang,Shuai Wang,Hong Wang 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5
This paper presents a novel remote sensing image fusion algorithm, which implements the intensity-hue-saturation (IHS) transform on panchromatic sharpening of multispectral data and the dual-tree compactly supported shearlet transform (DT CSST) during fusion. Shearlet transforms can provide almost optimal representation of the anisotropic features of an image. The spatial domain discrete implementation, the compactly supported shearlet transform (CSST), which represents the directions by dilation operations, are selected in the proposed fusion method. Since most of the prominent features of images, such as edges and regions, have limited sizes in the spatial domain, CSST is very suitable for image fusion. However, the conventional CSST is shift-variant, which causes distortions in fused images. With the embedded dual-tree (DT) sturcture in the CSST, the shift-variant properties can be effectively reduced. Combining the IHS transform and the DT CSST, an effective panchromatic and multispectral image fusion method is proposed in this paper. The experiments’ results suggest that the proposed method extract more spatial information from panchromatic images with less lost in spectral consistency compared to other fusion methods which are based on discrete wavelet transform (DWT), à trous wavelet transform, à trous shearlet transform, the dual-tree complex wave transform ( DT CWT), or the Curvelet transform.
Local field effects on the radiative lifetimes of Ce3+ in different hosts
Chang-Kui Duan,Michael F. Reid 한국물리학회 2006 Current Applied Physics Vol.6 No.3
For emitters embedded in media of various refractive indices, dierent theoretical models predict substantially dierent dependenciesof the spontaneous emission lifetime on the refractive index. It has been claimed that various measurements of 4f! 4f radiative lifetimesof Eu3+ in hosts with variable refractive index appear to favor the real-cavity model [D. Toptygin, J. Fluoresc. 13 (2003) 201 and ref-erences therein; G.M. Kumar, D.N. Rao, Phys. Rev. Lett. 91(2003) 203903]. The 5d! 4f radiative transition of rare-earth ions are dom-test of the dierent models. We analyze the lifetimes of the 5d! 4f transition of Ce3+ in hosts of refractive indices varying from 1.4 to2.2. The results favor the macroscopic virtual-cavity model based on the Lorentz local eld [D. Toptygin, J. Fluoresc. 13 (2003) 201].
Buckling Modes of Cold-Formed Thin-Walled Steel Beams Under Different Impact Positions
Chang Wu,Junwei Duan,Renhong Wang,Ziheng Yang 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.1
This paper aims to study the buckling mode of cold-formed thin-walled channel steel beams under different impact positions. The impact test of the thin-walled channel steel beams was carried out using a drop hammer to obtain the acceleration of the measuring point and the buckling mode of the member. The experimental results and ANSYS/LS-DYNA numerical simulation results are compared and analyzed. The results show that the acceleration curve change trend obtained from the test is similar to numerical simulation. The difference between the acceleration obtained by numerical simulation and the maximum value obtained by test accounts for 5.86% of the simulated value. Therefore, the dynamic response results of cold-formed thin-walled channel steel beams under numerical simulation can be effectively verified by the test. Numerical simulation methods are used to analyze the dynamic response of two groups of members under impact at different positions and the corresponding buckling modes. The results show that the buckling of the members at 1/2, 1/3, and 1/4 of the flange of the impact member is similar to the O-I mode under the same conditions. The buckling mode is half-O mode when the midpoint of the intersection line between flange and web is impacted. The buckling mode is U-shaped when the midpoint of the intersection line between flange and the curling edge is impact.
Structural Evolution of Sub-10 nm Octahedral Platinum–Nickel Bimetallic Nanocrystals
Chang, Qiaowan,Xu, Yuan,Duan, Zhiyuan,Xiao, Fei,Fu, Fang,Hong, Youngmin,Kim, Jeonghyeon,Choi, Sang-Il,Su, Dong,Shao, Minhua American Chemical Society 2017 NANO LETTERS Vol.17 No.6
<P>Octahedral Pt alloy nanocrystals (NCs) have shown excellent activities as electrocatalysts toward oxygen reduction reaction (ORR). As the activity and stability of NCs are highly dependent on their structure and the elemental distribution, it is of great importance to understand the formation mechanism of octahedral NCs and to rationally synthesize shape-controlled alloy catalysts with optimized ORR activity and stability. However, the factors controlling the structural and compositional evolution during the synthesis have not been well understood yet. Here, we systematically investigated the structure and composition evolution pathways of Pt-Ni octahedra synthesized with the assistance of W(CO)(6) and revealed a unique core-shell structure, consisting of a Pt core and a Pt-Ni alloy shell. Below 140 degrees C, sphere-like pure Pt NCs with the diameter of 3-4 nm first nucleated, followed by the isotropic growth of Pt-Ni alloy on the seeds at temperatures between 170 and 230 degrees C forming Pt@Pt-Ni core-shell octahedra with {111} facets. Owing to its unique structure, the Pt@Pt-Ni octahedra show an unparalleled stability during potential cycling, that is, no activity drop after 10 000 cycles between 0.6 and 1.0 V. This work proposes the Pt@Pt-Ni octahedra as a high profile electrocatalyst for ORR and reveals the structural and composition evolution pathways of Pt-based bimetallic NCs.</P>
Aggregation mechanism of fine fly ash particles in uniform magnetic field
Chang-Sui Zhao,Yong-Wang Li,Xin Wu,Duan-Feng Lu,Song Han 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.2
of fly ash particles with size range of 0.023-9.314m in a uniform magnetic field was inves-tigated for removing them. A binary collision-aggregation model evaluating particle aggregation coefficient was devel-oped. Based on the model, particle removal efficiency was calculated by solving the General Dynamic Equation. Thecomparison was done between the calculated and experimental data. The modeling aggregation coefficient shows thatthe aggregation coefficient increases with particle size, and the bigger the size difference between two particles is, thehigher than those of the smaller and bigger ones. The effect of the magnetic flux density on total particle removal effi-ciency is similar to that on aggregation coefficient. Before particles are saturatedly magnetized, their total removal effi-ciency increases with an increase in the magnetic flux density. Higher removal efficiency can also be caused by pro-longing the particle residence time in the magnetic field or increasing their mass concentration. The particle numbermedian diameter decreases with an increase in the total removal efficiency. Calculation results are found to coincideessentially with the experimental data.
NOx emission from incineration of organic liquid waste in a circulating fluidized bed
Chang-Sui Zhao,Hui-Chao Chen,Yong-wang Li,Duan-Feng Lu 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.5
incineration test of a toxic chemical organic waste liquid was conducted on a circulating fluidized bed(CFB) incinerator. The flue gas was measured online with the advanced SAE-19 flue gas analyzer. The effects of severalfactors, in terms of flow rate of waste liquid, ratio of waste liquid injected into dense bed of the CFB, excess air co-efficient, the secondary air fraction and bed temperature on NOx emissions, were verified. The experimental resultsthe excess air coefficient or the bed temperature and those decrease with increase in the ratio of waste liquid injectedinto the dense bed of the CFB or the secondary air fraction. During the test runs, NOx concentration in flue gas metthe national regulation on NOx emissions due to suppresive effect of low temperature and staged combustion in CFBon NOx formation.