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RISS 인기검색어
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- 저자 : Jiming Zheng (검색결과 8 건)
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Enhanced luminescence of Tb3+ by efficient energy transfer from Ce3+ in Sr2B5O9Cl host
Jiming Zheng,Chongfeng Guo,Xu Ding,Zhaoyu Ren,Jintao Bai 한국물리학회 2012 Current Applied Physics Vol.12 No.3
Ce3+ and Tb3+ co-doped Sr2B5O9Cl phosphors with intense green emission were prepared by the conventional high-temperature solid-state reaction technique. A broad band centered at about 315 nm was found in phosphor Sr2B5O9Cl: Ce3+, Tb3+ excitation spectrum, which was attributed to the 4f-5d transition of Ce3+. The typical sharp line emissions ranging from 450 to 650 nm were originated from the 5D4/7FJ (J ¼ 6, 5, 4, 3) transitions of Tb3+ ions. The photoluminescence (PL) intensity of green emission from Tb3+ was enhanced remarkably by co-doping Ce3+ in the Tb3+ solely doped Sr2B5O9Cl phosphor because of the dipoleedipole mechanism resonant energy transfer from Ce3+ to Tb3+ ions. The energy transfer process was investigated in detail. In light of the energy transfer principles, the optimal composition of phosphor with the maximum green light output was established to be Sr1.64Ce0.08Tb0.1Li0.18B5O9Cl by the appropriate adjustment of dopant concentrations. The PL intensity of Tb3+ in the phosphor was enhanced about 40 times than that of the Tb3+ single doped phosphor under the excitation of their optimal excitation wavelengths.
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Xinliang Zheng,Juan Feng,Jiarui Zhang,Hongna Xing,Jiming Zheng,Mingzi Wang,Yan Zong,Jintao Bai,Xinghua Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.3
High-quality neodymium oxychlorides nanocrystals with cubic shape were synthesized by a nonhydrolytic thermolysis route. The morphology and crystal structure of the neodymium oxychlorides nanocubes were characterized by transmission electron microscopy at the nanoscale. Transmission electron microscope (TEM) image shows that the neodymium oxychlorides nanocrystals are nearly monodispersed with cube-like shape. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns of numerous neodymium oxychlorides nanocubes suggest a pure crystal phase with tetragonal PbFCl matlockite structure. HRTEM image of individual neodymium oxychlorides nanocubes indicate that each nanocubes have a singlecrystalline nature with high quality. Unlike the anti-ferromagnetism of the bulk, the neodymium oxychlorides nanocubes show clearly anomalous ferromagnetic characteristic at room temperature. This finding provides a new platform for the exploration of diluted magnetic semiconductors, rare earth-based nanomaterials and so on.
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Yuanxian Zheng,Jiming Wang,Wenlong Zhao,Xianjie Cai,Yinlian Xu,Xiaolong Chen,Min Yang,Feiyan Huang,Lei Yu,Yuansheng He 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.3
Bacterial wilt, which is a major soil-borne disease with widespread occurrence, poses a severe danger in the field of tobacco production. However, there is very limited knowledge on bacterial wilt-induced microecological changes in the tobacco root system and on the interaction between Ralstonia solanacearum and fungal communities in the rhizosphere soil. Thus, in this study, changes in fungal communities in the rhizosphere soil of tobaccos with bacterial wilt were studied by 18S rRNA gene sequencing. The community composition of fungi in bacterial wilt-infected soil and healthy soil in two tobacco areas (Gengma and Boshang, Lincang City, Yunnan Province, China) was studied through the paired comparison method in July 2019. The results showed that there were significant differences in fungal community composition between the rhizosphere soil of diseased plants and healthy plants. The changes in the composition and diversity of fungal communities in the rhizosphere soil of tobaccos are vital characteristics of tobaccos with bacterial wilt, and the imbalance in the rhizosphere microecosystem of tobacco plants may further aggravate the disease.
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Aero-elastic wind tunnel test of a high lighting pole
Yaozhi Luo,Yucheng Wang,Jiming Xie,Chao Yang,Yanfeng Zheng 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.1
This paper presents a 1:25 multi-freedom aero-elastic model for a high lighting pole at the Zhoushan stadium. To validate the similarity characteristics of the model, a free vibration test was performed before the formal test. Beat phenomenon was found and eliminated by synthesis of vibration in the X and Y directions, and the damping ratio of the model was identified by the free decay method. The dynamic characteristics of the model were examined and compared with the real structure; the similarity results were favorable. From the test results, the major along-wind dynamic response was the first vibration component. The along-wind wind vibration coefficient was calculated by the China code and Eurocode. When the peak factor equaled 3.5, the coefficient calculated by the China code was close to the experimental result while Eurocode had a slight overestimation of the coefficient. The wind vibration coefficient during typhoon flow was analyzed, and a magnification factor was suggested in typhoon-prone areas. By analyzing the power spectrum of the dynamic cross-wind base shear force, it was found that a second-order vortex-excited resonance existed. The cross-wind response in the test was smaller than Eurocode estimation. The aerodynamic damping ratio was calculated by random decrement technique and the results showed that aerodynamic damping ratios were mostly positive at the design wind speed, which means that the wind-induced galloping phenomenon is predicted not to occur at design wind speeds.
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Manifold Sparse Coding Based Hyperspectral Image Classification
Yanbin Peng,Zhijun Zheng,Jiming Li,Zhigang Pan,Xiaoyong Li,Zhinian Zhai 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.12
Hyperspectral image classification has received an increasing amount of interest in recent years. However, when representing pixels as vectors, the dimensionality of feature space is high, which causes “curse of dimensionality” problem. In this paper, in order to alleviate the impact of above problem, a manifold sparse coding method is proposed. Firstly, matrix decomposition technique is used to find a concept set and calculates relative data projection in the concept set. Secondly, manifold learning regularization is imported into objective function to capture the intrinsic geometric structure in the data. Finally, LASSO regularization is used to obtain sparse representation of data projection. Experimental results on real hyperspectral image show that the proposed method has better performance than the other state-of-the-art methods.
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Aero-elastic wind tunnel test of a high lighting pole
Luo, Yaozhi,Wang, Yucheng,Xie, Jiming,Yang, Chao,Zheng, Yanfeng Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.1
This paper presents a 1:25 multi-freedom aero-elastic model for a high lighting pole at the Zhoushan stadium. To validate the similarity characteristics of the model, a free vibration test was performed before the formal test. Beat phenomenon was found and eliminated by synthesis of vibration in the X and Y directions, and the damping ratio of the model was identified by the free decay method. The dynamic characteristics of the model were examined and compared with the real structure; the similarity results were favorable. From the test results, the major along-wind dynamic response was the first vibration component. The along-wind wind vibration coefficient was calculated by the China code and Eurocode. When the peak factor equaled 3.5, the coefficient calculated by the China code was close to the experimental result while Eurocode had a slight overestimation of the coefficient. The wind vibration coefficient during typhoon flow was analyzed, and a magnification factor was suggested in typhoon-prone areas. By analyzing the power spectrum of the dynamic cross-wind base shear force, it was found that a second-order vortex-excited resonance existed. The cross-wind response in the test was smaller than Eurocode estimation. The aerodynamic damping ratio was calculated by random decrement technique and the results showed that aerodynamic damping ratios were mostly positive at the design wind speed, which means that the wind-induced galloping phenomenon is predicted not to occur at design wind speeds.
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