2019
2019
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Record 25 of
Title:Design of low noise processing technology based on digital domain
Author(s):Yao, Da-Lei(1,2); Xue, Jian-Ru(1); Bu, Fan(2); Zhu, Qing(2); Yi, Hong-Wei(2); Cao, Wei-Cheng(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11209 Issue: DOI: 10.1117/12.2547337 Published: 2019Abstract:In order to break through the bottleneck of traditional CCD camera in suppressing noise, this paper designs a new system of digital domain correlation double sampling. The CCD video signal is digitized by a high-speed, high-resolution A/D converter at a sampling frequency much higher than the readout rate, and then an optimal digital signal processing algorithm is designed for the characteristics of the CCD signal readout noise to suppress noise. Experiments show that the system can suppress the readout noise at 8.1 e- at 500K read rate, which can reduce the output noise of CCD more effectively. ? 2019 SPIE.Accession Number: 20200508092985 -
Record 26 of
Title:Long-short-term features for dynamic scene classification
Author(s):Huang, Yuanjun(1,2); Cao, Xianbin(1,2); Wang, Qi(3); Zhang, Baochang(4); Zhen, Xiantong(1,2); Li, Xuelong(5,6)Source: IEEE Transactions on Circuits and Systems for Video Technology Volume: 29 Issue: 4 DOI: 10.1109/TCSVT.2018.2823360 Published: April 2019Abstract:Dynamic scene classification has been extensively studied in computer vision due to its widespread applications. The key to dynamic scene classification lies in jointly characterizing spatial appearance and temporal dynamics to achieve informative representation, which remains an outstanding task in the literature. In this paper, we propose a unified framework to extract spatial and temporal features for dynamic scene representation. More specifically, we deploy two variants of deep convolutional neural networks to encode spatial appearance and short-term dynamics into short-term deep features (STDF). Based on STDF, we propose using the autoregressive moving average model to extract long-term frequency features (LTFF). By combining STDF and LTFF, we establish the long-short-term feature (LSTF) representations of dynamic scenes. The LSTF characterizes both spatial and temporal patterns of dynamic scenes for comprehensive and information representation that enables more accurate classification. Extensive experiments on three-dynamic scene classification benchmarks have shown that the proposed LSTF achieves high performance and substantially surpasses the state-of-the-art methods. ? 2018 IEEE.Accession Number: 20181605010421 -
Record 27 of
Title:Multi-component yttrium aluminosilicate (YAS) fiber prepared by melt-in-tube method for stable single-frequency laser
Author(s):Zhang, Yeming(1); Wang, Weiwei(1); Li, Jiang(2); Xiao, Xusheng(3); Ma, Zhijun(1); Guo, Haitao(3); Dong, Guoping(1); Xu, Shanhui(1); Qiu, Jianrong(1,4)Source: Journal of the American Ceramic Society Volume: 102 Issue: 5 DOI: 10.1111/jace.16072 Published: May 2019Abstract:The multi-component glass fibers have demonstrated their unique advantages in the application of single-frequency lasers due to their higher solubility of rare-earth ions and thus a higher gain per unit length in a compact fiber laser cavity. In this study, multi-component yttrium aluminosilicate (YAS) fiber with high doping concentration of Yb3+ was prepared by the "melt-in-tube" (MIT) method. A unit-length gain of 3 dB/cm was obtained in a 4.4 cm-long YAS fiber, the laser output slope efficiency reached 23.8% in a 10 cm-long Yb:YAS fiber. Single-frequency laser operation was achieved in a 1.7-cm-long Yb:YAS active fiber. To the best of our knowledge, this is the first demonstration of single-frequency laser with this YAS glass fiber as gain medium. The novel multi-component YAS fiber can be applied as a new gain material to realize single-frequency fiber laser. ? 2018 The American Ceramic SocietyAccession Number: 20184105911357 -
Record 28 of
Title:Isolated Pulmonary Nodules Characteristics Detection Based on CT Images
Author(s):Qiu, Shi(1); Guo, Qiang(2); Zhou, Dongmei(3); Jin, Yi(4); Zhou, Tao(5); He, Zhen'An(6)Source: IEEE Access Volume: 7 Issue: DOI: 10.1109/ACCESS.2019.2951762 Published: 2019Abstract:Pulmonary nodules are the main pathological changes of the lung. Malignant pulmonary nodules will be transformed into lung cancer, which is a serious threat to human health and life. Therefore, the detection of pulmonary nodules is of great significance to save lives. However, in the face of a large number of lung CT image sequences, doctors need to spend a lot of time and energy, and in the detection process will inevitably produce the problem of false detection and missed detection. Therefore, it is very necessary for computer-aided doctors to detect pulmonary nodules. It is difficult to segment pulmonary nodules accurately and recognize the characteristics of pulmonary nodules in CT images. A complete set of semi-automatic lung nodule extraction and feature identification system is established, which is in line with the doctor's diagnosis process. A segmentation algorithm of pulmonary nodules based on regional statistical information is proposed to extract pulmonary nodules accurately. This is the first time that dynamic time warping algorithm is applied in the field of image processing, focusing on the lung nodule boundary. On this basis, the recursive graph visualization model is established to realize the visualization of boundary similarity. Finally, in order to accurately identify the characteristics of pulmonary nodules, a video similarity distance discrimination system is introduced to quantify the similarity between the nodules to be examined and the pulmonary nodules in the database. The experimental results show that the algorithm can accurately identify the normal shape, lobulated shape and lobulated shape of pulmonary nodules. The average processing speed is 0.58s/nodule. To some extent, it can reduce the misdiagnosis caused by experience and fatigue. ? 2013 IEEE.Accession Number: 20200208020465 -
Record 29 of
Title:Microcomb-based photonic local oscillator for broadband microwave frequency conversion
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(1); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5,6,7); Mitchell, Arnan(2); Moss, David J.(1)Source: Optics InfoBase Conference Papers Volume: Part F160-OFC 2019 Issue: DOI: null Published: 2019Abstract:We report a broadband microwave mixer based on an integrated micro-comb source, with a photonic local oscillator at 48.9 GHz, a conversion efficiency of ?6.8 dB and a spurious suppression ratio of over 43.5 dB. ? OSA 2019 ? 2019 The Author(s)Accession Number: 20202208772204 -
Record 30 of
Title:Accurate optical vector network analyzer based on optical double-sideband suppressed carrier modulation
Author(s):Dai, Jian(1,3); Chen, Zenghui(1); Wang, Xiaoyang(2); Ye, Long(1); Zhang, Tian(1); Xu, Kun(1)Source: Optics Communications Volume: 447 Issue: DOI: 10.1016/j.optcom.2019.04.019 Published: 15 September 2019Abstract:A high-accuracy optical vector network analysis (OVNA)based on optical suppressed carrier double-sideband (DSB)modulation and the Pound Drever Hall (PDH)technique is proposed and demonstrated. The accurate and stable frequency responses can be achieved by transmitting the optical carrier suppressed DSB modulation signals through the DUT, and then detecting the reflected signals. Compared with the traditional DSB-based OVNA, the measurement accuracy is improved by eliminating the errors caused by the even-order sidebands. Furthermore, the stability of the OVNA system can be kept by using the PDH feedback loop. An experiment is accomplished. The frequency responses of the FP interferometer are achieved with little measurement error induced by high-order sidebands, and no repeated frequency response appears even when the test time reaches up to 30 min. This novel method is simple and accurate, and would be used for charactering the symmetric ultra-high Q optical devices. ? 2019 Elsevier B.V.Accession Number: 20192006913035 -
Record 31 of
Title:Disentangling the Luminescent Mechanism of Cs4PbBr6 Single Crystals from an Ultrafast Dynamics Perspective
Author(s):Liu, Rui-Tong(1); Zhai, Xin-Ping(1); Zhu, Zhi-Yuan(1); Sun, Bing(1); Liu, Duan-Wu(1); Ma, Bo(1); Zhang, Ze-Qi(1); Sun, Chun-Lin(1); Zhu, Bing-Li(2); Zhang, Xiao-Dong(3); Wang, Qiang(1); Zhang, Hao-Li(1)Source: Journal of Physical Chemistry Letters Volume: 10 Issue: 21 DOI: 10.1021/acs.jpclett.9b02590 Published: November 7, 2019Abstract:New all-inorganic perovskites like Cs4PbBr6 provide rich luminescent tools and particularly novel physical insights, including their zero-dimensional structure and controversial emitting mechanism. The ensuing debate over the origin of the luminescence of Cs4PbBr6 inspired us to tackle the issue through fabricating high-quality Cs4PbBr6 single crystals and employing ultrafast dynamics study. Upon photoexcitation, Cs4PbBr6 underwent dynamics steps distinct from that of CsPbBr3, including exciton migration to the defect level on a time scale of several hundred femtoseconds, exciton relaxation within the defect states on the picosecond time scale, and exciton recombination from the subnanosecond to nanosecond time scale. The observation disclosed that crystal defects of Cs4PbBr6 induced green emission while CsPbBr3 mainly relied on quantum confinement to emit at room temperature. The study provides an in-depth understanding of the photoinduced multistep dynamics steps of Cs4PbBr6 associated with display and photovoltaic applications, establishing Cs4PbBr6 as a new candidate for uses associated with the perovskite family of materials. Copyright ? 2019 American Chemical Society.Accession Number: 20194307588313 -
Record 32 of
Title:High Q RF transversal filter based on an 80-channel integrated microcomb source
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(1); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5,6,7); Mitchell, Arnan(2); Moss, David J.(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11200 Issue: DOI: 10.1117/12.2541202 Published: 2019Abstract:We demonstrate a high-Q RF transversal filter based on a 49GHz-FSR integrated microcomb source that provides 80 taps across the C-band. By employing an on-chip micro-ring resonator, we generate a broadband Kerr comb with a large number of comb lines and use it as a high-quality multi-wavelength source. A Q factor of 73.7, an out-of-band rejection of 48.9 dB, and a wide tunable range are demonstrated. The experimental results verify the feasibility of our approach as a solution towards implementing highly reconfigurable MPFs with a large tap number and reduced system complexity. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20200808205135 -
Record 33 of
Title:Microcomb-Based Photonic Local Oscillator for Broadband Microwave Frequency Conversion
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(1); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5,6,7); Mitchell, Arnan(2); Moss, David J.(1)Source: 2019 Optical Fiber Communications Conference and Exhibition, OFC 2019 - Proceedings Volume: Issue: DOI: 10.1364/ofc.2019.th3c.2 Published: April 22, 2019Abstract:We report a broadband microwave mixer based on an integrated micro-comb source, with a photonic local oscillator at 48.9 GHz, a conversion efficiency of -6.8 dB and a spurious suppression ratio of over 43.5 dB. ? 2019 OSA.Accession Number: 20192006917665 -
Record 34 of
Title:One-dimensional solitons in fractional Schr?dinger equation with a spatially modulated nonlinearity: nonlinear lattice
Author(s):Zeng, Liangwei(1,2); Zeng, Jianhua(1,2)Source: arXiv Volume: Issue: DOI: null Published: September 21, 2019Abstract:The existence and stability of stable bright solitons in one-dimensional (1D) media with a spatially periodical modulated Kerr nonlinearity are demonstrated by means of the linear-stability analysis and in direct numerical simulations. The nonlinear potential landscape can balance the fractional-order diffraction and thus stabilizes the solitons, making the model unique and governed by the recently introduced fractional Schr?dinger equation with a self-focusing cubic nonlinear lattice. Both 1D fundamental and multipole solitons (in forms of dipole and tripole ones) are found, which occupy one or three cells of the nonlinear lattice respectively, depending on the soliton’s power (intensity). We find that the profiles of the predicted soliton families are impacted intensely by the Lévy index α which denotes the level of fractional Laplacian, so does to their stability. The stabilization of soliton families is possible if α exceeds a threshold value, below which the balance between fractional-order diffraction and the spatially modulated focusing nonlinearity will be broken. Copyright ? 2019, The Authors. All rights reserved.Accession Number: 20200253873 -
Record 35 of
Title:Photonic wideband RF mixer based on an integrated microcomb source
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(1); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5,6,7); Mitchell, Arnan(2); Moss, David J.(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11200 Issue: DOI: 10.1117/12.2541201 Published: 2019Abstract:A broadband microwave mixer is demonstrated based on an integrated optical micro-comb source, with an operation bandwidth up to over 60 GHz, a conversion efficiency of-6.8 dB and a spurious suppression ratio of over 43.5 dB, and experimentally verify the RF performance up to 40 GHz. This approach to realizing microwave mixers offers reduced complexity, size, and potential cost for a wide range of applications to microwave systems. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20200808205246 -
Record 36 of
Title:One-dimensional gap solitons in quintic and cubic-quintic fractional nonlinear schr?dinger equations with a periodically modulated linear potential
Author(s):Zeng, Liangwei(1,2); Zeng, Jianhua(1,2)Source: arXiv Volume: Issue: DOI: null Published: September 21, 2019Abstract:Competing nonlinearities, such as the cubic (Kerr) and quintic nonlinear terms whose strengths are of opposite signs (the coefficients in front of the nonlinearities), exist in various physical media (in particular, in optical and matter-wave media). A benign competition between self-focusing cubic and self-defocusing quintic nonlinear nonlinearities (known as cubic-quintic model) plays an important role in creating and stabilizing the self-trapping of D-dimensional localized structures, in the contexts of standard nonlinear Schr?dinger equation. We incorporate an external periodic potential (linear lattice) into this model and extend it to the space-fractional scenario that begins to surface in very recent years—the nonlinear fractional Schr?dinger equation (NLFSE), therefore obtaining the cubic-quintic or the purely quintic NLFSE, and investigate the propagation and stability properties of self-trapped modes therein. Two types of one-dimensional localized gap modes are found, including the fundamental and dipole-mode gap solitons. Employing the techniques based on the linear-stability analysis and direct numerical simulations, we get the stability regions of all the localized modes; and particularly, the anti-Vakhitov-Kolokolov criterion applies for the stable portions of soliton families generated in the frameworks of quintic-only nonlinearity and competing cubic-quintic nonlinear terms. Copyright ? 2019, The Authors. All rights reserved.Accession Number: 20200255553