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A note on the novel 4D Einstein–Gauss–Bonnet gravity

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Communications in Theoretical Physics 2020年第9期72卷 89-95页

作者： Wen-yuan ai Centre for Cosmology Particle Physics and PhenomenologyUniversite catholique de LouvainLouvainla-Neuve B-134&Belgium

Recently, a novel 4 D Einstein–Gauss–Bonnet gravity has been proposed by Glavan and Lin(2020 Phys. Rev. Lett. 124 081301) by rescaling the coupling α→α(D-4) and taking the limit D→ 4 at the level of equations of motion. This prescription, though was shown to bring non-trivial effects for some spacetimes with particular symmetries, remains mysterious and calls for scrutiny. Indeed, there is no continuous way to take the limit D→4 in the higher Ddimensional equations of motion because the tensor indices depend on the spacetime dimension and behave discretely. On the other hand, if one works with 4 D spacetime indices the contribution corresponding to the Gauss–Bonnet term vanishes identically in the equations of motion. A necessary condition(but may not be sufficient) for this procedure to work is that there is an embedding of the 4 D spacetime into the higher D-dimensional spacetime so that the equations in the latter can be properly interpreted after taking the limit. In this note, working with2 D Einstein gravity, we show several subtleties when applying the method used in(2020 ***. Lett. 124 081301).

关键词： Einstein–Gauss–Bonnet gravity modified gravity theories general relativity

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基于嵌入式人工智能设备的流星光学监测系统

天文学报 2024年第1期65卷 53-66页

作者：贺田贾鹏李广伟王艾元太原理工大学电子信息与光学工程学院太原030012 中国科学院国家天文台北京100101 张璧古堡介休032000

流星光学监测网是定位陨石和观测火流星的基础科研设施.流星光学监测系统利用光学相机高速采集天空图像,使用嵌入式系统实时处理数据,能够快速识别流星并获取流星位置和陨石落点信息,是构成流星监测网的关键仪器.为提高流星光学监测系... 详细信息

流星光学监测网是定位陨石和观测火流星的基础科研设施.流星光学监测系统利用光学相机高速采集天空图像,使用嵌入式系统实时处理数据,能够快速识别流星并获取流星位置和陨石落点信息,是构成流星监测网的关键仪器.为提高流星光学监测系统获取信息的实时性及准确性,提出了一种基于嵌入式人工智能设备的流星光学监测系统.该系统由软件及硬件部分组成:硬件部分包括观测设备(商用高空抛物摄像头)以及数据处理设备(嵌入式人工智能设备);软件部分运行于数据处理设备内,主要包括控制界面模块、流星监测模块、数据管理模块.实际工作时,摄像头采集天空视频信息,流星监测模块从视频流中实时监测流星并存储包含流星视频的数据,数据管理模块将流星位置信息实时传回数据中心用于预警.观测结束后,将原始观测数据同步至数据中心用于后续科学研究.在整个系统中,流星监测模块决定了整个监测系统的实时性及准确性.该系统采用嵌入式人工智能设备与人工智能算法结合的方法构建流星监测模块.通过使用实测数据对搭载监测模块性能进行测试,结果表明:流星监测模块能够达到0.28%的低误检率以及100%的召回率,且数据处理速度达到了Mobilenetv2的8倍.进一步将包含监测模块的整个流星光学监测系统部署于太原理工大学-张壁古堡远程天文台,通过实测表明流星光学监测系统实用中能达到100%的召回率和较低的误检率.

关键词：流星天文仪器技术图像处理方法数据分析

Longitudinal Susceptibility of S=1/2 Low-Dimensional Heisenberg Ferromagnet in a Magnetic Field

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Communications in Theoretical Physics 2008年第5期49卷 1349-1352页

作者： CHEN yuan XIANG Ying HU ai-yuan Department of Physics Guangzhou University Guangzhou 510006 China School of Information Engineering Guangdong University of Technology Guangzhou 510006 China

Longitudinal susceptibifity of the spin-1/2 low-dimensional Heisenberg ferromagnet in a magnetic field, is studied by the Green＇s function method within the random phase approximation. The static and dynamic longitudinal susceptibilities are calculated in the low- and high-field regions. Power laws for the position and height of the static susceptibility maximum are shown not to support the predictions of Landau theory.

关键词： Heisenberg ferromagnet longitudinal susceptibility Green's function

Phase transition of the frustrated antiferromagntic J1-J2-J3 spin-1/2 Heisenberg model on a simple cubic lattice

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Frontiers of physics 2019年第1期14卷 137-146页

作者： ai-yuan Hu Huai-Yu Wang College of Physics and Electronic Engineering Chongqing Normal University Chongqing 401331 China Department of Physics Tsinghua University Beijing 100084 China

We have comprehensively investigated the frustrated J1-J2-J3 Heisenberg model on a simple cubic lattice. This model allows three regimes of magnetic order, viz., (π;π;π), (0;π;π) and (0;0;π), denoted as AF1, AF2, and AF3, respectively. The effects of the interplay of neighboring couplings on the model are studied in the entire temperature range. The zero temperature magnetic properties of this model are discussed utilizing the linear spin wave (LSW) theory, nonlinear spin wave (NLSW) theory, and Green’s function (GF) method. The zero temperature phase diagrams evaluated by the LSW and NLSW methods are illustrated, and are observed to exhibit different parameter boundaries. In certain regions and along the parameter boundaries, the possible phase transformations driven by the parameters are discussed. The results obtained using the LSW, NLSW, and GF methods are compared with those obtained using the series expansion (SE) method, and are observed to be in good agreement when the value of J2 is not close to the parameter boundaries. The ground state energies obtained using the LSW and NLSW methods are close to that obtained using the SE method. At finite temperatures, only the GF method is employed to evaluate the magnetic properties, and the calculated phase diagram is observed to be identical to the classical phase diagram. The results indicate that at the parameter boundaries, a temperature-driven first-order phase transition between AF1 and AF2 may occur along the boundary line. Along the AF1-AF3 and AF2-AF3 boundary lines, AF3 is less stable than AF1 and AF2. Our calculated critical temperature agrees with that obtained using Monte Carlo simulations and pseudofermion functional renormalization group scheme.

关键词： quantized spin models quantum phase transitions antiferromagnetics

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毛叶山桐子油成分快速分析方法的建立与应用

贵州农业科学 2024年第4期52卷 114-123页

作者：旷怡黄磊苑嫒四川大学生命科学学院四川成都610064 贵州省农业生态与资源保护站贵州贵阳550000

【目的】探明快速高效检测毛叶山桐子油中甘油三酯的定性和定量分析方法,为毛叶山桐子油品质鉴定和综合开发利用提供检测方法和参考依据。【方法】建立UPLC-PDA、UPLC-MS和UPLC-ELSD 3种方法检测不同地区毛叶山桐子油中甘油三酯组分和含... 详细信息

【目的】探明快速高效检测毛叶山桐子油中甘油三酯的定性和定量分析方法,为毛叶山桐子油品质鉴定和综合开发利用提供检测方法和参考依据。【方法】建立UPLC-PDA、UPLC-MS和UPLC-ELSD 3种方法检测不同地区毛叶山桐子油中甘油三酯组分和含量,并比较3种方法检测的灵敏度及选择性,确定最佳检测方法。【结果】UPLC-MS可对毛叶山桐子油中1-十七烷酸-2-花生四烯酸-3-亚油酸、1,2-油酸-3-亚油酸、1,-亚油酸-2-油酸-3-亚麻酸等14种甘油三酯组分进行定量和定性分析,检测范围和灵敏度均优于UPLC-PDA和UPLC-ELSD。UPLC-MS应用显示,毛叶山桐子油中TG11和TG14是影响13个不同产地毛叶山桐子果实及其不同部位油的主要因素。【结论】UPLC-MS是最适鉴定毛叶山桐子油中甘油三酯组成的方法,能够快速准确地对毛叶山桐子油进行成分鉴定、品质分析及质量控制。

关键词：毛叶山桐子油甘油三酯 UPLC-MS 品质鉴定

基于数据挖掘技术探析针灸治疗肿瘤相关性失眠的选穴规律

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针刺研究 2024年第7期49卷 726-735页

作者：叶敏张乐乐袁爱红解鸿宇夏玉杨骏安徽中医药大学第一临床医学院合肥230031 安徽中医药大学第一附属医院针灸康复科合肥230031 经脉脏腑相关安徽省重点实验室合肥230038

目的:运用数据挖掘技术分析针灸治疗肿瘤相关性失眠的选穴规律。方法:检索中国知网、万方、维普、PubMed等数据库从建库至2024年1月5日针灸治疗肿瘤相关性失眠的相关文献,建立针灸治疗肿瘤相关性失眠的处方数据库,对使用频次、归经、分... 详细信息

目的:运用数据挖掘技术分析针灸治疗肿瘤相关性失眠的选穴规律。方法:检索中国知网、万方、维普、PubMed等数据库从建库至2024年1月5日针灸治疗肿瘤相关性失眠的相关文献,建立针灸治疗肿瘤相关性失眠的处方数据库,对使用频次、归经、分布等进行描述性分析,运用SPSS Modeler18.0 Apriori算法对处方进行关联规则分析,Cytoscape3.9.1软件绘制复杂网络图,SPSS26.0软件对高频腧穴进行聚类分析。结果:纳入文献41篇,提取针灸处方67条,涉及腧穴89个,总频次447次;腧穴使用频次排名前4位的是百会、三阴交、神门、神庭;所选经脉主要是督脉、脾经、膀胱经、任脉、心经、胃经等;选穴多集中在头项部和上、下肢部;特定穴中使用频次较高的为五输穴、交会穴、原穴;腧穴配伍中,神庭-三阴交-神门-百会四穴关联最强;前12位高频腧穴可分为3个有效聚类群。结论:针灸治疗肿瘤相关性失眠以扶正固本、兼以祛邪、燮理阴阳、通督调神、宁心安神为治疗原则,核心穴组为神庭-三阴交-神门-百会,还可加用足三里、印堂以增强治疗效果。

关键词：肿瘤相关性失眠针灸选穴规律数据挖掘

Distributed robust power control in two-tier vehicle networks under uncertain channel environments

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Digital Communications and Networks 2023年第3期9卷 734-742页

作者： Zhixin Liu Jiawei Su yuan-ai Xie Yazhou yuan Yi Yang Xinping Guan School of Electrical Engineering Yanshan UniversityQinhuangdao066004China School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai200240China

This paper proposes a novel optimization scheme to support stable and reliable vehicle-to-everything connections in two-tier networks,where the uplink channel of the cellular user is reused by underlay vehicle-to-vehicle ***,considering complex channel fading and high-speed vehicle movement,the cer-tainty assumption is impractical and fails to maintain power control strategy in reality in the traditional statical vehicular *** than the perfect channel state information assumption,the first-order Gauss-Markov process which is a probabilistic model affected by vehicle speed and fading is introduced to describe imperfect channel ***,interference management is a major challenge in reusing communications,especially in uncertain channel *** control is an effective way to realize interference management,and optimal power allocation can ensure that interference of the user meets the communication *** this study,the sum-rate-oriented power control scheme and minimum-rate-oriented power control scheme were implemented to manage interference and satisfy different design *** both of these schemes are non-convex and intractable,the Bernstein approximation and successive convex approximation methods were adopted to transform the original problems into convex ***,a novel distributed robust power control al-gorithm was developed to determine the optimal *** performance of the algorithm was evaluated through numerical simulations,and the results indicate that the proposed algorithm is effective in vehicular communication networks with uncertain channel environments.

关键词： Vehicle-to-Everything communications Vehicular two-tier networks Channel uncertainty Power control

Joint Resource Allocation and Admission Control in Sliced Fog Radio Access Networks

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China Communications 2020年第8期17卷 14-30页

作者： yuan ai Gang Qiu Chenxi Liu Yaohua Sun State Key Laboratory of Network and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China LTE&5G Wireless Product R&D Institute ZTE CorporationShenzhen 518057China

Network slicing based fog radio access network(F-RAN) has emerged as a promising architecture to support various novel applications in 5 G-and-beyond wireless networks. However, the co-existence of multiple network slices in F-RANs may lead to significant performance degradation due to the resource competitions among different network slices. In this paper, the downlink F-RANs with a hotspot slice and an Internet of Things(Io T) slice are considered, in which the user equipments(UEs) of different slices share the same spectrum. A novel joint resource allocation and admission control scheme is developed to maximize the number of UEs in the hotspot slice that can be supported with desired quality-of-service, while satisfying the interference constraint of the UEs in the Io T slice. Specifically, the admission control and beamforming vector optimization are performed in the hotspot slice to maximize the number of admitted UEs, while the joint sub-channel and power allocation is performed in the Io T slice to maximize the capability of the UEs in the Io T slice tolerating the interference from the hotspot slice. Numerical results show that our proposed scheme can effectively boost the number of UEs in the hotspot slice compared to the existing baselines.

关键词： NOMA fog radio access networks resource allocation admission control

Edge computing technologies for Internet of Things： a primer

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Digital Communications and Networks 2018年第2期4卷 77-86页

作者： yuan ai Mugen Peng Kecheng Zhang Key Laboratory of Universal Wireless Communications for Ministry of Education Beijing University of Posts and Telecommunications China

with the rapid development of mobile intemet and Internet of Things applications, the conventional centralized cloud computing is encountering severe challenges, such as high latency, low Spectral Efficiency （SE）, and nonadaptive machine type of communication. Motivated to solve these challenges, a new technology is driving a trend that shifts the function of centralized cloud computing to edge devices of networks. Several edge computing technologies originating from different backgrounds to decrease latency, improve SE, and support the massive machine type of communication have been emerging. This paper comprehensively presents a tutorial on three typical edge computing technologies, namely mobile edge computing, cloudlets, and fog computing. In particular, the standardization efforts, principles, architectures, and applications of these three technologies are summarized and compared. From the viewpoint of radio access network, the differences between mobile edge computing and fog computing are highlighted, and the characteristics of fog computing-based radio access network are discussed. Finally, open issues and future research directions are identified as well.

关键词： Intemet of Things (loT) Mobile edge computing Cloudlets Fog computing