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Crystallinity dependence of electrochemical properties for LiFePO_4

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Rare Metals 2015年第5期34卷 334-337页

作者： Ting Zhao xiang-jun zhang xiang Li Shi-Gang Lu Research and Development Centre for Vehicle Battery and Energy Storage General Research Institute for Nonferrous Metals

LiFePOa composites were prepared by solid state reactions at different temperatures and time. The crystalline structure and morphology of the composites were analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, while X-ray absorption spectroscopy （XAS） was employed to characterize the crystallinity. Experimental results show that the electrochemical properties do not monotonously get better with the decrease of particle size and the traditional long reaction time is needless. Moreover, XAS is an effective technique to discover the change in crystallinity.

关键词： Lithium ion battery LiFePO4 Crystallinity

Effect of Sn on Corrosion Behavior of Ultra-pure 17 mass% Cr Ferritic Stainless Steels in Sulphuric Acid

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Journal of Iron and Steel Research International 2016年第10期23卷 1044-1053页

作者： xiang-jun zhang Fei GAO Zhen-yu LIU State Key Laboratory of Rolling and Automation Northeastern University School of Material and Metallurgy Northeastern University

The effect of Sn on corrosion behavior of ferritic stainless steels in 20mass% H2SO4 was investigated by alternating current and direct current electrochemical methods and gravimetric tests at 25 ℃.The results show that Sn can effectively improve general corrosion resistance of ferritic stainless steels in H2SO4,mainly due to highly raised hydrogen evolution overpotential which is in favour of strong suppression of hydrogen evolution reaction,and inhibitive effect of dissolved Sn^2＋ on elementary anodic *** increasing Sn content,the better corrosion resistance can be *** Electrochemical Impedance Spectroscopy（EIS）includes four time constants and can be perfectly fitted by equivalent circuit：Rs（CdlRct）（QadsRads（RL1（L1（RL2L2））））.

关键词： stainless steel tin sulphuric acid general corrosion hydrogen overpotential

Corrosion Behavior of High Performance Offshore Platform Steel with Chromium and Nickel Addition in the Environment Containing Chloride Ions

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Journal of Iron and Steel Research International 2015年第6期22卷 496-505页

作者： Yan-lei ZHOU xiang-jun zhang Tao JIA Zhen-yu LIU State Key Laboratory of Rolling and Automation Northeastern University

The characterization of corrosion products formed on a high performance offshore platform steel in the en- vironment containing chloride ions has been investigated by scanning electron microscopy （SEM）, X ray diffraction （XRD）, electron probe microanalysis （EPMA） and electrochemical impedance spectroscopy （EIS）. The results re- veal that the corrosion process can be divided into the initial stage and the later stage. The main constituents of rust layers are c~ FeOOH, 13-FeOOH, y-FeOOH, Fe：^（）~ and large amounts of amorphous compounds. With increasing corrosion time, the mass fraction of a-FeOOH and Fe：~ O,, increased, while that of y-FeOOH and ^-FeOOH changed slightly. The enrichment of Cr and Ni at the inner/outer interface, especially the side of inner rust, can be observed in the later corrosion stage of Cr Ni steel, which can promote the formation of compact inner rust layer, impeding the transmission of corrosion mediums and slowing down the electrochemical reaction process.

关键词： offshore platform steel alloying element corrosion resistance rust layer electrochemical measurement

TiO_(2)-coated LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)cathode materials with enhanced cycle performance for Li-ion batteries

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Rare Metals 2021年第7期40卷 1719-1726页

作者： Wei-Wei Li xiang-jun zhang Jiang-Ju Si Jie Yang Xue-Yi Sun College of Chemistry and Chemical Engineering Xinxiang UniversityXinxiang 453003China R&D Centre for Vehicle Battery and Energy Storage General Research Institute for Nonferrous MetalsBeijing 100088China

Ni-rich cathode material is one of the most promising materials for Li-ion batteries in electric ***,fading capacity,poor cyclic stability and high p H value are still major challenges,which suppress its practical *** this study,spherical LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)powders with 0.4 wt%TiO_(2)coating layer were prepared by impregnation-hydrolysis *** electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM)and X-ray diffraction(XRD)results show that TiO_(2)is uniformly coated on the surface of LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)particle and slightly embedded into LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)*** 100 cycles at 2.0 C,0.4 wt%TiO_(2)-coated LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)electrode delivers much higher discharge capacity retention(77.0%)than the pristine LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)electrode(63.3%).The excellent cycling performance of 0.4 wt%Ti O_(2)-coated LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)electrode at a high discharge ratio is due to a TiO_(2)coating layer which can effectively reduce the direct contact between cathode material and electrolyte,suppress the oxidation of electrolyte,improve electrical conductivity of the electrode and increase the stability of the structure.

关键词： Li-ion batteries Cathode materials TiO_(2) LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2) Enhanced cycle performance

Effects of Al contents on microstructure and properties of hot-dip Zn-Al alloy coatings on hydrogen reduced hot-rolled steel without acid pickling

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Journal of Iron and Steel Research International 2017年第10期24卷 1032-1040页

作者： Zhi-feng Li Yong-quan He Guang-ming Cao jun-jian Tang xiang-jun zhang Zhen-yu Liu State Key Laboratory of Rolling and Automation Northeastern University School of Mechatronics Engineering Zhengzhou University of Aeronautics

A new hot-dip galvanizing method was employed on hot-rolled low carbon *** effects of Al contents on microstructure,micro-hardness and corrosion resistance of Zn-Al alloy coatings were systematically *** composition,microstructure and element distribution in Zn-Al alloy coatings were analyzed using X-ray diffraction（XRD）and electron probe micro analysis（EPMA）,*** is found that Al content（0.6-6.0 wt.%）in galvanizing zinc affects surface quality and adhesion between coatings and matrix in the newly developed *** addition,with increasing Al content,micro-hardness significantly increased due to the increase in Zn-Al eutectoid *** polarization and electrochemical impedance spectroscopy（EIS）also revealed that increase in Al plays a noticeable role in improving the corrosion resistance of Zn-Al alloy coatings.

关键词： Hot-rolled steel strip Hydrogen reduction Eutectoid structure Micro-hardnessCorrosion resistance Zn-Al alloy coating

Centralized light-wave WDM-PON employing DQPSK downstream and OOK remodulated upstream signals

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The Journal of China Universities of Posts and Telecommunications 2010年第4期17卷 125-128页

作者： zhang Wei-feng XIN xiang-jun zhang Qi zhang Zi-xing NAI Wei SHI Yan School of Electronic Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

A novel architecture for wavelength-division-multiplexing passive optical network （WDM-PON） with centralized light-wave is proposed and demonstrated. At the optical line terminal （OLT） session of this architecture, optical differential quadrature phase shift keying （DQPSK） modulated signal with constant-intensity at 10 Gbit/s is utilized for downstream transmission. At the optical network unit （ONU）, part of the downstream optical power is remodulated with on-off keying （OOK） intensity modulation at 10 Gbit/s for upstream without additional laser. Simulation results show that the power penalties of the downstream for 20 km single-mode fiber （SMF） transmission and multi-channels are negligible. While for the upstream, the power penalties are obvious. The simulation results and analysis also reflect that by reducing the launch power of DQPSK transmitters, power penalties can be reduced, although the transmission distance is limited.

关键词： WDM-PON DQPSK remodulation centralizedlight sources

Quantum simulation of Hofstadter butterfly with synthetic gauge fields on two-dimensional superconducting-qubit lattices

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Frontiers of physics 2023年第6期18卷 283-290页

作者： Wei Feng Dexi Shao Guo-Qiang zhang Qi-Ping Su jun-xiang zhang Chui-Ping Yang School of Physics Hangzhou Normal UniversityHangzhou 311121China School of Physics Zhejiang UniversityHangzhou 310027China

Motivated by recent realizations of two-dimensional(2D)superconducting-qubit lattices,we propose a protocol to simulate Hofstadter butterfly with synthetic gauge fields in superconducting *** on the existing 2D superconducting-qubit lattices,we construct a generalized Hofstadter model on zigzag lattices,which has a fractal energy spectrum similar to the original Hofstadter *** periodically modulating the resonant frequencies of qubits,we engineer a synthetic gauge field to mimic the generalized Hofstadter Hamiltonian.A spectroscopic method is used to demonstrate the Hofstadter butterfly from the time evolutions of experimental *** numerically simulate the dynamics of the system with realistic parameters,and the results show a butterfly spectrum *** proposal provides a promising way to realize the Hofstadter butterfly on the latest 2D superconducting-qubit lattices and will stimulate the quantum simulation of novel properties induced by magnetic fields in superconducting circuits.

关键词： quantum simulation superconducting circuits superconducting qubit quantum computation

NUMERICAL AND EXPERIMENTAL STUDY ON LIQUID-SOLID FLOW IN A HYDROCYCLONE

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Journal of Hydrodynamics 2009年第3期21卷 408-414页

作者： WANG Li-yang ZHENG Zhi-chu WU Ying-xiang GUO jun zhang jun TANG Chi Laboratory of Applied Fluid Dynamics Division of Engineering Sciences Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

Hydrocyclones are widely used in industry, of which the geometrical design using CFD techniques is gaining more popularity in recent years. In this study, the Euler-Euler approach and the Reynolds stress model are applied to simulate the liquid-solid flowfield in a hydrocyclone. The methodology is validated by a good agreement between experimental data and numerical results. Within the research range, the simulation indicates that the liquid-solid separation mainly occurs in the conical segment, and increasing conical height or decreasing cylindrical height helps to improve the grade efficiencies of solid particles. Based on these results, two of the same hydrocyclones are designed and installed in series to establish a liquid-solid separation system. Many experiments are then conducted under different conditions, in which the effects of the water cut and the second hydrocyclone on the separation are investigated. The results also confirm that smaller solid particles are more susceptible to the inlet conditions, and the second hydrocyclone plays a more important role as the water cut reduces.

关键词： hydrocyclone liquid-solid flow model efficiency

Restricted Arc-Connectivity of Harary Digraphs

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Journal of the Operations Research Society of China 2024年第2期12卷 540-547页

作者： jun-Hao zhang Ji-xiang Meng College of Mathematics and System Science Xinjiang UniversityUrumqi 830046XinJiangChina

The h-restricted arc-connectivity of a digraph is an important parameter to measure fault-tolerance of interconnection *** paper determines that the h-restricted arc-connectivity of the Harary digraph D=G(n;1,2,.:,k)i... 详细信息

关键词： Restricted arc-connectivity λ_(h)(D) Super-λ_(h) λ_(h)-Atom λ_(h)-Superatom