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Tunneling conductance in graphene ferromagnet/p wave superconductor junctions

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science china(Physics,Mechanics & Astronomy) 2012年第4期Mechanics & Astronomy) .卷 649-653页

作者： LI XiaoWei 1,2*,CHEN HuaBao 1 & LIU ShuJing 1 1 School of Physics and electronic electrical engineering,Huaiyin Normal university,Huaian 223300,china 2 state key laboratory of Functional Materials for Informatics,Shanghai Institute of Microsystem and Information technology,Chinese Academy of sciences,Shanghai 200050,china 1. School of Physics and electronic electrical engineering Huaiyin Normal University Huaian 223300 China2. State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

Using the extended Blonder-Tinkham-Klapwijk formalism,we investigate the conductance spectra of graphene ferromagnet/p wave superconductor *** is found that the conductance spectra are affected by the p wave pairing *** ferromagnetic exchange energy in the ferromagnet can suppress Andreev retroreflection but enhance the specular Andreev reflection in graphene ferromagnet/p wave superconductor *** conductance decreases with increasing exchange energy Eh for EhEF.

关键词： graphene ferromagnet p wave superconductor tunneling conductance

electromagnetic wave absorbing properties and hyperfine interactions of Fe–Cu–Nb–Si–B nanocomposites

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Chinese Physics B 2014年第8期23卷 50-54页

作者：韩满贵郭韦吴燕辉刘明 Magundappa L. Hadimanic state key laboratory of electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China Analytical and Testing Center Sichuan University Department of electrical and Computer engineering Iowa State University

The Fe-Cu-Nb-Si-B alloy nanocomposite containing two ferromagnetic phases （amorphous phase and nanophase phase） is obtained by properly annealing the as-prepared alloys. High resolution transmission electron microscopy （HR- TEM） images show the coexistence of these two phases. It is found that Fe-Si nanograins are surrounded by the retained amorphous ferromagnetic phase. Mossbauer spectroscopy measurements show that the nanophase is the D03-type Fe- Si phase, which is employed to find the atomic fractions of resonant 57Fe atoms in these two phases. The microwave permittivity and permeability spectra of Fe-Cu-Nb-Si-B nanocomposite are measured in the frequency range of 0.5 GHz- 10 GHz. Large relative microwave permeability values are obtained. The results show that the absorber containing the nanocomposite flakes with a volume fraction of 28.59% exhibits good microwave absorption properties. The reflection loss of the absorber is less than -10 dB in a frequency band of 1.93 GHz-3.20 GHz.

关键词： Mossbauer spectroscopy magnetic permeability nanocrystalline alloys

engineering of electronic and optical properties of ZnO thin films via Cu doping

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Chinese Physics B 2013年第4期22卷 491-494页

作者：张国恒邓小燕薛华向钢 key laboratory for electronic Materials of the state National Affairs Commission of PRC School of Electrical Engineering Northwest University for Nationality Department of Physics and key laboratory for Radiation Physics and technology of Ministry of Education Sichuan University

ZnO thin films doped with different Cu concentrations are fabricated by reactive magnetron sputtering technique. XRD analysis indicates that the crystal quality of the ZnO：Cu film can be enhanced by a moderate level of Cu-doping in the sputtering process. The results of XPS spectra of zinc, oxygen, and copper elements show that Cu-doping has an evident and complicated effect on the chemical state of oxygen, but little effect on those of zinc and copper. Interestingly, further investigation of the optical properties of ZnO：Cu samples shows that the transmittance spectra exhibit both red shift and blue shift with the increase of Cu doping, in contrast to the simple monotonic behavior of the Burstein–Moss effect. Analysis reveals that this is due to the competition between oxygen vacancies and intrinsic and surface states of oxygen in the sample. Our result may suggest an effective way of tuning the bandgap of ZnO samples.

关键词： ZnO thin films Cu doping optical properties bandgap tuning

Predistortion of high speed optical OFDM signal for aliasing-free receiving in multiple low-bandwidth receiver system

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Chinese Optics Letters 2010年第4期8卷 377-380页

作者：程林闻和郑小平张汉一郭奕理 state key laboratory on Integrated Optoelectronics/Tsinghua National laboratory for Information science and technology Department of Electronic EngineeringTsinghua University

A cost-effective method of multi-receiver optical orthogonal frequency-division multiplexing（OOFDM） system is proposed to reduce the requirement for the speed of the receiver and the size of fast Fourier transform（FFT）.The sampling rate of analog-to-digital converters（ADCs） can be reduced to 1/N of the original signal bandwidth in an N-receiver *** by signal predistortion at the transmitter, aliasing-free signal can be retrieved independently and directly at the low speed receivers.A back-to-back experimental result is given for a two-receiver *** effect of the electrical filters added before the ADC is studied and the analysis for filters optimization is given.

关键词： Cost reduction Fast Fourier transforms Orthogonal frequency division multiplexing

Switching effects in superconductor/ferromagnet/superconductor graphene junctions

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Chinese Physics B 2013年第12期22卷 460-464页

作者：李晓薇刘丹鲍艳辉 School of Physics and electronic electrical engineering and Jiangsu key laboratory for Chemistry of Low-Dimensional Materials Huaiyin Normal University state key laboratory of Functional Materials for Informatics (Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences) School of Physics Northeast Normal University

The Josephson effect in the superconductor/ferromagnet/superconductor（SFS） graphene Josephson junction is studied using the Dirac Bogoliubov-de Gennes（DBdG） formalism. It is shown that the SFS graphene junction drives 0–π transition with the increasing of p=h0L/vFhˉ, which captures the effects of both the exchange field and the length of the junction; the spin-down current is dominant. The 0 state is stable for p state is stable for p > pc, where the free energy minima are at φg= 0 and φg= π, respectively. The coexistence of the 0 and π states appears in the vicinity of pc.

关键词： superconductor junction grapheme switching effect

Study on magnetism of Pr_(0.45)(Ca_(1-x)Sr_x)_(0.55) MnO_3 samples

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Rare Metals 2011年第6期30卷 595-601页

作者： TANG Yonggang WANG Guiying YANG Gang MAO Qiang PENG Zhensheng Cultivating Base of Anhui key laboratory of Spintronics and Nano-materials Research Suzhou 234000 China Department of electrical and Electromc Engmeertng Suzhou University Suzhou 234000 China Hefei National laboratory for Microscopic Matter sciences University of Science and Technology of China Hefei 230026 China

The polycrystalline samples of Pro.45（Ca1-xSrx）0.55MnO3 （x = 0.0, 0.2, 0.4, 0.6） were prepared by solid-state reaction. Influence of Sr2＋ substitution for Ca2＋ at A site on magnetism was studied through the measurements of X-ray diffraction （XRD） spectrum, the magnetization-temperature （M-T） curves and electron spin resonance （ESR） curves. The results show that the magnetism strengthens and charge ordering weakens gradually with the increase of Sr2＋ substitution amount, respectively. The transition of paramagnetism（PM）-antiferromagnetism（AFM） occurs below the transition temperature of charge ordering （Tco）, and there is tittle ferromagnetic phase in the antiferromagnetic background at the lower temperature, which results in complex magnetic phases of the samples. Ferromagnetic clusters appear and grow larger with the increase of substitution amount./n addition, the reentrant spin-glass behavior appears at about 41 K. The magnetism phenomenon of the samples is mainly due to the competition between double exchange and Jahn-Teller coupling. The Jahn-Teller coupling becomes weak, and the double exchange wins the advantage in the competition with the increase of substitution amount, which leads to the magnetism variation of the system.

关键词： magnetism charge ordering Sr2+ substitution reentrant spin-glass state

Wide-Area Backup Protection System based on Fuzzy-Fusion

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Wide-Area Backup Protection System based on Fuzzy-Fusion

On the Estimation of Stability Boundaries of Nonlinear Dynamic Systems

2011 International Conference on advanced Power System Automation and Protection(APAP 2011)

作者： TIAN Cong-cong WEN Ming-hao LIU Hang state key laboratory of advanced electromagnetic engineering and technology Electric Power Security and High Efficiency laboratory wuhan 430074 Hubei Province china

A wide-area backup protection system based on distributed communication and centralized decision-making is proposed, the system determines its communication range and fault location algorithm according to the information of distance protection within the substation, a fuzzy-fusion method is proposed based on the information within the communication range, and then using the result of the fuzzy decision-making to realize fault judgment. Simulation test based on IEEE 5-bus system demonstrates that the method is effective.

关键词： distributed communication centralized decision-making fuzzy-fusion decision making fuzzy-reasoning

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On the Estimation of Stability Boundaries of Nonlinear Dynam...

Force Feedback in Teleoperation of Space Robot with Time-Delay

2011 Chinese Control and Decision Conference（CCDC）

作者： Feng Liu,Wei Wei,and Shengwei Mei the state key laboratory of Power Systems,Department of electrical engineering and Applied electronic technology,Tsinghua university,100084 Beijing,china.

The expansion methodology monotonically enlarges the estimated stability region of a general system so that the true stability boundary can be *** has advantages to reduce the conservativeness of the general system and to construct feasible algorithms for large-scale and complicated *** paper provides fundamentals for the expansion theory of stability region estimation,locally and *** shows how the initial level set of energy function can be expanded via the diffeomorphism defined by the flow map so that the level set can approach to the exact boundary,even when the initial level set is not entirely within the true stability *** a generalization can broaden the valid scope to which the expansion approach can be *** addition,the rigorous topological characteristics of the determined local and global boundaries by such expansion are presented *** provides a theoretical justification for the use of expansion schemes for those local estimation methods based on energy function,such as the Controlling Unstable Equilibrium Point （CUEP） *** theoretical results also indicate that the estimation conservativeness of the conventional methods based on energy function can be significantly ***,the proposed theory is tested on a simplified three-machine power system to verify its validation.

关键词： nonlinear system energy function stability region

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Force Feedback in Teleoperation of Space Robot with Time-Del...