Chu X.,Zhejiang Agriculture And forestry University |
Wen W.,Huaihua University
Optics Express | Year: 2014
Quantitative description of the self-healing ability of a beam is very important for studying or comparing the self-healing ability of different beams. As describing the similarity by using the angle of two infinite-dimensional complex vectors in Hilbert space, the angle of two intensity profiles is proposed to quantitatively describe the self-healing ability of different beams. As a special case, quantitative description of the self-healing ability of a Bessel-Gaussian beam is studied. Results show that the angle of two intensity profiles can be used to describe the self-healing ability of arbitrary beams as the reconstruction distance for quantitatively describing the self-healing ability of Bessel beam. It offers a new method for studying or comparing the self-healing ability of different beams. © 2014 Optical Society of America.
Chen W.,Huaihua University
Dalton Transactions | Year: 2015
Sr2+ and Si4+ ion doped LaAlO3:Eu phosphors were synthesized through a high-temperature solid-state reaction route. Their phase component and photoluminescence properties were investigated. Under ultraviolet (UV) light excitation, the phosphors show simultaneously blue emission of the Eu2+ ion and orange-red emission of the Eu3+ ion. The relative emission intensity of both Eu2+ and Eu3+ ions can be tuned by changing the doping concentration of the Sr2+, Si4+ and Eu3+ ions. In contrast to the Sr2+ ion, the incorporation of Si4+ ion can effectively enhance the emission of Eu2+. The optimal doping concentration of the Eu3+ and Si4+ ions are about 0.02 and 0.03, respectively. The results indicate that the phosphor may be a potential candidate for white LED lighting applications. © The Royal Society of Chemistry 2015.
Li S.H.,Huaihua University
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials | Year: 2010
To study the chemical constituents from Lithocarpus polystachyus. Compounds were isolated and purified with silica gel, and there structures were identified by chemical property and spectral data. Nine compounds were isolated as phloridzin (I), phloretin (II), dihydrochalcone-2'-beta-D-glucopyranoside (III), daucossterol (IV), beta-sitosterol (V), quercetin (VI), luteolin (VII), quercitrin (VI), oleanolic acid (IX). Compounds II, IV - IX are isolated from this plant for the first time.
Ding X.,Huaihua University |
Chen G.,Hunan Agricultural University
Optics and Laser Technology | Year: 2014
We propose an optical color image cryptosystem based on position multiplexing technique and phase truncation operation. Compared with the reported color image encryption method, we employ the position multiplexing technique to encrypt the color image in only one spatial channel. Meanwhile, our proposed method can maintain the nonlinear characteristic of the cryptosystem and avoid various types of the currently existing attacks, especially the iterative attack. Simulation results are presented to demonstrate the security and robustness performance of the proposed method. © 2013 Elsevier Ltd.
Xiaopeng D.,Huaihua University
Optics Communications | Year: 2014
A hybrid attack method, which is based on an iteration process and the decisive role of phase in the propagation process of light, is proposed to break the double image encryption system based on a nonlinear algorithm. The whole attack process contains three steps. First, an approximate value of the encoded image is achieved by using the phase retrieval algorithm when the encryption key, placed in the Fourier spectrum plane, and the ciphertext are used as the two constraints. Then, an approximate value of the joint power spectrum (JPS) is obtained based on the result of the first step. Finally, two approximate values of the original images are obtained by the use of the approximate value of the JPS and other two encryption keys. The simulation results show that the hybrid attack is valid and the cryptosystem is vulnerable to this attack. © 2013 Elsevier B.V.
Deng X.,Huaihua University |
Deng X.,Zhejiang University |
Zhao D.,Zhejiang University
Optics and Laser Technology | Year: 2012
A single-channel color image encryption is proposed based on asymmetric cryptosystem. The color components respectively multiplied with three random phase encryption keys are first combined into one gray image using convolution for further encoding into a real-value gray ciphertext with the asymmetric cryptosystem. Then four decryption keys, which are different from encryption keys and generated in the encryption process, can be used for image decryption. As a result, a more compact and robust system, permitting a real-value gray ciphertext to be transmitted, has been obtained. The feasibility and effectiveness of the proposed method are demonstrated by numerical results. © 2011 Elsevier Ltd. All rights reserved.
Yang Y.,Huaihua University
Proceedings - 2010 7th International Conference on Fuzzy Systems and Knowledge Discovery, FSKD 2010 | Year: 2010
Information hiding technology is a hot spot in information security, and is applied in the fields of digital multimedia copyright protection and secret communication. According to the analysis of the characteristics of browser in parsing HTML of the web page and the little capacity available for information hided in web page, a new efficient web page information hiding method with tag attributes has been proposed in this paper, which overcomes the shortcoming of the ability of imperceptibility and the ability of contradict with the machine filtration of traditional web page information hiding algorithms and improves the embedded capacity of the other algorithm based on tag attributes. This method has good performances in invisibility and higher applied value as proved by the experiments. ©2010 IEEE.
Chen W.,Huaihua University
Journal of Alloys and Compounds | Year: 2013
A series of Ce3+ activated Sr3AlO4F phosphors were synthesized by a high-temperature solid-state method. The Ce 3+ ions occupy two distinct Sr2+ sites in the host. The phosphors exhibit strong absorption in the spectral range of near-UV to blue light with a maximum at ∼400 nm. The emission color may be efficiently tuned by controlling the composition of phosphor, which is interpreted in terms of the site occupancy, energy transfer and crystal structure. The results show that the phosphor is a potential light-emitting diode (LED) phosphor. © 2012 Elsevier B.V. All rights reserved.
Chen W.,Huaihua University |
Zhou A.,Huaihua University
Journal of Physical Chemistry C | Year: 2012
Well-dispersed YBO3:Eu phosphors were synthesized by a reverse microemulsion method with solvothermal treatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence spectroscopy (PL) were used to characterize the products. The products with donut-like morphology comprised of numerous nanorods exhibit a blue-light emission of Eu2+ and an improved red-light emission of Eu3+, and their relative intensity can be tuned by controlling the Eu concentration to generate white light. The absorption band locates in the spectral range 250-450 nm with a maximum at about 370 nm, which just overlaps the emission band of near-ultraviolet light-emitting diodes (LEDs). This indicates that the YBO 3:Eu have potential application in white LEDs. The luminescence mechanism is explained simply, and the YBO3:Eu were also synthesized by a chemical precipitation to compare their morphology and luminescence properties. © 2012 American Chemical Society.
Deng X.,Huaihua University
Optics Letters | Year: 2015
I comment on the recent Letter by Cai et al. [Opt. Lett. 40, 475 (2015).], in which the authors claimed that the method can resist the special attack. However, I think their attack analysis and algorithm are ill-considered and worth discussing. © 2015 Optical Society of America.