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Pilot-Free End-to-End Underwater Acoustic Communication System Based on Autoencoder

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Journal of Communications and Information Networks 2024年第3期9卷 233-243页

作者： Yizhe Wang Deqing Wang Liqun Fu School of informatics and Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of Ministry of EducationXiamen UniversityXiamen 361005China

The long delay spreads and significant Doppler effects of underwater acoustic(UWA)channels make the design of the UWA communication system more *** this paper,we propose a learning-based end-to-end framework for UWA communications,leveraging a double feature extraction network(DFEN)for data *** DFEN consists of an attentionbased module and a mixer-based module for channel feature extraction and data feature extraction,*** the diverse nature of UWA channels,we propose a stack-network with a two-step training strategy to enhance *** avoiding the use of pilot information,the proposed network can learn data mapping that is robust to UWA *** results show that our proposed algorithm outperforms the baselines by at least 2 dB under bit error rate(BER)10^(−2)on the simulation channel,and surpasses the compared neural network by at least 5 dB under BER 5×10^(−2)on the experiment channels.

关键词： underwater acoustic communications autoencoder time-varying channel

Reassessing the contributions of terrestrial waters to sea level variations in the South China Sea and its response to alternating ENSO events

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Science China Earth Sciences 2024年第7期67卷 2253-2267页

作者： Pengfei YANG Hok Sum FOK Zhongtian MA MOE Key laboratory of Geospace Environment and Geodesy&MNR Key laboratory of Geophysical Geodesy School of Geodesy and GeomaticsWuhan UniversityWuhan 430079China Hubei Luojia laboratory Wuhan 730079China Department of Land Surveying and Geo-informatics The Hong Kong Polytechnic UniversityHong Kong 999077China

Regional sea level variability is linked to regional terrestrial water and the El Ni?o-Southern Oscillation(ENSO).This study assessed the relationships between the sea level variations in the South China Sea(SCS)and ENSO,the impact of terrestrial water storage(TWS)on non-steric sea level(NSSL),and the contributions of steric sea level(SSL)and NSSL to sea level anomaly(SLA),*** 2003 to 2015,the SLAs exhibited a long-term trend of 6.65±0.78 mm/yr,which was primarily attributed to the ***,during 2003-2015,ENSO events alternating with varying intensities might also be responsible for the unusually high SLA *** to the SSLs,the NSSLs contributed the seasonal signals to the SLAs,while the NSSLs changes were largely explained by the TWS in the Mekong River Basin at the seasonal scale and in the Pearl River Basin and Red River Basin at other time *** contrast to the TWS,the contributions of precipitation and evapotranspiration were relatively minor.A negative correlation between the sea level variations and ENSO was also found,with cross-correlation coefficients between the oceanic Ni?o index and SLAs/SSLs/NSSLs of -0.36/-0.37/-0.62 with lags of 2/3/2 months,*** findings systematically reassessed the contributions of different components to the sea level *** study provided a benchmark for in-depth analysis of the impacts of terrestrial water and other potential causes on sea level rise in the SCS.

关键词： South China Sea Sea level variations Terrestrial water storage ENSO

Urban growth scenario projection using heuristic cellular automata in arid areas considering the drought impact

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Journal of Arid Land 2024年第4期16卷 580-601页

作者： TANG Xiaoyan FENG Yongjiu LEI Zhenkun CHEN Shurui WANG Jiafeng WANG Rong TANG Panli WANG Mian JIN Yanmin TONG Xiaohua College of Surveying&Geo-informatics Tongji UniversityShanghai 200092China Shanghai Key laboratory of Space Mapping and Remote Sensing for Planetary Exploration Tongji UniversityShanghai 200092China

Arid areas with low precipitation and sparse vegetation typically yield compact urban pattern,and drought directly impacts urban site selection,growth processes,and future *** simulation and projection based on cellular automata(CA)models is important to achieve sustainable urban development in arid *** developed a new CA model using bat algorithm(BA)named bat algorithm-probability-of-occurrence-cellular automata(BA-POO-CA)model by considering drought constraint to accurately delineate urban growth patterns and project future scenarios of Urumqi City and its surrounding areas,located in Xinjiang Uygur Autonomous Region,*** calibrated the BA-POO-CA model for the drought-prone study area with 2000 and 2010 data and validated the model with 2010 and 2020 data,and finally projected its urban scenarios in *** results showed that BA-POO-CA model yielded overall accuracy of 97.70%and figure-of-merits(FOMs)of 35.50%in 2010,and 97.70%and 26.70%in 2020,*** inclusion of drought intensity factor improved the performance of BA-POO-CA model in terms of FOMs,with increases of 5.50%in 2010 and 7.90%in 2020 than the model excluding drought intensity *** suggested that the urban growth of Urumqi City was affected by drought,and therefore taking drought intensity factor into account would contribute to simulation *** BA-POO-CA model including drought intensity factor was used to project two possible scenarios(i.e.,business-as-usual(BAU)scenario and ecological scenario)in *** the BAU scenario,the urban growth dominated mainly in urban fringe areas,especially in the northern part of Toutunhe District,Xinshi District,and Midong *** exceptional and extreme drought areas as a spatial constraint,the urban growth was mainly concentrated in the"main urban areas-Changji-Hutubi"corridor urban pattern in the ecological *** results of this research can help to adjust urban planning and development *** mode

关键词： bat algorithm cellular automata(CA) probability-of-occurrence drought intensity algorithm-probability-of-occurrence-cellular automata(BA-POO-CA)model arid areas

Understandings of Urban Sustainability in China:a Bibliometric Analysis Using Chinese Literatures

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Journal of Geodesy and Geoinformation Science 2024年第1期7卷 105-122页

作者： WU Shuang YUE Yang LI Xuesong Department of Urban informatics School of Architecture and Urban PlanningShenzhen UniversityShenzhen 518060China Shenzhen Key laboratory of Spatial Smart Sensing and Services Guangdong Key Laboratory for Urban InformaticsShenzhen UniversityShenzhen 518060China.

Cities hold a critical responsibility for achieving the Sustainable Development Goals(SDGs)due to their high population density,extensive resource consumption,and significant economic *** examine the present state of understandings regarding urban sustainability(SDG 11:Sustainable Cities and Communities)within Chinese research communities,this study collected 15950 papers from 1994 to 2022 on the 12 indicators of SDG 11,from the China National Knowledge Infrastructure(CNKI),a hub of Chinese academic papers,that directly relate to *** research topics on SDG 11 were identified for each indicator using bibliometrics analysis *** high-frequency keywords and clusters of keywords over the last three decades reveal that existing studies primarily concentrated on the physical aspects,such as transportation and environment,while there is a lack of consideration of societal *** indicates a limited and biased understanding of the urban sustainability within the Chinese academic ***,it is crucial to prioritize the societal aspects in order to develop a research agenda that further advances urban sustainability.

关键词： urban sustainability SDG 11 bibliometric Chinese research communities

Decentralized control in active distribution grids via supervised and reinforcement learning

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Energy and AI 2024年第2期16卷 137-149页

作者： Stavros Karagiannopoulos Petros Aristidou Gabriela Hug Audun Botterud laboratory for Information and Decision Systems(LIDS) Massachusetts Institute of TechnologyCambridgeUSA EEH-Power Systems laboratory ETH Zurichhysikstrasse 38092 ZurichSwitzerland Department of Electrical Engineering Computer Engineering&InformaticsCyprus

While moving towards a low-carbon, sustainable electricity system, distribution networks are expected to host a large share of distributed generators, such as photovoltaic units and wind turbines. These inverter-based resources are intermittent, but also controllable, and are expected to amplify the role of distribution networks together with other distributed energy resources, such as storage systems and controllable loads. The available control methods for these resources are typically categorized based on the available communication network into centralized, distributed, and decentralized or local. Standard local schemes are typically inefficient, whereas centralized approaches show implementation and cost concerns. This paper focuses on optimized decentralized control of distributed generators via supervised and reinforcement learning. We present existing state-of-the-art decentralized control schemes based on supervised learning, propose a new reinforcement learning scheme based on deep deterministic policy gradient, and compare the behavior of both decentralized and centralized methods in terms of computational effort, scalability, privacy awareness, ability to consider constraints, and overall optimality. We evaluate the performance of the examined schemes on a benchmark European low voltage test system. The results show that both supervised learning and reinforcement learning schemes effectively mitigate the operational issues faced by the distribution network.

关键词： Supervised learning Reinforcement learning Deep deterministic policy gradient Decentralized control Active distribution systems

A method for extracting the preseismic gravity anomalies over the Tibetan Plateau based on the maximum shear strain using GRACE data

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Earth and Planetary Physics 2024年第4期8卷 589-608页

作者： Hui Wang DongMei Song XinJian Shan Bin Wang College of Oceanography and Space informatics China University of Petroleum(East China)Qingdao 266580China PCI Technology Group Co. Ltd.Guangzhou 510660China laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266200China State Key laboratory of Earthquake Dynamics Beijing 100029China

The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in *** Gravity Recovery And Climate Experiment(GRACE)satellite data can be used to detect gravity changes associated with large ***,previous GRACE satellite-based seismic gravity-change studies have focused more on coseismic gravity changes than on preseismic gravity ***,the noise of the north–south stripe in GRACE data is difficult to eliminate,thereby resulting in the loss of some gravity information related to tectonic *** explore the preseismic gravity anomalies in a more refined way,we first propose a method of characterizing gravity variation based on the maximum shear strain of gravity,inspired by the concept of crustal *** offset index method is then adopted to describe the gravity anomalies,and the spatial and temporal characteristics of gravity anomalies before earthquakes are analyzed at the scales of the fault zone and plate,*** this work,experiments are carried out on the Tibetan Plateau and its surrounding areas,and the following findings are obtained:First,from the observation scale of the fault zone,we detect the occurrence of large-area gravity anomalies near the epicenter,oftentimes about half a year before an earthquake,and these anomalies were distributed along the fault ***,from the observation scale of the plate,we find that when an earthquake occurred on the Tibetan Plateau,a large number of gravity anomalies also occurred at the boundary of the Tibetan Plateau and the Indian ***,the aforementioned experiments confirm that the proposed method can successfully capture the preseismic gravity anomalies of large earthquakes with a magnitude of less than 8,which suggests a new idea for the application of gravity satellite data to earthquake research.

关键词： Gravity Recovery And Climate Experiment(GRACE)data maximum shear strain offset index K preseismic gravity anomalies Tibetan Plateau fault zone

Low phase noise K-band signal generation using polarization diverse single-soliton integrated microcombs

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Photonics Research 2024年第6期12卷 1175-1185页

作者： ALWALEED ALDHAFEERI HSIAO-HSUAN CHIN TRISTAN MELTON DONG IL LEE ALLEN CHU WENTING WANG MINGBIN YU PATRICK GUO-QIANG LO DIM-LEE KWONG CHEE WEI WONG Fang Lu Mesoscopic Optics and Quantum Electronics laboratory University of CaliforniaLos AngelesCalifornia 90095USA Institute of Microelectronics A*STARSingapore 117865Singapore State Key laboratory of Functional Materials for informatics Shanghai Institute of Microsystem and Information Technologyand Shanghai Industrial Technology Research InstituteShanghai 200050China

Frequency microcombs with microwave and millimeter-wave repetition rates provide a compact solution for coherent communication and information *** implementation of these microcombs using a CMOS-compatible platform further paves the way for large-scale photonic integration and ***,we demonstrate free-running soliton microcombs with K-band repetition rates with very low phase noise over a 4 GHz pump detuning range reaching−117(−123)dBc/Hz at 10 kHz offset for a 19.7(10)GHz carrier without active pump stabilization,exceeding commercial electronic microwave oscillators at frequency offsets above 40 *** minimum laser noise to soliton microwave signal transduction factor observed is−*** noise performance is achieved using a hybridized dual-mode for soliton generation to achieve passive thermal stabilization and minimal soliton spectrum shift from prior Raman scattering and dispersive wave *** further examine the locking of the repetition rate to an external ultrastable photonic oscillator to illustrate the feasibility of phase noise suppression below the thermorefractive noise limits of microresonator frequency combs.

关键词： pump polarization millimeter

Sequential Inverse Optimal Control of Discrete-Time Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 608-621页

作者： Sheng Cao Zhiwei Luo Changqin Quan the Graduate School of System informatics Kobe University Kobe 657-8501Japan

This paper presents a novel sequential inverse optimal control(SIOC)method for discrete-time systems,which calculates the unknown weight vectors of the cost function in real time using the input and output of an optimally controlled discrete-time *** proposed method overcomes the limitations of previous approaches by eliminating the need for the invertible Jacobian *** calculates the possible-solution spaces and their intersections sequentially until the dimension of the intersection space decreases to *** remaining one-dimensional vector of the possible-solution space’s intersection represents the SIOC *** paper presents clear conditions for convergence and addresses the issue of noisy data by clarifying the conditions for the singular values of the matrices that relate to the possible-solution *** effectiveness of the proposed method is demonstrated through simulation results.

关键词： Inverse optimal control promised calculation step sequential calculation

A survey on federated learning:a perspective from multi-party computation

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Frontiers of Computer Science 2024年第1期18卷 93-103页

作者： Fengxia LIU Zhiming ZHENG Yexuan SHI Yongxin TONG Yi ZHANG Institute of Artificial Intelligence and Key laboratory of Mathematics informatics Behavioral Semantics Beihang UniversityBeijing 100191China State Key laboratory of Software Development Environment and Advanced Innovation Center for Future Blockchain and Privacy Computing Beihang UniversityBeijing 100191China Pengcheng laboratory Shenzhen 518055China Zhongguancun laboratory Beijing 100190China Institute for Mathematical Sciences and Engineering Research Center of Financial Computing and Digital Engineering Renmin University of ChinaBeijing 100872China

Federated learning is a promising learning paradigm that allows collaborative training of models across multiple data owners without sharing their raw *** enhance privacy in federated learning,multi-party computation can be leveraged for secure communication and computation during model *** survey provides a comprehensive review on how to integrate mainstream multi-party computation techniques into diverse federated learning setups for guaranteed privacy,as well as the corresponding optimization techniques to improve model accuracy and training *** also pinpoint future directions to deploy federated learning to a wider range of applications.

关键词： sfederated learning multi-party ycomputation privacy-preserving data mining distributed learning