Frequency and magnetic properties in the range of 10 kHz to 100 MHz for nanocrystal Fe -Co alloy

Yongsheng Liu,Jincang Zhang,Liming Yu,Guangqiang Jia,Yufeng Zhang,Xinyan Wang,Shixun Cao 한국물리학회 2004 Current Applied Physics Vol.4 No.5

Fe-based soft magnetic alloy with Co-doping was fabricated by high-energy milling. The X-ray diraction (XRD) results exhibita single phased structure,which could be regarded as BCC-like FeCo solid solution,was formed. Moreover,it has also been demonstrated that a nanocrystalline FeCo alloy was obtained and the evaluated grain sizes were about 712 nm. The frequency dependence of the initial permeability and magnetic losses,as well as DC-magnetization measurements,was systematically studiedthen. The results show that thefn (fn is the frequency when the curve of the No.n sample has a minimum value) shifts to the higherfrequency with the increasing Co content in the range of 10 kHz to 100 MHz,while the magnetic losses of the samples decrease withthe increasing Co content at the high frequency (800 kHz to 20 MHz). The Co-doping increases the cut-o frequencies of thesamples and makes the initial permeability to keep a constant value in a wider frequency range. The corresponding peak value of theinitial permeability as function of Co-doping concentration turns to the region of low Co concentration. For the long milling time,the loss apparently decreases beyond 1 MHz.

Magnetic alignment of MnBi crystals and magnetic properties of MnBi-Bi composites

Yongsheng Liu,Jincang Zhang,Zhongming Ren,Shixun Cao,Xiaoyong Zhang,Guangqiang Jia,Kang Deng,Xi Li,Junxi Zhang 한국물리학회 2007 Current Applied Physics Vol.7 No.5

Below Curie temperatureTC, MnBi crystals are aligned alongc-axis in a Bi matrix under a fabrication eldHfof 0.5 T. AboveTC,this alignment is also accomplished by quenching under a highHfof 10 T. Such a method has a prominent feature that MnBi crystalsgrow preferentially and congregate along theHfdirection. Magnetic testing shows a pronounced anisotropy in magnetization in direc-tions normal and parallel toHf, resulting from the alignment. In the case of the alignment belowTC,Hfincreases the transition temper-ature of spin-reorientation and the change in magnetization.

Effect of heat treatment on the crystallization toughening of tailing-derived glass-ceramics

Du Yongsheng,Yang Xiaowei,Zhang Hongxia,Zhang Xuefeng,Zhao Ming,Chen Hua,Ouyang Shunli,Li Baowei 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.12

The effect of heat treatment to a parent glass of the composition CaO-MgO-Al2O3-SiO2 (CMAS) on the course ofcrystallization and properties of the Bayan Obo east mine tailing glass-ceramics is examined. The crystallization behavior,phase composition, morphology and structure of glass-ceramics are characterized. The results indicate that the phases formedin the glass-ceramics are augite and the initial nucleation phases are magnetite, which can be proved by differential scanningcalorimetry (DSC), X-ray diffraction (XRD) and scanning transmission electron microscope (STEM). Heat treatment plays asignificant role in improving the crystallization process, fracture characteristics, modulus and bending strength. All of theseproperties reach a maximum for the fully crystallized glass-ceramic. Scanning electron microscope (SEM) and atomic forcemicroscope (AFM) are used to reveal the topography of the fracture surfaces. The intergranular fracture can be observed onthe fracture surface.

Patterned growth of ZnO nanorods and their field emission properties

Ning Zhang,Ke Yu,Yongsheng Zhang,Wei Bai,Ziqiang Zhu 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Patterned zinc oxide (ZnO) nanorods were fabricated on the different patterned silicon nanocrystallite (SiNC) substrates via a simple thermal evaporation method without any catalyst. The as-synthesized products were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), respectively. The efficient field emission with low turn-on and threshold field, 3.5 V/㎛ and 8.1 V/㎛, was obtained. The experimental results demonstrate that these products could be one of the promising candidates for field emission displays. Patterned zinc oxide (ZnO) nanorods were fabricated on the different patterned silicon nanocrystallite (SiNC) substrates via a simple thermal evaporation method without any catalyst. The as-synthesized products were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), respectively. The efficient field emission with low turn-on and threshold field, 3.5 V/㎛ and 8.1 V/㎛, was obtained. The experimental results demonstrate that these products could be one of the promising candidates for field emission displays.

Effect of aggregates of elements induced by rare earth doping on toughening of tailing-derived glass-ceramics

Du Yongsheng,Ma Jie,Zhang Xuefeng,Zhang Hongxia,Chen Hua,Ouyang Shunli,Baowei Li 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.4

Tailings glass-ceramics doped with different proportion of CeO2 were prepared by conventional melts and controllable crystallization. The effect of CeO2 on the microstructure, element distribution characteristics and fracture toughness of glassceramics was studied in this paper. Significant change in microstructure was not observed with the addition of rare earth oxide, but the phenomenon of element aggregates begins to appear in glass-ceramics and the element enrichment of Si, Al, Na and Ce can be observed in the element aggregates. As a result, the integrity of the glass network structure can be improved and the strength of glass phase contributed to the enhancement of fracture toughness. The doping of 3.0% CeO2 achieved a remarkable improvement on fracture toughness that reached 2.86 MPa*m1/2 with a Vickers hardness of 8.49 GPa.

Graphene oxide template-confined fabrication of hierarchical porous carbons derived from lignin for ultrahigh-efficiency and fast removal of ciprofloxacin

Wenna Ge,Zhiping Zhou,Peng Zhang,Qingfang Zhang,Zhen Cao,Ruilong Zhang,Yongsheng Yan,Jiangdong Dai 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-

Here, a new hierarchical porous carbon was first prepared from sodium lignosulphonate (SLS), an industrial by-product, via a confined carbonization and alkali activation methods using graphene oxide (GO) as template, and was used for ciprofloxacin (CIP) removal. The addition of GO nanosheets remarkably affected the morphology and pore structure. GLHPC-1, obtained at GO/SLS weight ratio of 1:100, possess a largest specific surface area of 3223 m2 g−1 and pore volume of 2.275 cm3 g−1, and thus exhibited an ultrahigh adsorption of 980.4 mg g−1 at 318 K and fast adsorption rate, as well as a good recycle ability in practice.

Effect of Ar dilution flow rate on LPCVD a boron-doped carbon coating from BCl3-C3H6-H2-Ar mixtures

Yongsheng Liu,Litong Zhang,Laifei Cheng,Wenbin Yang,Yongdong Xu 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.3

A boron-doped carbon coating was deposited from a BCl3-C3H6-H2-Ar system by LPCVD. The effects of the Ar dilution flow rate on deposition rates, morphologies, compositions and bonding states were investigated. Deposition rates were almost the same, about 250 nm/h with different Ar dilution flow rate. Surface morphologies were also almost the same. The flat conchoidal aspect of the fracture surface transformed to a laminated structure with an increase in the Ar dilution flow rate. The carbon concentration was above 76.3 at.%, and the boron concentration was less than 17.9 at.%. The boron concentration increased with an increase in the Ar dilution flow rate, corresponding to a decreasing carbon concentration. The main bonding state of boron was B-sub-C and BC2O. The whole deposition process was dominated by a PyC formation reaction, which led to almost the same deposition rate with different Ar dilution flow rates. A boron-doped carbon coating was deposited from a BCl3-C3H6-H2-Ar system by LPCVD. The effects of the Ar dilution flow rate on deposition rates, morphologies, compositions and bonding states were investigated. Deposition rates were almost the same, about 250 nm/h with different Ar dilution flow rate. Surface morphologies were also almost the same. The flat conchoidal aspect of the fracture surface transformed to a laminated structure with an increase in the Ar dilution flow rate. The carbon concentration was above 76.3 at.%, and the boron concentration was less than 17.9 at.%. The boron concentration increased with an increase in the Ar dilution flow rate, corresponding to a decreasing carbon concentration. The main bonding state of boron was B-sub-C and BC2O. The whole deposition process was dominated by a PyC formation reaction, which led to almost the same deposition rate with different Ar dilution flow rates.

A novel lattice structure topology optimization method with extreme anisotropic lattice properties

Zhang Chenghu,Liu Jikai,Yuan Zhiling,Xu Shuzhi,Zou Bin,Li Lei,Ma Yongsheng 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.5

This research presents a lattice structure topology optimization (LSTO) method that significantly expands the design space by creating a novel candidate lattice that assesses an extremely large range of effective material properties. About the details, topology optimization is employed to design lattices with extreme directional tensile or shear properties subject to different volume fraction limits and the optimized lattices are categorized into groups according to their dominating properties. The novel candidate lattice is developed by combining the optimized elementary lattices, by picking up one from each group, and then parametrized with the elementary lattice relative densities. In this way, the LSTO design space is greatly expanded for the ever increased accessible material property range. Moreover, the effective material constitutive model of the candidate lattice subject to different elementary lattice combinations is pre-established so as to eliminate the tedious in-process repetitive homogenization. Finally, a few numerical examples and experiments are explored to validate the effectiveness of the proposed method. The superiority of the proposed method is proved through comparing with a few existing LSTO methods. The options of concurrent structural topology and lattice optimization are also explored for further enhancement of the mechanical performance.

A hybrid method for dynamic stiffness identification of bearing joint of high speed spindles

Yongsheng Zhao,Bingbing Zhang,Guoping An,Zhifeng Liu,Ligang Cai 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1

Bearing joint dynamic parameter identification is crucial in modeling the high speed spindles for machining centers used to predict the stability and natural frequencies of high speed spindles. In this paper, a hybrid method is proposed to identify the dynamic stiffness of bearing joint for the high speed spindles. The hybrid method refers to the analytical approach and experimental method. The support stiffness of spindle shaft can be obtained by adopting receptance coupling substructure analysis method, which consists of series connected bearing and joint stiffness. The bearing stiffness is calculated based on the Hertz contact theory. According to the proposed series stiffness equation, the stiffness of bearing joint can be separated from the composite stiffness. Then, one can obtain the bearing joint stiffness fitting formulas and its variation law under different preload. An experimental set-up with variable preload spindle is developed and the experiment is provided for the validation of presented bearing joint stiffness identification method. The results show that the bearing joint significantly cuts down the support stiffness of the spindles, which can seriously affects the dynamic characteristic of the high speed spindles.

Feature Selection of Nonperforming Loans in Chinese Commercial Banks

Zhang Yu,Yu Gang,Guan Yongsheng,Yang Donghui 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.3

In recent years, huge amounts of nonperforming loans (NPLs) of commercial banks have become one of the biggest obstacles constraining reform and development in Chinese commercial banks. Finding a way to control the banks’ NPLs is a core issue that it continues to be explored and researched in the finance. In this paper, PCA and relief algorithm in data mining methods were adopted to extract and analyze NPLs characteristics in commercial banks through contrasting the performing and nonperforming loans records, based on the predecessors’ literatures. In this paper, a bank's loans data with 96 features and 10415 samples is collected. At last, we construct nonperforming loans of commercial banks classification model. Our research is very important for capturing warning signal timely, detection of NPLs and sound operation of commercial banks.