2016
2016
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Record 277 of
Title:A target detection method for hyperspectral image based on mixture noise model
Author(s):Zheng, Xiangtao(1,2); Yuan, Yuan(1); Lu, Xiaoqiang(1)Source: Neurocomputing Volume: 216 Issue: DOI: 10.1016/j.neucom.2016.08.015 Published: December 5, 2016Abstract:Subpixel hyperspectral detection is a kind of method which tries to locate targets in a hyperspectral image when the spectrum of the targets is given. Due to its subpixel nature, targets are often smaller than one pixel, which increases the difficulty of detection. Many algorithms have been proposed to tackle this problem, most of which model the noise in all spatial points of hyperspectral image by multivariate normal distribution. However, this model alone may not be an appropriate description of the noise distribution in hyperspectral image. After carefully studying the distribution of hyperspectral image, it is concluded that the gradient of noise also obeys normal distribution. In this paper two detectors are proposed: mixture gradient structured detector (MGSD) and mixture gradient unstructured detector (MGUD). These detectors are based on a new model which takes advantage of the distribution of the gradient of the noise. This makes the detectors more accordant with the practical situation. To evaluate the performance of the proposed detectors, three different data sets, including one synthesized data set and two real-world data sets, are used in the experiments. Results show that the proposed detectors have better performance than current subpixel detectors. ? 2016 Elsevier B.V.Accession Number: 20164603015647 -
Record 278 of
Title:Selective level set segmentation using fuzzy region competition
Author(s):Li, Bing Nan(1); Qin, Jing(2); Wang, Rong(3); Wang, Meng(4); Li, Xuelong(5)Source: IEEE Access Volume: 4 Issue: DOI: 10.1109/ACCESS.2016.2590440 Published: 2016Abstract:Deformable models and level set methods have been extensively investigated for computerized image segmentation. However, medical image segmentation is yet one of open challenges owing to diversified physiology, pathology, and imaging modalities. Existing level set methods suffer from some inherent drawbacks in face of noise, ambiguity, and inhomogeneity. It is also refractory to control level set segmentation that is dependent on image content and evolutional strategies. In this paper, a new level set formulation is proposed by using fuzzy region competition for selective image segmentation. It is able to detect and track the arbitrary combination of selected objects or image components. To the best of our knowledge, this new formulation should be one of the first proposals in a framework of region competition for selective segmentation. Experiments on both synthetic and real images validate its advantages in selective level set segmentation. ? 2013 IEEE.Accession Number: 20164202915464 -
Record 279 of
Title:Segmentation of White Blood Cell from Acute Lymphoblastic Leukemia Images Using Dual-Threshold Method
Author(s):Li, Yan(1,2); Zhu, Rui(1); Mi, Lei(1); Cao, Yihui(1,2); Yao, Di(3)Source: Computational and Mathematical Methods in Medicine Volume: 2016 Issue: DOI: 10.1155/2016/9514707 Published: 2016Abstract:We propose a dual-threshold method based on a strategic combination of RGB and HSV color space for white blood cell (WBC) segmentation. The proposed method consists of three main parts: preprocessing, threshold segmentation, and postprocessing. In the preprocessing part, we get two images for further processing: one contrast-stretched gray image and one H component image from transformed HSV color space. In the threshold segmentation part, a dual-threshold method is proposed for improving the conventional single-threshold approaches and a golden section search method is used for determining the optimal thresholds. For the postprocessing part, mathematical morphology and median filtering are utilized to denoise and remove incomplete WBCs. The proposed method was tested in segmenting the lymphoblasts on a public Acute Lymphoblastic Leukemia (ALL) image dataset. The results show that the performance of the proposed method is better than single-threshold approach independently performed in RGB and HSV color space and the overall single WBC segmentation accuracy reaches 97.85%, showing a good prospect in subsequent lymphoblast classification and ALL diagnosis. ? 2016 Yan Li et al.Accession Number: 20214511124006 -
Record 280 of
Title:A design of driving circuit for star sensor imaging camera
Author(s):Li, Da-Wei(1); Yang, Xiao-Xu(1); Han, Jun-Feng(1); Liu, Zhao-Hui(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9796 Issue: DOI: 10.1117/12.2228887 Published: 2016Abstract:The star sensor is a high-precision attitude sensitive measuring instruments, which determine spacecraft attitude by detecting different positions on the celestial sphere. Imaging camera is an important portion of star sensor. The purpose of this study is to design a driving circuit based on Kodak CCD sensor. The design of driving circuit based on Kodak KAI-04022 is discussed, and the timing of this CCD sensor is analyzed. By the driving circuit testing laboratory and imaging experiments, it is found that the driving circuits can meet the requirements of Kodak CCD sensor. ? 2016 SPIE.Accession Number: 20163502747262 -
Record 281 of
Title:Investigation of femtosecond laser-induced periodic surface structure on tungsten
Author(s):Li, Chen(1,2,3); Cheng, Guanghua(1,3); Razvan, Stoian(3)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 36 Issue: 5 DOI: 10.3788/AOS201636.0532001 Published: May 10, 2016Abstract:Femtosecond laser-induced periodic surface structure (LIPSS) has the potential applications in tunable thermal source, tribology, super-hydrophilicity, super-hydrophobicity, marking and so on. LIPSS formation and mechanism on tungsten with a 800 nm femtosecond laser are investigated. The electromagnetic energy distribution on random rough surface after the first laser pulse and the energy distribution of electromagnetic field induced by low-spatial-frequency LIPSS after 20 pulses are simulated by Sipe interference model and finite-difference time-domain (FDTD) method. The formation mechanism of low-spatial-frequency and high-spatial-frequency LIPSS (HSFL) is disclosed. The evolution of surface morphology and the phenomena of spatial period decreasing with the increase of laser pulse number are also investigated. ? 2016, Chinese Lasers Press. All right reserved.Accession Number: 20162102427173 -
Record 282 of
Title:Analysis of the redundancy of Fourier telescopy transmitter array and its redundancy-strehl ratio-target texture distribution characteristic
Author(s):Zhang, Yu(1); Luo, Xiu-Juan(1); Cao, Bei(1); Chen, Ming-Lai(1); Liu, Hui(1); Xia, Ai-Li(1); Lan, Fu-Yang(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 65 Issue: 11 DOI: 10.7498/aps.65.114201 Published: June 5, 2016Abstract:The Fourier telescopy is a kind of active illumination imaging with high resolution by using multi-interfering fringes generated by the multi-beams from the large transmitter arrays. According to the imaging principle, the beams from one laser source are split and each beam is applied with a different tiny frequency shift so that the interfering fringes may moving across the target. The configuration of the beams changes so that they would generate fringes in different spatial frequencies and different directions. Recently, most of researches focused on the factors such as the baseline scale and data sampling efficiency that may affect the imaging quality. However, there are other two factors, i.e., the configuration of the transmitter and its redundancy, which need studying. In Fourier telescopy, if the direction and spatial frequency of the fringe patterns that are generated by the change of different baseline configurations match each other, the target surface information would be a crucial factor that affects the image quality. In the first part of this article, the practicability of zero redundancy of baseline is analyzed. The results show that the baseline cannot have zero redundancy due to the iteration algorithm. Then the minimum redundancy is analyzed and the minimum redundancy line is proposed. By using the Strehl ratio as the merit of the imaging quality, the concept of redundancy-strehl ratio-target texture distribution (RST) and calculation method are proposed. This method integrates the transmitter redundancy, target detail information and image quality together. The distribution of RST value on the frequency plane is compared with the minimum redundancy line. If the RST point is located on the horizontal side compared with the line, the target detail information on this baseline is mainly in the horizontal direction. On the other hand, if the RST point is located on the longitude side, the target information is mainly in the longitude direction. Therefore this new proposed method reveals the relationship between target spatial information and the baseline configuration. In this article T-shaped transmitter array is adopted, and the Fourier components are mainly distributed on the rectangle plane. According to this relationship and calculated RST value, the working transmitter may continuously rectify its scale and shifting patterns so that the spatial frequencies and directions of fringes may match the target Fourier components in time. In this article, three simulated images and two real images are tested by the proposed method, and the results show that the RST values and the distributions well reveale the relationship between the detailed information and the baseline configurations. Now the Fourier telescopy follows the procedure from laboratory setup to the real system research. Considering the convenience and cost of project realization, this method is helpful for analyzing the real system of the transmitter configuration and enhancing working efficiency. ? 2016 Chinese Physical Society.Accession Number: 20162502522378 -
Record 283 of
Title:Frequency linkage between the dual frequency combs based on the polarization-maintaining femtosecond fiber laser
Author(s):Xu, Xin(1); Feng, Ye(1); Liu, Yuan-Shan(1); Wu, Guan-Hao(2); Wang, Yi-Shan(1); Wei, Ru-Yi(3); Zhao, Wei(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 45 Issue: 6 DOI: 10.3788/gzxb20164506.0614001 Published: June 1, 2016Abstract:The frequency linkage between the dual frequency combs was realized by using of the tracking feedback controlling circuit. The linkage characteristic was studied when the master frequency comb's frquency is changed automatically and manully respectively. The results show that, the frequency of the slave frequency comb is varied following the automatic or manual frequency scanning of the master frequency comb. The max correlation coifficient between the frequency of the dual frequency combs is up to 0.99, which demonstrates the better linkage characteristic. Finally, the linked dual frequency combs was used in the abosulate distance measurement. The measured distance is 1.332 m, the interval is 0.2 s, the standard deviation of the experimental results is 0.35 μm with 16 times, and the measurement precision is less than 1 μm. ? 2016, Science Press. All right reserved.Accession Number: 20162502529678 -
Record 284 of
Title:Initial cumulative effects in femtosecond pulsed laser-induced periodic surface structures on bulk metallic glasses
Author(s):Li, Chen(1,2,3); Zhang, Hao(1); Cheng, Guanghua(2); Faure, Nicolas(1); Jamon, Damien(1); Colombier, Jean-Philippe(1); Stoian, Razvan(1)Source: Journal of Laser Micro Nanoengineering Volume: 11 Issue: 3 DOI: 10.2961/jlmn.2016.03.0014 Published: 2016Abstract:We investigate initial cumulative irradiation effects leading to variable surface topographies and nanoscale roughness, and triggering eventually the formation of laser-induced periodic surface structures (LIPSS) on Zr-based bulk metallic glasses (Zr41.2Ti13.8Cu12.5Ni10Be25.5 (at%)). We discuss interconnected aspects related to electronic excitation and optical transients, potential variations in the cartography of thermally-driven chemical modifications and topographical features assisting the surface coupling of the electromagnetic field. The transient optical properties of Zr-based BMG surfaces upon ultrafast irradiation, measured by a two-angle time-resolved single-pump double-probe ellipsometry method, show a remarkable constancy up to the point of optical damage and rapid gas-phase transition beyond. In intermediate and low exposure conditions, in the vicinity of the damage domain, multi-pulse incubation effects determine the appearance of nanoscale surface structures. The aspects discussed here involve primarily the progression of nanoscale structuring with an increasing number of fs laser pulses starting from a rough surface and evolving towards ordered corrugation. We emphasize the role of initial roughness in determining light coupling and the generation of regular stationary patterns of scattered light, localized energy absorption and spatially-variant ablation or modulated temperature-driven factors for surface relief. From a material perspective, energy dispersive X-ray spectrometry (EDX) analysis shows potential selective vaporization of light elements, leading to gradual compositional changes and proving a spatially-modulated temperature pattern. A formation scenario is proposed involving interference between the incident laser and scattered light potentially mediated by localized surface plasmons. Finite-difference time-domain (FDTD) simulations are applied to validate the mechanism, showing that LIPSS appear intrinsically related to the surface superposition of electromagnetic waves.Accession Number: 20164603012498 -
Record 285 of
Title:Frequency comb generation in the green using silicon nitride microresonators
Author(s):Wang, Leiran(1,2); Chang, Lin(1); Volet, Nicolas(1); Pfeiffer, Martin H. P.(3); Zervas, Michael(3); Guo, Hairun(3); Kippenberg, Tobias J.(3); Bowers, John E.(1)Source: Laser and Photonics Reviews Volume: 10 Issue: 4 DOI: 10.1002/lpor.201600006 Published: July 1, 2016Abstract:Optical frequency combs enable precision measurements in fundamental physics and have been applied to a growing number of applications, such as molecular spectroscopy, LIDAR and atmospheric trace-gas sensing. In recent years, the generation of frequency combs has been demonstrated in integrated microresonators. Extending their spectral range to the visible is generally hindered by strong normal material dispersion and scattering losses. In this paper, we report the first realization of a green-light frequency comb in integrated high-Q silicon nitride (SiN) ring microresonators. Third-order optical non-linearities are utilized to convert a near-infrared Kerr frequency comb to a broadband green light comb. The 1-THz frequency spacing infrared comb covers up to 2/3 of an octave, from 144 to 226 THz (or 1327-2082 nm), and the simultaneously generated green-light comb is centered around 570-580 THz (or 517-526 nm), with comb lines emitted down to 517 THz (or 580 nm) and up to 597 THz (or 502 nm). The green comb power is estimated to be as high as ?9.1 dBm in the bus waveguide, with an on-chip conversion efficiency of ?34 dB. The proposed approach substantiates the feasibility of on-chip optical frequency comb generation expanding to the green spectral region or even shorter wavelengths. (Figure presented.) . ? 2016 by WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimAccession Number: 20162802584886 -
Record 286 of
Title:Graphene-induced unique polarization tuning properties of excessively tilted fiber grating
Author(s):Jiang, Biqiang(1,2); Yin, Guolu(2); Zhou, Kaiming(2,3); Wang, Changle(2); Gan, Xuetao(1); Zhao, Jianlin(1); Zhang, Lin(2)Source: Optics Letters Volume: 41 Issue: 23 DOI: 10.1364/OL.41.005450 Published: December 1, 2016Abstract:By exploiting the polarization-sensitive coupling effect of graphene with the optical mode, we investigate the polarization modulation properties of a hybrid waveguide of graphene-integrated excessively tilted fiber grating (Ex-TFG). The theoretical analysis and experimental results demonstrate that the real and imaginary parts of complex refractive index of fewlayer graphene exhibit different effects on transverse electric (TE) and transverse magnetic (TM) cladding modes of the Ex-TFG, enabling stronger absorption in the TE mode and more wavelength shift in the TM mode. Furthermore, the surrounding refractive index can modulate the complex optical constant of graphene and then the polarization properties of the hybrid waveguide, such as resonant wavelength and peak intensity. Therefore, the unique polarization tuning property induced by the integration of the graphene layer with Ex-TFG may endow potential applications in all-in-one fiber modulators, fiber lasers, and biochemical sensors. ? 2016 Optical Society of America.Accession Number: 20165103139660 -
Record 287 of
Title:Refractometer probe based on a reflective carbon nanotube-modified microfiber Bragg grating
Author(s):Jiang, Biqiang(1,2); Xue, Meng(1); Zhao, Chenyang(1); Mao, Dong(1); Zhou, Kaiming(2,3); Zhang, Lin(2); Zhao, Jianlin(1)Source: Applied Optics Volume: 55 Issue: 25 DOI: 10.1364/AO.55.007037 Published: September 1, 2016Abstract:A carbon nanotube (CNT)-modified microfiber Bragg grating (MFBG) is proposed to measure the refractive index with a strong enhancement of the sensitivity in the low refractive index region. The introduction of the CNT layer influences the evanescent field of the MFBG and causes modification of the reflection spectrum. With the increase of the surrounding refractive index (SRI), we observe significant attenuation to the peak of the Bragg resonance, while its wavelength remains almost unchanged. Our detailed experimental results disclose that the CNT-MFBG demonstrates strong sensitivity in the low refractive index range of 1.333-1.435, with peak intensity up to -53.4 dBm/refractive index unit, which is 15-folds higher than that of the uncoated MFBG. Therefore, taking advantage of the CNT-induced evanescent field enhancement, the reflective MFBG probe presents strong sensing capability in biochemical fields. ? 2016 Optical Society of America.Accession Number: 20163802812987 -
Record 288 of
Title:Generation of an optical frequency comb in the green with silicon nitride microresonators
Author(s):Volet, Nicolas(1); Chang, Lin(1); Wang, Leiran(1,2); Pfeiffer, Martin H.P.(3); Zervas, Michael(3); Guo, Hairun(3); Kippenberg, Tobias J.(3); Bowers, John E.(1)Source: Optics InfoBase Conference Papers Volume: Issue: DOI: Published: 2016Abstract:The first realization of a green-light frequency comb is reported in a silicon nitride ring microresonator, from third-order non-linear interaction of a near-infrared 1-THz spacing Kerr comb spanning 2/3 of an octave. ? OSA 2016.Accession Number: 20223512643175