2014
2014
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Record 289 of
Title:GaAs film for photon-enhanced thermionic emission solar harvesters
Author(s):Tang, Weidong(1,2); Yang, Wenzheng(3); Yang, Yang(1,2); Sun, Chuandong(3); Cai, Zhipeng(1,2)Source: Materials Science in Semiconductor Processing Volume: 25 Issue: DOI: 10.1016/j.mssp.2013.10.009 Published: September 2014Abstract:A novel concept for solar electricity generation named photon-enhanced thermionic emission (PETE) was recently proposed for harvesting solar photonic and thermionic energies simultaneously. Comparative investigations showed that the conversion efficiency of PETE can theoretically exceed 40%. In this paper, an electric field-assisted PETE experiment was carried out to demonstrate the possibility of using GaAs epitaxial films in PETE solar devices. The solar photonic and thermionic effects were simulated by a red light-emitting diode array and a heat resistor, respectively. Surface electron affinity was decreased by an electric field instead of Cs/Cs-O coating. The experimental results agreed with calculated values, and a distinct enhancement was observed in the thermionic emission produced by photoexcitation compared with thermionic field emission produced by an illuminated sample and the sample emission obtained in the dark. ? 2013 Elsevier Ltd.Accession Number: 20142517831081 -
Record 290 of
Title:Line-plane-switching infrared fiber imaging bundle
Author(s):Zhan, Huan(1,2); Yan, Xingtao(1,2); Zhang, Aidong(1); Li, Fu(1); Yang, Jianfeng(1); Lin, Aoxiang(1)Source: Optics InfoBase Conference Papers Volume: Issue: DOI: Published: 2014Abstract:Using line-plane-switching infrared fiber imaging bundle made from As2S3 glass fibers with core of 40 μm, clad of 45 μm, and error of 1% in diameter, we demonstrated push-broom infrared sensing imaging. ? 2014 OSA.Accession Number: 20143718149871 -
Record 291 of
Title:Local coordinate concept factorization for image representation
Author(s):Liu, Haifeng(1); Yang, Zheng(1); Yang, Ji(1); Wu, Zhaohui(1); Li, Xuelong(2)Source: IEEE Transactions on Neural Networks and Learning Systems Volume: 25 Issue: 6 DOI: 10.1109/TNNLS.2013.2286093 Published: June 2014Abstract:Learning sparse representation of high-dimensional data is a state-of-the-art method for modeling data. Matrix factorization-based techniques, such as nonnegative matrix factorization and concept factorization (CF), have shown great advantages in this area, especially useful for image representation. Both of them are linear learning problems and lead to a sparse representation of the images. However, the sparsity obtained by these methods does not always satisfy locality conditions. For example, the learned new basis vectors may be relatively far away from the original data. Thus, we may not be able to achieve the optimal performance when using the new representation for other learning tasks, such as classification and clustering. In this paper, we introduce a locality constraint into the traditional CF. By requiring the concepts (basis vectors) to be as close to the original data points as possible, each datum can be represented by a linear combination of only a few basis concepts. Thus, our method is able to achieve sparsity and locality simultaneously. We analyze the complexity of our novel algorithm and demonstrate the effectiveness in comparison with the state-of-the-art approaches through a set of evaluations based on real-world applications. ? 2012 IEEE.Accession Number: 20142217774054 -
Record 292 of
Title:GaAs film for photon-enhanced thermionic emission solar harvesters
Author(s):Tang, Weidong(1,2); Yang, Wenzheng(3); Yang, Yang(1,2); Sun, Chuandong(3); Cai, Zhipeng(1,2)Source: Materials Science in Semiconductor Processing Volume: 25 Issue: DOI: 10.1016/j.mssp.2013.10.009 Published: September 2014Abstract:A novel concept for solar electricity generation named photon-enhanced thermionic emission (PETE) was recently proposed for harvesting solar photonic and thermionic energies simultaneously. Comparative investigations showed that the conversion efficiency of PETE can theoretically exceed 40%. In this paper, an electric field-assisted PETE experiment was carried out to demonstrate the possibility of using GaAs epitaxial films in PETE solar devices. The solar photonic and thermionic effects were simulated by a red light-emitting diode array and a heat resistor, respectively. Surface electron affinity was decreased by an electric field instead of Cs/Cs-O coating. The experimental results agreed with calculated values, and a distinct enhancement was observed in the thermionic emission produced by photoexcitation compared with thermionic field emission produced by an illuminated sample and the sample emission obtained in the dark. ? 2013 Elsevier Ltd. All rights reserved.Accession Number: 20144900278760 -
Record 293 of
Title:Mid-infrared emissions of Pr3+-doped GeS2-Ga2S3-CdI2chalcohalide glasses
Author(s):Lu, Chunfeng(1); Guo, Haitao(1); Xu, Yantao(1); Hou, Chaoqi(1); Lu, Min(1); He, Xin(2); Wang, Pengfei(1); Li, Weinan(1); Peng, Bo(2)Source: Materials Research Bulletin Volume: 60 Issue: DOI: 10.1016/j.materresbull.2014.09.003 Published: December 2014Abstract:For elucidation of the glass composition's influence on the spectroscopic properties in the chalcohalide system and the discovery of a new material for applications in mid-infrared fiber-lasers, a serial Pr3+-doped (100 - x)(0.8GeS2·0.2Ga2S3)xCdI2(x = 5, 10, 15 and 20) chalcohalide glasses were prepared. ～4.6 μm mid-infrared fluorescence emission from Pr3+in the sulfide glass is successfully observed at room temperature excited by a 2.01 μm Tm3+:YAG ceramic laser system, and the effective line-width of fluorescence band is 106-227 nm. Intense compositional dependence of mid-infrared emissions is found. The radiative rates of Pr3+ions in these glasses were calculated by using the Judd-Ofelt theory. ? 2014 Elsevier Ltd. All rights reserved.Accession Number: 20143900071659 -
Record 294 of
Title:Celestial positioning method and observation analysis for space object
Author(s):Liu, Mei-Ying(1); Wang, Hu(1); Wen, De-Sheng(1); Ran, Xiao-Qiang(1); Zhao, Hui(1); Yang, Shao-Dong(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 11 DOI: 10.3788/gzxb20144311.1112005 Published: November 1, 2014Abstract:A method based on weighted least squares surface fitting was studied, which was used for astronomical observation space target. This method can be used in celestial positioning of high-precision and large data quantity, and it is also very simple. Through observing the real sky, the star maps continuously were calculated. The results show that the fitting mean square errors are all less than 4″ in the direction of ascension and declination. The positioning accuracy in the direction of declination is better than that of ascension, the max positioning error of the observed stars are 5.13″ and 1.74″ in the direction of ascension and declination. It's demonstrated that the effects of star centroid errors are reduced, and the match up errors are also removed. The utilization of observed data and the precision of celestial positioning is improved. The method is well suited for application. ?, 2014, Chinese Optical Society. All right reserved.Accession Number: 20144900301554 -
Record 295 of
Title:Wide-bandwidth zero-dispersion slow light in MKRs with a two-ring parallel connection structure based on an analogue of electromagnetically induced transparency
Author(s):Xu, Yiping(1,2); Ren, Liyong(1); Ma, Chengju(1,2); Wang, Yingli(1); Liang, Jian(1); Qu, Enshi(1)Source: Journal of Modern Optics Volume: 61 Issue: 13 DOI: 10.1080/09500340.2014.922629 Published: July 29, 2014Abstract:Based on an analog of electromagnetically induced transparency (EIT) in microfiber knot resonators with a two-ring parallel connection structure, a wide bandwidth and zero-dispersion slow-light waveguide is proposed. The EIT-like transmission spectrum with the variation of wavelengths for different coupling coefficients is numerical simulated. By appropriately adjusting the coupling coefficients of the two knot rings, a group time delay of about 72.4 ps with a flat wavelength bandwidth of about 82.7 pm and a full width at half-maximum of about 228 pm at one of the induced transparency windows is achieved theoretically. And the group time delay dispersion at the same induced transparency window nearly reaches to zero with a wavelength bandwidth of about 82.7 pm. ? 2014 Taylor & Francis.Accession Number: 20143017972322 -
Record 296 of
Title:Learning from errors in super-resolution
Author(s):Tang, Yi(1); Yuan, Yuan(2)Source: IEEE Transactions on Cybernetics Volume: 44 Issue: 11 DOI: 10.1109/TCYB.2014.2301732 Published: November 2014Abstract:A novel framework of learning-based super-resolution is proposed by employing the process of learning from the estimation errors. The estimation errors generated by different learning-based super-resolution algorithms are statistically shown to be sparse and uncertain. The sparsity of the estimation errors means most of estimation errors are small enough. The uncertainty of the estimation errors means the location of the pixel with larger estimation error is random. Noticing the prior information about the estimation errors, a nonlinear boosting process of learning from these estimation errors is introduced into the general framework of the learning-based super-resolution. Within the novel framework of super-resolution, a low-rank decomposition technique is used to share the information of different super-resolution estimations and to remove the sparse estimation errors from different learning algorithms or training samples. The experimental results show the effectiveness and the efficiency of the proposed framework in enhancing the performance of different learning-based algorithms. ? 2013 IEEE.Accession Number: 20144500159217 -
Record 297 of
Title:Imaging of large-area microchannel plates using phosphor screens
Author(s):Wang, X.(1,2); Setru, S.U.(1); Xie, J.(1); Mane, A.(1); Demarteau, M.(1); Wagner, R.(1)Source: Journal of Instrumentation Volume: 9 Issue: 11 DOI: 10.1088/1748-0221/9/11/P11011 Published: November 1, 2014Abstract:A testing system was built, using UV illumination at 254 nm and a cathodoluminescent phosphor screen, to measure the gain uniformity of large area (20 x 20 cm2) microchannel plates. The phosphor screen image is captured with a wide-angle CMOS digital camera (4032 x 3024 pixels) and analyzed. First a reference MCP is illuminated and the generated phosphor screen image is captured with a CCD camera. In a second step, another image is captured with the MCP under test inserted between the reference MCP and the phosphor screen. The ratio of the two images is analyzed and provides a quantitative measure of the relative gain uniformity of the MCP under test. ? 2014 IOP Publishing Ltd and Sissa Medialab srl.Accession Number: 20145200359419 -
Record 298 of
Title:Experimental studies of multiple pulses in a passively ytterbium-doped fiber laser based on graphene-oxide saturable absorber
Author(s):Huang, Shi-Sheng(1); Wang, Yong-Gang(2); Li, Hui-Quan(1); Lin, Rong-Yong(1); Yan, Pei-Guang(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 63 Issue: 8 DOI: 10.7498/aps.63.084202 Published: 2014Abstract:The different multiple pulse phenomena are experimentally studied in a passively mode-locked ytterbium-doped fiber laser based on graphene-oxide saturable absorber (GOSA) with net normal dispersion cavity. At the same pump power with different polarization orientations, we observe the multiple pulse phenomena, including harmonic mode-locking of rectangular pulses, dissipative solitons, quasi-harmonic mode-locking, periodical peak modulation, multipulse bunches, multipulse cluster, and chaotic multipulse. The inserted 2 nm narrow bandwidth filter is important for limiting the gain bandwidth and shaping pulses. Adjusting the polarization controller is equivalent to changing the gain in the laser cavity, which is the main reason for the formation of different multiple pulses states. This is the first time that different multiple pulses states have been observed in an-normal-dispersion Yb-doped fiber laser with graphene-oxide saturable absorber. These results could extend the understanding of multiple pulse dynamics in GOSA mode-locked fiber lasers. ? 2014 Chinese Physical Society.Accession Number: 20141917700439 -
Record 299 of
Title:Simple method of optical ring cavity design and its applications
Author(s):Wen, Qiao(1,2); Zhang, Xiaojun(1,2); Liang, Zongsen(1,2); Wang, Yonggang(3); Sun, Liqun(4); Niu, Hanben(2)Source: Optics Express Volume: 22 Issue: 12 DOI: 10.1364/OE.22.014782 Published: June 16, 2014Abstract:When an optical ring cavity is designed, the beam radii at some special positions, especially at the beam waists are very interested in, since the gain mediums, nonlinear crystals and others important optical elements are generally located at the beam waist. In this paper, we firstly presented a simple method for designing optical ring cavities based on the selfconsistency theory and the fact that q parameter is uniquely determined by the waist beam radius and its position. This approach is different from ABCD method and it no longer requires cumbersome calculation. The calculations of designing optical ring cavities are simplified because q parameter only has imaginary part at beam waist plane. Moreover, designing the resonant cavity through the calculation of beam waist radii and their position has great practical significance, because it is very easy to adjust the waist radii and the positions at the important optical elements. We employed this method to design an end-pumped six-mirror ring cavity continuous-wave passively mode locked laser. The experiment of a highly stabilized continuous-wave mode locked (CWML) laser was investigated and the results coincided with the theoretical studies very well. The investigation results show that the simple method can be used to design optical ring cavities conveniently, intuitively and efficiently. ? 2014 Optical Society of America.Accession Number: 20142617876208 -
Record 300 of
Title:A 66 fs highly stable single wall carbon nanotube mode locked fiber laser
Author(s):Yu, Zhenhua(1); Wang, Yonggang(2); Zhang, Xiao(1); Dong, Xinzheng(1); Tian, Jinrong(1); Song, Yanrong(1)Source: Laser Physics Volume: 24 Issue: 1 DOI: 10.1088/1054-660X/24/1/015105 Published: January 2013Abstract:We demonstrate a highly stable mode locked fiber laser based on single wall carbon nanotubes The mode locking is achieved by the evanescent field interaction of the propagating light with a single wall carbon nanotube saturable absorber in a microfiber The pulse width is 66 fs which to the best of our knowledge is the shortest pulse achieved in a carbon nanotube mode locked fiber laser The maximum average output power is 26 mW which is about 20 times larger than that of a typical carbon nanotube mode locked fiber laser The center of the wavelength is 1555 nm with 54 nm spectral width The repetition rate is 146 MHz To investigate the laser's stability the output pulses are monitored for 120 h and there is no significant degradation of the laser spectral width or shape ? 2014 Astro Ltd.Accession Number: 20140117169415