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Search Results: 1 - 10 of 42785 matches for " Yujun Xu "
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Strongly Convergence Theorem of m-accretive Operators
Yujun Liu,Sumei Xu
Modern Applied Science , 2009, DOI: 10.5539/mas.v1n2p41
Abstract: Let X be a real Banach space, we will introduce a modifieations of the Mann iterations in a uniformly smooth Banach, Where satisfied some conditions, then we will prove the strongly space, ((1))(1)xuxJx {}, 1nnnnrn n to a zero of accretive operators. This theorem extend (Kim and Xu, Nonlinear convergence of the sequence {}x n Analysis) results. (Kim, 2005, pp.51-60)
Thermal expansion in lead zirconate titanate
Yujun Feng,Zhuo Xu,Xi Yao
Chinese Science Bulletin , 2002, DOI: 10.1360/02tb9299
Abstract: The volume anomalies with temperature variations in tin-modified lead zirconate titanate ceramics are investigated. Experimental results show that the volume changes are related to the phase transitions induced with temperature. The magnitude and orientation of crystal volume changes are dependent on the particular phase transition. When antiferroelectrics is transformed to ferroelectrics or paraelectrics the volume expands. Oppositely when ferroelectrics is transformed to antiferroelectrics or paraelectrics the volume contracts. In the transition of antiferroelectric orthorhombic structure to tetragonal structure or ferroelectric low-temperature rhombohedral structure to high-temperature rhombohedral structure, there are also revealed apparent anomalies in the curves of thermal expansion. Among them, the volume strain caused by the transition between antiferroelectrics and ferroelectrics is the biggest in magnitude, and the linear expansion dL/L0 and the expansion coefficient (dL/L 0)/dT can reach 2.8 × 10 3 and 7.5 × 10 4 K 1 respectively.
Electron emission from La-doped Pb(Zr,Sn,Ti)O3 anti-ferroelectrics by pulse electric field and the relevant physical mechanism
LinLi Zhang,YuJun Feng,Zhuo Xu,ZhaoXuan Sheng
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0432-8
Abstract: We investigate the characteristics of emission current waves of antiferroelectric cathode material lanthanum-doped lead zirconate stannate titanate (PLZST) triggered by pulse field, and analyze the relationship of the emission current waveforms with the extraction voltage. The close correlation between the triggering pulse polarity and emission current waveform observed evidences the relevant physical process of electron emission. We speculate that the primary emission may result from local phase transition and field emission in the vicinity of triple junctions, and the plasma formation may enhance the electron emission.
Pyroelectric spectrum in Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics
Yujun Feng,Zhuo Xu,Tongqing Yang,Xi Yao
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02886071
Abstract: The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFEA-AFEB or ferroelectric FEL-FEH transition, which are not detected by the conventional dielectric measurement.
Properties of PbLa(Zr,Sn,Ti)O3 ceramics near ferroelectric-antiferroelectric phase boundary
Zhonghua Dai,Xi Yao,Zhuo Xu,Yujun Feng,Jun Wang
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-008-1000-3
Abstract: Two chemical compositions PbLa(Zr,Sn,Ti)O3 (PLZST) ceramics near the ferroelectric-antiferroelectric (FE/AFE) phase boundary were prepared by a traditional solid-state reaction process. The electrostriction properties under the electric field and the influence of hydrostatic pressure on the phase transition and the dielectric properties of these PLZST ceramics have been studied. Under the AC electric field, the strain of these two samples reached 0.21% and 0.13%, respectively. With increasing pressure, the FE/AFE phase transition temperature of the antiferroelectrics decreased and the antiferroelectric-paraelectric (AFE/PE) phase transition temperature increased, while the ferroelectric-paraelectric (FE/PE) phase transition temperature of the ferroelectrics decreased.
Light transport behaviours in quasi-1D disordered waveguides composed of random photonic lattices
Yuchen Xu,Hao Zhang,Yujun Lin,Heyuan Zhu
Physics , 2015,
Abstract: We present a numerical study on the light transport properties which are modulated by the disorder strength in quasi-one-dimensional disordered waveguide which consists of periodically arranged scatterers with random dielectric constant. The transport mean free path is found to stay inversely proportional to the square of the relative fluctuation of the dielectric constant as in the 1D and 2D cases but with . The transport properties of light through a sample with a fixed size can be modulated from ballistic to localized regime as well, and a generalized scaling function is defined to determine the light transport status in such a sample. The calculation of the diffusion coefficient and the energy density profile of the most transmitted eigenchannel clearly exhibits the transition of transport behaviour from diffusion to localization.
ELDA: Towards Efficient and Lightweight Detection of Cache Pollution Attacks in NDN
Zhiwei Xu,Bo Chen,Ninghan Wang,Yujun Zhang,Zhongcheng Li
Computer Science , 2015,
Abstract: As a promising architectural design for future Internet, named data networking (NDN) relies on in-network caching to efficiently deliver name-based content. However, the in-network caching is vulnerable to cache pollution attacks (CPA), which can reduce cache hits by violating cache locality and significantly degrade the overall performance of NDN. To defend against CPA attacks, the most effective way is to first detect the attacks and then throttle them. Since the CPA attack itself has already imposed a huge burden on victims, to avoid exhausting the remaining resources on the victims for detection purpose, we expect a lightweight detection solution. We thus propose ELDA, an Efficient and Lightweight Detection scheme against cache pollution Attacks, in which we design a Lightweight Flajolet-Martin (LFM) sketch to monitor the interest traffic. Our analysis and simulations demonstrate that, by consuming a few computation and memory resources, ELDA can effectively and efficiently detect CPA attacks.
Properties of PbLa(Zr,Sn, Ti)O3 ceramics near ferroelectric-antiferroelectric phase boundary
Properties of PbLa(Zr,Sn, Ti)O3 ceramics near ferroelectric-antiferroelectric phase boundary

DAI Zhonghua,YAO Xi,XU Zhuo,FENG Yujun,WANG Jun,
DAI
,Zhonghua,YAO,Xi,XU,Zhuo,FENG,Yujun,WANG,Jun

科学通报(英文版) , 2006,
Abstract: Two chemical compositions PbLa(Zr,Sn, Ti)O3 (PLZST) ceramics near the ferroelectric-anti- ferroelectric (FE/AFE) phase boundary were pre- pared by a traditional solid-state reaction process. The electrostriction properties under the electric field and the influence of hydrostatic pressure on the phase transition and the dielectric properties of these PLZST ceramics have been studied. Under the AC electric field, the strain of these two samples reached 0.21% and 0.13%, respectively. With increasing pressure, the FE/AFE phase transition temperature of the antiferroelectrics decreased and the antiferro- electric-paraelectric (AFE/PE) phase transition tem- perature increased, while the ferroelectric-paraelec- tric (FE/PE) phase transition temperature of the ferroelectrics decreased.
Influence of pulse polarity on electron emission property of antiferroelectric ceramic
ZhaoXuan Sheng,YuJun Feng,Jie Cui,Xuan Huang,Zhuo Xu,XinLi Sun
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0259-8
Abstract: The electron emission property of a novel antiferroelectric cathode material lanthanum-doped lead zirconate stannate titanate (PLZST) on the application of positive or negative triggering voltage pulses has been investigated. All experiments were performed in a vacuum of 10 5 Torr and at room temperature. It was discovered that there were two electron emission pulses when low positive triggering voltage was applied to the rear electrode, and three electron emission pulses when high positive triggering voltage was applied. However there were always two electron emission pulses when negative triggering pulses were applied. This phenomenon is proposed to be a result of both field electron emission at triple junctions and electron emission caused by polarization reversal. The experimental observations indicate that domain movement in the vicinity close to the triple junction under application of the triggering voltage pulse may be a primary origin of electron emission from PLZST.
Effects of temperature on hydrostatic pressure-induced FE-AFE phase transition in PbLa(Zr, Sn, Ti)O3 ceramics
Zhuo Xu,Yujun Feng,Shuguang Zheng,An Jin,Fanglin Wang,Xi Yao
Chinese Science Bulletin , 2001, DOI: 10.1007/BF02900585
Abstract: Hydrostatic pressure-induced ferroelectricantiferroelectric (FE-AFE) phase transition and the pressure dependence of dielectric properties in La-doped Pb(Zr,Sn, Ti)O3 ceramics were researched; the effects of temperature on hydrostatic pressure-induced FE-AFE phase transition and dielectric properties of the samples were studied. It was found that the temperature made the FE-AFE phase transition pressure decrease, and there existed the behavior of dielectric frequency dispersion and phase transition diffusion in the dielectric-pressure spectrum. These phenomena were very useful to enrich and develop the knowledge on the diffused phase transition behavior of polycomponent relaxor ferroelectric.
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