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Zhao J.,Luoyang Normal College | Zhang X.,Luoyang Key Laboratory of Laser Spectroscopy Technology | Liu S.,Luoyang Key Laboratory of Laser Spectroscopy Technology | Zhang W.,Luoyang Key Laboratory of Laser Spectroscopy Technology | Liu Z.,Luoyang Key Laboratory of Laser Spectroscopy Technology
Journal of Alloys and Compounds | Year: 2013

In this paper, BiFe1-xNixO3 (x = 0, 0.05, 0.10, 0.15, 0.20, and 0.25) nanoparticles were synthesized by a sol-gel process X-ray diffraction (XRD), and Raman technique analysis showed that a rhombohedrally distorted BiFeO3 structure with compressive lattice distortion induced by the Ni substitution at Fe sites. Superconducting QUantum Interference Device (SQUID) results showed that, compared with BiFeO3 prepared under similar conditions, the magnetic properties were significantly enhanced at room temperature. The enhanced ferromagnetism was attributed to the size confinement effect of the nanostructures, the ferromagnetic exchange between the neighboring Fe3+ and Ni3+ ions, and the changing of the Fe-O-Fe bond angle. Superparamagnetism with blocking temperature of 10 K for BiFe0.95Ni0.05O3, 75 K for BiFe0.85Ni0.15O3, 125 K for BiFe 0.80Ni0.20O3, and 200 K for BiFe 0.75Ni0.25O3 was also observed. © 2013 Elsevier B.V. All rights reserved.


Tan Y.-G.,Luoyang Normal College | Cai Q.-Y.,CAS Wuhan Institute of Physics and Mathematics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

Recently, Lucamarini et al. proposed the device-independent entanglement-based Bennett 1992 protocol [Phys. Rev. A 86, 032325 (2012)PLRAAN1050-294710.1103/PhysRevA.86.032325]. By exploiting the results in device-independent quantum key distribution with the Clauser-Horne-Shimony-Holt inequality, they claimed the security of their protocol. We will show, however, the way of encoding and the process for the latent eavesdropper to obtain the illegal information are different in these two protocols. Thus the security of their protocol cannot rely on Bell's theorem only. © 2016 American Physical Society.


Tan Y.G.,Luoyang Normal College | Cai Q.Y.,CAS Wuhan Institute of Physics and Mathematics
European Physical Journal D | Year: 2010

In this paper, we consider the controllably secure quantum key distribution (QKD) with coherent source, i.e., the practical decoy state QKD with finite resource is studied within the scope of some controllable security parameters. Our simulation shows the controllably secure QKD is more resource-consuming compared with the practical decoy QKD with relatively statistical fluctuation. However, further numerically solutions show that both protocols agree well with each other in the asymptotic limit, where the resource is large enough but not infinite. Our work shows the dark counts will contribute apparently to the transmission distance when communication distance approaches to the asymptotic limit. It also shows that both the secure transmission distance and the rate of the secure final key can be increased apparently when the security estimation parameters are not fixed but numerically optimized. © 2009 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.


Ding C.,Luoyang Normal College | Cai Y.,Soochow University of China | Korotkova O.,University of Miami | Zhang Y.,Luoyang Normal College | Pan L.,Luoyang Normal College
Optics Letters | Year: 2011

The scattering of a partially coherent plane-wave pulse on a Gaussian-correlated, quasi-homogeneous random medium is investigated. The analytical expressions for the temporal coherence length and the pulse duration of the scattered field are derived. We demonstrate that the scattering-induced changes in the temporal coherence length and the pulse duration may be used to determine the correlation function of the scattering potential of the medium. © 2011 Optical Society of America.


Wang P.,Capital Normal University | Liu Z.,Luoyang Normal College
Journal of Raman Spectroscopy | Year: 2013

We report surface enhanced Raman spectroscopy (SERS) of Darling-Dennison resonance of thiourea on Ag electrode excited at 514.5 nm laser excitation. Darling-Dennison resonance indicates that two degenerate Raman modes interact with each other and their degenerate first-order overtone modes obtain energy and appear in Raman spectra. Our study showed that the ratio of intensity of the Darling-Dennison resonance is up to 0.24 of its fundamental Raman intensity, when the applied electrode voltage is at -0.4 V versus the saturated calomel electrode. This phenomenon was also observed on the Ag island film surface at ambient condition. These observations demonstrated strong evidence for Darling-Dennison resonance band in SERS. The implications of these observations are also discussed. Copyright © 2013 John Wiley & Sons, Ltd. Darling-Dennison resonance indicates that two degenerate Raman modes interact with each other and their degenerate first-order overtone modes obtain energy and appear in Raman spectra. The surface-enhanced Raman spectroscopy (SERS) of thiourea on Ag electrode excited at 514.5 nm laser excitation was obtained, and the combinational modes, which attributed to Darling-Dennison resonance, were observed in SERS on electrode and on silver island film, respectively, because of strong anharmonicity. Copyright © 2013 John Wiley & Sons, Ltd.


Ding C.,University of Sichuan | Pan L.,Luoyang Normal College | Lu B.,University of Sichuan
Applied Physics B: Lasers and Optics | Year: 2010

By using the generalized Huygens-Fresnel diffraction integral, the analytical expressions for the cross-spectral density matrix, spectral degree of polarization, orientation angle and degree of ellipticity of polarization ellipse of apertured stochastic electromagnetic modified Bessel-Gauss beams (MBGBs) through a paraxial optical ABCD system are derived, and used to study the changes in the state of polarization of apertured stochastic electromagnetic MBGBs propagating in free space. The invariance of the on-axis state of polarization of unapertured stochastic electromagnetic MBGBs propagating through paraxial optical ABCD systems is illustrated analytically and numerically. For apertured stochastic electromagnetic MBGBs, the on-axis spectral degree of polarization, orientation angle and degree of ellipticity of polarization ellipse increase with increasing propagation distance, and approach asymptotic values when the propagation distance is large enough. There is a uniform distribution region of the state of polarization around the center of the beams whose range decreases with increasing truncation parameter. In addition, the state of polarization of apertured stochastic electromagnetic MBGBs upon propagation can be modulated by controlling the truncation parameter. © 2009 Springer-Verlag.


Li J.,Taiyuan University of Science and Technology | Ding C.,Luoyang Normal College | Lu B.,University of Sichuan
Applied Physics B: Lasers and Optics | Year: 2011

By using the extended Huygens-Fresnel principle, the analytical expressions for the generalized Stokes parameters of random electromagnetic Gaussian Schell-model (GSM) vortex beams propagating through atmospheric turbulence are derived, and used to study the changes in spectral Stokes parameters of random electromagnetic GSM vortex beams in atmospheric turbulence and to compare the results of random electromagnetic GSM vortex-free beams. The influence of atmospheric turbulence on the spectral Stokes parameters is analyzed. The validity of our results is interpreted physically. © Springer-Verlag 2010.


Ding C.,Luoyang Normal College | Korotkova O.,University of Miami | Zhang Y.,Luoyang Normal College | Pan L.,Luoyang Normal College
Optics Express | Year: 2014

A new class of partially coherent pulses of Schell type with cosine-Gaussian temporal degree of coherence is introduced. Such waves are termed the Cosine-Gaussian Schell-model (CGSM) pulses. The analytic expression for the temporal mutual coherence function of the CGSM pulse in dispersive media is derived and used to study the evolution of its intensity distribution and its temporal degree of coherence. Further, the numerical calculations are performed in order to show the dependence of the intensity profile and the temporal degree of coherence of the CGSM pulse on the incident pulse duration, the initial temporal coherence length, the order-parameter n and the dispersion of the medium. The most important feature of the novel pulsed wave is its ability to split into two pulses on passage in a dispersive medium at some critical propagation distance. Such critical distance and the subsequent evolution of the split pulses are shown to depend on the source parameters and on the properties of the medium in which the pulse travels. © 2014 Optical Society of America.


Shi Y.P.,Luoyang Normal College
Advanced Materials Research | Year: 2014

A kind of MELP vocode is designed based on DSP TMS320VC5509A in this article. Firstly, it expatiates the MELP algorithm,then the idea of modeling and realization process on DSP based is proposed. At last we can complete the function simulation of the encoding and decoding system,and the experiment result shows that the synthetical signals fit well with the original ones, and the quality of the speech got from the vocoder is good. © (2014) Trans Tech Publications, Switzerland.


Shi Y.P.,Luoyang Normal College
WIT Transactions on Information and Communication Technologies | Year: 2014

A kind of MELP vocoder based on FPGA is designed in this paper. Firstly, it expatiate the MELP algorithm, then the idea of modeling and realization process on FPGA by using DSP Builder in Matlab based is proposed. At last we can complete the function simulation of the encoding and decoding system, and the simulation result shows that the synthetical signals fit well with the original ones, and the quality of the speech got from the vocoder is good. © 2014 WIT Press.

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