Numerical Study of the Exchange Bias in Magnetic Systems with a Heterogeneous Morphology

Yong Hu,An Du,Ze Xianyu 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Microstructural Evolution and Mechanical Properties of Semi-Solid Al15Mg45Li39Ca0.5Si0.5 Light-Weight High Entropy Alloys Fabricated by Isothermal Heat Treatment

Yong Hu,Fei Liu,Longzhi Zhao,Yanchuan Tang,Haitao Jiao 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.5

Al15Mg45Li39Ca0.5Si0.5 LW-HEAs with a density of 1.45 g/cm3 was designed and fabricated by magnetic suspension furnace. The non-dendritic globular microstructures of Al15Mg45Li39Ca0.5Si0.5LW-HEAs were prepared by isothermal heat treatment,and the effects of isothermal temperatures and holding times on the microstructures of semi-solid Al15Mg45Li39Ca0.5Si0.5LW-HEAs were investigated by optical microscope and scanning electron microscope. The results indicate that the phasesof Al15Mg45Li39Ca0.5Si0.5LW-HEAs consist of HCP phases and intermetallic compounds. With the increase of isothermaltemperature, the average grain size increases and the shape factor increases first and then decreases. With the prolongationof holding time, the average grain size increases first, then decreases and then increases again, and the shape factor alsoincreases first and then decreases. The semi-solid Al15Mg45Li39Ca0.5Si0.5LW-HEAs have a low coarsening coefficient. Compared with the as-cast Al15Mg45Li39Ca0.5Si0.5LW-HEAs, the ultimate strength, plasicity and hardness of smei-solidAl15Mg45Li39Ca0.5Si0.5LW-HEAs are improved by 25.7%, 18.5% and 89.7%, respectively.

Adaptive MR damper cable control system based on piezoelectric power harvesting

Xinchun Guan,Yonghu Huang,Hui Li,Jinping Ou 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.10 No.1

To reduce the vibration of cable-stayed bridges, conventional magnetorheological (MR) damper control system (CMRDS), with separate power supply, sensors and controllers, is widely investigated. In this paper, to improve the reliability and performance of the control system, one adaptive MR damper control system (AMRDS) consisting of MR damper and piezoelectric energy harvester (PEH) is proposed. According to piezoelectric effect, PEH can produce energy for powering MR damper. The energy is proportional to the product of the cable displacement and velocity. Due to the damping force changing with the energy, the new system can be adjustable to reduce the cable vibration. Compared with CMRDS, the new system is structurally simplified, replacing external sensor, power supply and controller with PEH. In the paper, taking the N26 cable of Shandong Binzhou Yellow River Bridge as example, the design method for the whole AMRDS is given,and simple formulas for PEH are derived. To verify the effectiveness of the proposed adaptive control system, the performance is compared with active control case and simple Bang-Bang semi-active control case. It is shown that AMRDS is better than simple Bang-Bang semi-active control case, and still needed to be improved in comparison with active control case.

Eu3þ, Liþ doped CaWO4 nanorods: Synthesis, emission-decay curves and effective-refractive index

Xiuna Tian,Guicheng Jiang,Yonghu Chen,Min Yin 한국물리학회 2014 Current Applied Physics Vol.14 No.12

In the present paper, CaWO4: Eu3þ, Liþ nanorods have been successfully synthesized via an oleic acid (OA)-assisted solvethermal route. The transmission electron microscope (TEM) photograph shows that the CaWO4: Eu3þ, Liþ nanorods are monodisperse and uniform nanorods with average diameter of 26 nm. The optical properties of Eu3þ in CaWO4 samples, including photoluminescence (PL) excitation spectra and luminescent decay curves, are investigated in detail. Due to the form of the nanorods, the relative contribution of CTB to the nanorods sample is greater than that to the bulk counterparts. The decay time of the 5D0 level (ranging from 0.94 to 0.65 ms, depending on the filling factor of the nanorods) of the nanorods is longer than that of the bulk counterpart mainly due to the reduction in the size of the nanorods, which introduces an effective-refractive index smaller than the refractive index of CaWO4.

Functional mechanisms for diabetic nephropathy-associated genetic variants

Hong Xu,Chengxin Gong,Yonghu Xu,Yongfang Fan,Xingzi Liu,Chaopeng Xiong,Luling He,Changle Liu,Shenqiang Rao,Wen Xiao,Lu Ding,Lan Tang,Fangfang Hu,Mengqi Xiong,Mei Yang,Shangdong Liang 한국유전학회 2016 Genes & Genomics Vol.38 No.7

Diabetic nephropathy (DN) is one of the major complications of diabetes. A tremendous amount of genetic variations have been identified to be associated with DN. However, most of them only generate from statistical associations at the DNA level, generally without direct functional evidence regarding their association mechanisms underlying DN. Based on the publicly available datasets and resources, this study performed integrative analyses (expression quantitative trait loci analysis, differential gene expression analysis and functional prediction analysis) to detect the molecular functional mechanisms underlying the associations for DN. Among 150 selected (P\E-4) genetic associations that were archived in the public databases, two single nucleotide polymorphisms (SNPs) (rs3135377 and rs9469220) have been found to act as cis-effect regulators of the ‘‘identified’’ gene (HLADRA and HLA-DRB1). These eQTL genes have differential expression signals in the DN-associated cell groups. These SNPs were predicted as regulatory sites by utilizing online prediction tools. Our data suggest potential mechanistic links underlying the association between DN and two identified SNPs. These results could help us to have a deeper understanding of the functional relevance of genetic variants with susceptibility to DN, which is useful for pursuit of in-depth validation studies to dissect their involvements and molecular functional mechanisms in DN.

Adaptive MR damper cable control system based on piezoelectric power harvesting

Guan, Xinchun,Huang, Yonghu,Li, Hui,Ou, Jinping Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.10 No.1

To reduce the vibration of cable-stayed bridges, conventional magnetorheological (MR) damper control system (CMRDS), with separate power supply, sensors and controllers, is widely investigated. In this paper, to improve the reliability and performance of the control system, one adaptive MR damper control system (AMRDS) consisting of MR damper and piezoelectric energy harvester (PEH) is proposed. According to piezoelectric effect, PEH can produce energy for powering MR damper. The energy is proportional to the product of the cable displacement and velocity. Due to the damping force changing with the energy, the new system can be adjustable to reduce the cable vibration. Compared with CMRDS, the new system is structurally simplified, replacing external sensor, power supply and controller with PEH. In the paper, taking the N26 cable of Shandong Binzhou Yellow River Bridge as example, the design method for the whole AMRDS is given, and simple formulas for PEH are derived. To verify the effectiveness of the proposed adaptive control system, the performance is compared with active control case and simple Bang-Bang semi-active control case. It is shown that AMRDS is better than simple Bang-Bang semi-active control case, and still needed to be improved in comparison with active control case.

Temperature dependent luminescence of Dy3þ doped BaYF5 nanoparticles for optical thermometry

Zhongmin Cao,Shaoshuai Zhou,Guicheng Jiang,Yonghu Chen,Changkui Duan,Min Yin 한국물리학회 2014 Current Applied Physics Vol.14 No.8

Dy3þ doped BaYF5 nanoparticles with tetragonal structure were synthesized by hydrothermal method and solvothermal method. The structural and the luminescent properties of the samples were characterized by X-ray diffraction pattern, TEM and photoluminescence spectra. Emission of Dy3þ originated from 4I15/2 located at 450 nm and 4F9/2 located at 478 nm, 573 nm and 660 nm were observed under excitation of 355 nm laser. Behavior of fluorescence intensity ratio with temperature increasing from room temperature to approximately 800 K was investigated. And the optimum temperature range for thermometry is obtained to be 550e800 K according to its sensitivity-temperature relation, indicating the potential application of BaYF5:Dy3þ as a luminescent temperature sensor.

Performance analysis of two-dimensional DOA estimation for uniform circular array

Chen Liupeng,Mou Weihua,Lv Zhicheng,Zhang Yonghu,Hu Lizhi,Ou Gang 한국통신학회 2023 ICT Express Vol.9 No.5

Perturbation analysis of direction of arrival (DOA) estimation has been studied mostly on one-dimensional arrays rather than planar arrays, which remains room for exploration. For uniform circular arrays with various model errors, we establish the corresponding system model. Then a performance analysis of the two-dimensional MUSIC algorithm is proposed by first-order error analysis and verified by simulation. The results show that the root-mean-squared error of DOA estimation is proportional to the standard deviation of the model errors, including gain-phase errors, sensor position errors, and mutual coupling effect.

A new red-emitting phosphor of Eu3+-doped Sr2MgMoxW1−xO6 for solid state lighting

Shuo Li,Xiantao Wei,Kaimo Deng,Xiuna Tian,Yanguang Qin,Yonghu Chen,Min Yin 한국물리학회 2013 Current Applied Physics Vol.13 No.7

The white light-emitting diode has recently attracted great attention as a promising candidate for next generation lighting. The solid solution of Sr1.80Eu0.10Li0.10MgMoxW1-xO6 was synthesized via hightemperature solid-state reaction and this solid solution is treated as a promising red emitting phosphor for white light-emitting diodes. In our cases, the X-ray diffraction, excitation spectra, emission spectra and decay curves of these solid solutions were measured as a function of the Mo/W ratio to characterize the structural and luminescent properties. The excitation bands of the series of phosphors are consistent well with the region of near ultraviolet light, and the phosphors present better color purity than the commercial phosphor Y2O2S:Eu3þ in current use. Taking these properties into consideration,this kind of material may find a great potential application as a red phosphor for near-ultraviolet excited white light-emitting diodes.

Eu3+-site occupation in CaTiO3 perovskite material at low temperature

Fengfeng Chi,Yanguang Qin,Shaoshuai Zhou,Xiantao Wei,Yonghu Chen,Changkui Duan,Min Yin 한국물리학회 2017 Current Applied Physics Vol.17 No.1

In order to clarify the site occupancy of rare-earth ions in rare-earth doped perovskite materials, the undoped pure CaTiO3 and Eu3þ-doped CaTiO3 samples with a series of Ca/Ti ratio were synthesized via high-temperature solid-state reaction method. X-ray diffraction (XRD) powder patterns confirm that the crystal structure keeps invariant at various Ca/Ti ratios. Measurement results of unit-cell parameters and X-ray photoelectron spectroscopy (XPS) indicate that Eu3þ ions enter into the Ca2þ site. The highresolution photoluminescence spectra of Eu3þ ions at 20 K in all samples did not witness a significant change under the excitation at different wavelength, implying that Eu3þ ions occupy only one type of site. Considering the small spectral splitting range of 5D0/7F2 transition and the large intensity ratio of 5D0 / 7F2/5D0 / 7F1, it can be concluded that Eu3þ occupies Ca2þ site with larger coordinate numbers rather than Ti4þ site.