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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Xinwei Du Qian Wang Pooi-Yuen Kam Guangdong Provincial Key Laboratory of Interdisciplinary Research and Application for Data Science BNU-HKBU United International College Zhuhai China College of Information Engineering Zhejiang University of Technology Hangzhou China School of Science and Engineering Chinese University of Hong Kong Shenzhen Shenzhen China

We propose a joint maximum likelihood (ML)/ maximum a posteriori probability (MAP) frequency offset (FO) and linear phase noise (LPN) estimation scheme for coherent optical communications. By designing the pilot symbols as unmodulated signal with known amplitude, the joint estimation can be simplified to the estimation of frequency and phase of a complex single sinusoid. We then utilize an ML Mth power approach to iteratively estimate the phase on those unknown transmitted symbols. The Cramér-Rao lower bounds are derived and the optimum estimation performance of the proposed algorithms are verified through simulations.

关键词： Phase noise Maximum likelihood estimation Maximum likelihood detection Symbols Frequency estimation Optical fiber communication Optical noise

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Optimal Trajectory Planning and Task Assignment for UAV-assisted Fog Computing

arXiv

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arXiv 2022年

作者： Liu, Shuaijun Yin, Jiaying Zeng, Zishu Wu, Jingjin Department of Statistics and Data Science BNU-HKBU United International College Zhuhai519087 China Li Ka Shing Faculty of Medicine The University of Hong Kong Pokfulam Hong Kong School of Engineering The Hong Kong University of Science and Technology Kowloon Hong Kong Guangdong Provincial Key Laboratory of Interdisciplinary Research Application for Data Science China

Fog computing is an emerging distributed computing model for the Internet of Things (IoT). It extends computing and caching functions to the edge of wireless networks. Uncrewed Aerial Vehicles (UAVs) provide adequate support for fog computing. UAVs can not only act as a relay between mobile users and physically remote edge devices to avoid costly long-range wireless communications but also are equipped with computing facilities that can take over specific tasks. In this paper, we aim to optimize the energy efficiency of a fog computing system assisted by a single UAV by planning the trajectories of the UAV and assigning computing tasks to different devices, including the UAV itself. We propose two algorithms based on the classical Ant Colony and Particle Swarm Optimization techniques and solve the problem by continuous convex approximation. Unlike most existing studies where the trajectories are assumed to be straight lines, we account for the effect of obstacles, such as buildings, and deliberately avoid them during the trajectory planning phase. Through extensive simulation experiments, we demonstrate that our proposed approach can achieve significantly better energy efficiency than existing benchmark algorithms. Copyright © 2022, The Authors. All rights reserved.

关键词： Fog computing

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Optimal Trajectory Planning and Task Assignment for UAV-assisted Fog Computing

Optimal Trajectory Planning and Task Assignment for UAV-assi...

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IEEE International Conference on High Performance Computing and Communications (HPCC)

作者： Shuaijun Liu Jiaying Yin Zishu Zeng Jingjin Wu Department of Statistics and Data Science BNU-HKBU United International College Zhuhai China Li Ka Shing Faculty of Medicine The University of Hong Kong Pokfulam Hong Kong SAR China School of Engineering The Hong Kong University of Science and Technology Kowloon Hong Kong SAR China Guangdong Provincial Key Laboratory of Interdisciplinary Research and Application for Data Science

Fog computing is an emerging distributed computing model for the realization of the Internet of Things (IoT). It extends computing and caching functions to the edge of wireless networks. Unmanned Aerial Vehicles (UAVs) provide effective support for fog computing, as UAVs can not only act as a relay between mobile users and physically remote edge devices to avoid costly long-range wireless communications, but also are equipped with computing facilities that can take over certain tasks. In this paper, we aim to optimize the energy efficiency of a fog computing system assisted by a single UAV, by planning the trajectories of the UAV and assigning computing tasks to different devices including the UAV itself. We propose two algorithms based on the classical Ant Colony and Particle Swarm Optimization techniques, and solve the problem by continuous convex approximation. Different from most existing studies where the trajectories are assumed to be straight lines, we account for the effect of obstacles, such as buildings, and deliberately avoid them during the trajectory planning phase. We demonstrate, through extensive simulation experiments, that our proposed approach can achieve significantly better energy efficiency compared to existing benchmark algorithms.

关键词： Trajectory planning Computational modeling Wireless networks Autonomous aerial vehicles Energy efficiency Trajectory Internet of Things

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Maximum Likelihood Estimation of Polarization States in Coherent Optical Communications

Maximum Likelihood Estimation of Polarization States in Cohe...

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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Shuai Liu Xinwei Du Changyuan Yu Faculty of Science and Technology BNU-HKBU United International College Zhuhai China Guangdong Provincial Key Laboratory of Interdisciplinary Research and Application for Data Science BNU-HKBU United International College Zhuhai China Department of Electronic and Information Engineering The Hong Kong Polytechnic University Hung Hom

In this paper, a polarization state estimation algorithm in coherent optical communication systems is proposed based on the maximum likelihood (ML) method. Through the derivation, we obtain the analytical solutions of the polarization states and deduce the corresponding Cramér-Rao Lower Bounds (CRLBs). The proposed ML estimator not only can achieve the optimum estimation with merely 16 pilot symbols, but also shows great tolerance to the additive white Gaussian noise (AWGN) and linear phase noise (LPN). Simulation results verify the accuracy, efficiency and robustness of the proposed ML estimator.

关键词： Phase noise Maximum likelihood estimation AWGN Simulation Symbols Robustness Optical fiber communication

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The Newly Launching Hood System for Tunnel Shield Machines: Design and On-Site Operation

SSRN

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SSRN 2023年

作者： Lin, Yunhong Chang, Ruicheng Yao, Zhengyu Chen, Zhong He, Hongming Guangzhou Metro Design and Research Institute Co. Ltd Guangdong Guangzhou China Faculty of Land Resources Engineering Kunming University of Science and Technology Kunming630093 China School of Geographic Sciences East China Normal University Shanghai200241 China Key Laboratory of Geographic Information Science Ministry of Education East China Normal University Shanghai200241 China Key Laboratory of Spatial-temporal Big Data Analysis and Application of Natural Resources in Megacities Ministry of Natural Resources Shanghai200241 China

The resolution of engineering risks and problems during the shield machine launching process has become a crucial research topic in the industry. To address this issue, we conducted a study on a newly launching hood system for unconsolidated soil conditions. Based on the concept of active pressurization and using a new sealing device, we applied an active pressurized sealing system throughout the construction process from the shield breakthrough door to the ring beam of the door. The research results demonstrated that the newly launching hood system is suitable for various unconsolidated soil layers and shield machine sizes, with three models of 20m, 40m, and above 40m water pressure. By using the technology of pressurizing the soil before turning the cutterhead to grind the surrounding structure, a good sealing effect was achieved. Moreover, station end settlement data showed that the use of the newly launching hood system does not have a negative impact on the surrounding environment during construction. The launching hood system for tunnel shield provides an excellent solution for the risks faced in shield machine operations. © 2023, The Authors. All rights reserved.

关键词： Grinding (machining)

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The Newly Receiving Hood System for Tunnel Shield Machines: Design and Implementation

SSRN

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SSRN 2023年

作者： Lin, Yunhong Guo, Xiaodong Yao, Zhengyu Chen, Zhong He, Hongming Guangzhou Metro Design and Research Institute Co. Ltd Guangdong Guangzhou China School of Geographic Sciences East China Normal University Shanghai200241 China Key Laboratory of Geographic Information Science Ministry of Education East China Normal University Shanghai200241 China Key Laboratory of Spatial-temporal Big Data Analysis and Application of Natural Resources in Megacities Ministry of Natural Resources Shanghai200241 China Faculty of Land Resources Engineering Kunming University of Science and Technology Kunming630093 China

How to solve the current engineering risks and problems faced in the shield receiving process has become an important research hotspot in the industry. To this end, we have carried out research into newly receiving hood system for tunnel shield machines under unreinforced ground conditions. Based on the concept of active pressurization, a new type of sealing device is used, using an active pressurized sealing system for the whole process from the shield breaking gate to the construction of the ring beam of the gate. The results of the study show that the newly receiving hood system is suitable for all kinds of unreinforced soils and all sizes of shield machines, and is set up in three models of 20m, 40m and super 40m water pressure, using the technique of building pressure in the earth bin before turning the knife plate to grind the enclosure to achieve a good sealing effect. In addition, the station end settlement data shows that with the new initiation technique the works are carried out without negative impact on the surrounding environment. The study proposes a new receiving hood system that provides a good solution to the risks faced by shield operations. © 2023, The Authors. All rights reserved.

关键词： Tunneling machines

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A Combined Immersed Finite Element and Conservative Semi-Lagrangian Scheme for Plasma-Material Interactions

SSRN

引用

SSRN 2023年

作者： Liu, Hongtao Chen, Mengyu Cai, Xiaofeng Cao, Yong Lapenta, Giovanni School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen518055 China Center for Mathematical Plasma Astrophysics Department of Mathematics KU Leuven Leuven3001 Belgium Research Center for Mathematics Beijing Normal University Zhuhai519087 China Guangdong Provincial Key Laboratory of Interdisciplinary Research and Application for Data Science BNU-HKBU United International College Zhuhai519087 China

In this paper, the immersed finite element (IFE) coupled with the conservative semi-Lagrangian (CSL) kinetic scheme is developed for plasma-material interactions. The proposed method (IFE-CSL) enjoys respective advantages of the IFE and CSL, i.e, the flexibility and efficiency for treating complex boundary conditions, mass conservation and being free from the Courant-Friedrichs-Lewy (CFL) condition. In the current IFE-CSL, the IFE method based on structured interface-independent meshes is developed for the spatial discretization of the field equation, which provides an accurate approach with convenient implementations to solve the field problems with irregular interface. The CSL scheme combined with an immersed method termed half-way ghost-cell is proposed for the spatial discretization of the Vlasov equation, which enables the proposed method to exactly conserve mass and conveniently handle curved boundaries. Then the IFE and CSL method are coupled via the charge density depending on full kinetic or hybrid kinetic model, where the appropriate IFE solver is developed for the linear or nonlinear Poisson equation, respectively. In the current IFE-CSL, different geometries can be treated automatically for both IFE and CSL through the specific geometric information. As a result, the proposed CSL-IFE can be conveniently and efficiently applied to simulate the plasma-material interactions with structured interface-independent meshes. Finally, several numerical experiments are performed to demonstrate the capabilities of the proposed method. © 2023, The Authors. All rights reserved.

关键词： Vlasov equation

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Robust Causal Learning for the Estimation of Average Treatment Effects

arXiv

引用

arXiv 2022年

作者： Huang, Yiyan Leung, Cheuk Hang Wu, Qi Yan, Xing Ma, Shumin Yuan, Zhiri Wang, Dongdong Huang, Zhixiang School of Data Science The City University of Hong Kong Hong Kong Institute of Statistics and Big Data Renmin University of China China Division of Science and Technology BNU-HKBU United International College China JD Digits-CityU Joint Lab The City University of Hong Kong Hong Kong JD Digits China Guangdong Provincial Key Laboratory of Interdisciplinary Research and Application for Data Science BNU-HKBU United International College China

Many practical decision-making problems in economics and healthcare seek to estimate the average treatment effect (ATE) from observational data. The Double/Debiased Machine Learning (DML) is one of the prevalent methods to estimate ATE in the observational study. However, the DML estimators can suffer an error-compounding issue and even give an extreme estimate when the propensity scores are misspecified or very close to 0 or 1. Previous studies have overcome this issue through some empirical tricks such as propensity score trimming, yet none of the existing literature solves this problem from a theoretical standpoint. In this paper, we propose a Robust Causal Learning (RCL) method to offset the deficiencies of the DML estimators. Theoretically, the RCL estimators i) are as consistent and doubly robust as the DML estimators, and ii) can get rid of the error-compounding issue. Empirically, the comprehensive experiments show that i) the RCL estimators give more stable estimations of the causal parameters than the DML estimators, and ii) the RCL estimators outperform the traditional estimators and their variants when applying different machine learning models on both simulation and benchmark datasets. Copyright © 2022, The Authors. All rights reserved.

关键词： Machine learning

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G3SR: Global Graph Guided Session-based Recommendation

arXiv

引用

arXiv 2022年

作者： Deng, Zhi-Hong Wang, Chang-Dong Huang, Ling Lai, Jian-Huang Yu, Philip S. School of Computer Science and Engineering Sun Yat-sen University Guangzhou China Key Laboratory of Machine Intelligence and Advanced Computing Ministry of Education China School of Computer Science and Engineering Sun Yat-sen University Guangzhou China Guangdong Key Laboratory of Information Security Technology Guangzhou China College of Mathematics and Informatics South China Agricultural University Guangzhou China Guangdong Provincial Key Laboratory of Public Finance and Taxation with Big Data Application China University of Illinois at Chicago ChicagoIL United States

Session-based recommendation tries to make use of anonymous session data to deliver high-quality recommendation under the condition that user-profiles and the complete historical behavioral data of a target user are unavailable. Previous works consider each session individually and try to capture user interests within a session. Despite their encouraging results, these models can only perceive intra-session items and cannot draw upon the massive historical relational information. To solve this problem, we propose a novel method named G3SR (Global Graph Guided Session-based Recommendation). G3SR decomposes the session-based recommendation workflow into two steps. First, a global graph is built upon all session data, from which the global item representations are learned in an unsupervised manner. Then, these representations are refined on session graphs under the graph networks, and a readout function is used to generate session representations for each session. Extensive experiments on two real-world benchmark datasets show remarkable and consistent improvements of the G3SR method over the state-of-the-art methods, especially for cold items. Copyright © 2022, The Authors. All rights reserved.

关键词： Graph neural networks

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可持续发展情景下丝绸之路沿线国家土地利用及其对陆地碳库影响

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science Bulletin 2023年第7期68卷 740-749页

作者：曹敏田雅吴凯陈旻陈玉胡雪孙中昶左丽君林键骆磊朱瑞许振赐 Temenoujka Bandrova Milan Konecny 袁文平郭华东林珲闾国年 Key Laboratory of Virtual Geographic Environment Ministry of EducationNanjing Normal UniversityNanjing 210023China International Research Center of Big Data for Sustainable Development Goals Beijing 100094China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China School of Geography and Environment Jiangxi Normal UniversityNanchang 330022China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China The Key Laboratory of Urban Land Resources Monitoring and Simulation Ministry of Natural ResourcesShenzhen 518034China Sierra Nevada Research Institute University of CaliforniaMerced CA 95348USA Institute of High Performance Computing Agency for ScienceTechnology and ResearchSingapore 138632Singapore Department of Geography the University of Hong KongHong Kong 999077China Laboratory on Cartography University of ArchitectureCivil Engineering and GeodesySofia 1164Bulgaria Laboratory on Geoinformatics and Cartography Institute of GeographyMasaryk UniversityBrno 60177Czech Republic School of Atmospheric Sciences Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Sun Yat-sen UniversityZhuhai 519082China Key Laboratory of Poyang Lake Wetland and Watershed Research Ministry of EducationJiangxi Normal UniversityNanchang 330022China

可持续发展目标(SDGs)呼吁全世界共同采取行动,促进繁荣并保护地球.本研究面向SDGs构建了环境、粮食和经济等可持续发展情景,预测2020~2030年丝绸之路沿线国家的土地利用变化,并分析其对陆地碳库的影响。研究表明:未来土地利用变化及其... 详细信息

可持续发展目标(SDGs)呼吁全世界共同采取行动,促进繁荣并保护地球.本研究面向SDGs构建了环境、粮食和经济等可持续发展情景,预测2020~2030年丝绸之路沿线国家的土地利用变化,并分析其对陆地碳库的影响。研究表明:未来土地利用变化及其对陆地碳库的影响在不同情景下存在显著差异。在可持续环境情景下,林地得到了有效保护,相较于2020年中国林地碳储量增加了约0.60%;在可持续粮食情景下,耕地流失得到了缓解,尤其在南亚及东南亚地区的耕地面积呈现上升趋势:在可持续经济情景下,城市扩张速度加快,引起的碳损失量最多这项研究有助于推进丝绸之路沿线甚至全球可持续发展进程,为探寻可持续发展路径提供了科学依据。

关键词： Sustainable development goals(SDGs) Land-use projection Carbon pool Scenarios System dynamics model Cellular automata

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