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Audio-guided self-supervised learning for disentangled visual speech representations

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Frontiers of Computer Science 2024年第6期18卷 186353-186353页

作者： FENG Dalu YANG Shuang SHAN Shiguang CHEN Xilin Key Laboratory of Intelligent information Processing of Chinese Academy of sciences institute of Computing Technology Chinese Academy of sciences University of Chinese Academy of sciences

In this paper, we propose a novel two-branch framework to learn the disentangled visual speech representations based on two particular observations. Its main idea is to introduce the audio signal to guide the learning of speech-relevant cues and introduce a bottleneck to restrict the speech-irrelevant branch from learning high-frequency and fine-grained speech cues. Experiments on both the word-level and sentence-level audio-visual speech datasets LRW and LRS2-BBC show the effectiveness. Our future work is to explore more explicit auxiliary tasks and constraints beyond the reconstruction task of the speech-relevant and irrelevant branch to improve further its ability of capturing speech cues in the video. Meanwhile, it’s also a nice try to combine multiple types of knowledge representations [10] to further boost the obtained speech epresentations, which is also left for the future work.

关键词： Knowledge representation

Numerical Simulation of Thermocapillary Convection with Evaporation Induced by Boundary Heating

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Fluid Dynamics & Materials Processing 2024年第7期20卷 1667-1686页

作者： O.N.Goncharova V.B.Bekezhanova Altai State University Institute of Mathematics and Information TechnologiesBarnaul656049Russia institute of Computational Modelling SB RAS Department of Differential Equations of MechanicsKrasnoyarsk660036Russia

The dynamics of a bilayer system filling a rectangular cuvette subjected to external heating is *** influence of two types of thermal exposure on the flow pattern and on the dynamic contact angle is *** particular,the cases of local heating from below and distributed thermal load from the lateral walls are *** simulation is carried out within the frame of a two-sided evaporative convection model based on the Boussinesq approximation.A benzine–air system is considered as reference *** variation in time of the contact angle is described for both heating *** lateral heating,near-wall boundary layers emerge together with strong convection,whereas the local thermal load from the lower wall results in the formation of multicellular motion in the entire volume of the fluids and the appearance of transition regimes followed by a steady-state *** results of the present study can aid the design of equipment for thermal coating or drying and the development of methods for the formation of patterns with required structure and morphology.

关键词： Thermocapillary convection two-phase system numerical modeling contact angle

Temporal and spatial evolution of global major grain trade patterns

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Journal of Integrative Agriculture 2024年第3期23卷 1075-1086页

作者： Ziqi Yin Jiaxuan Hu Jing Zhang Xiangyang Zhou Lingling Li Jianzhai Wu Agricultural information institute Chinese Academy of Agricultural SciencesBeijing 100081China institute of Scientific and Technical information of China Beijing 100038China Zibo Agricultural Science Research institute Zibo 255000China Zibo institute for Digital Agriculture and Rural Research Zibo 255000China

The complex and volatile international landscape has significantly impacted global grain supply security. This study uses a complex network analysis model to examine the evolution and trends of the global major grain trade from 1990 to 2020, focusing on network topology, centrality ranking, and community structure. There are three major findings. First, the global major grain trade network has expanded in scale, with a growing emphasis on diversification and balance. During the study period, the United States, Canada, China, and Brazil were the core nodes of the network. Grain-exporting countries were mainly situated in Asia, the Americas, and Europe, and importing countries in Asia, Africa, and Europe. Second, a significant increase in the number of high centrality countries with high export capacity occurred, benefiting from natural advantages such as fertile land and favorable climates. Third, the main global grain trade network is divided into four communities, with the Americas-Europe community being the largest and most widespread. The formation of the community pattern was influenced by geographic proximity, driven by the core exporting countries. Therefore, the world needs to enhance the existing trade model, promote the multi-polarization of the grain trade network, and establish a global vision for the future community. Countries and regions should participate actively in global grain trade security governance and institutional reform, expand trade links with other countries, and optimize import and export policies to reduce trade risks.

关键词： grain trade pattern evolution complex network

Demonstration of acousto-optical modulation based on a thin-film AlScN photonic platform

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Photonics Research 2024年第6期12卷 1138-1149页

作者： KEWEI BIAN ZHENYU LI YUSHUAI LIU SUMEI XU XINGYAN ZHAO YANG QIU YUAN DONG QIZE ZHONG TAO WU SHAONAN ZHENG TING HU School of Microelectronics Shanghai UniversityShanghai 201800China School of information Science and Technology ShanghaiTech UniversityShanghai 201210China Shanghai institute of Microsystem and information Technology Chinese Academy of SciencesShanghai 200050China University of Chinese Academy of sciences Beijing 100049China

Acousto-optic(AO)modulation technology holds significant promise for applications in microwave and optical signal ***-film scandium-doped aluminum nitride(AlScN),with excellent piezoelectric properties and a wide transparency window,is a promising candidate for achieving on-chip AO modulation with a fabri-cation process compatible with complementary metal-oxide-semiconductor(CMOS)*** study presents,to the best of our knowledge,the first demonstration of AO modulators with surface acoustic wave generation and photonic waveguides monolithically integrated on a 400-nm-thick film of AlScN on an *** intramodal AO modulation is realized based on an AlScN straight waveguide,and the modulation efficiency is significantly enhanced by 12.3 dB through the extension of the AO interaction length and the utilization of bidirectional acoustic *** intermodal AO modulation and non-reciprocity are further demonstrated based on a multi-mode spiral waveguide,achieving a high non-reciprocal contrast(>10 dB)across an optical bandwidth of 0.48 *** research marks a significant stride forward,representing an advancement in the realization of microwave photonic filters,magnet-free isolators,and circulators based on the thin-film AlScN photonic platform.

关键词： waveguide film microwave

Security estimation of LWE via BKW algorithms

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Cybersecurity 2024年第1期7卷 71-87页

作者： Yu Wei Lei Bi Xianhui Lu Kunpeng Wang SKLOIS Institute of Information EngineeringCASBeijingChina School of Cyber Security University of Chinese Academy of SciencesBeijingChina

The Learning With Errors(LWE)problem is widely used in lattice-based cryptography,which is the most promising post-quantum cryptography *** are a variety of LWE-solving methods,which can be classified into four groups:lattice methods,algebraic methods,combinatorial methods,and exhaustive *** Blum–Kalai–Wasserman(BKW)algorithm is an important variety of combinatorial algorithms,which was first presented for solving the Learning Parity With Noise(LPN)problem and then extended to solve *** this paper,we give an overview of BKW algorithms for solving *** introduce the framework and key techniques of BKW algorithms and make comparisons between different BKW algorithms and also with lattice methods by estimating concrete security of specific LWE *** also briefly discuss the current problems and potential future directions of BKW algorithms.

关键词： Post-quantum cryptography Learning with errors problem Lattice-based cryptography Security estimation

70 Gbps PAM-4850-nm oxide-confined VCSEL without equalization and pre-emphasis

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Journal of Semiconductors 2024年第5期45卷 5-7页

作者： Anjin Liu Bao Tang Zhiyong Li Wanhua Zheng Key Laboratory of Optoelectronic Materials and Devices Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Accelink technologies co. LtdWuhan 430205China Key Laboratory of Solid-State Optoelectronics information Technology Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

Directly modulated 850-nm vertical-cavity surface-emitting lasers(VCSELs)with the advantages of low cost,high modulation speed,good reliability,and low power consumption,are the key sources in the optical interconnects with multimode fibers for the supercomputers,data centers,and machine learning applications[1−3].Typically,non-return-tozero(NRZ)modulation format is used.

关键词： return confined fibers

Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode

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Frontiers of Optoelectronics 2024年第2期17卷 99-112页

作者： Aleksandr Ushakov Kseniia Mamaeva Leonid Seleznev Georgy Rizaev Vladimir Bukin Timophey Dolmatov Pavel Chizhov Vladimir Bagdasarov Sergey Garnov Prokhorov General Physics institute of the Russian Academy of sciences Moscow 119991Russia Physical institute Russian Academy of SciencesMoscow 119991Russia Moscow institute of Physics and Technology Dolgoprudny 141700Russia Russian institute for Scientific and Technical information Moscow 125190Russia

In this paper,we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum *** use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kV/cm external electric field for the photo-emitted electron *** of terahertz pulses energy as a function of emitted charge density,incidence angle of optical radiation and applied electric field have been *** and polarization characteristics of generated terahertz pulses have also been *** proposed semi-analytical model and simulations in COMSOL Multiphysics prove the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.

关键词： Electron emission Vacuum photodiode Ultrafast excitation Terahertz

Extreme value theory applied to the auroral electrojet indices

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Earth and Planetary Physics 2024年第2期8卷 375-381页

作者： Si Chen Hong Yuan Yong Wei Guang Yang FengZheng Yu Aerospace information Research institute Chinese Academy of SciencesBeijing 100094China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China

The study of extreme weather and space events has gained paramount importance in modern society owing to rapid advances in high *** and describing exceptional occurrences plays a crucial role in making decisive assessments of their potential impact on technical,economic,and social aspects in various *** research focuses on analyzing the hourly values of the auroral electrojet(AE)geomagnetic index from 1957 to 2019 by using the peak over threshold method in extreme value *** fitting the generalized Pareto distribution to extreme AE values,shape parameter indices were derived,revealing negative values that establish an upper bound for this time ***,it became evident that the AE values had reached a plateau,suggesting that extreme events exceeding the established upper limit are *** a result,although the need for diligent precautions to mitigate the consequences of such extreme events persists,surpassing the upper limit of AE values becomes increasingly *** is also possible to observe an aurora in the middle-and low-latitude regions during the maximum period of the AE index.

关键词： auroral electrojet indices extreme value theory extreme events

Two-dimensional-lag complex logistic map with complex parameters and its encryption application

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Chinese Physics B 2024年第5期33卷 324-335页

作者：张芳芳武金波寇磊马凤英吴黎明张雪 School of information and Automation Engineering Qilu University of Technology (Shandong Academy of Sciences)Jinan 250353China institute of Oceanographic Instrumentation Qilu University of Technology (Shandong Academy of Sciences)Qingdao 266000China

With the rapid development of internet technology,security protection of information has become more and more prominent,especially information *** the great advantages of chaotic encryption,we propose a 2D-lag complex logistic map with complex parameters(2D-LCLMCP)and corresponding encryption ***,we present the model of the 2D-LCLMCP and analyze its chaotic properties and system stability through fixed points,Lyapunov exponent,bifurcation diagram,phase diagram,***,a block cipher algorithm based on the 2D-LCLMCP is proposed,the plaintext data is preprocessed using a pseudorandom sequence generated by the *** on the generalized Feistel cipher structure,a round function F is constructed using dynamic S-box and DNA encoding rules as the core of the block cipher *** generalized Feistel cipher structure consists of two F functions,four XOR operations,and one permutation operation per *** symmetric dynamic round keys that change with the plaintext are generated by the ***,experimental simulation and performance analysis tests are *** results show that the block cipher algorithm has low complexit,good diffusion and a large key *** the block length is 64 bits,only six rounds of encryption are required to provide sufficient security and robustness against cryptographic attacks.

关键词： logistic map block ciphers chaotic system encryption