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Near-field channel estimation for extremely large-scale Terahertz communications

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Science China(Information Sciences) 2024年第9期67卷 213-228页

作者： Songjie YANG Yizhou PENG Wanting LYU Ya LI Hongjun HE Zhongpei ZHANG chau YUEN National Key Laboratory of Wireless Communications University of Electronic Science and Technology of China Future Research Laboratory China Mobile Research Institute School of Electrical and Electronics Engineering Nanyang Technological University

Future Terahertz communications exhibit significant potential in accommodating ultra-high-rate services. Employing extremely large-scale array antennas is a key approach to realize this potential, as they can harness substantial beamforming gains to overcome the severe path loss and leverage the electromagnetic advantages in the near field. This paper proposes novel estimation methods designed to enhance efficiency in Terahertz widely-spaced multi-subarray(WSMS) systems. Initially, we introduce three sparse channel representation methods: polar-domain representation(PD-R), multi-angular-domain representation(MADR), and two-dimensional polar-angular-domain representation(2D-PAD-R). Each method is meticulously developed for near-field WSMS channels, capitalizing on their sparsity characteristics. Building on this,we propose four estimation frameworks using the sparse recovery theory: polar-domain estimation(PD-E),multi-angular-domain estimation(MAD-E), two-stage polar-angular-domain estimation(TS-PAD-E), and two-dimensional polar-angular-domain estimation(2D-PAD-E). Particularly, 2D-PAD-E, integrating a 2D dictionary process, and TS-PAD-E, with its sequential approach to angle and distance estimation, stand out as particularly effective for near-field angle-distance estimation, enabling decoupled calculation of these parameters. Overall, these frameworks provide versatile and efficient solutions for WSMS channel estimation,balancing low complexity with high-performance outcomes. Additionally, they represent a fresh perspective on near-field signal processing.

关键词： Terahertz communications near field channel estimation widely-spaced multi-subarray sparse recovery

An Improved Golden Jackal Optimization Algorithm Based on Multi-strategy Mixing for Solving Engineering Optimization Problems

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Journal of Bionic Engineering 2024年第2期21卷 1092-1115页

作者： Jun Wang Wen-chuan Wang Kwok-wing chau Lin Qiu Xiao-xue Hu Hong-fei Zang Dong-mei Xu College of Water Resources North China University of Water Resources and Electric PowerZhengzhou450046People’s Republic of China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong KongPeople’s Republic of China

Nowadays,optimization techniques are required in various engineering domains to find optimal solutions for complex *** a result,there is a growing tendency among scientists to enhance existing nature-inspired algorithms using various evolutionary strategies and to develop new nature-inspired optimization methods that can properly explore the feature *** recently designed nature-inspired meta-heuristic,named the Golden Jackal Optimization(GJO),was inspired by the collaborative hunting actions of the golden jackal in nature to solve various challenging ***,like other approaches,the GJO has the limitations of poor exploitation ability,the ease of getting stuck in a local optimal region,and an improper balancing of exploration and *** overcome these limitations,this paper proposes an improved GJO algorithm based on multi-strategy mixing(LGJO).First,using a chaotic mapping strategy to initialize the population instead of using random parameters,this algorithm can generate initial solutions with good diversity in the search ***,a dynamic inertia weight based on cosine variation is proposed to make the search process more realistic and effectively balance the algorithm's global and local search ***,a position update strategy based on Gaussian mutation was introduced,fully utilizing the guidance role of the optimal individual to improve population diversity,effectively exploring unknown regions,and avoiding the algorithm falling into local *** evaluate the proposed algorithm,23 mathematical benchmark functions,CEC-2019 and CEC2021 tests are *** results are compared to high-quality,well-known optimization *** results of the proposed method are compared from different points of view,including the quality of the results,convergence behavior,and *** superiority and high-quality performance of the proposed method are demonstrated by comparing the ***,to demonstrate

关键词： Golden jackal optimization Chaotic mapping Dynamic inertia weight Dimensional Gaussian variation Muskingum

Riding towards a sustainable future:an evaluation of bike sharing’s environmental benefits in Xiamen Island,China

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Geography and Sustainability 2024年第2期5卷 276-288页

作者： Jianxiao Liu Meilian Wang Pengfei Chen Chaoxiang Wen Yue Yu KW chau Department of Real Estate and Construction Faculty of ArchitectureThe University of Hong KongPokfulamHong Kong 999077China Department of Land Surveying and Geo-informatics The Hong Kong Polytechnic UniversityHung HomHong Kong 999077China School of Geospatial Engineering and Science Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Department of Urban Planning School of Architecture and Civil EngineeringXiamen UniversityXiamen 550002China Ronald Coase Centre for Property Rights Research HKUrbanLabThe University of Hong KongPokfulamHong Kong 999077China

In the pursuit of sustainable urbanization,Bike-Sharing Services(BSS)emerge as a pivotal instrument for promoting green,low-carbon *** BSS is often commended for its environmental benefits,we offer a more nuanced analysis that elucidates previously neglected *** the Dominant Travel Distance Model(DTDM),we evaluate the potential of BSS to replace other transportation modes for specific journey based on travel *** multiscale geographically weighted regression(MGWR),we illuminate the relationship between BSS’s environmental benefits and built-environment *** life cycle analysis(LCA)quantifies greenhouse gas(GHG)emissions from production to operation,providing a deeper understanding of BSS’s environmental ***,our study focuses on Xiamen Island,a Chinese“Type Ⅱ large-sized city”(1–3 million population),contrasting with the predominantly studied“super large-sized cities”(over 10 million population).Our findings highlight:(1)A single BSS trip in Xiamen Island reduces GHG emissions by an average of 19.97 g CO_(2)-eq,accumulating monthly savings of 144.477 t CO_(2)-eq.(2)Areas in the southwest,northeast,and southeast of Xiamen Island,characterized by high population densities,register significant BSS environmental benefits.(3)At a global level,the stepwise regression model identifies five key built environment factors influencing BSS’s GHG mitigation.(4)Regionally,MGWR enhances model precision,indicating that these five factors function at diverse spatial scales,affecting BSS’s environmental benefits variably.

关键词： Greenhouse gases Shared mobility Carbon emission Multiscale geographically weighted regression Travel behavior Urban mobility

Refractory Ventricular Fibrillation with Underlying Coronary Artery Disease after COVID-19 Vaccine-Kounis Syndrome or Coincidence

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Case Reports in Clinical Medicine 2024年第8期13卷 309-314页

作者： Elaine M. C. chau Cardiology Centre Hong Kong Sanatorium & Hospital Hong Kong SAR China

A 63-year-old man with diabetes and asymptomatic coronary artery disease developed refractory ventricular arrhythmia at 20 hours at rest after his second COVID-19 vaccine. Despite significant stenosis in the coronary arteries, there was no evidence of acute or old myocardial infarction, heart failure, myocarditis or structural abnormalities on post-mortem to account for the substrate for the fatal arrhythmia. The refractory and incessant nature of the ventricular fibrillation and post-mortem finding of a grossly elevated unexplained IgE level (in the absence of acute myocardial infarction) suggested the possibility of Kounis Syndrome or allergic acute coronary syndrome.

关键词： Refractory Ventricular Fibrillation COVID-19 Vaccine Kounis Syndrome

面向全息MIMO 6G通信的电磁信道建模理论与方法

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电子与信息学报 2024年第5期46卷 1940-1950页

作者：黄崇文季然魏丽宫铁瑞陈晓明沙威杨军张朝阳 Yuen chau 浙江大学信息与电子工程学院杭州310027 新加坡科技与设计大学新加坡487372 西安交通大学信息与通信工程学院西安710049 中兴通讯股份有限公司深圳518000 新加坡南洋理工大学新加坡639798

全息多输入多输出(HMIMO)是6G通信中的新兴技术,相应阵列由固定物理孔径下的密布天线单元组成。全息MIMO是电磁约束下Massive MIMO天线技术的拓展。全息MIMO系统在有效提升无线通信性能方面具有极大的潜力。比如,可用最小的功率损耗实... 详细信息

全息多输入多输出(HMIMO)是6G通信中的新兴技术,相应阵列由固定物理孔径下的密布天线单元组成。全息MIMO是电磁约束下Massive MIMO天线技术的拓展。全息MIMO系统在有效提升无线通信性能方面具有极大的潜力。比如,可用最小的功率损耗实现尽可能大的连续孔径,灵活控制目标方向的电磁波传输等。但是,由于全息MIMO系统包含大量的紧密分布的天线单元,且单元之间的距离小于半波长,因而造成严重的电磁耦合作用。这些耦合使传统的独立同分布的信道假设失效。因此,如何设计一个有效且贴近实际的信道建模成为当前全息MIMO研究中最具挑战性的问题之一。针对该挑战,该文研究了基于电磁场理论的4种信道建模方式,它们都能很好描述全息MIMO系统中的电磁波传输特征。第1种是基于平面格林函数的精确信道建模方式,该方式将自由空间中点对点的格林函数扩展到平面之间积分形式的格林函数,通过积分计算来构造两个全息MIMO平面之间的通信信道,但该方法的复杂度较高。第2, 3种方法则分别采用了平面波展开和球面波展开来近似全息MIMO的通信信道,这两种方案的复杂度更低。其中,基于平面波展开的信道建模形式相对简单,更适用于远场,但是会低估单元强耦合时的最大系统容量;基于球面波展开的信道建模能更好捕捉电磁波信道几何特征,但其复杂度较高。最后介绍基于随机格林函数的信道建模方法,主要描述富散射环境或瑞利信道中电磁波的随机特性。

关键词：全息MIMO通信电磁波理论信道建模

IgG4 Coronary Arteritis Presenting as a Cardiac Pseudo-Tumour

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Case Reports in Clinical Medicine 2024年第9期13卷 345-352页

作者： Elaine Mo-Chee chau Catherine Yuet-Hung Wong Raymond Hin-Suen Liang Cardiology Centre Hong Kong Sanatorium & Hospital Hong Kong SAR China Nuclear Medicine Department Hong Kong Sanatorium & Hospital Hong Kong SAR China Comprehensive Oncology Centre Hong Kong Sanatorium & Hospital Hong Kong SAR China

We report on an unusual case presenting with a cardiac pseudo-tumour on echocardiogram, which corresponded to a large soft tissue mural thickening around the mid-right coronary artery. There were similar but not as thick mural lesions around other parts of the coronary arteries. The so-called “pigs-in-a-blanket” sign on computed tomography (CT) scan was pathognomonic of IgG4 coronary arteritis. The IgG4 level was grossly elevated at more than 10 times the upper limit of normal. Positron emission tomography (PET)-CT scans with 18F-fluoro-deoxy-glucose (FDG) and 68Ga-Fibroblast Activation Protein Inhibitor (FAPI) were performed to assess the extent of organ involvement of the IgG4-related disease. The patient was treated with 8 injections of rituximab with good serological response. However, the coronary arteritis findings on CT scan remained unchanged.

关键词： IgG4-Related Disease Coronary Arteritis Cardiac Pseudo-Tumour “Pigs-in-a-Blanket” Sign

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巴西柠檬草

上海蔬菜 2024年第1期 90-92页

作者： Lin chau Ming 巴西圣保罗州立大学农业科学学院圣保罗博图卡图18610-034

巴西柠檬草为一种药用植物,用途广泛,开发前景广阔。从巴西柠檬草叶片中提取出的精油可用于制作香水、香薰,其精油中含有柠檬醛和萜类化合物,可用于趋避害虫、预防植物病害,巴西柠檬草茶具有较强的抗氧化和抗菌活性,是治疗流感的民间偏... 详细信息

巴西柠檬草为一种药用植物,用途广泛,开发前景广阔。从巴西柠檬草叶片中提取出的精油可用于制作香水、香薰,其精油中含有柠檬醛和萜类化合物,可用于趋避害虫、预防植物病害,巴西柠檬草茶具有较强的抗氧化和抗菌活性,是治疗流感的民间偏方,且巴西柠檬草生长势强,对栽培管理要求不高,水肥需求量少,适合小农户栽培。该文介绍了巴西柠檬草的形态特征、生长习性、药用价值。

关键词：巴西柠檬草精油柠檬醛预防病虫害

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中国新能源股票市场收益及其波动相关性

复旦学报（自然科学版） 2024年第2期63卷 236-245,256页

作者：熊鸿军石峰周家贤上海电机学院商学院上海201306 南宁师范大学经济与管理学院广西南宁530299 澳门城市大学商学院中国澳门999078

本文利用2017年9月至2022年9月中国中证新能源指数、中证航空主题指数、中证医药健康100策略指数、中证农业主题指数和中证有色金属指数的交易日收盘价数据,采用3种多元GARCH模型(CCC-GARCH、DCC-GARCH和ADCC-GARCH)探索中国新能源公司... 详细信息

本文利用2017年9月至2022年9月中国中证新能源指数、中证航空主题指数、中证医药健康100策略指数、中证农业主题指数和中证有色金属指数的交易日收盘价数据,采用3种多元GARCH模型(CCC-GARCH、DCC-GARCH和ADCC-GARCH)探索中国新能源公司与航空公司、医药健康公司、农业公司以及有色金属公司之间的动态股票收益与波动相关性。条件均值方程的估计结果显示,航空公司、医药健康公司与农业公司滞后1期的股票收益显著影响新能源公司的当期股票收益。CCC-GARCH、DCC-GARCH和ADCC-GARCH模型估计的条件相关系数表明,样本期内中国新能源公司的股票回报与有色金属公司的股票回报的条件相关性最大,其次依次为航空公司、农业公司和医药健康公司。通过滚动向前一步的动态条件相关性检验也表明了估计结果的稳定性。因此,投资者可以考虑将有色金属公司的股市表现作为预测新能源公司股票回报的先行指标,以降低投资风险。

关键词：新能源股票市场多元GARCH模型 CCC-GARCH模型 DCC-GARCH模型 ADCC-GARCH模型

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墙上的别样风景

现代装饰（家居） 2016年第3期 68-75页

作者： Alan Wisniewski àlvaro Goula&Pablo Figuera Anette Stabel David Quan Erika Kovesdi Edward Lee Filippo Mambretti Jordan Murphy Joel Yatscoff Moe Takemura Michelle Ivankovic Michelle Ivankovic&Laura Carwardine rebobdesign Sung Wook Park wesley chau 伏平范嘉苑

墙是一种象征,在远离文明的荒滩野漠,它会滋生家的联想;墙是一段历史,在纵横古今的变迁时代,它承载着一个王朝的盛哀;墙是一个屏障,在进退攻守的人际交往中,它是守护心灵的桥头堡;墙是一道风景,在四季轮回的辗转交织间,它呈现着大自然... 详细信息

墙是一种象征,在远离文明的荒滩野漠,它会滋生家的联想;墙是一段历史,在纵横古今的变迁时代,它承载着一个王朝的盛哀;墙是一个屏障,在进退攻守的人际交往中,它是守护心灵的桥头堡;墙是一道风景,在四季轮回的辗转交织间,它呈现着大自然的万般风情。如今,随着现代人对家居环境的要求日益提高,如何将家装扮得既有个性又富有内涵和独特的品味。

关键词：风景墙人际交往家居环境桥头堡大自然现代人承载