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Automatic video colorization based on contrastive learning and optical flow

Multimedia Tools and Applications 2024年第21期83卷 59985-60001页

作者： Xiao, Shuyu Wang, Yongfang Wang, Yihan Shanghai Institute for Advanced Communication and Data Science School of Communication and Information Engineering Shanghai University Shanghai200444 China

Video colorization is the process of assigning reasonable color values to gray videos. Most of the existing video colorization methods use an image colorization algorithm directly regardless of correlation between frames in videos. Besides, these methods need reference, but it is difficult to obtain the guidance of users or reference images in practical applications. To overcome this limitation, we propose an automatic video colorization based on contrastive learning and optical flow. Contrastive learning optimizes the temporal correlation loss between the feature vectors of the gray video frame patches and the generated color video frame patches during training, which ensures the consistency of image content at the patch level. The optical flow module maintains the temporal consistency of colored videos by minimizing temporal correlation loss. In particular, the perceptual loss is introduced to improve the subjective colorization effect. Experiments show that the proposed algorithm outperforms the existing methods in terms of subjective quality. To reproduce the results, we release the source code at: https://***/orange-416/CLAC-GAN. © The Author(s), under exclusive licence to Springer science+Business Media, LLC, part of Springer Nature 2023.

关键词： Optical flows

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The Transformation of Normalization Standard of Smith Chart for Microwave Networks With Multiple Impedance Transmission Lines

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IEEE Microwave and Wireless Technology Letters 2025年第4期35卷 384-387页

作者： Yi, Zixuan Hu, Peipei Yang, Xue-Xia Li, Meiling Zeng, Dan Shanghai Institute for Advanced Communication and Data Science Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai University Shanghai200444 China

The Smith chart is a graphical approach for solving impedance matching problems in the microwave circuit design, which provides visualized traces, but it is not applicable to address impedance discontinuities graphically, especially for multiple-impedance transmission lines (TLs) within microwave networks. In this letter, a novel transformation of normalization standard (TNS) method is proposed, which is applied to the Smith chart to solve the aforementioned problem. Then, TNS traces are derived and applied to the classical Smith chart, obtaining an improved Smith chart. In addition, the TNS idea is applied to the microwave circuit design examples. The proposed TNS method provides a convenient visualized way for the design of microwave circuits with multi-impedance TLs. © 2023 IEEE.

关键词： Integrated circuit design

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Broadband Optical Coupler based on the Helical Long-Period Gratings Inscribed in Seven-Core Fibers

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Journal of Lightwave Technology 2025年第12期43卷 5820-5828页

作者： Chen, Siyu Jiang, Chen Ma, Yuehui Zhao, Yunhe Fan, Xiaolong Mou, Chengbo Liu, Yunqi Shanghai University Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai Institute for Advanced Communication and Data Science School of Communication and Information Engineering Shanghai 200444 China Advanced Photonic Technology Lab Nanjing210023 China Shanghai Maritime University Institute of Logistics Science and Engineering Shanghai201306 China

We propose a broadband optical coupler based on cladding mode coupling of identical helical long-period gratings (HLPGs) inscribed in different cores of seven-core fibers (SCFs). The influence of the surrounding refractive index and offset distance between the input grating and tapping grating on the coupling efficiency of the coupler was investigated numerically and experimentally. A total peak coupling efficiency of 75.7% was achieved experimentally under the conditions of a surrounding refractive index of 1.454 and an offset distance of 90 mm when the light is launched into the center core of the SCF. The proposed optical coupler could have promising applications in multi-core fiber amplifiers and space-division multiplexing optical communications. © 1983-2012 IEEE.

关键词： Space division multiple access

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Recent progress of in‑fber WGM microsphere resonator

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Frontiers of Optoelectronics 2023年第2期16卷 25-62页

作者： Yong Yang Zijie Wang Xiaobei Zhang Qi Zhang Tingyun Wang Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced CommunicationShanghai Institute for Advanced Communication and Data ScienceShanghai UniversityShanghai 200444China

In-fber whispering gallery mode(WGM)microsphere resonators have received remarkable attention due to the superiorities of compact structure,high stability and *** an in-fber structure,WGM microsphere resonators have been demonstrated in various applications,such as sensors,flters and lasers,which have signifcant impacts on modern ***,we review recent progress of in-fber WGM microsphere resonators,which involve fbers of diverse structures and microspheres of diferent ***,a brief introduction is given to in-fber WGM microsphere resonators,from structures to ***,we focus on recent progresses in this feld,including in-fber couplers based on conventional fbers,capillaries and micro-structure hollow fbers,and passive/active ***,future developments of the in-fber WGM microsphere resonators are envisioned.

关键词： Whispering gallery mode Microsphere resonator In-fber device Sensor

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Explosive synchronization of multi-layer complex networks based on star connection between layers with delay

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Chinese Physics B 2023年第10期32卷 343-349页

作者：金彦亮韩钱源郭润珠高塬沈礼权 Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced CommunicationShanghai Institute for Advanced Communication and Data ScienceShanghai UniversityShanghai 200072China School of Communication and Information Engineering Shanghai UniversityShanghai 200000China

Explosive synchronization(ES)is a kind of first-order jump phenomenon that exists in physical and biological *** recent years,researchers have focused on ES between single-layer and multi-layer *** research on complex networks with delay has focused on single-layer or double-layer networks,multi-layer networks are seldom *** this paper,we propose a Kuramoto model of frequency weights in multi-layer complex networks with delay and star connections between *** theoretical analysis and numerical verification,the factors affecting the backward critical coupling strength are *** results show that the interaction between layers and the average node degree has a direct effect on the backward critical coupling strength of each layer *** location of the delay,the size of the delay,the number of network layers,the number of nodes,and the network topology are revealed to have no direct impact on the backward critical coupling strength of the *** is introduced to explore the influence of delay and other related parameters on ES.

关键词： multi-layer networks Kuramoto model explosive synchronization delay

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Multimodal contrastive learning for radiology report generation

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Journal of Ambient Intelligence and Humanized Computing 2023年第8期14卷 11185-11194页

作者： Wu, Xing Li, Jingwen Wang, Jianjia Qian, Quan School of Computer Engineering and Science Shanghai University Shanghai200444 China Shanghai Institute for Advanced Communication and Data Science Shanghai University Shanghai200444 China

Automated radiology report generation can not only lighten the workload of clinicians but also improve the efficiency of disease diagnosis. However, it is a challenging task to generate semantically coherent radiology reports that are also highly consistent with medical images. To meet the challenge, we propose a Multimodal Recursive model with Contrastive Learning (MRCL). The proposed MRCL method incorporates both visual and semantic features to generate "Impression" and "Findings" of radiology reports through a recursive network, in which a contrastive pre-training method is proposed to improve the expressiveness of both visual and textual representations. Extensive experiments and analyses prove the efficacy of the proposed MRCL, which can not only generate semantically coherent radiology reports but also outperform state-of-the-art methods. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

关键词： Semantics

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Recticoil for Efficient Compact Inductive Power Transfer

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IEEE Transactions on Power Electronics 2025年第7期40卷 10154-10164页

作者： Yi, Zixuan Qin, Yuanyuan Yang, Xue-Xia Shao, Yaoxia Zeng, Dan Li, Meiling Shanghai University School of Communication and Information Engineering Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai Institute for Advanced Communication and Data Science Shanghai200444 China Hangzhou City University School of Information and Electrical Engineering Hangzhou310015 China

The MHz inductive power transfer (IPT) system has broad application prospects due to its high safety, longer transmission distance, and better tolerance for misalignment. However, the increase in frequency will lead to an increased loss of lumped components, such as inductors and capacitors, in peripheral circuits, thereby reducing efficiency. This is currently the bottleneck problem encountered by MHz IPT. To address this key challenge, researchers have tried to remove the lumped components in the peripheral circuit while ensuring the functions of the IPT system. One successful and beneficial attempt is the self-resonant coil, which replaces traditional lumped resonant capacitors with distributed capacitors formed by coil turn-to-turn capacitance, ensuring compensation for leakage inductance and eliminating reactive power. This innovative integration makes efficiency and integration greatly improved. In this article, the novel coil named Recticoil, on which the rectification function is integrated further, is proposed for efficient compact IPT. Recticoil can directly output dc power without additional compensation and rectification circuits. By analyzing a toroidal coil where two separate conductors generate a voltage differential, and incorporating two diodes, resulting in a dc output. Subsequently, the self-resonant coil replaces the toroidal coil to form Recticoil, and the equivalent circuits of Recticoil are given and analyzed. In addition, the analysis and test method of rectification efficiency is given. The experimental results show that the Recticoil achieves a rectification efficiency as high as 97.25% at 6.78 MHz, outperforming both the bridge rectifier and the Class E rectifier. Additionally, the compact construction of Recticoil eliminates the volume of traditional rectifiers. All of these advantages of Recticoil render it a promising candidate for applications in wearables and miniaturized devices. © 1986-2012 IEEE.

关键词： Equivalent circuits

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Multiparameter sensor based on the long-period fiber gratings inscribed in a pre-twisted polarization-maintaining fiber

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IEEE Sensors Journal 2025年第11期25卷 19315-19322页

作者： Chen, Siyu Jiang, Chen Ma, Yuehui Fan, Xiaolong Zhao, Yunhe Mou, Chengbo Liu, Yunqi Shanghai University Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai Institute for Advanced Communication and Data Science School of Communication and Information Engineering 99 Shangda Road Shanghai200444 China Nanjing210023 China Shanghai Maritime University Institute of Logistics Science and Engineering Shanghai201306 China

We demonstrate the fabrication of pre-twisted long-period fiber gratings (PT-LPFGs) in polarization-maintaining fibers (PMFs) using a CO2 laser. This technique leverages pre-twisted fibers combined with laser exposure, eliminating the need for precise alignment along the PMF axis, a key limitation of conventional single-side CO2 laser methods. The PT-LPFGs with the periods of 420 to 480 μm were successfully fabricated, achieving a maximum polarization-dependent loss (PDL) exceeding 20 dB at the resonance wavelength. The dual-dips resonance of the LP11 core mode was observed in the 1.0 μm wavelength band. Further chemical etching was applied to adjust the cladding mode resonance wavelength near the dispersion turning point (DTP). This adjustment enabled dual-dips resonance with LP14 and LP15 cladding modes along the PMF’s slow and fast axes, respectively, within the 2.0 μm wavelength band. The sensing performance of PT-LPFGs near the DTP was evaluated. Experimental results demonstrate that these gratings exhibit a high sensitivity of up to 14100 nm/RIU for the surrounding refractive index range of 1.448 to 1.457. Furthermore, the temperature and strain sensitivities were measured to be at 713 pm/°C and -49.4 pm/μΕ, respectively. These findings highlight the potential of PT-LPFGs for high-sensitivity fiber sensors, PDL compensators, and other advanced optical applications. © 2001-2012 IEEE.

关键词： Polarization-maintaining fiber

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Monolithic 50 GHz tunable microwave signal generation based on erbium-doped lithium niobate dual lasers

Monolithic 50 GHz tunable microwave signal generation based ...

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CLEO: science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Cai, Minglu Zhang, Xujia Li, Tianyi Shi, Hao Li, Tieying Cao, Xianyi Cui, Zekun Chen, Jianping Wu, Kan Shanghai Institute for Advanced Communication and Data Science State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China

The monolithic erbium-doped lithium niobate lasers can achieve a tunable wavelength range of 56.25 GHz and generate a 50 GHz microwave signal with a side-mode suppression ratio of 35 dB by dual lasers. © Optica P... 详细信息

关键词： Monolithic microwave integrated circuits

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High-resolution and High-rate Dual-comb FMCW Lidar with Coherent Comb Stitching

High-resolution and High-rate Dual-comb FMCW Lidar with Cohe...

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CLEO: science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Cao, Xianyi Wang, Long Li, Tianyi Cai, Minglu Wu, Guiling Chen, Jianping Wu, Kan Shanghai Institute for Advanced Communication and Data Science State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China

A dual-comb FMCW Lidar with coherent comb stitching (CCS) technique is firstly demonstrated. CCS can simultaneously achieve 65 GHz high frequency sweeping range, millimeter-level ranging resolution and 100 kHz high vo... 详细信息

关键词： Pulse amplitude modulation

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