2016
2016
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Record 361 of
Title:Detection of hyperspectral small targets based on projection pursuit optimized by bee colony
Author(s):Wu, Yiquan(1,2); Zhou, Yang(1); Long, Yunlin(1)Source: Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument Volume: 37 Issue: 6 DOI: Published: June 1, 2016Abstract:In order to further improve the operation speed and reduce the false alarm rate of the unsupervised detection method for small targets in hyperspectral remote sensing images, a detection method based on the projection pursuit (PP) optimized by improved artificial bee colony (ABC) optimization algorithm and K-nearest neighbor (KNN) is proposed in this paper. Firstly, the kernel principal component analysis (KPCA) method is adopted to perform the dimension reduction of the original hyperspectral remote sensing images. Then, the method jointly defining the kurtosis and skewness according to the neighborhood pixels is proposed, the combination of the kurtosis and skewness is taken as the projection index. The improved artificial bee colony algorithm is taken as the optimization algorithm. The projection pursuit is used to obtain the projection images layer by layer from the low dimensional hyperspectral remote sensing images, and the small targets are extracted according to the histogram of these projection images. Finally, the linear discriminant analysis (LDA) is used to extract the features of the pixels, and the weighted K-nearest neighbor method is used to purify the preliminary detection results of the small targets. A large number of experiment results show that compared with the RX method, independent component analysis (ICA) method and the projection pursuit method based on chaotic particle swarm optimization (CPSO), the proposed method not only can detect the small targets in hyperspectral remote sensing image accurately, but also has faster operation speed. ? 2016, Science Press. All right reserved.Accession Number: 20163102663156 -
Record 362 of
Title:Thermal behavior of microchannel cooled high power diode laser arrays
Author(s):Wu, Dihai(1); Zhang, Pu(1); Nie, Zhiqiang(1); Xiong, Lingling(1); Song, Yunfei(1,2); Zhu, Qiwen(1); Lu, Yao(1,2); Dang, Yifan(1,2,3); Liu, Xingsheng(1,3)Source: 2016 17th International Conference on Electronic Packaging Technology, ICEPT 2016 Volume: Issue: DOI: 10.1109/ICEPT.2016.7583183 Published: October 4, 2016Abstract:Heat generation in the active region leads to high junction temperature that significantly affects electrical and optical properties, reliability and lifetime of high power diode laser arrays. It is of great importance to understand the thermal behavior to improve the devices. Compared to conduction cooling techniques, diode laser arrays packaged on microchannel heat sinks have superior capability to dissipate the large amount of heat so as to deliver higher output power and ensure high reliability. In this paper, numerical approach based on finite element method (FEM) and computational fluid dynamics (CFD) was employed to investigate thermal properties of microchannel cooled (MCC) high power diode laser arrays. The static and transient thermal behavior of the devices operated in continuous wave (CW) mode at different water flow rates have been studied in detail. The thermal resistance contributed from the laser chip, solder interface and MCC heat sink was revealed. The correlation between thermal resistance and water flow rate was analyzed. The thermal time constants were derived to characterize the three distinct heating processes related to active region, copper heat sink and copper/water interface. Non-uniformity of junction temperature across the diode laser array was discussed by thermal crosstalk employing the independent emitter analysis. Understanding thermal phenomena in diode laser arrays could offer useful guidelines in optimizing the operating conditions, MCC heat sink structures and packaging architectures for enhanced performance and reliability. ? 2016 IEEE.Accession Number: 20164502990989 -
Record 363 of
Title:A robust haze-removal scheme in polarimetric dehazing imaging based on automatic identification of sky region
Author(s):Zhang, Wenfei(1,2,3); Liang, Jian(1,3); Ju, Haijuan(1,3); Ren, Liyong(1); Qu, Enshi(1); Wu, Zhaoxin(2)Source: Optics and Laser Technology Volume: 86 Issue: DOI: 10.1016/j.optlastec.2016.07.015 Published: December 1, 2016Abstract:Quality enhancement of images acquired in hazy conditions is a significant research area in civil and military applications. The polarimetric dehazing methods have been exploited to dehaze hazy images and have proven to be effective in enhancing their quality. In this paper, by combining the polarimetric imaging technique and the dark channel prior technique, a robust haze-removal scheme is presented for the first time. On the one hand, the polarimetric imaging technique has advantages in recovering detailed information well, especially in dense hazy conditions; on the other hand, the dark channel prior technique provides a much more precise and convenient way to estimate the airlight radiance through extracting the sky region automatically. The experiments verify the practicability and effectiveness of the proposed dehazing scheme in quality enhancement of hazy images. Furthermore, comparison study demonstrates that the proposed scheme is superior to some sophisticated methods in terms of the visibility and contrast. We believe this scheme is beneficial in the image dehazing applications, especially for real-time applications. ? 2016 Elsevier LtdAccession Number: 20163202690299 -
Record 364 of
Title:Alignment method of off-axis RC reflective optical system
Author(s):Zhang, Xue-Min(1,2); Xing, Song(1); Zhang, Zhi-Jun(1); Hou, Xiao-Hua(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9682 Issue: DOI: 10.1117/12.2245135 Published: 2016Abstract:Off-axis optical system has a wide application in space optics and remote detective area. The high surface shape accuracy can be ensured with the development of advanced manufacture technique. So the only condition which limits the wide application of off-axis optical system is how to realize the precise alignment of it. Based on a RC reflective optical system whose diameter is 400mm, the alignment method which combines the high resolution initial placement and computer-aided alignment is introduced. By designing a system which can measure the off-axis fabrication and off-axis angle precisely, the high resolution initial placement of off-axis mirror can be ensured with a measurement accuracy of ±0.05mm and ±10". The good initial placement can give a good initial state, so the computer-aided model can be converged well. The experiment shows that a system which has a good initial placement could have a good wave aberration of 0.04λ after three times iteration adjustment. ? 2016 SPIE.Accession Number: 20164903095194 -
Record 365 of
Title:Influence of electrode types on the electrohydrodynamic instability patterning process: a comparative study
Author(s):Liu, Minzhe(1,2); Li, Hefu(1); Yu, Weixing(3); Wang, Taisheng(1); Liu, Zhenyu(1); Desmulliez, Marc. P. Y.(4)Source: RSC Advances Volume: 6 Issue: 113 DOI: 10.1039/C6RA05596F Published: 2016Abstract:This article studies the effect that different types of patterned electrodes have on the electrohydrodynamic instability patterning (EHDIP) process for the faithful replication of micro- and nanostructures. Two types of patterned electrodes are studied. One is fully conductive, i.e. both pattern and substrate are conductive. The other type has conductive microstructures fabricated on a dielectric substrate. By employing the COMSOL? Multiphysics software package, a rigorous numerical simulation of the EHDIP process has been carried out for both types of electrodes. The simulation results show that both electrodes can realize a faithful replication of the micro- and nanostructures once the variable, ΔE/Δx, reaches the critical value. Moreover, it is demonstrated that a fully conductive template is preferred if a small polymer film thickness is employed; a partially conductive electrode is preferred for larger film thickness. These results provide guidelines for the better control of the EHDIP process in order to realize the perfect pattern replication of structures for a variety of applications in MEMS or micro/nanofluidics. ? The Royal Society of Chemistry.Accession Number: 20164903095495 -
Record 366 of
Title:A numerical algorithm to evaluate the transient response for a synchronous scanning streak camera using a time-domain Baum–Liu–Tesche equation
Author(s):Pei, Chengquan(1); Tian, Jinshou(2); Wu, Shengli(1); He, Jiai(3); Liu, Zhen(1)Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 832 Issue: DOI: 10.1016/j.nima.2016.06.061 Published: October 1, 2016Abstract:The transient response is of great influence on the electromagnetic compatibility of synchronous scanning streak cameras (SSSCs). In this paper we propose a numerical method to evaluate the transient response of the scanning deflection plate (SDP). First, we created a simplified circuit model for the SDP used in an SSSC, and then derived the Baum–Liu–Tesche (BLT) equation in the frequency domain. From the frequency-domain BLT equation, its transient counterpart was derived. These parameters, together with the transient-BLT equation, were used to compute the transient load voltage and load current, and then a novel numerical method to fulfill the continuity equation was used. Several numerical simulations were conducted to verify this proposed method. The computed results were then compared with transient responses obtained by a frequency-domain/fast Fourier transform (FFT) method, and the accordance was excellent for highly conducting cables. The benefit of deriving the BLT equation in the time domain is that it may be used with slight modifications to calculate the transient response and the error can be controlled by a computer program. The result showed that the transient voltage was up to 1000?V and the transient current was approximately 10?A, so some protective measures should be taken to improve the electromagnetic compatibility. ? 2016 Elsevier B.V.Accession Number: 20162702554803 -
Record 367 of
Title:A widely tunable photonic-assisted microwave notch filter with high linearity using a dual-parallel Mach - Zehnder modulator
Author(s):Wang, Xin(1,2,3); Deng, Ye(2); Wang, Wen-Ting(2); Yuan, Hai-Qing(2); Bai, Jin-Hua(2); Liu, Yu(2)Source: Chinese Physics Letters Volume: 33 Issue: 10 DOI: 10.1088/0256-307X/33/10/104202 Published: October 2016Abstract:A widely tunable microwave photonic (MWP) notch filter with high linearity based on a dual-parallel Mach-Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. The motivation of this work lies in the fact that the MWP notch filter previously reported has nonlinear distortions generally induced by the nonlinear property of electro-optic devices. In this scheme, even-order modulated sidebands at the DPMZM output are effectively suppressed by properly adjusting bias voltages of the DPMZM, which are the dominant factor to induce the nonlinear distortions into the MWP notch filter. The proposed scheme is theoretically analyzed and experimentally verified. ? 2016 Chinese Physical Society and IOP Publishing Ltd.Accession Number: 20220711666401 -
Record 368 of
Title:High-precision algorithm of surface parameter of parabolic primary mirror for space solar telescope
Author(s):Xu, Guangzhou(1,3); Ruan, Ping(1); Yang, Jianfeng(1); Li, Fu(1); Yan, Xingtao(1); Wang, Sen(2)Source: Optik Volume: 127 Issue: 22 DOI: 10.1016/j.ijleo.2016.08.066 Published: November 1, 2016Abstract:The parabolic primary mirror (PM) of space solar telescope is sensitive to the serious external loads and surface variation of PM has large influence on the optical performance of the telescope. To evaluate the PM change under the external loads accurately, the high-precision algorithm based on the comprehensive surface parameter is presented. The discrete error of finite element discretization of optical surface is concerned for the first time and the elimination of discrete error is discussed as well. The calculation method of surface parameter including rigid body displacement, surface focus and root mean square is researched. Based on the high-precision algorithm, the surface parameter of PM under the isothermal temperature change is calculated and the law curve of surface parameter is also obtained with the change of temperature. The significant simulation result of surface parameter can effectively evaluate the surface change and guide the structure and environmental adaptation design of the PM. ? 2016 Elsevier GmbHAccession Number: 20163702782909 -
Record 369 of
Title:Photonics generation of frequency-shift keying radio-frequency signal using nonlinear polarization rotation in a highly nonlinear fiber
Author(s):Wang, Xin(1,2); Li, Wei(2); Li, Ming(2); Zhu, Ning Hua(2)Source: Optical Engineering Volume: 55 Issue: 10 DOI: 10.1117/1.OE.55.10.106118 Published: October 1, 2016Abstract:We experimentally demonstrate an all-optical approach for generating frequency-shift keying (FSK) radio-frequency (RF) signal based on nonlinear polarization rotation (NPR) in a highly nonlinear fiber (HNLF). A continuous wave probe beam is polarization-rotated by an optical amplitude-shift keying control beam via NPR in the HNLF. After removing the undesired control beam by a tunable optical filter, the polarization-rotated probe beam is converted to an intensity-modulated optical signal using a polarizer. By carefully adjusting the polarization controller before the polarizer and the optical power of the control beam, FSK RF signals are generated after photodetection. ? 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20233214502421 -
Record 370 of
Title:Lung nodules detection in CT images using gestalt-based algorithm
Author(s):Shi, Qiu(1,2); Desheng, Wen(1); Ying, Cui(3); Jun, Feng(4)Source: Chinese Journal of Electronics Volume: 25 Issue: 4 DOI: 10.1049/cje.2016.07.009 Published: July 10, 2016Abstract:To overcome low accuracy and high false positive of existing computer-aided lung nodules detection. We propose a novel lung nodule detection scheme based on the Gestalt visual cognition theory. The proposed scheme involves two parts which simulate human eyes cognition features such as simplicity, integrity and classification. Firstly, lung region was segmented from lung Computed tomography (CT) sequences. Then local threedimensional information was integrated into the Maximum intensity projection (MIP) images from axial, coronal and sagittal profiles. In this way, lung nodules and vascular are strengthened and discriminated based on pathologic image characteristics of lung nodules. The experimental database includes fifty-three high resolution CT images contained lung nodules, which had been confirmed by biopsy. The experimental results show that, the accuracy rate of the proposed algorithm achieves 91.29%. The proposed framework improves performance and computation speed for computer aided nodules detection. ? 2016 Chinese Institute of Electronics.Accession Number: 20203209031245 -
Record 371 of
Title:Status of the large area MCP-PMT in China
Author(s):Gao, Feng(1); Qian, Sen(1); Liu, Shulin(1); Ning, Zhe(1); Wang, Yifang(1); Zhao, Tianchi(1); Heng, Yuekun(1); Liu, Hulin(2); Li, Weihua(2); Tian, Jinshou(2); Wei, Yonglin(2); Xin, Liwei(2); Huang, Guorui(3); Li, Dong(3); Ren, Ling(3); Sun, Jianning(2); Si, Shuguang(3); Qi, Ming(4)Source: Proceedings of Science Volume: Part F128556 Issue: DOI: Published: 2016Abstract:For the next generation neutrino experiment, number of experienced researchers and engineers in research institutes and companies related to PMT fabrication in China jointly worked on the large area MCP-PMT collaboration group. In the past 5 years by collaborative work, the 8-inch and 20-inch prototypes were produced. And also get the high detection efficiency 20-inch MCP-PMT for JUNO in 2015, and get the 75% order of the JUNO-PMT. This manuscript will introduce the progress of the R&D of this new design of the MCP-PMT, also the performance tested result in the PMT Lab in IHEP. ? Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).Accession Number: 20173003990712 -
Record 372 of
Title:The new high-speed switching study of ultra-short laser pulse technology
Author(s):Sun, Bo(1,2,3); Gou, Yongsheng(1,2,3); Wang, Dahui(4); Liu, Baiyu(1,2); Zhao, Xueqing(4); Bai, Yonglin(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9686 Issue: DOI: 10.1117/12.2242364 Published: 2016Abstract:Ultrafast phenomenon has presented widely in natural phenomenon and scientific and technological research. Therefore, study on ultrafast phenomenon is of great important in many research and technology fields. In recent years, the development and application of ultra-short laser pulse has been covered many areas. It has been developed into a powerful tool used to research ultrafast phenomena. In the implementation process of the ultra-short laser pulses, high-speed switching plays a vital role. The difficulty of high-speed switching design is to make the ultrafast electric pulse load on the both ends of the crystal with minimum distortion and delay. It is very difficult to switch electro-optic crystal at a high frequency in traditional method. In this paper, a new method is designed, which combined the electro-optic crystal and micro-strip line. The crystal is a part of the transmission path and the signal path of the micro-strip line is broadened or narrowed continuously to make the impedance matching to 50 ohm. The good match between pulse signal and the crystal make sure the high frequency switches of the crystal. The amplitude loss is less than 11%, and the delay is less than 1 nanosecond. ? 2016 SPIE.Accession Number: 20164903096321