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Deployment of Polar Codes for Mission-Critical Machine-Type Communication Over Wireless Networks

Computers, Materials & Continua 2022年第4期71卷 573-592页

作者： Najib Ahmed Mohammed Ali Mohammed Mansoor Rodina Binti Ahmad Saaidal Razalli Bin Azzuhri Department of Software Engineering Faculty of Computer Science and Information TechnologyUniversity of Malaya50603Kuala Lumpur Malaysia 2Department of Computer System&TechnologyFaculty of Computer Science and Information TechnologyUniversity of Malaya50603Kuala LumpurMalaysia

Mission critical Machine-type Communication(mcMTC),also referred to as Ultra-reliable Low Latency Communication(URLLC),has become a research *** is primarily characterized by communication that provides ultra-high reliability and very low latency to concurrently transmit short commands to a massive number of connected *** the reduction in physical(PHY)layer overhead and improvement in channel coding techniques are pivotal in reducing latency and improving reliability,the current wireless standards dedicated to support mcMTC rely heavily on adopting the bottom layers of general-purpose wireless standards and customizing only the upper *** mcMTC has a significant technical impact on the design of all layers of the communication protocol *** this paper,an innovative bottom-up approach has been proposed for mcMTC applications through PHY layer targeted at improving the transmission reliability by implementing ultra-reliable channel coding scheme in the PHY layer of IEEE 802.11a standard bearing in mind short packet transmission *** achieve this aim,we analyzed and compared the channel coding performance of convolutional codes(CCs),low-density parity-check(LDPC)codes,and polar codes in wireless network on the condition of short data packet *** Viterbi decoding algorithm(VA),logarithmic belief propagation(Log-BP)algorithm,and cyclic redundancy check(CRC)successive cancellation list(SCL)(CRC-SCL)decoding algorithm were adopted to CC,LDPC codes,and polar codes,***,a new PHY layer for mcMTC has been *** reliability of the proposed approach has been validated by simulation in terms of Bit error rate(BER)and packet error rate(PER)***-to-noise ratio(SNR).The simulation results demonstrate that the reliability of IEEE 802.11a standard has been significantly improved to be at PER=10−5 or even better with the implementation of polar *** results also show that the general-purpose wireless net

关键词： Machine-type communication mission-critical applications MTC URLLC M2M wireless networks polar codes

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Study on the Influence of Reactor system LOCA Modeling Mode on Dynamic Analysis 23rd

Study on the Influence of Reactor System LOCA Modeling Mode ...

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23rd Pacific Basin Nuclear Conference, PBNC 2022

作者： Shuai, Liu Xuan, Huang Zhipeng, Feng Zhongxiu, Zeng Huanhuan, Qi Xiaozhou, Jiang Harbin Engineering University Harbin China Science and Technology on Reactor System Design Technology Laboratory Sichuan Chengdu China

ISBN: (纸本)9789811987793

The reactor system has a large scale of components. And the system dynamic analysis model for loss of coolant accidents (LOCA) contains many non-linear factors. The transient calculation analysis takes a long time and the convergence is difficult to guarantee. In this paper, two different analysis models (complete three-loop model and single-loop model) of the first loop system of reactor are established for comparative analysis. The analysis shows that the calculation error of the main position load in the two different model is within 10%. The decoupling influence of the wave tube and the reactor inlet and outlet on the system dynamic characteristics is within an acceptable range. When the single loop model is used, it is necessary to decouple the reactor pressure vessel and pressurizer. And the simplified boundary is adapted to simulate its effect on the whole loop. The single-loop dynamic analysis model based on the decoupling criterion can greatly reduce the calculation scale and meet the calculation accuracy, which can be used to calculate the LOCA dynamic characteristics of the reactor system quickly. The model can also be used for seismic analysis of reactor system. And using this model for reactor system dynamic analysis can greatly improve the calculation efficiency. Please copy you summary here. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Loss of coolant accidents

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A robust statistical prediction model for late-summer heavy precipitation days in North China

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science China Earth sciences 2025年第1期68卷 158-171页

作者： Shunli JIANG Tingting HAN Xin ZHOU Huijun WANG Zhicong YIN Xiaolei SONG Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of EducationNanjing University for Information Science and TechnologyNanjing210044China Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai519080China

Recently,heavy precipitation(HP)events have occurred frequently in North China(NC),causing devastating economic losses and human ***,the short-term climate prediction of HP is quite *** year-to-year increment(DY)method and sliding correlations,we developed a robust seasonal prediction model for late-summer HP days(HPDs)in NC during 1982–2022,utilizing three independent predictors—February sea surface temperature(SST)in the Indian Ocean(SST_IO),February snow depth over North Asia(SDE_NA),and May melted snow depth in NC(MSDE_NC).The SST_IO anomalies affect NC's precipitation through the Pacific-Japan *** SDE_NA anomalies are associated with East Asian anomalous anticyclone by southeastern propagation of Rossby wave at *** MSDE_NC anomalies are followed by vertical motion and moisture anomalies in situ and thereby cause precipitation *** prediction model can well simulate the variations of the HPDs,with a correlation coefficient(CC)of 0.81(0.65)between the observed and predicted HPDs_DY(HPDs_anomaly).The percentage with the same sign for 15 extreme HPDs_anomaly years(PSSE)is 100%.Moreover,in the cross-validation test during 1982–2022,the PSSE for HPDs_anomaly is as high as 100%,along with a low rootmean-square error of *** independent hindcasts during 2013–2022,the CC between the observed and predicted HPDs_DY(HPDs_anomaly)is 0.93(0.83),together with high Nash-Sutcliffe efficiency(0.82)and agreement index(0.89).Specifically,the predictions are broadly consistent with the observations for 2015,2016,2017,2021,and 2022,reflecting excellent performance of this prediction model of HPDs in NC.

关键词： Heavy precipitation at North China Year-to-year increment approach Robust seasonal prediction Sea surface temperature Snow depth

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Spin Transport Properties of MnBi_(2)Te_(4)-Based Magnetic Tunnel Junctions

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Chinese Physics Letters 2023年第8期40卷 80-85页

作者：董新龙贾鑫严志申学敏李泽宇乔振华许小红 College of Physics and Information Engineering Shanxi Normal UniversityTaiyuan 030031China Key Laboratory of Magnetic Molecules and Magnetic Information Materials of the Ministry of Education Research Institute of Materials ScienceShanxi Normal UniversityTaiyuan 030031China International Center for Quantum Design of Functional Materials University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

The van der Waals heterojunctions,stacking of different two-dimensional materials,have opened unprecedented opportunities to explore new physics and device ***,combining the density functional theory with non-equilibrium Green’s function technique,we systematically investigate the spin-polarized transport properties of van der Waals magnetic tunnel junctions(MTJs),Cu/MnBi_(2)Te_(4)/MnBi_(2)Te_(4)/Cu and Cu/MnBi_(2)Te_(4)/hBN/n·MnBi_(2)Te_(4)/Cu(n=1,2,3).It is found that the maximum tunnel magnetoresistance of Cu/MnBi_(2)Te_(4)/hBN/3·MnBi_(2)Te_(4)/Cu MTJs can reach 162.6%,exceeding the system with only a single layer MnBi_(2)Te_(4).More interestingly,our results indicate that Cu/MnBi_(2)Te_(4)/h-BN/n·MnBi_(2)Te_(4)/Cu(n=2,3)MTJs can realize the switching function,while Cu/MnBi_(2)Te_(4)/h-BN/3·MnBi_(2)Te_(4)/Cu MTJs exhibit the negative differential *** Cu/MnBi_(2)Te_(4)/h-BN/3·MnBi_(2)Te_(4)/Cu in the parallel state shows a spin injection efficiency of more than 83.3%.Our theoretical findings of the transport properties will shed light on the possible experimental studies of MnBi_(2)Te_(4)-based van der Waals magnetic tunneling junctions.

关键词： exceeding equilibrium

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Optimal crater landmark selection based on optical navigation performance factors for planetary landing

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Chinese Journal of Aeronautics 2023年第3期36卷 254-270页

作者： Yi XIU Shengying ZHU Rui XU Maodeng LI School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration Ministry of Industry and Information TechnologyBeijing 100081China Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of EducationBeijing 100081China Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control EngineeringBeijing 100091China

Planetary craters are natural navigation landmarks that widely exist and are easily *** navigation based on crater landmarks has become an important autonomous navigation method for planetary *** to the increase in observed crater landmarks and the limitation of onboard computation,the selection of good crater landmarks has gradually become a research hotspot in the field of landmark-based optical *** paper designs a fast crater landmark selection method,which not only considers the configuration observability of crater subsets but also focuses on the influence on navigation performance arising from the measurement uncertainty and the matching confidence of craters,which is different from other landmark selection *** factor of measurement uncertainty,which is anisotropic,correlated and nonidentically distributed,is quantified and integrated into selection based on crater pairing detection and localization error *** addition,the concept of the crater matching confidence factor is introduced,which reflects the possibility of 2D projection measurements corresponding to 3D *** with the configuration observability factor,the crater landmark selection indicator is ***,the effectiveness of the proposed method is verified by Monte Carlo simulations.

关键词： Crater-based optical navigation Crater landmark selection Crater matching Measurement uncertainty Planetary landing

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Carrier and microstructure tuning for improving the thermoelectric properties of Ag_(8)SnSe_(6)via introducing SnBr_(2)

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Journal of Advanced Ceramics 2022年第7期11卷 1144-1152页

作者： Zhonghai YU Xiuxia WANG Chengyan LIU Yiran CHENG Zhongwei ZHANG Ruifan SI Xiaobo BAI Xiaokai HU Jie GAO Ying PENG Lei MIAO Guangxi Key Laboratory of Information Materials Electronical Information Materials and Devices Engineering Research Center of Ministry of EducationSchool of Materials Science and EngineeringGuilin University of Electronic TechnologyGuilin 541004China

The argyrodite compounds(2 A(12)/B X6 m n n^(m+)+--(Am+=Li^(+),Cu^(+),and Ag^(+);Bn^(+)=Ga^(3+),Si^(4+),Ge^(4+),Sn^(4+),P^(5+),and As^(5+);and X^(2−)=S^(2−),Se^(2−),or Te^(2−)))have attracted great attention as excellent thermoelectric(TE)materials due to their extremely low lattice thermal conductivity(κl).Among them,Ag_(8)SnSe_(6)-based TE materials have high potential for TE ***,the pristine Ag_(8)SnSe_(6)materials have low carrier concentration(<1017 cm^(−3)),resulting in low power *** this study,a hydrothermal method was used to synthesize Ag_(8)SnSe_(6)with high purity,and the introduction of SnBr_(2)into the pristine Ag_(8)SnSe_(6)powders has been used to simultaneously increase the power factor and decrease the thermal conductivity(κ).On the one hand,a portion of the Br−ions acted as electrons to increase the carrier concentration,increasing the power factor to a value of~698 mW·m^(−1)·K^(−2)at 736 *** the other hand,some of the dislocations and nanoprecipitates(SnBr_(2))were generated,resulting in a decrease ofκl(~0.13 W·m^(−1)·K^(−1))at 578 *** a result,the zT value reaches~1.42 at 735 K for the sample Ag8Sn1.03Se5.94Br0.06,nearly 30%enhancement in contrast with that of the pristine sample(~1.09).The strategy of synergistic manipulation of carrier concentration and microstructure by introducing halogen compounds could be applied to the argyrodite compounds to improve the TE properties.

关键词： Ag_(8)SnSe_(6) thermoelectric(TE)performance lattice thermal conductivity SnBr_(2) introduction hydrothermal method

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Multi-frequency smartphone positioning performance evaluation:insights into A-GNSS PPP-B2b services and beyond

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Satellite Navigation 2024年第3期5卷 93-118页

作者： Jiale Wang Chuang Shi Fu Zheng Cheng Yang Xu Liu Shuo Liu Ming Xia Guifei Jing Tuan Li Wu Chen Qingcheng Li Yong Hu Yuan Tian Yunfeng Shan School of Electronic and Information Engineering Beihang University37 Xueyuan RoadBeijing100191China Research Institute for Frontier Science Beihang University37 Xueyuan RoadBeijing100191China Key Laboratory of Navigation and Communication Fusion Technology Ministry of Industry and Information Technology37 Xueyuan RoadBeijing100191China School of Land Science and Geomatics China University of GeosciencesBeijing100083China Institute of Technology and Standards China Academy of Information and Communications TechnologyBeijing100095China The Department of Land Surveying and Geo-Information Hong Kong Polytechnic UniversityHung HomHong Kong

In August 2023,Xiaomi unveiled the Redmi K60 Ultra,the first multi-frequency smartphone integrated with BeiDou-3 Navigation Satellite system Precise Point Positioning(PPP-B2b)services and employing PPP technology as the primary positioning *** positioning enhancement service is provided by the Assisted Global Navigation Satellite system(A-GNSS)location platform developed by the China Academy of information and Communications *** signaling interaction between the server and the users strictly adheres to the Third Generation of Mobile Communications technology Partnership Project Long-Term Evolution Positioning Protocol and the Open Mobile Alliance Secure User Plane Location *** comprehensively evaluate the Redmi K60 Ultra’s capabilities,this study designed six distinct experimental scenarios and conducted comprehensive research on multi-frequency and multi-GNSS observation noise,Time to First Fix(TTFF),as well as the performance of both GNSS-based and network-based *** results indicate that the GNSS chipset within the Redmi K60 Ultra has achieved a leading position in the consumer market concerning supported satellite constellations,frequencies,and observation accuracy,and is comparable to some low-cost GNSS receivers.A-GNSS positioning can reduce the TTFF from 30 to under 5 s,representing an improvement of over 85%in the cold start speed compared to a standalone GNSS *** positioning results show that the A-GNSS PPP-B2b service can achieve positioning performance with RMS errors of less than 1.5 m,2.5 m,and 4 m in open-sky,realistic,and challenging urban *** to GNSS-based positioning,cellular network-based Observed Time Difference of Arrival(OTDOA)positioning achieves an accuracy ranging from tens to hundreds of meters in various experimental scenarios and currently functions primarily as coarse location ***,this study explores the potential of the Three-Dimensional Mapping-

关键词： Multi-frequency smartphone 3GPP LPP OMA SUPL Observation noise TTFF A-GNSS PPP-B2b OTDOA 3DMAGNSS NLOS

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Climatic drivers of the Canadian wildfire episode in 2023

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Atmospheric and Oceanic science Letters 2024年第4期17卷 23-28页

作者： Yihan Hu Xu Yue Chenguang Tian Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&Technology(NUIST)NanjingChina

2023年5月加拿大发生极端野火事件并持续4个月时间.野火污染物排放对当地和下风向的空气质量造成了严重影响.本文对驱动此次野火事件的气象因子和相关大尺度环流进行了探究.研究表明,此次极端野火排放的二氧化碳相较往年同期增长了0.37G... 详细信息

2023年5月加拿大发生极端野火事件并持续4个月时间.野火污染物排放对当地和下风向的空气质量造成了严重影响.本文对驱动此次野火事件的气象因子和相关大尺度环流进行了探究.研究表明,此次极端野火排放的二氧化碳相较往年同期增长了0.37Gt (527.1%).受罗斯贝波频散影响,同期加拿大中西部区域出现持续的位势高度正异常,促进气流下沉并引发局地高温,中西部区域5-6月最高温平均上升8.11℃,部分区域甚至超过10℃,导致野火排放的显著增长.受有利地形和泛北极地区快速增暖的影响,预期未来加拿大中西部发生极端野火的概率可能会显著上升.

关键词：野火气候变化遥相关极端天气碳排放

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Event-enhanced synthetic aperture imaging

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science China(information sciences) 2025年第3期68卷 388-390页

作者： Siqi LI Shaoyi DU Jun-Hai YONG Yue GAO Beijing National Research Center for Information Science and Technology School of SoftwareTsinghua University Institute for Brain and Cognitive Sciences Beijing Laboratory of Brain and Cognitive IntelligenceTsinghua University National Key Laboratory of Human-Machine Hybrid Augmented Intelligence National Engineering Research Center for Visual Information and ApplicationsInstitute of Artificial Intelligence and Robotics Xi'an Jiaotong University

Synthetic aperture imaging(SAI) methods aim to see through dense occlusions and reconstruct the target scene behind occlusions. Traditional frame-based SAI methods,e.g., DeOccNet [1], take the occluded light field ima...

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On Privacy-Preserving Task Assignment for Heterogeneous Users in Mobile Crowdsensing 26

On Privacy-Preserving Task Assignment for Heterogeneous User...

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26th International Conference on Computer Supported Cooperative Work in Design, CSCWD 2023

作者： Zhang, Ji Li, Peng Huang, Weiyi Nie, Lei Bao, Haizhou Liu, Qin Wuhan University of Science and Technology School of Computer Science and Technology China Hubei Province Key Laboratory of Intelligent Information Processing and Real-Time Industrial System China Wuhan University School of Cyber Science and Engineering China

ISBN: (纸本)9798350331684

Task assignment is a key challenge in mobile crowd-sensing because of the varying capabilities of crowd users. Location-based task assignment schemes require users to upload their location to an untrusted platform, which raises many privacy concerns. However, stronger privacy preservation may lead to lower system utility. It is challenging to maximize system utility under privacy preservation for users. In this paper, we propose a privacy-preserving task assignment for heterogeneous users (PTAH) problem in mobile crowdsensing. Specifically, we divide users into two groups: private users with location privacy requirements and public users without location privacy requirements. We first design a privacy-preserving mechanism to obfuscate the actual location of private users. Then we construct a relationship graph based on the locations between users and tasks. We prove that the PTAH problem is an NP-hard problem, so to maximize the system utility, we propose an approximation algorithm based on the greedy algorithm. Then we propose a multi-thread cooperative simulated annealing algorithm to search for a better approximate solution. Finally, we conducted simulations based on the widely-used real-world Roma dataset. The results show that our proposed algorithm consistently outperforms other baseline algorithms. © 2023 IEEE.

关键词： Location

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