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An Efficient Federated Learning Framework Deployed in Resource-Constrained IoV:User Selection and Learning Time Optimization Schemes

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China Communications 2023年第12期20卷 111-130页

作者： Qiang Wang Shaoyi xu rongtao xu Dongji Li School of Electronics and Information Engineering Beijing Jiaotong UniversityBeijing 100044China National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China

In this article,an efficient federated learning(FL)Framework in the Internet of Vehicles(IoV)is *** the considered model,vehicle users implement an FL algorithm by training their local FL models and sending their models to a base station(BS)that generates a global FL model through the model *** each user owns data samples with diverse sizes and different quality,it is necessary for the BS to select the proper participating users to acquire a better global ***,considering the high computational overhead of existing selection methods based on the gradient,the lightweight user selection scheme based on the loss decay is *** to the limited wireless bandwidth,the BS needs to select an suitable subset of users to implement the FL ***,the vehicle users’computing resource that can be used for FL training is usually limited in the IoV when other multiple tasks are required to be *** local model training and model parameter transmission of FL will have significant effects on the latency of *** address this issue,the joint communication and computing optimization problem is formulated whose objective is to minimize the FL delay in the resource-constrained *** solve the complex nonconvex problem,an algorithm based on the concave-convex procedure(CCCP)is proposed,which can achieve superior performance in the small-scale and delay-insensitive FL *** to the fact that the convergence rate of CCCP method is too slow in a large-scale FL system,this method is not suitable for delay-sensitive *** solve this issue,a block coordinate descent algorithm based on the one-step projected gradient method is proposed to decrease the complexity of the solution at the cost of light performance *** are conducted and numerical results show the good performance of the proposed methods.

关键词： block coordinate descent concave-convex procedure federated learning learning time resource allocation

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Link Budget and Enhanced Communication Distance for Ambient Internet of Things

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ZTE Communications 2024年第1期22卷 16-23页

作者： YANG Yibing LIU Ming xu rongtao WANG Gongpu GONG Wei School of Computer and Information Technology Beijing Jiaotong UniversityBeijing 100044China School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044China School of Computer Science and Technology University of Science and Technology of ChinaHefei 230026China

Backscatter communications will play an important role in connecting everything for beyond 5G(B5G)and 6G *** open challenge for backscatter communications is that the signals suffer a round-trip path loss so that the communication distance is *** this paper,we first calculate the communication distance upper bounds for both uplink and downlink by measuring the tag sensitivity and reflection *** is found that the activation voltage of the envelope detection diode of the downlink tag is the main factor limiting the back-scatter communication *** on this analysis,we then propose to implement a low-noise amplifier(LNA)module before the envelope detection at the tag to enhance the incident signal *** experimental results on the hardware platform show that our method can increase the downlink communication range by nearly 20 m.

关键词： ambient IoT(AIoT) B5G backscatter communication link budget low-noise amplifier(LNA) Release 19 tag chip sensitivity upper bounds

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无源反向散射通信系统载波频偏位置快速检测算法

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电子与信息学报 2023年第7期45卷 2311-2316页

作者：王公仆许亚婷许荣涛陈霞艾渤北京交通大学计算机与信息技术学院北京100044 北京交通大学电子信息工程学院北京100044

近来无源反向散射通信技术作为绿色物联网的关键技术,引起了广泛的关注。在无源反向散射通信系统中,收发节点与反射节点的振荡器差异、相对运动以及环境变化,导致接收端和发送端存在载波频率偏移(CFO)。CFO对信号检测和系统性能有重要影... 详细信息

近来无源反向散射通信技术作为绿色物联网的关键技术,引起了广泛的关注。在无源反向散射通信系统中,收发节点与反射节点的振荡器差异、相对运动以及环境变化,导致接收端和发送端存在载波频率偏移(CFO)。CFO对信号检测和系统性能有重要影响,而当前多数无源反向散射通信系统研究忽略了CFO。该文设计了一种适用于频移键控调制(FSK)的CFO快速检测方法,不需要导频就能快速有效检测出CFO是否存在并找出存在的位置。首先,根据信号在CFO存在与否的不同,采用去直流后取模方法对信号进行处理,而后根据处理后的信号的特点,基于累积和(CUSUM)设计快速检测算法对载波频偏出现的位置进行检测,并对理论分析结果进行仿真验证,仿真结果表明取模检测可以有效检测出CFO出现的位置。

关键词：反向散射通信载波频偏快速检测物联网

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衰落信道下两发送天线MIMO系统V-BLAST算法研究(英文)

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北京交通大学学报 2010年第5期34卷 146-153页

作者：许荣涛钟章队陈建谋北京交通大学轨道交通控制与安全国家重点实验室北京100044 台湾华夏技术学院资产与物业管理系

对两发送天线MI MO系统在相关瑞利和莱斯信道下V-BLAST检测算法的性能进行了分析,推导出最优和固定检测两种方案中第一步和第二步的误码率.相对于独立同分布瑞利信道,考察了相关瑞利信道和莱斯信道对接收信噪比的影响;相对于固定检测方... 详细信息

对两发送天线MI MO系统在相关瑞利和莱斯信道下V-BLAST检测算法的性能进行了分析,推导出最优和固定检测两种方案中第一步和第二步的误码率.相对于独立同分布瑞利信道,考察了相关瑞利信道和莱斯信道对接收信噪比的影响;相对于固定检测方案,讨论了最优检测算法对信噪比的提升.理论分析和仿真结果表明,瑞利信道相关性或莱斯信道的直达波分量会减弱最优检测方案对信噪比的提升.

关键词：多输入输出天线系统垂直空时结构最优检测顺序复Wishart分布

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无源物联网的编码技术研究

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物联网学报 2023年第3期7卷 24-31页

作者：杨义冰许荣涛陈霞王公仆艾渤北京交通大学计算机与信息技术学院北京100091 北京交通大学电子信息工程学院北京100091 北京交通大学轨道交通控制与安全国家重点实验室北京100091

无源反向散射通信技术能让传感器摆脱电池的束缚,避免繁杂的人工维护,有效降低传感器的成本。无源反向散射通信技术已被认为是实现无源物联网的关键技术之一。由于无源传感器节点资源受限,如何利用编码技术提高系统可靠性成为无源物联... 详细信息

无源反向散射通信技术能让传感器摆脱电池的束缚,避免繁杂的人工维护,有效降低传感器的成本。无源反向散射通信技术已被认为是实现无源物联网的关键技术之一。由于无源传感器节点资源受限,如何利用编码技术提高系统可靠性成为无源物联网的挑战性难题。聚焦无源物联网无源节点的编码和解码技术,首先,系统阐述传统信道编码发展历程,以及现有的RFID信道编码解码方案;然后,选择适合无源反向散射通信技术的3种编码方案;最后,仿真比较这3种编码方案的性能并总结优缺点。

关键词：无源物联网反向散射编码

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Kilowatt high average power narrow-linewidth nanosecond all-fiber laser

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High Power Laser Science and Engineering 2014年第1期2卷 45-48页

作者： rongtao Su Pu Zhou Xiaolin Wang Rumao Tao Xiaojun xu College of Optoelectronic Science and Engineering National University of Defense Technology

A high power narrow-linewidth nanosecond all-fiber laser based on the master oscillator power amplifier(MOPA)configuration is demonstrated. A pulsed seed with high repetition rate of 10 MHz was generated by modulating a continuous-wave(CW) single-frequency fiber laser at ～1064 nm by using an electro-optic intensity modulator(EOIM).After multi-stage cascaded power amplification, the average power was boosted to be kilowatt level. The pulses from the main amplifier had a pulse width of ～3 ns and an average/peak power of 913 W/28.6 kW. Further power scaling of the pulses was limited by stimulated Raman scattering(SRS) for the moment, method for SRS suppression and further power scaling was briefly discussed.

关键词： fiber laser nanosecond pulsed laser narrow linewidth stimulated Raman scattering

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High power linearly polarized fiber laser：Generation, manipulation and application

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Science China(Technological Sciences) 2017年第12期60卷 1784-1800页

作者： ZHOU Pu HUANG Long xu JiangMing MA PengFei SU rongtao WU Jian LIU ZeJin College of Optoelectronic Science and Engineering National University of Defense Technology Changsha 410073 China

Linearly-polarized(LP) fiber lasers, which could find wide potential applications such as coherent detection, coherent/spectral beam combining, nonlinear frequency conversion, have been a research focus in recent years. In this paper, we will present a general review on the achievements of various kinds of high power LP fiber laser and its applications for the first time. The recent progress in high power LP fiber oscillator, including fiber oscillator based on active fiber, Raman fiber laser and Random distributed feedback fiber laser are summarized. Power scaling of LP fiber laser by using active-fiber based power amplifier, passive-fiber based Raman amplifier, and active/passive fiber based hybrid fiber amplifier has been achieved. Polarization-maintained active fiber based power amplifier and non-polarization-maintained active fiber based power amplifier incorporating active polarization control are specially introduced in detail. High power LP fiber laser with diversified property, such as narrow-linewidth, wavelength-tunable and ultrashort pulse operation, are summarized. Various kinds application of high power LP fiber laser, including beam combining,supercontinumm generation, mid-infrared lasing, structured light field and ultrasonic generation, are presented at the end of this paper.

关键词： linear polarized fiber laser high power raman fiber laser polarization control pulsed fiber laser

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Effects of flooding stress on the photosynthetic apparatus of leaves of two Physocarpus cultivars

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Journal of Forestry Research 2018年第4期29卷 1041-1051页

作者： Huihui Zhang Peng Feng Wei Yang Xin Sui Xin Li Wei Li rongtao Zhang Siyu Gu Nan xu College of Resources and Environment Northeast Agricultural University College of Life Science Northeast Agricultural University Natural Resources and Ecology Institute Heilongjiang Academy of Sciences

We applied under pot-culture conditions and the double-casing pot method to study the characteristics of photosynthetic gas exchange and chlorophyll fluorescence in the leaves of Physocarpus amurensis Maxim （PA） and Physocarpus opulifolius under flooding stress. Our results indicate a significantly higher flooding tolerance of P. opulifolius compared to P. amurensis. Especially in P. amurensis, the limitation of non-stomatal factors played a major role in the advanced stages of flooding stress, observed as a rapid increase of the intercellular C02 con- centration （Ci） and a decrease of the stomatal limitation value （Ls）. The maximal PSII photochemical efficiencies （Fv/Fm） and actual photochemical efficiency （60PSU） in the leaves of P. opulifolius were extent of decrease during the than in P. amurensis. In significantly higher, and the flooding process was smaller addition, the non-chemical quenching （NPQ） in the leaves of P. opulifolius significandy increased from the 10th day under flooding stress, while the variation of NPQ in the leaves of P. amurensis was much smaller. This indicates that the leaves of P. opulifolius had not only higher PSII photochemical activity, but also improved tolerance to flooding stress, which may be caused by its ability to dissipate excess excitation energy by starting NPQ. At the 16th day under flooding stress, the PLABS significantly decreased with greater extent of decrease than Fv/Fm in the leaves of both Physocarpus, but the decreasing extent of PIABS in P. opulifolius was significantly smaller than in P. amurensis. In the 16th day under flooding stress, the fluorescence at J and I point （VJ and V1） in P. amurensis were significantly higher, and the extent of increase in VJ was greater than V1. However, the variations of VJ and V1 in the leaves of P. opulifolius were smaller, suggesting that the damage sites of flooding stress to PSII in the leaves of P. amurensis were mainly located in the electron transport process from QA at th

关键词： Physocarpus amurensis Maxim Physocarpusopulifolius Photosynthesis capacity Chlorophyll fluorescence characteristics

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Nonlinear photoresponse of metallic graphene-like VSe2 ultrathin nanosheets for pulse laser generation

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Science China(Information Sciences) 2019年第12期62卷 141-148页

作者： Tao WANG Xinyao SHI Jin WANG Yijun xu Jie CHEN Zhuo DONG Man JIANG Pengfei MA rongtao SU Yanxing MA Jian WU Kai ZHANG Pu ZHOU College of Advanced Interdisciplinary Studies National University of Defense Technology i-Lab Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Vacuum Interconnected Nanotech Workstation Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of Sciences

Vanadium diselenide(VSe2), a typical metallic behaviour material among transition metal dichalcogenides(TMDCs) family, exhibits excellent photoelectric characteristics with a zero band gap, missing applicaiotn in pulse generation. In this work, a high-quality VSe2 saturable absorber(SA) was synthesized through a liquid-phase exfoliation method. The saturable absorption of obtained VSe2-SA was characterized systematically. The measured modulation depth was 9.9%, and the saturated intensity was 533.8 μJ/cm2. By incorporating this optical modulator into a ytterbium-doped fiber laser cavity, a stable passively Q-switched laser could be achieved. The pulse had the central wavelength of 1064.03 nm. As the pump power was increased, the repetition rate increased from 24.3 k Hz to 35.6 k Hz, and the pulse duration decreased from7.21 μs to 5.27 μs. The output power had the maximum value of 28.55 m W. These results indicated that VSe2 is an effective candidate to generate pulse laser due to its excellent nonlinear optical properties and universal photoelectric response, which may advance the applications of VSe2-based nonlinear optics and photoelectric devices.

关键词： transition metal dichalcogenides VSe2 saturable absorber pulse laser fiber laser

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Quantifying growth and breakage of agglomerates in fluid-particle flow using discrete particle method

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Chinese Journal of Chemical Engineering 2018年第5期26卷 914-921页

作者： Lingfeng Zhou Junwu Wang Wei Ge Shiwen Liu Jianhua Chen Ji xu Limin Wang Feiguo Chen Ning Yang rongtao Zhou Lin Zhang Qi Chang Philippe Ricoux Alvaro Fernandez State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China Tianjin University Tianjin 300072 China TOTALSA - R&D Groupe Paris 92069 France Total Research & Technology Feluy Belgium Germany

The cohesive solids in liquid flows are featured by the dynamic growth and breakage of agglomerates, and the difficulties in the development, design and optimization of these systems are related to this significant *** this paper, discrete particle method is used to simulate a solid–liquid flow system including millions of cohesive particles, the growth rate and breakage rate of agglomerates are then systematically investigated. It was found that the most probable size of the agglomerates is determined by the balance of growth and breakage of the agglomerates the cross point of the lines of growth rate and breakage rate as a function of the particle numbers in an agglomerate, marks the most stable agglomerate size. The finding here provides a feasible way to quantify the dynamic behaviors of growth and breakage of agglomerates, and therefore offers the possibility of quantifying the effects of agglomerates on the hydrodynamics of fluid flows with cohesive particles.

关键词： Agglomerate Growth and breakage Quantification Discrete particle method

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