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Dynamic resource allocation schemes for eMBB and URLLc services in 5G wireless networks

Intelligent and converged Networks 2022年第2期3卷 145-160页

作者： Xianghui Han Kai Xiao Ruiqi Liu Xing Liu george c.alexandropoulos Shi Jin State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen 518055Chinaand also with the Wireless Research InstituteZTE CorporationBeijing 100029China National Mobile communications Research Laboratory Southeast UniversityNanjing 210096China Department of Informatics and Telecommunications National and Kapodistrian University of AthensAthens 15784Greece

The fifth generation(5G)of wireless networks features three core use cases,namely ultra-reliable and low latency communications(URLLc),massive machine type communications(mMTc),and enhanced mobile broadband(eMBB).These use cases co-exist in many practical scenarios and compete for the same set of time and frequency resources,resulting in a natural trade-off in their *** this paper,a network supporting both URLLc and eMBB modes of operation is *** guarantee the ultra low latency requirement of URLLc,a dynamic resource allocation scheme indicated by a two-dimensional bitmap is *** approach is capable to achieve finer granularity as well as lower false cancellation rate compared to the state-of-the-art methods.A novel power control and indication method is also proposed to dynamically provide different power control parameters to the user equipment(UE),while guaranteeing the reliability requirement of URLLc and minimizing the impact to *** addition,we devise a dynamic selection mechanism(DSM)to accommodate diverse scenarios,which is empowered with load prediction to become more *** extensive system-level simulation results for eMBB-URLLc co-existence scenarios showcase that the perceived throughput of eMBB UEs is increased by 45.3%,while about 13.3% more UEs are enjoying URLLc services with at most 84% transmit power savings compared to the state-of-the-art methods.

关键词： the fifth generation(5G) co-existence enhanced mobile broadband(eMBB) multiplexing resource allocation power control ultra-reliable and low latency communications(URLLc) uplink

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Reconfiguring wireless environments via intelligent surfaces for 6G: reflection, modulation, and security

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Science china(Information Sciences) 2023年第3期66卷 60-79页

作者： Jindan XU chau YUEN chongwen HUANG Naveed UL HASSAN george c.alexandropoulos Marco DI RENZO Mérouane DEBBAH Engineering Product Development Pillar Singapore University of Technology and Design college of Information Science and Electronic Engineering Zhejiang University Department of Electrical Engineering Lahore University of Management Sciences Department of Informatics and Telecommunications National and Kapodistrian University of Athens Technology Innovation Institute Université Paris-Saclay CNRS Centrale Supélec Laboratoire des Signaux et Systèmes

The reconfigurable intelligent surface(RIS) has been recognized as an essential enabling technology for sixth-generation(6G) mobile communication networks. An RIS comprises a large number of small and low-cost reflecting elements whose parameters can be dynamically adjusted with a programmable *** of these elements can effectively reflect a phase-shifted version of the incident electromagnetic wave. By configuring the wave phases in real time, the propagation environment of the information-bearing signals can be dynamically manipulated to enhance communication reliability, boost transmission rate, expand cellular coverage, and strengthen communication security. In this study, we provide an overview on RIS-assisted wireless communications. Specifically, we elaborate on the state-of-the-art enabling techniques for the RIS technology as well as their corresponding substantial benefits from the perspectives of RIS reflection and RIS modulation. With these benefits, we envision the integration of RISs into emerging applications for6G. In addition, communication security is of unprecedented importance in future 6G networks with ubiquitous wireless services in multifarious verticals and areas. We highlight potential contributions of RISs to physical-layer security, in terms of secrecy rate and secrecy outage probability, exemplified by a typical case study from both theoretical and numerical aspects. Finally, we discuss challenges and opportunities on the deployment of RISs in practice to motivate future research.

关键词： reconfigurable intelligent surface physical-layer security RIS-assisted wireless communications phase modulation 6G

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Reconfigurable intelligent surfaces for wireless communications:Overview of hardware designs,channel models,and estimation techniques

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Intelligent and converged Networks 2022年第1期3卷 1-32页

作者： Mengnan Jian george c.alexandropoulos Ertugrul Basar chongwen Huang Ruiqi Liu Yuanwei Liu chau Yuen the Wireless Research Institute ZTE CorporationBeijing 100029China the State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen 518055China Department of Informatics and Telecommunications National and Kapodistrian University of AthensAthens 15784Greece communications Research and Innovation Laboratory(coreLab) Department of Electrical and Electronics EngineeringKoçUniversityIstanbul 34450Turkey college of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China School of Electronic Engineering and computer Science Queen Mary University of LondonLondonE14NSUK. the Engineering Product Development(EPD)Pillar Singapore University of Technology and DesignSingapore 487372Singapore

The demanding objectives for the future sixth generation(6G)of wireless communication networks have spurred recent research efforts on novel materials and radio-frequency front-end architectures for wireless connectivity,as well as revolutionary communication and computing *** the pioneering candidate technologies for 6G belong the reconfigurable intelligent surfaces(RISs),which are artificial planar structures with integrated electronic circuits that can be programmed to manipulate the incoming electromagnetic field in a wide variety of *** RISs in wireless networks have been recently advocated as a revolutionary means to transform any wireless signal propagation environment to a dynamically programmable one,intended for various networking objectives,such as coverage extension and capacity boosting,spatiotemporal focusing with benefits in energy efficiency and secrecy,and low electromagnetic field *** by the recent increasing interests in the field of RISs and the consequent pioneering concept of the RIS-enabled smart wireless environments,in this paper,we overview and taxonomize the latest advances in RIS hardware architectures as well as the most recent developments in the modeling of RIS unit elements and RIS-empowered wireless signal *** also present a thorough overview of the channel estimation approaches for RIS-empowered communications systems,which constitute a prerequisite step for the optimized incorporation of RISs in future wireless ***,we discuss the relevance of the RIS technology in the latest wireless communication standards,and highlight the current and future standardization activities for the RIS technology and the consequent RIS-empowered wireless networking approaches.

关键词： reconfigurable intelligent surfaces beyond 5G 6G channel modeling hardware architecture channel estimation smart wireless environment standardization

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Wireless communications empowered by reconfigurable intelligent surfaces: Model-based vs model-free channel estimation

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Journal of Information and Intelligence 2023年第3期1卷 253-266页

作者： Li Wei chongwen Huang george c.alexandropoulos Ahmet M.Elbir Zhaohui Yang Zhaoyang Zhang Marco Di Renzo Merouane Debbah chau Yuen Engineering Product Development Pillar Singapore University of Technology and DesignSingapore 487372Singapore college of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China Department of Informatics and Telecommunications National and Kapodistrian University of Athens15784 AthensGreece Interdisciplinary centre for Security Reliability and TrustUniversity of LuxembourgL-4365 Esch-sur-AlzetteLuxembourgand Duzce UniversityDuzce 81620Turkey Universite Paris-Saclay CNRSCentraleSupelecLaboratoire des Signaux et Systemes91192France Khalifa University of Science and Technology Abu DhabiUnited Arab Emirates School of Electrical and Electronics Engineering Nanyang Technological UniversitySingapore 639798Singapore

Reconfigurable intelligent surfaces(RISs)are lately being attractive for their great potential in future sixth generation wireless communications(6G),which is attributed to their affordable energy consumption and easy ***,the large numbers of low-cost reflecting elements comprising RISs impose challenges for channel acquisition in various RIS-based wireless applications,such as RIS-enhanced orthogonal frequency-division multiplexing and multi-user multipleinput multiple-output *** this article,we first overview the state-of-the-art RIS hardware architectures designed to assist channel estimation for RIS-empowered wireless communication *** also overview existing channel estimation approaches,which are categorized into model-based and model-free techniques,and discuss their advantages and limitations depending on the RIS *** challenges with RIS-empowered systems in terms of hardware and other parameter limitations are presented,together with future research directions for channel estimation in RIS-based wireless systems,such as RISs with extremely large numbers of elements,multi-hop communications with RISs,and frequency division duplexing for high mobility systems.

关键词： Reconfigurable intelligent surfaces channel estimation Model-based methods Model-free methods

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Maintaining Positive Momentum Africa faces a bright economic outlook despite internal and external challenges

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chinAfrica 2025年第1期17卷 27-29页

作者： george MUSIIME Development Watch centre Uganda COVER STORY

It’s that time of the year again when we find ourselves reflecting on the year that was and the year *** the African continent,many countries are still recovering from the aftershocks of the cOVID-19 pandemic and are doing so amid a fraught geopolitical *** tensions have,to some extent,created hurdles in the path of Africa’s *** African Development Bank has attributed the economic slowdown on the continent toastronomical inflation caused by soaring food andenergy prices. These issues have been aggravatedby the current geopolitical chaos and climatechange. Nevertheless, the continent is projectedto grow at a steady rate of 4.3 percent in *** means that Africa will retain its positionas the fastest-growing region after Asia. This isdriven by several positive factors.

关键词： continent Africa African

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Traveling wave effect on the seismic response of a steel arch bridge subjected to near fault ground motions

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Earthquake Engineering and Engineering Vibration 2007年第3期6卷 245-257页

作者：徐艳 george c Lee McEER University at BuffaloNY 14260 USA Department of Bridge EngineeringTongji UniversityShanghai 200092China McEER University at BuffaloNY 14260USA

In the 1990s, several major earthquakes occurred throughout the world, with a common observation that near fault ground motion （NFGM） characteristics had a distinct impact on causing damage to civil engineering structures that could not be predicted by using far field ground motions. Since then, seismic responses of structures under NFGMs have been extensively examined, with most of the studies focusing on structures with relatively short fundamental periods, where the traveling wave effect does not need to be considered. However, for long span bridges, especially arch bridges, the traveling wave （only time delay considered） effect may be very distinct and is therefore important. In this paper, the results from a case study on the seismic response of a steel arch bridge under selected NFGMs is presented by considering the traveling wave effect with variable apparent velocities. The effects of fling step and long period pulses of NFGMs on the seismic responses of the arch bridge are also discussed.

关键词： traveling wave effect arch bridge near fault ground motion fling step long period pulses

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Polyethylene glycol fusion repair of severed rat sciatic nerves reestablishes axonal continuity and reorganizes sensory terminal fields in the spinal cord

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Neural Regeneration Research 2025年第7期20卷 2095-2107页

作者： Emily A.Hibbard Liwen Zhou cathy Z.Yang Karthik Venkudusamy Yessenia Montoya Alexa Olivarez george D.Bittner Dale R.Sengelaub Program in Neuroscience Indiana UniversityBloomingtonINUSA Department of Neuroscience University of Texas at AustinAustinTXUSA

Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically *** used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic *** have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor ***,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target *** this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic *** adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative control)the application of *** action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury *** success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days *** 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish ***-fusion repair reestablished axonal *** to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal ***,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repa

关键词： axotomy dorsal horn peripheral nerve injury plasticity polyethylene glycol(PEG) sciatic nerve sensory terminals wheat germ agglutinin horseradish peroxidase

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Time derivative of earthquake acceleration

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Earthquake Engineering and Engineering Vibration 2005年第1期4卷 1-16页

作者： george c. Lee Multidisciplinary center for Earthquake Engineering Research University at Buffalo Buffalo NY 14261-0025 USAProfessor

Unlike acceleration, velocity, and displacement, the time derivative ofacceleration (TDoA) of ground motion has not been extensively studied. In this paper, the basiccharacteristics of TDoA are evaluated based on records from the 1999 chi-chi, earthquake (Mw 7.6)and one of its aftershocks (Mw 6.2). It is found that the maximum TDoA at a free-field station wasover 31,200 cm/s3 (31.8 g/s); and the duration of 'strong' TDoA, between the first and the last timepoints exceeding 2,000 cm/s3 (2 g/s), was almost one minute near the epicenter area. Since groundTDoA sensors are not commonly available, the time series are calculated by direct numericaldifferentiation of acceleration time series. Relative error analysis shows that the error isnon-transitive and total error is within 4%. The density function of TDoA amplitude, frequencycontent and spatial distribution of peak ground jerk (PGJ) are evaluated. The study also includesexamination of some TDoA responses from a seven-story building and comparison of ground TDoA withthe limit TDoA used in the transportation industry for ride comfort. Some potential impacts of TDoAon humans have also been reviewed.

关键词： time derivation of acceleration peak ground jerk acceleration time series earthquake ground motion earthquake effect on human activities

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Urban china in Transformation:Hybrid Economy,Juxtaposed Space,and New Testing Ground for Geographical Enquiries

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chinese Geographical Science 2011年第1期21卷 1-16页

作者： george c S LIN Department of Geography University of Hong Kong

History has brought us into a significant moment when the majority of the human kind has taken up resi-dence in urban settlements. The focus of global urbanization has shifted to the developing world and the center of manufacturing is no longer confined to the Global North. This paper provides a periodical assessment of the current status of china's urban transformation in the global context of a shifting emphasis of industrialization and urbaniza-tion. china's phenomenal urban transformation deserves a special attention not only because of its unparalleled scale and speed but also because of its distinct trajectory of growth that does not conform to normal theoretical ex-pectations. The results of assessment revealed an urban economy with remarkable hybridity, a society that is in-creasingly stratified, polarized, and segregated, and a juxtaposed urban space undergoing restless and pervasive transformation. A decentering world should entail a decentering knowledge production. A critical reflection upon the chinese patterns and processes of urban transformation has identified 4 main issues with great potentials for inno-vative knowledge production, namely: 1) privatization and economic development; 2) state, society, and space; 3) urbanization of capital, labor, and land; and 4) the environment and chinese political ecology. The paper closes with the remark that a rapidly transforming urban china has presented itself as a fertile and resourceful testing ground for critical and innovative geographic enquiries.

关键词： urban geography urbanization chinese cities political economy china

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Towards establishing practical multi-hazard bridge design limit states

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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 333-340页

作者： Zach Liang george c.Lee Department of Mechanical and Aerospace Engineering Unidersity at Buffalo Depart of civil Structural and Environmental Engineering University at Buffalo

In the U.S., the current Load and Resistance Factor Design （LRFD） Specifications for highway bridges is a reliability-based formulation that considers failure probabilities of bridge components due to the actions of typical dead load and frequent vehicular loads. Various extreme load effects, such as earthquake and vessel collision, are on the same reliability-based platform. Since these extreme loads are time variables, combining them with not considered frequent. non- extreme loads is a significant challenge. The number of design limit state equations based on these failure probabilities can be unrealistically large and unnecessary from the view point of practical applications. Based on the opinion of AASHTO State Bridge Engineers, many load combinations are insignificant in their states. This paper describes the formulation of a criterion to include only the necessary load combinations to establish the design limit states. This criterion is established by examining the total failure probabilities for all possible time-invariant and time varying load combinations and breaking them down into partial terms. Then, important load combinations can be readily determined quantitatively,

关键词： multi-hazards load and resistance factor design re.liability based bridge design specifications design limit state equations

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