2024

• Record 121 of
  
  Title:Random laser emission at 1064 and 1550 nm in a Er/Yb co-doped fiber-based dual-wavelength random fiber laser
  
  Author(s):Li, Zhe; She, Shengfei; Li, Gang; Gao, Qi; Ju, Pei; Gao, Wei; Sun, Chuandong; Wang, Yishan
  Source: OPTICS EXPRESS  Volume: 32  Issue: 4  DOI: 10.1364/OE.508025  Published: 2024  
  Abstract:Dual-wavelength fiber lasers operating with a wide spectral separation are of considerable importance for many applications. In this study, we propose and experimentally explore an all-fiberized dual-wavelength random fiber laser with bi-directional laser output operating at 1064 and 1550 nm, respectively. A specially designed Er/Yb co-doped fiber, by optimizing the concentrations of the co-doped Er, Yb, Al and P, was developed for simultaneously providing Er ions gain and Yb ions gain for RFL. Two spans of single mode passive fibers are employed to providing random feedback for 1064 and 1550 nm random lasing, respectively. The RFL generates 5.35 W at 1064 nm and 6.61 W at 1550 nm random lasers. Two power amplifiers (PA) enhance the seed laser to 50 W at 1064 nm with a 3 dB bandwidth of 0.31 nm and 20 W at 1550 nm with a 3 dB bandwidth of 1.18 nm. Both the short- and long-term time domain stabilities are crucial for practical applications. The output lasers of 1064 and 1550 nm PAs are in the single transverse mode operating with a nearly Gaussian profile. To the best of our knowledge, this is the first demonstration of a dual-wavelength RFL, with a spectral separation as far as about 500 nm in an all -fiber configuration.
  Accession Number:
  ISSN: 1094-4087
  eISSN:
• Record 122 of
  
  Title:Snapshot compressive imaging at 855 million frames per second for aluminium planar wire array Z-pinch
  
  Author(s):Yao, Zhiming; Ji, Chao; Sheng, Liang; Song, Yan; Liu, Zhen; Han, Changcai; Zhou, Haoyu; Duan, Baojun; Li, Yang; Hei, Dongwei; Tian, Jinshou; Xue, Yanhua
  Source: OPTICS EXPRESS  Volume: 32  Issue: 4  DOI: 10.1364/OE.512450  Published: 2024  
  Abstract:This paper present a novel, integrated compressed ultrafast photography system for comprehensive measurement of the aluminium planar wire array Z-Pinch evolution process. The system incorporates a large array streak camera and embedded encoding to improve the signal-to-noise ratio. Based on the QiangGuang-I pulsed power facility, we recorded the complete continuous 2D implosion process of planar wire array Z-Pinch for the first time. Our results contribute valuable understanding of imploding plasma instabilities and offer direction for the optimization of Z-Pinch facilities.
  Accession Number:
  ISSN: 1094-4087
  eISSN:
• Record 123 of
  
  Title:Feasible spindle speed interval identification method for large aeronautical component robotic milling system
  
  Author(s):Wang, Zhanxi; Zhang, Banghai; Gao, Wei; Qin, Xiansheng; Zhang, Yicha; Zheng, Chen
  Source: MECHATRONICS  Volume: 99  Issue:   DOI: 10.1016/j.mechatronics.2024.103143  Published: 2024  
  Abstract:Robotic machining systems have been widely implemented in the assembly sites of large components of aircraft, such as wings, aircraft engine rooms, and wing boxes. Milling is the first step in aircraft assembly. It is considered one of the most significant processes because the quality of the subsequent drilling, broaching, and riveting steps depend strongly on the milling accuracy. However, the chatter phenomenon may occur during the milling process because of the low rigidity of the components of the robotic milling system (i.e., robots, shape-preserving holders, and rod parts). This may result in milling failure or even fracture of the robotic milling system. This paper presents a feasible spindle speed interval identification method for large aeronautical component milling systems to eliminate the chatter phenomenon. It is based on the chatter stability model and the analysis results of natural frequency and harmonic response. Firstly, the natural frequencies and harmonics of the main components of the robot milling system are analyzed, and the spindle speed that the milling system needs to avoid is obtained. Then, a flutter stability model considering the instantaneous cutting thickness is established, from which the critical cutting depth corresponding to the spindle speed can be obtained. Finally, the spindle speed interval of the robotic milling system could be optimized based on the results obtained from the chatter stability model and the analysis result of the natural frequency and harmonic response of the milling system. The effectiveness of the proposed spindle speed interval identification method is validated through time-domain simulation and experimental results of the large aeronautical component milling system.
  Accession Number: 103143
  ISSN: 0957-4158
  eISSN:
• Record 124 of
  
  Title:Effective correction of dissolved organic carbon interference in nitrate detection using ultraviolet spectroscopy combined with the equivalent concentration offset method
  
  Author(s):Dong, Jing; Tang, Junwu; Wu, Guojun; Xin, Yu; Li, Ruizhuo; Li, Yahui
  Source: RSC ADVANCES  Volume: 14  Issue: 8  DOI: 10.1039/d3ra08000e  Published: 2024  
  Abstract:Nitrate contamination in water sources poses a substantial environmental and health risk. However, accurate detection of nitrate in water, particularly in the presence of dissolved organic carbon (DOC) interference, remains a significant analytical challenge. This study investigates a novel approach for the reliable detection of nitrate in water samples with varying levels of DOC interference based on the equivalent concentration offset method. The characteristic wavelengths of DOC were determined based on the first-order derivatives, and a nitrate concentration prediction model based on partial least squares (PLS) was established using the absorption spectra of nitrate solutions. Subsequently, the absorption spectra of the nitrate solutions were subtracted from that of the nitrate-DOC mixed solutions to obtain the difference spectra. These difference spectra were introduced into the nitrate prediction model to calculate the equivalent concentration offset values caused by DOC. Finally, a DOC interference correction model was established based on a binary linear regression between the absorbances at the DOC characteristic wavelengths and the DOC-induced equivalent concentration offset values of nitrate. Additionally, a modeling wavelength selection algorithm based on a sliding window was proposed to ensure the accuracy of the nitrate concentration prediction model and the equivalent concentration offset model. The experimental results demonstrated that by correcting the DOC-induced offsets, the relative error of nitrate prediction was reduced from 94.44% to 3.36%, and the root mean square error of prediction was reduced from 1.6108 mg L-1 to 0.1037 mg L-1, which is a significant correction effect. The proposed method applied to predict nitrate concentrations in samples from two different water sources shows a certain degree of comparability with the standard method. It proves that this method can effectively correct the deviations in nitrate measurements caused by DOC and improve the accuracy of nitrate measurement. A simple and rapid method for DOC interference correction based on an equivalent concentration offset method was proposed to address the challenging issue of DOC interference in nitrate detection in aquatic environments.
  Accession Number:
  ISSN:
  eISSN: 2046-2069
• Record 125 of
  
  Title:Multiple marine algae identification based on three-dimensional fluorescence spectroscopy and multi-label convolutional neural network
  
  Author(s):Li, Ruizhuo; Gao, Limin; Wu, Guojun; Dong, Jing

  Source: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY  

  Volume: 311 DOI: 10.1016/j.saa.2024.123938  Published: 2024  

  Abstract:Accurate identification of algal populations plays a pivotal role in monitoring seawater quality. Fluorescencebased techniques are effective tools for quickly identifying different algae. However, multiple coexisting algae and their similar photosynthetic pigments can constrain the efficacy of fluorescence methods. This study introduces a multi -label classification model that combines a specific Excitation -Emission matric convolutional neural network (EEM-CNN) with three-dimensional (3D) fluorescence spectroscopy to detect single and mixed algal samples. Spectral data can be input directly into the model without transforming into images. Rectangular convolutional kernels and double convolutional layers are applied to enhance the extraction of balanced and comprehensive spectral features for accurate classification. A dataset comprising 3D fluorescence spectra from eight distinct algae species representing six different algal classes was obtained, preprocessed, and augmented to create input data for the classification model. The classification model was trained and validated using 4448 sets of test samples and 60 sets of test samples, resulting in an accuracy of 0.883 and an F1 score of 0.925. This model exhibited the highest recognition accuracy in both single and mixed algae samples, outperforming comparative methods such as ML-kNN and N-PLS-DA. Furthermore, the classification results were extended to three different algae species and mixed samples of skeletonema costatum to assess the impact of spectral similarity on multilabel classification performance. The developed classification models demonstrated robust performance across samples with varying concentrations and growth stages, highlighting CNN's potential as a promising tool for the precise identification of marine algae.

  Accession Number: 123938

  ISSN: 1386-1425

  eISSN: 1873-3557
• Record 126 of
  
  Title:Entanglement Generation of Polar Molecules via Deep Reinforcement Learning
  
  Author(s):Zhang, Zuo-Yuan; Sun, Zhaoxi; Duan, Tao; Ding, Yi-Kai; Huang, Xinning; Liu, Jin-Ming
  Source: JOURNAL OF CHEMICAL THEORY AND COMPUTATION  Volume: 20  Issue: 5  DOI: 10.1021/acs.jctc.3c01214  Published: 2024  
  Abstract:Polar molecules are a promising platform for achieving scalable quantum information processing because of their long-range electric dipole-dipole interactions. Here, we take the coupled ultracold CaF molecules in an external electric field with gradient as qubits and concentrate on the creation of intermolecular entanglement with the method of deep reinforcement learning (RL). After sufficient training episodes, the educated RL agents can discover optimal time-dependent control fields that steer the molecular systems from separate states to two-qubit and three-qubit entangled states with high fidelities. We analyze the fidelities and the negativities (characterizing entanglement) of the generated states as a function of training episodes. Moreover, we present the population dynamics of the molecular systems under the influence of control fields discovered by the agents. Compared with the schemes for creating molecular entangled states based on optimal control theory, some conditions (e.g., molecular spacing and electric field gradient) adopted in this work are more feasible in the experiment. Our results demonstrate the potential of machine learning to effectively solve quantum control problems in polar molecular systems.
  Accession Number:
  ISSN: 1549-9618
  eISSN: 1549-9626
• Record 127 of
  
  Title:Three-dimensional Bose-Einstein gap solitons in optical lattices with fractional diffraction
  
  Author(s):Chen, Zhiming; Liu, Xiuye; Xie, Hongqiang; Zeng, Jianhua
  Source: CHAOS SOLITONS & FRACTALS  Volume: 180  Issue:   DOI: 10.1016/j.chaos.2024.114558  Published: 2024  
  Abstract:Compared with low-dimensional solitons that are widely studied in various realizable nonlinear physical systems, the properties and dynamics of three-dimensional solitons and vortices have not been well disclosed yet. Using numerical simulations and theoretical analysis, we here address the existence, structural property, and dynamics of three-dimensional gap solitons and vortices (with topological charge s = 1) of Bose-Einstein condensates moving by Levy flights (characterized by fractional diffraction operators, Levy index 1 < alpha <= 2) in optical lattices. We stress that previously the localized modes have only been revealed in low-dimensional nonlinear fractional systems in one- and two-dimensional periodic potentials, our study presented here thus drives the associated nonlinear-wave research into three-dimensional configurations. The three-dimensional optical lattices exhibit a nontrivial wide band-gap feature, within which the matter-wave localized gap modes could be excited. The stability and instability regions of both three-dimensional gap modes are obtained via direct perturbed simulations, shedding light on multidimensional soliton physics in nonlinear fractional systems with periodic potentials.
  Accession Number: 114558
  ISSN: 0960-0779
  eISSN: 1873-2887
• Record 128 of
  
  Title:Room-temperature MoTe2/InSb heterostructure large-area terahertz detector
  
  Author(s):Wang, Jiatong; Zhang, Min; Zhou, Zhiwen; Li, Ling; Song, Qi; Yan, Peiguang
  Source: INFRARED PHYSICS & TECHNOLOGY  Volume: 137  Issue:   DOI: 10.1016/j.infrared.2024.105190  Published: 2024  
  Abstract:As a building block for terahertz system, terahertz detector is expected to achieve high-performance, roomtemperature, low-cost and large-area detection available. However, the state-of-the-art technologies still suffer from various drawbacks. This paper presents a MoTe2/InSb heterostructure large-area terahertz detector. With the photoactive region of heterostructure, carriers are allowed to assemble within the interface due to the carrier mobility difference, resulting in detection sensitivity improvement. The structures and bonding of MoTe2/InSb heterostructure were characterized by Raman spectroscopy. Besides, large-scale interdigital electrodes with subwavelength spacing are employed at the bottom of photoactive region, which contrasts with normal electrodes coated on both sides of the active layer, endowing a large effective detection area of 2 mm x 6.65 mm with the detector. Subwavelength electrodes spacing not only facilitates the directional migration of carriers, but also induces electromagnetic induced well (EIW) effects to obtain extraordinary performance. As a result, the detector achieves a noise equivalent power (NEP) of 2.66 pW Hz-1/2 and a detectivity (D*) of 0.53 x 1012 cm Hz1/ 2 W-1 under 0.1 THz radiation at room temperature. The proposed high-performance terahertz detector exhibits remarkable prospects in varieties of applications.
  Accession Number: 105190
  ISSN: 1350-4495
  eISSN: 1879-0275
• Record 129 of
  
  Title:STCF conceptual design report (Volume 1): Physics & detector
  
  Author(s):Achasov, M.; Ai, X. C.; An, L. P.; Aliberti, R.; An, Q.; Bai, X. Z.; Bai, Y.; Bakina, O.; Barnyakov, A.; Blinov, V.; Bobrovnikov, V.; Bodrov, D.; Bogomyagkov, A.; Bondar, A.; Boyko, I.; Bu, Z. H.; Cai, F. M.; Cai, H.; Cao, J. J.; Cao, Q. H.; Cao, X.; Cao, Z.; Chang, Q.; Chao, K. T.; Chen, D. Y.; Chen, H.; Chen, H. X.; Chen, J. F.; Chen, K.; Chen, L. L.; Chen, P.; Chen, S. L.; Chen, S. M.; Chen, S.; Chen, S. P.; Chen, W.; Chen, X.; Chen, X. F.; Chen, X. R.; Chen, Y.; Chen, Y. Q.; Cheng, H. Y.; Cheng, J.; Cheng, S.; Cheng, T. G.; Dai, J. P.; Dai, L. Y.; Dai, X. C.; Dedovich, D.; Denig, A.; Denisenko, I.; Dias, J. M.; Ding, D. Z.; Dong, L. Y.; Dong, W. H.; Druzhinin, V.; Du, D. S.; Du, Y. J.; Du, Z. G.; Duan, L. M.; Epifanov, D.; Fan, Y. L.; Fang, S. S.; Fang, Z. J.; Fedotovich, G.; Feng, C. Q.; Feng, X.; Feng, Y. T.; Fu, J. L.; Gao, J.; Gao, Y. N.; Ge, P. S.; Geng, C. Q.; Geng, L. S.; Gilman, A.; Gong, L.; Gong, T.; Gou, B.; Gradl, W.; Gu, J. L.; Guevara, A.; Gui, L. C.; Guo, A. Q.; Guo, F. K.; Guo, J. C.; Guo, J.; Guo, Y. P.; Guo, Z. H.; Guskov, A.; Han, K. L.; Han, L.; Han, M.; Hao, X. Q.; He, J. B.; He, S. Q.; He, X. G.; He, Y. L.; He, Z. B.; Heng, Z. X.; Hou, B. L.; Hou, T. J.; Hou, Y. R.; Hu, C. Y.; Hu, H. M.; Hu, K.; Hu, R. J.; Hu, W. H.; Hu, X. H.; Hu, Y. C.; Hua, J.; Huang, G. S.; Huang, J. S.; Huang, M.; Huang, Q. Y.; Huang, W. Q.; Huang, X. T.; Huang, X. J.; Huang, Y. B.; Huang, Y. S.; Husken, N.; Ivanov, V.; Ji, Q. P.; Jia, J. J.; Jia, S.; Jia, Z. K.; Jiang, H. B.; Jiang, J.; Jiang, S. Z.; Jiao, J. B.; Jiao, Z.; Jing, H. J.; Kang, X. L.; Kang, X. S.; Ke, B. C.; Kenzie, M.; Khoukaz, A.; Koop, I.; Kravchenko, E.; Kuzmin, A.; Lei, Y.; Levichev, E.; Li, C. H.; Li, C.; Li, D. Y.; Li, F.; Li, G.; Li, G.; Li, H. B.; Li, H.; Li, H. N.; Li, H. J.; Li, H. L.; Li, J. M.; Li, J.; Li, L.; Li, L.; Li, L. Y.; Li, N.; Li, P. R.; Li, R. H.; Li, S.; Li, T.; Li, W. J.; Li, X.; Li, X. H.; Li, X. Q.; Li, X. H.; Li, Y.; Li, Y. Y.; Li, Z. J.; Liang, H.; Liang, J. H.; Liang, Y. T.; Liao, G. R.; Liao, L. Z.; Liao, Y.; Lin, C. X.; Lin, D. X.; Lin, X. S.; Liu, B. J.; Liu, C. W.; Liu, D.; Liu, F.; Liu, G. M.; Liu, H. B.; Liu, J.; Liu, J. J.; Liu, J. B.; Liu, K.; Liu, K. Y.; Liu, K.; Liu, L.; Liu, Q.; Liu, S. B.; Liu, T.; Liu, X.; Liu, Y. W.; Liu, Y.; Liu, Y. L.; Liu, Z. Q.; Liu, Z. Y.; Liu, Z. W.; Logashenko, I.; Long, Y.; Lu, C. G.; Lu, J. X.; Lu, N.; Lu, Q. F.; Lu, Y.; Lu, Y.; Lu, Z.; Lukin, P.; Luo, F. J.; Luo, T.; Luo, X. F.; Luo, Y. H.; Lyu, H. J.; Lyu, X. R.; Ma, J. P.; Ma, P.; Ma, Y.; Ma, Y. M.; Maas, F.; Malde, S.; Matvienko, D.; Meng, Z. X.; Mitchell, R.; Nefediev, A.; Nefedov, Y.; Olsen, S. L.; Ouyang, Q.; Pakhlov, P.; Pakhlova, G.; Pan, X.; Pan, Y.; Passemar, E.; Pei, Y. P.; Peng, H. P.; Peng, L.; Peng, X. Y.; Peng, X. J.; Peters, K.; Pivovarov, S.; Pyata, E.; Qi, B. B.; Qi, Y. Q.; Qian, W. B.; Qian, Y.; Qiao, C. F.; Qin, J. J.; Qin, J. J.; Qin, L. Q.; Qin, X. S.; Qiu, T. L.; Rademacker, J.; Redmer, C. F.; Sang, H. Y.; Saur, M.; Shan, W.; Shan, X. Y.; Shang, L. L.; Shao, M.; Shekhtman, L.; Shen, C. P.; Shen, J. M.; Shen, Z. T.; Shi, H. C.; Shi, X. D.; Shwartz, B.; Sokolov, A.; Song, J. J.; Song, W. M.; Song, Y.; Song, Y. X.; Sukharev, A.; Sun, J. F.; Sun, L.; Sun, X. M.; Sun, Y. J.; Sun, Z. P.; Tang, J.; Tang, S. S.; Tang, Z. B.; Tian, C. H.; Tian, J. S.; Tian, Y.; Tikhonov, Y.; Todyshev, K.; Uglov, T.; Vorobyev, V.; Wan, B. D.; Wang, B. L.; Wang, B.; Wang, D. Y.; Wang, G. Y.; Wang, G. L.; Wang, H. L.; Wang, J.; Wang, J. H.; Wang, J. C.; Wang, M. L.; Wang, R.; Wang, R.; Wang, S. B.; Wang, W.; Wang, W. P.; Wang, X. C.; Wang, X. D.; Wang, X. L.; Wang, X. L.; Wang, X. P.; Wang, X. F.; Wang, Y. D.; Wang, Y. P.; Wang, Y. Q.; Wang, Y. L.; Wang, Y. G.; Wang, Z. Y.; Wang, Z. Y.; Wang, Z. L.; Wang, Z. G.; Wei, D. H.; Wei, X. L.; Wei, X. M.; Wen, Q. G.; Wen, X. J.; Wilkinson, G.; Wu, B.; Wu, J. J.; Wu, L.; Wu, P.; Wu, T. W.; Wu, Y. S.; Xia, L.; Xiang, T.; Xiao, C. W.; Xiao, D.; Xiao, M.; Xie, K. P.; Xie, Y. H.; Xing, Y.; Xing, Z. Z.; Xiong, X. N.; Xu, F. R.; Xu, J.; Xu, L. L.; Xu, Q. N.; Xu, X. C.; Xu, X. P.; Xu, Y. C.; Xu, Y. P.; Xu, Y.; Xu, Z. Z.; Xuan, D. W.; Xue, F. F.; Yan, L.; Yan, M. J.; Yan, W. B.; Yan, W. C.; Yan, X. S.; Yang, B. F.; Yang, C.; Yang, H. J.; Yang, H. R.; Yang, H. T.; Yang, J. F.; Yang, S. L.; Yang, Y. D.; Yang, Y. H.; Yang, Y. S.; Yang, Y. L.; Yang, Z. W.; Yang, Z. Y.; Yao, D. L.; Yin, H.; Yin, X. H.; Yokozaki, N.; You, S. Y.; You, Z. Y.; Yu, C. X.; Yu, F. S.; Yu, G. L.; Yu, H. L.; Yu, J. S.; Yu, J. Q.; Yuan, L.; Yuan, X. B.; Yuan, Z. Y.; Yue, Y. F.; Zeng, M.; Zeng, S.; Zhang, A. L.; Zhang, B. W.; Zhang, G. Y.; Zhang, G. Q.; Zhang, H. J.; Zhang, H. B.; Zhang, J. Y.; Zhang, J. L.; Zhang, J.; Zhang, L.; Zhang, L. M.; Zhang, Q. A.; Zhang, R.; Zhang, S. L.; Zhang, T.; Zhang, X.; Zhang, Y.; Zhang, Y. J.; Zhang, Y. X.; Zhang, Y. T.; Zhang, Y. F.; Zhang, Y. C.; Zhang, Y.; Zhang, Y.; Zhang, Y. M.; Zhang, Y. L.; Zhang, Z. H.; Zhang, Z. Y.; Zhang, Z. Y.; Zhao, H. Y.; Zhao, J.; Zhao, L.; Zhao, M. G.; Zhao, Q.; Zhao, R. G.; Zhao, R. P.; Zhao, Y. X.; Zhao, Z. G.; Zhao, Z. X.; Zhemchugov, A.; Zheng, B.; Zheng, L.; Zheng, Q. B.; Zheng, R.; Zheng, Y. H.; Zhong, X. H.; Zhou, H. J.; Zhou, H. Q.; Zhou, H.; Zhou, S. H.; Zhou, X.; Zhou, X. K.; Zhou, X. P.; Zhou, X. R.; Zhou, Y. L.; Zhou, Y.; Zhou, Y. X.; Zhou, Z. Y.; Zhu, J. Y.; Zhu, K.; Zhu, R. D.; Zhu, R. L.; Zhu, S. H.; Zhu, Y. C.; Zhu, Z. A.; Zhukova, V.; Zhulanov, V.; Zou, B. S.; Zuo, Y. B.
  Source: FRONTIERS OF PHYSICS  Volume: 19  Issue: 1  DOI: 10.1007/s11467-023-1333-z  Published: 2024  
  Abstract:The super tau-charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5 x 1035 cm-2 center dot s-1 or higher. The STCF will produce a data sample about a factor of 100 larger than that of the present tau-charm factory - the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R&D and physics case studies.
  Accession Number: 14701
  ISSN: 2095-0462
  eISSN: 2095-0470
• Record 130 of
  
  Title:Compensation control strategy for photoelectric stabilized platform based on disturbance observation
  
  Author(s):Chang, Sansan; Cao, Jianzhong; Pang, Ji; Zhou, Feihang; Chen, Weining
  Source: AEROSPACE SCIENCE AND TECHNOLOGY  Volume: 145  Issue:   DOI: 10.1016/j.ast.2024.108909  Published: 2024  
  Abstract:The accuracy and stability of the photoelectric stabilized platform will be inevitably affected by the friction disturbance and the base platform disturbance in the actual operation. To improve the disturbance rejection performance, two kinds of the disturbance observers are employed and compared in this paper, including the adaptive proportion-integrator observer and the robust sliding mode observer. The disturbances of the friction torque and the moving base are observed, then these observed values are compensated to the voltage loop by the feedback and feedforward, respectively. While the disturbances of the friction torque and the shaking base are compensated, the parameters of the speed stability loop are also tuned to improve the performance of this photoelectric stabilized platform. Finally, the effectiveness of the proposed method is verified by both simulations and experiments. The results show that the proposed disturbance compensation control method based on the sliding mode observer has strong robustness and can effectively reduce the impact of system disturbances.
  Accession Number: 108909
  ISSN: 1270-9638
  eISSN: 1626-3219
• Record 131 of
  
  Title:Dark Light Image-Enhancement Method Based on Multiple Self-Encoding Prior Collaborative Constraints
  
  Author(s):Guan, Lei; Dong, Jiawei; Li, Qianxi; Huang, Jijiang; Chen, Weining; Wang, Hao
  Source: PHOTONICS  Volume: 11  Issue: 2  DOI: 10.3390/photonics11020190  Published: 2024  
  Abstract:The purpose of dark image enhancement is to restore dark images to visual images under normal lighting conditions. Due to the ill-posedness of the enhancement process, previous enhancement algorithms often have overexposure, underexposure, noise increases and artifacts when dealing with complex and changeable images, and the robustness is poor. This article proposes a new enhancement approach consisting in constructing a dim light enhancement network with more robustness and rich detail features through the collaborative constraint of multiple self-coding priors (CCMP). Specifically, our model consists of two prior modules and an enhancement module. The former learns the feature distribution of the dark light image under normal exposure as an a priori term of the enhancement process through multiple specific autoencoders, implicitly measures the enhancement quality and drives the network to approach the truth value. The latter fits the curve mapping of the enhancement process as a fidelity term to restore global illumination and local details. Through experiments, we concluded that the new method proposed in this article can achieve more excellent quantitative and qualitative results, improve detail contrast, reduce artifacts and noise, and is suitable for dark light enhancement in multiple scenes.
  Accession Number: 190
  ISSN:
  eISSN: 2304-6732
• Record 132 of
  
  Title:Miniaturizable Phase-Sensitive Amplifier Based on Vector Dual-Pump Structure for Phase Regeneration of PDM Signal
  
  Author(s):Jia, Shuaiwei; Xie, Zhuang; Shao, Wen; Han, Xiaotian; Su, Yulong; Meng, Jiacheng; Gao, Duorui; Wang, Wei; Xie, Xiaoping
  Source: IEEE PHOTONICS JOURNAL  Volume: 16  Issue: 1  DOI: 10.1109/JPHOT.2023.3335923  Published: 2024  
  Abstract:Phase sensitive amplification is indispensable in promoting applications such as all-optical regenerators, quantum communications, all-optical analog-to-digital conversion, and long-distance communications. In this article, we proposed a vector dual-pump nondegenerate phase-sensitive amplification scheme based on ultra-silicon-rich nitride (Si7N3) waveguide, and theoretically verified its capability for all-optical regeneration of phase-encoded polarization-division multiplexing (PDM) signal without the need for complex polarization diversity structures. We achieved a gain extinction ratio (GER) of similar to 37.5 dB by using a 3-mm-long Si7N3 waveguide with a high nonlinear coefficient (similar to 279 /W/m). Signal quality before and after regeneration is characterized by constellation diagram and error vector magnitude (EVM). The results show that the EVM of the degraded PDM differential phase-shift keying (DPSK) signals with two polarization states of 54% and 53.8%, can be improved to 13.6% and 13.6%, respectively, after regeneration, directly illustrating the remarkable phase noise suppression effect. The applicability of the scheme in PDM quadrature phase shift keying (QPSK) signals was further investigated. Similarly, the EVMs of the two polarization states of the deteriorated QPSK signals are optimized from 28.9% and 29.3% to 13.7% and 13.9%, respectively. The proposed scheme has promising applications in integrated all-optical processing systems and long-distance transmission of optical communications.
  Accession Number: 7200112
  ISSN: 1943-0655
  eISSN: 1943-0647