2020
2020
-
Record 49 of
Title:Broadband RF channelization using microcombs
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(2); Boes, Andreas(2); Nguyen, Thach G.(3); Chu, Sai T.(1); Little, Brent E.(4); Morandotti, Roberto(1); Mitchell, Arnan(1); Moss, David J.(1)Source: 2020 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2020 - Proceedings Volume: Issue: DOI: 10.1364/CLEOPR.2020.C7F_4 Published: August 2020Abstract:We demonstrate RF channelizers based on 49GHz microcombs. 92 parallel channels and an instantaneous bandwidth of 8.08GHz are achieved for high-resolution RF spectral channelization. This approach is promising for integrated photonic RF receivers. ? 2020 IEEE.Accession Number: 20205209688195 -
Record 50 of
Title:All-dielectric metasurface with multi-function in the near-infrared band
Author(s):Zhang, Xiaodong(1); Kong, Depeng(2); Liu, Sujuan(1); Wang, Haiyan(1)Source: Journal of the Optical Society of America A: Optics and Image Science, and Vision Volume: 37 Issue: 11 DOI: 10.1364/JOSAA.398245 Published: November 2020Abstract:This paper presents an approach to design the all-dielectric metasurface with multi-function in the near-infrared range of 1.5–1.6 μm. Based on the geometric phase principle, the all-dielectric metasurface is composed of the Si nanopillar and the SiO2 substrate as an emitter unit distributed in a 21 × 21 array. Under the incidence of the circularly polarized light at 1550 nm, the metasurface works as a vortex-beam generator with high performance which generates the vortex beam with topological charges of ±1, and the mode purity of the vortex beam is 90.66%. Under the incidence of the linearly polarized light at 1550 nm, the metasurface also works as the azimuthally/radially polarized beam generator with high performance, and the purities of the azimuthally and the radially polarized beams are 92.52% and 91.02%, respectively. Moreover, the metasurface generates different output spots under the different incident lights which can be applied to optical encryption, and the metasurface with the phase gradient also can be used as the dual-channel encoder/decoder in optical communication. The simulated results are in good agreement with the theoretical derivation. The designed metasurface may become a potential candidate as a multi-function photon device in the integrated optical system in the future. ? 2020 Optical Society of America.Accession Number: 20220811703991 -
Record 51 of
Title:Effects of axial ultrasonic vibration on grinding quality in peripheral grinding and end grinding of ULE
Author(s):Sun, Guoyan(1,2); Shi, Feng(1); Ma, Zhen(2)Source: International Journal of Advanced Manufacturing Technology Volume: 109 Issue: 7-8 DOI: 10.1007/s00170-020-05761-5 Published: August 1, 2020Abstract:Axial ultrasonic vibration–assisted grinding has been widely proved to be effective on the ground quality as well as efficiency for hard and brittle materials. However, the deference of two typical modes, axial ultrasonic vibration–assisted peripheral grinding (AUPG, vibration directions are parallel to the ground surface) and axial ultrasonic vibration–assisted end grinding (AUEG, vibration directions are vertical to the ground surface), exerting on the grinding process has not yet been thoroughly investigated. In this paper, the single grain kinematic functions corresponding to AUPG and AUEG have been created to theoretically analyze the interactional mechanism of peripheral grinding and end grinding respectively. For AUPG and AUEG, their axial ultrasonic vibrations are capable of increasing the dynamic contact length, decreasing the chip thickness, but their different effects on grinding behavior need further investigation. A series of comparative experiments have been conducted subsequently, and the results show that under the identical material removal rate, axial vibration in AUPG and AUEG can decrease the grinding forces, while AUEG is with a lower one than AUPG with a factor of 39.80%. With regard to the ground surface quality and subsurface damage, AUPG shows a positive effect while AUEG shows a negative role. The grinding kinematic, grinding force, ground surface quality, and subsurface damage have been analyzed in terms of the axial ultrasonic vibration effect on the peripheral grinding and end grinding behavior theoretically and experimentally, the conclusion will be meaningful for researchers to choose the appropriate approach in applying axial ultrasonic vibration to grinding optical elements. ? 2020, Springer-Verlag London Ltd., part of Springer Nature.Accession Number: 20203109001683 -
Record 52 of
Title:Openmre: A numerical platform for mre study
Author(s):Li, Bing Nan(1); Shan, Xiang(1); Xiang, Kui(2); Kobayashi, Etsuko(3); Wang, Meng(4); Li, Xuelong(5)Source: IEEE Transactions on Systems, Man, and Cybernetics: Systems Volume: 50 Issue: 3 DOI: 10.1109/TSMC.2017.2717481 Published: March 2020Abstract:Magnetic resonance elastography (MRE) offers a noninvasive solution to visualize the mechanical properties of soft tissue, but the study suffers from expensive magnetic resonance scanning. Moreover, translating MRE wave images into soft tissue elasticity is a nontrivial issue for clinical professionals and healthcare practitioners. An interactive system-OpenMRE-is thus developed with the aid of ImageJ for numerical MRE study. It is comprised of two comparatively independent toolkits, namely MREA for simulation and MREP for interpretation. MREA mainly deals with the forward problem of MRE, and provides a numerical platform to determine the propagation and distribution of specially designed elastic wave. It is possible to numerically study some state-of-The-Art paradigms including multisource and multifrequency MRE. The resultant wave images are interpretable in MREP that is designed for the inverse problem of MRE. It consists of the algorithms for phase unwrapping, directional filtering, and elasticity reconstruction. In a word, OpenMRE offers the MRE community a convenient and well-functioning system for interactive MRE study. ? 2013 IEEE.Accession Number: 20172903947104 -
Record 53 of
Title:Design of an Eight-band Filter Imaging System
Author(s):Sun, Bang-Yong(1,2); Yuan, Nian-Zeng(1); Hu, Bing-Liang(2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 49 Issue: 5 DOI: 10.3788/gzxb20204905.0511001 Published: May 1, 2020Abstract:Aiming at the problems of fuzzy reconstructed image and loss of high-frequency information caused by low sampling rate of multi-spectral filter array, sparse Raw data and so on, a new eight-spectral filter array distribution scheme is proposed, which is based on neighborhood gradient extension method to reconstruct the spectral Raw image. Firstly, based on the binary tree generation method, an eight-band filter distribution scheme with equal spatial probability ratio is designed in the 4×4 array of repetitive arrays. Then, for the sparse Raw image directly acquired by the sensor, the gradient information of sampling points in each spectrum segment is calculated. On the basis of maintaining the image structure features and texture information, the pixel value and gradient value of sampling points in the neighborhood are used to reconstruct the unsampled points, so as to obtain the complete spectral image information. Finally, based on the reconstructed eight-band spectral images, the pseudo-inverse matrix method is used to reconstruct the 31-band spectral values of each pixel position. The results show that compared with the mainstream image reconstruction methods, the proposed algorithm improves the peak signal-to-noise ratio and composite peak signal-to-noise ratio of reconstructed eight-band spectral images, reduces the mean square error of the spectrum, and better preserves the texture and edges of the image. Reduced artifacts such as color artifacts and image blur in multi-spectral filter array imaging. ? 2020, Science Press. All right reserved.Accession Number: 20202708884361 -
Record 54 of
Title:Neural-Adaptive Finite-Time Formation Tracking Control of Multiple Nonholonomic Agents with a Time-Varying Target
Author(s):Zhou, Kai-Bo(1); Wu, Xiao-Kang(1); Ge, Ming-Feng(2); Liang, Chang-Duo(2); Hu, Bing-Liang(3)Source: IEEE Access Volume: 8 Issue: DOI: 10.1109/ACCESS.2020.2980894 Published: 2020Abstract:This paper investigates the leader-following formation tracking problem (FTP) for multiple nonholonomic agent systems (MNASs) in the presence of external disturbances and parametric uncertainties, where both the kinematics and dynamics of the agents are taken into consideration. A novel finite-time distributed controller-estimator algorithm (DCEA) is designed to handle such a challenging problem. Based on Lyapunov stability method, the sufficient conditions for finite-time stability of the closed-loop system are derived. Finally, the simulation results are presented to demonstrate the effectiveness and the robustness of the proposed DCEA. ? 2013 IEEE.Accession Number: 20201708572736 -
Record 55 of
Title:Prediction of end-of-season tuber yield and tuber set in potatoes using in-season uav-based hyperspectral imagery and machine learning
Author(s):Sun, Chen(1,2); Feng, Luwei(1); Zhang, Zhou(1); Ma, Yuchi(1); Crosby, Trevor(3); Naber, Mack(3); Wang, Yi(3)Source: Sensors (Switzerland) Volume: 20 Issue: 18 DOI: 10.3390/s20185293 Published: September 2, 2020Abstract:Potato is the largest non-cereal food crop in the world. Timely estimation of end-of-season tuber production using in-season information can inform sustainable agricultural management decisions that increase productivity while reducing impacts on the environment. Recently, unmanned aerial vehicles (UAVs) have become increasingly popular in precision agriculture due to their flexibility in data acquisition and improved spatial and spectral resolutions. In addition, compared with natural color and multispectral imagery, hyperspectral data can provide higher spectral fidelity which is important for modelling crop traits. In this study, we conducted end-of-season potato tuber yield and tuber set predictions using in-season UAV-based hyperspectral images and machine learning. Specifically, six mainstream machine learning models, i.e., ordinary least square (OLS), ridge regression, partial least square regression (PLSR), support vector regression (SVR), random forest (RF), and adaptive boosting (AdaBoost), were developed and compared across potato research plots with different irrigation rates at the University of Wisconsin Hancock Agricultural Research Station. Our results showed that the tuber set could be better predicted than the tuber yield, and using the multi-temporal hyperspectral data improved the model performance. Ridge achieved the best performance for predicting tuber yield (R2 = 0.63) while Ridge and PLSR had similar performance for predicting tuber set (R2 = 0.69). Our study demonstrated that hyperspectral imagery and machine learning have good potential to help potato growers efficiently manage their irrigation practices. ? 2020 by the authors. Licensee MDPI, Basel, Switzerland.Accession Number: 20203809198874 -
Record 56 of
Title:Anomalous ring-connected optical vortex array
Author(s):Li, Xinzhong(1,2); Zhang, Hao(1)Source: Optics Express Volume: 28 Issue: 9 DOI: 10.1364/OE.390985 Published: April 27, 2020Abstract:In this study, an anomalous ring-connected optical vortex array (ARC-OVA) via the superposition of two grafted optical vortices (GOVs) with different topological charges (TCs) has been proposed. Compared with conventional OVAs, the signs and distribution of the OVs can be individually modulated, while the number of OVs remains unchanged. In particular, the positive and negative OVs simultaneously appear in the same intensity ring. Additionally, the size of the dark core occupied by the OV can be modulated, and the specific dark core is shared by a pair of plus–minus OVs. This work deepens our knowledge about connected OVAs and facilitates new potential applications, especially in particle manipulation and optical measurement. ? 2020 Optical Society of America under the terms of the OSA Open Access Publishing AgreementAccession Number: 20202108694721 -
Record 57 of
Title:Enhanced four-wave mixing in micro-ring resonators with integrated 2D layered graphene oxide films
Author(s):Wu, Jiayang(1); Yang, Yunyi(1); Zhang, Yuning(1); Qu, Yang(1); Jia, Linnan(1); Xu, Xingyuan(1); Chu, Sai T.(2); Little, Brent E.(3); Morandotti, Roberto(4); Jia, Baohua(1); Mossa, David J.(1)Source: 2020 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2020 - Proceedings Volume: Issue: DOI: 10.1364/CLEOPR.2020.C11E_4 Published: August 2020Abstract:Two-dimensional layered graphene oxide films are integrated with micro-ring resonators to experimentally demonstrate enhanced four-wave mixing, achieving up to \sim7.6 - dB enhancement in conversion efficiency for a uniformly coated device and \sim10.3 - dB for a patterned device. ? 2020 IEEE.Accession Number: 20205209687965 -
Record 58 of
Title:Space Debris Detection Using Feature Learning of Candidate Regions in Optical Image Sequences
Author(s):Xi, Jiangbo(1); Xiang, Yaobing(2); Ersoy, Okan K.(3); Cong, Ming(1); Wei, Xin(4,5); Gu, Junkai(1)Source: IEEE Access Volume: 8 Issue: DOI: 10.1109/ACCESS.2020.3016761 Published: 2020Abstract:Space debris detection is important in space situation awareness and space asset protection. In this article, we propose a method to detect space debris using feature learning of candidate regions. The acquired optical image sequences are first processed to remove hot pixels and flicker noise, and the nonuniform background information is removed by the proposed one dimensional mean iteration method. Then, the feature learning of candidate regions (FLCR) method is proposed to extract the candidate regions and to detect space debris. The candidate regions of space debris are precisely extracted, and then classified by a trained deep learning network. The feature learning model is trained using a large number of simulated space debris with different signal to noise ratios (SNRs) and motion parameters, instead of using real space debris, which make it difficult to extract a sufficient number of real space debris with diverse parameters in optical image sequences. Finally, the candidate regions are precisely placed in the optical image sequences. The experiment is performed using the simulated data and acquired image sequences. The results show that the proposed method has good performance when estimating and removing background, and it can detect low SNR space debris with high detection probability. ? 2013 IEEE.Accession Number: 20203809183223 -
Record 59 of
Title:Squared peak-to-peak algorithm for the spectral interrogation of short-cavity fiber-optic Fabry–Perot sensors
Author(s):Chen, Haibin(1,2); Zhang, Yao(1,4); Li, Yang(2,3); Jing, Xin(2,3); Yuan, Suzhe(2,3); Zhang, Xiongxing(1,4); Wang, Wei(1,4); Liu, Rong(1,4); Guo, Quanmin(5)Source: Applied Optics Volume: 59 Issue: 4 DOI: 10.1364/AO.382169 Published: February 1, 2020Abstract:The cavity length of short-cavity Fabry–Perot (FP) sensors cannot be effectively interrogated using the conventional peak-to-peak method if the spectrum of the exciting source is not wide enough. In this paper, we propose a squared peak-to-peak algorithm for interrogation of short-cavity fiber-optic FP sensors. By squaring the DC-filtered reflection spectrum of an FP sensor in the frequency domain, we produce an additional peak, with which the cavity length of a sensor can be estimated using the same calculations as performed with the conventional peak-to-peak method. For investigation of the feasibility of this technique, we conducted simulations and practical experiments analyzing fiber-optic FP sensors with cavity lengths in the range of 15–25 μm. The maximum error in cavity length estimated using the proposed algorithm in experiments was 0.030 μm. ? 2020 Optical Society of America.Accession Number: 20200508115914 -
Record 60 of
Title:A method for improving the detection accuracy of the spot position of the four-quadrant detector in a free space optical communication system
Author(s):Wang, Xuan(1,2,3); Su, Xiuqin(1); Liu, Guizhong(2); Han, Junfeng(1); Wang, Kaidi(1,3); Zhu, Wenhua(1,3)Source: Sensors (Switzerland) Volume: 20 Issue: 24 DOI: 10.3390/s20247164 Published: December 2, 2020Abstract:In a free space optical communication system, the beacon light will lose most of its energy after long-distance transmission, and the background light from the universe will strongly interfere with it. The four-quadrant detector (4QD) has been widely used in optical communication systems as a high-precision spot position detection sensor. However, if the light signal falling on the 4QD is too weak, the electrical signal of the output position will be very weak, and it will easily be affected by or even submerged in noise. To solve this problem, we propose a method for improving the spot position detection accuracy. First, we analyzed the solution relationship between the actual position of the spot and the output signal of the 4QD, with a Gaussian spot as the incident light model. The output current signal of the detector was then transimpedance-amplified by an analog circuit and the output voltage signal with noise was digitally filtered. An error compensation factor and the gap size of the detector were introduced into the traditional spot position detection model. High-precision spot position information for the 4QD in a complex environment was then obtained using the improved spot position detection model. Experimental results show that the maximum spot position detection error for this method was only 0.0277 mm, and the root mean square error was 0.0065 mm, when the 4QD was in a high background noise environment. The spot position detection accuracy was significantly improved compared with traditional detection algorithms. Real-time detection can therefore be achieved in practical applications. ? 2020 by the authors. Licensee MDPI, Basel, Switzerland.Accession Number: 20205109666536