2016

• Record 313 of
  
  Title:Experimental study on the push-broom infrared imaging system based on line-plane-switching fiber bundle
  
  Author(s):Yan, Xingtao(1); Li, Fu(1); Ma, Xiaolong(1); Lv, Juan(1); He, Yinghong(1); Zhao, Yiyi(1); Bu, Fan(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 10157  Issue:   DOI: 10.1117/12.2246936  Published: 2016  
  Abstract:The use of line-plane-switching infrared fiber bundle to achieve wide field of view push-broom infrared imaging has been studied with experiment. In this technology, the linear array end of the imaging fiber bundle is used as a long-linear array infrared detector, and the plane array end of the bundle is coupled by a mature small scale Infrared Focal Plane Array (IRFPA). It can evade the difficulty of getting the long-linear array infrared detector directly, and has a signally significance to the development of internal infrared imaging technology. Based on the introduction of the composition, working principle of this novel infrared optical system, the system principle-demonstrating experiment has been accomplished. The line-plane-switching fiber bundle used in this experiment is 64×9 format plane array and 192×3 format linear array. It is made from chalcogenide glass fibers, possessing core (As40S59.5Se0.5) of 45 μm, cladding (As40S60) of 5 μm, and error of 1% in diameter. Perfect imaging results prove that this novel technology is feasibility and superiority. The analysis of the experiment makes a foundation for the subsequent further verification experiments. © 2016 SPIE.
  Accession Number: 20170503310137
• Record 314 of
  
  Title:Topology optimization design of space rectangular mirror
  
  Author(s):Qu, Yanjun(1,2); Wang, Wei(1); Liu, Bei(1,2); Li, Xupeng(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 10154  Issue:   DOI: 10.1117/12.2247396  Published: 2016  
  Abstract:A conceptual lightweight rectangular mirror is designed based on the theory of topology optimization and the specific structure size is determined through sensitivity analysis and size optimization in this paper. Under the load condition of gravity along the optical axis, compared with the mirrors designed by traditional method using finite element analysis method, the performance of the topology optimization reflectors supported by peripheral six points are superior in lightweight ratio, structure stiffness and the reflective surface accuracy. This suggests that the lightweight method in this paper is effective and has potential value for the design of rectangular reflector. © 2016 SPIE.
  Accession Number: 20170503309984
• Record 315 of
  
  Title:Speed up deep neural network based pedestrian detection by sharing features across multi-scale models
  
  Author(s):Jiang, Xiaoheng(1); Pang, Yanwei(1); Li, Xuelong(2); Pan, Jing(1,3)
  Source: Neurocomputing  Volume: 185  Issue:   DOI: 10.1016/j.neucom.2015.12.042  Published: April 12, 2016  
  Abstract:Deep neural networks (DNNs) have now demonstrated state-of-the-art detection performance on pedestrian datasets. However, because of their high computational complexity, detection efficiency is still a frustrating problem even with the help of Graphics Processing Units (GPUs). To improve detection efficiency, this paper proposes to share features across a group of DNNs that correspond to pedestrian models of different sizes. By sharing features, the computational burden for extracting features from an image pyramid can be significantly reduced. Simultaneously, we can detect pedestrians of several different scales on one single layer of an image pyramid. Furthermore, the improvement of detection efficiency is achieved with negligible loss of detection accuracy. Experimental results demonstrate the robustness and efficiency of the proposed algorithm. © 2015 The Authors.
  Accession Number: 20160101761934
• Record 316 of
  
  Title:Regularized Taylor Echo State Networks for Predictive Control of Partially Observed Systems
  
  Author(s):Xiang, Kui(1); Li, Bing Nan(2); Zhang, Liyan(1); Pang, Muye(1); Wang, Meng(3); Li, Xuelong(4)
  Source: IEEE Access  Volume: 4  Issue:   DOI: 10.1109/ACCESS.2016.2582478  Published: 2016  
  Abstract:The existing neural networks suffer from partial observation while modeling and controlling dynamic systems. In this paper, a new linearized recurrent neural network, the Taylor expanded echo state network (TESN), is proposed for predictive control of partially observed dynamic systems. Two schemes of regularization, ridge regression and sparse regression, are imposed on TESNs to tackle the issue of ill-conditioned estimation. Furthermore, two estimators, lasso and elastic net, are investigated for sparse regression. Regularized learning is found to improve the estimation consistency of readout coefficients and, at the same time, suppress the accumulation of linearization residues in a prediction horizon. A series of experiments was carried out, and the results verified that regularized learning is contributive to TESNs in predictive control of partially observed dynamic systems. © 2016 IEEE.
  Accession Number: 20163702802624
• Record 317 of
  
  Title:Optical waveform monitoring based on a free-running mode-locked femtosecond fibre laser and four-wave mixing in a highly nonlinear fibre
  
  Author(s):Liu, Y.(1); Zhang, J.-G.(2); Tang, D.(3)
  Source: Opto-Electronics Review  Volume: 24  Issue: 2  DOI: 10.1515/oere-2016-0010  Published: June 1, 2016  
  Abstract:Optical sampling based on ultrafast optical nonlinearities is a useful technique to monitor the waveforms of ultrashort optical pulses. In this paper, we present a new implementation of optical waveform sampling systems by employing our newly constructed free-running mode-locked fibre laser with a tunable repetition rate and a low timing jitter, an all-optical waveform sampler with a highly nonlinear fibre (HNLF), and our developed computer algorithm for optical waveform display and measurement, respectively. Using a femtosecond fibre laser to generate the highly stable optical sampling pulses and exploiting the four-wave mixing effect in a 100m-long HNLF, we successfully demonstrate the all-optical waveform sampling of a 10GHz optical clock pulse sequence with a pulse width of 1.8 ps and a 80Gbit/s optical data signal, respectively. The experimental results show that waveforms of the tested optical pulse signals are accurately reproduced with a pulse width of 2.0 ps. This corresponds to a temporal resolution of 0.87 ps for optical waveform measurement. Moreover, the optical eye diagram of a 10Gbit/s optical data signal with a 1.8 ps pulse width is also accurately measured by employing our developed optical sampling system. © 2016 by Walter de Gruyter Berlin/Boston.
  Accession Number: 20162002399630
• Record 318 of
  
  Title:Lab-on-fiber electrophoretic trace mixture separating and detecting an optofluidic device based on a microstructured optical fiber
  
  Author(s):Yang, Xinghua(1,2); Guo, Xiaohui(1); Li, Song(1); Kong, Depeng(3); Liu, Zhihai(1); Yang, Jun(1); Yuan, Libo(1)
  Source: Optics Letters  Volume: 41  Issue: 8  DOI: 10.1364/OL.41.001873  Published: April 15, 2016  
  Abstract:We report an in-fiber integrated electrophoretic trace mixture separating and detecting an optofluidic optical fiber sensor based on a specially designed optical fiber. In this design, rapid in situ separation and simultaneous detection of mixed analytes can be realized under electro-osmotic flow in the microstructured optical fiber. To visually display the in-fiber separating and detecting process, two common fluorescent indicators are adopted as the optofluidic analytes in the optical fiber. Results show that a trace amount of the mixture (0.15 μL) can be completely separated within 3.5 min under a high voltage of 5 kV. Simultaneously, the distributed information of the separated analytes in the optical fiber can be clearly obtained by scanning along the optical fiber using a 355 nm laser. The emission from the analytes can be efficiently coupled into the inner core and guides to the remote end of the optical fiber. In addition, the thin cladding around the inner core in the optical fiber can prevent the fluorescent cross talk between the analytes in this design. Compared to previous optical fiber optofluidic devices, this device first realizes simultaneously separating treatment and the detection of the mixed samples in an optical fiber. Significantly, such an in-fiber integrated separating and detecting optofluidic device can find wide applications in various analysis fields involves mixed samples, such as biology, chemistry, and environment. © 2016 Optical Society of America.
  Accession Number: 20161802317699
• Record 319 of
  
  Title:High-power, high-efficiency 808 nm laser diode array
  
  Author(s):Wang, Zhen-Fu(1); Yang, Guo-Wen(1,2); Wu, Jian-Yao(2); Song, Ke-Chang(2); Li, Xiu-Shan(1); Song, Yun-Fei(1)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 65  Issue: 16  DOI: 10.7498/aps.65.164203  Published: August 20, 2016  
  Abstract:High-power, high-efficiency 808 nm laser diode arrays for pumping solid-state lasers have been widely used in industrial, scientific, medical and biological applications. The tendency of development of 808 nm laser diode pumping with high power, high efficiency and long lifetime is well-known. Diode-pumped solid-state system with high-efficiency laser diode array has many advantages such as compact volume, lower weight and energy saving. Currently, commercial 808 nm diode laser arrays with lower power conversion efficiency of about 50%-55%, due to the optical absorption losses for GaAs-based epitaxial materials, have been reported. In order to reduce series resistance and thermal resistance, heavily doped p-type waveguide and cladding layers are employed. However, the absorption loss on the free carriers in heavily doped p-type layers is dominant, leading to a lower power conversion efficiency. In order to achieve a high efficiency, the following requirements must be considered: improving the internal quantum efficiency by reducing the carrier leakage and increasing the electron injection efficiency; minimizing the voltage drop by optimizing the operating voltage; reducing the series resistance and thermal resistance of device; minimizing the internal loss including free-carrier absorption loss and scattering loss by designing optimized waveguide and cladding structure. In this paper, optimizing the epitaxial structure and fabricating technologies are demonstrated to achieve the high efficiency and high power. The asymmetric broad waveguide epitaxial structure with lower absorption loss in p-type waveguide and cladding layer is designed in order to achieve the above goals. The high-efficiency epitaxial structure is optimized including the thickness, doping and composition for each layer structure. The strained quantum well diode laser with lower transparency current and higher differential is of benefit to achieving the high power. A novel asymmetric broad waveguide structure is designed by optimizing the waveguide thickness and component of p-waveguide so as to reduce carrier absorption loss, the optical absorption loss in this epitaxial structure is achieved to be as low as 0.63 cm-1. The wafer is grown by metalorganic chemical vapor deposition on an n-GaAs substrate. The optimized growth conditions and substrates orientation are extensively studied to improve the crystal quality and reduce the internal loss and defects. The wafer is processed using standard procedures. For the fabricated 1-cm laser diode array mounted on P-side down on copper microchannel cooled heatsink, the device shows an output power of 150 W under an operating current of 135 A with an emitting wavelength of 809 nm, an operating voltage of 1.76 V, a slope efficiency of as high as 1.25 W/A, and maximum power conversion efficiency of as high as 65.5%, which is the highest level of 808 nm diode laser array with an output power of 150 W. © 2016 Chinese Physical Society.
  Accession Number: 20163502738082
• Record 320 of
  
  Title:Recent Advances in Cloud Radio Access Networks: System Architectures, Key Techniques, and Open Issues
  
  Author(s):Peng, Mugen(1); Sun, Yaohua(1); Li, Xuelong(2); Mao, Zhendong(1); Wang, Chonggang(3)
  Source: IEEE Communications Surveys and Tutorials  Volume: 18  Issue: 3  DOI: 10.1109/COMST.2016.2548658  Published: Third Quarter 2016  
  Abstract:As a promising paradigm to reduce both capital and operating expenditures, the cloud radio access network (C-RAN) has been shown to provide high spectral efficiency and energy efficiency. Motivated by its significant theoretical performance gains and potential advantages, C-RANs have been advocated by both the industry and research community. This paper comprehensively surveys the recent advances of C-RANs, including system architectures, key techniques, and open issues. The system architectures with different functional splits and the corresponding characteristics are comprehensively summarized and discussed. The state-of-The-Art key techniques in C-RANs are classified as: The fronthaul compression, large-scale collaborative processing, and channel estimation in the physical layer; and the radio resource allocation and optimization in the upper layer. Additionally, given the extensiveness of the research area, open issues, and challenges are presented to spur future investigations, in which the involvement of edge cache, big data mining, social-Aware device-To-device, cognitive radio, software defined network, and physical layer security for C-RANs are discussed, and the progress of testbed development and trial test is introduced as well. © 1998-2012 IEEE.
  Accession Number: 20163602764978
• Record 321 of
  
  Title:A-Optimal Projection for Image Representation
  
  Author(s):He, Xiaofei(1); Zhang, Chiyuan(1); Zhang, Lijun(2); Li, Xuelong(3)
  Source: IEEE Transactions on Pattern Analysis and Machine Intelligence  Volume: 38  Issue: 5  DOI: 10.1109/TPAMI.2015.2439252  Published: May 1, 2016  
  Abstract:We consider the problem of image representation from the perspective of statistical design. Recent studies have shown that images are possibly sampled from a low dimensional manifold despite of the fact that the ambient space is usually very high dimensional. Learning low dimensional image representations is crucial for many image processing tasks such as recognition and retrieval. Most of the existing approaches for learning low dimensional representations, such as principal component analysis (PCA) and locality preserving projections (LPP), aim at discovering the geometrical or discriminant structures in the data. In this paper, we take a different perspective from statistical experimental design, and propose a novel dimensionality reduction algorithm called A-Optimal Projection (AOP). AOP is based on a linear regression model. Specifically, AOP finds the optimal basis functions so that the expected prediction error of the regression model can be minimized if the new representations are used for training the model. Experimental results suggest that the proposed approach provides a better representation and achieves higher accuracy in image retrieval. © 1979-2012 IEEE.
  Accession Number: 20161802324160
• Record 322 of
  
  Title:Properties study of the fractional order high order Bessel vortex beam using vector wave analysis
  
  Author(s):Li, Xinzhong(1); Tai, Yuping(2); Li, Hehe(1); Wang, Jingge(1); Nie, Zhaogang(3); Tang, Jie(4); Wang, Hui(1); Yin, Chuanlei(1)
  Source: Zhongguo Jiguang/Chinese Journal of Lasers  Volume: 43  Issue: 6  DOI: 10.3788/CJL201643.0605002  Published: June 10, 2016  
  Abstract:The electric vector feature of fractional high-order Bessel vortex beam (FBV) is studied based on the vector wave analysis. Under the tightly focused and non-tightly focused conditions, the changes of three electric-field components of Ex, Ey and Ez are studied with the topological charges (TCs) from 2.1 to 3 in the increment of 0.1. Moreover, the Ex component of the FBV beam with integer and half integer TCs are comparatively analyzed during the process of the imaging scheme from tightly focused to non-tightly focused conditions. Numerical simulation results show that there are obvious difference within the three electric-field components and the circular symmetry of the bright rings are all broken. Under the non-tightly focused conditions, the circular symmetry of Ex component intensity increases. However, the distribution of Ey and Ez components demonstrate same with that under the tightly focused conditions. The circular symmetry of the Ex component of integer TCs bright rings gradually increased during the process of the imaging scheme from tightly focused to non-tightly focused conditions. Different with those, the formation of the half-integer TCs bright rings patterns remain unchanged and only has a magnification velationship. © 2016, Chinese Lasers Press. All right reserved.
  Accession Number: 20162502529837
• Record 323 of
  
  Title:Ultrafast interrogation of fully distributed chirped fibre Bragg grating strain sensor
  
  Author(s):Ahmad, Eamonn J(1); Wang, Chao(1); Feng, Dejun(1,2); Yan, Zhijun(3,4); Zhang, Lin(3)
  Source: 2016 IEEE Photonics Conference, IPC 2016  Volume:   Issue:   DOI: 10.1109/IPCon.2016.7831190  Published: January 23, 2017  
  Abstract:A novel ultrafast and high spatial-resolution interrogation method for fully distributed chirped fibre Bragg grating sensors based on photonic time-stretch frequency-domain reflectometry is presented. Real-Time interrogation at measurement speed of 50 MHz with a spatial resolution of 35 μm was experimentally demonstrated. © 2016 IEEE.
  Accession Number: 20171003412702
• Record 324 of
  
  Title:Incoherent ptychography in Fresnel domain with simultaneous multi-wavelength illumination
  
  Author(s):Pan, An(1,3); Wang, Dong(2,3); Shi, Yi-Shi(3,4); Yao, Bao-Li(1); Ma, Zhen(1); Han, Yang(1,3)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 65  Issue: 12  DOI: 10.7498/aps.65.124201  Published: June 20, 2016  
  Abstract:Single wavelength illumination is used in the traditional ptychography. Even though using multi-wavelength to improve image quality, it takes the scheme of illuminating in turn due to the requirement of coherence. So far, the addition of incoherent modes has been regarded as a nuisance in diffractive imaging. Here we propose a scheme of incoherent ptychography and an algorithm of information multiplexing that uses the multi-wavelength illumination simultaneously, which are demonstrated in experiment and simulation. Compared with the scheme of traditional ptychography, it can recover not only the object well, but also the spectral response of the object, probes of complex value and spectral weight of each wavelength respectively. This method obtains much information about the object and owns the multichannel and multispectral merits. Meanwhile, by means of color image coding, this method can retrieve true color images and enhance the image quality. The proposed algorithm has strong robustness. Besides, we also investigate how many modes can be recovered by this method. The work may open up possibilities for information multiplexing in ptychography and multispectral microscopy imaging over various applications. © 2016 Chinese Physical Society.
  Accession Number: 20162702554001