An open architecture for converged Internet of Things (IoT) is proposed in this paper.By using this model,the various and huge amount of data can be converted into converged data and then encapsulated as service packa...An open architecture for converged Internet of Things (IoT) is proposed in this paper.By using this model,the various and huge amount of data can be converted into converged data and then encapsulated as service packages.Moreover,a Representational State Transfer (REST) platform has been implemented in the lab environment.The merit of this architecture is the enhancement of data efficiency.Experimental results are provided to show the benefits of the proposed architecture.展开更多
As the complexity of deep learning(DL)networks and training data grows enormously,methods that scale with computation are becoming the future of artificial intelligence(AI)development.In this regard,the interplay betw...As the complexity of deep learning(DL)networks and training data grows enormously,methods that scale with computation are becoming the future of artificial intelligence(AI)development.In this regard,the interplay between machine learning(ML)and high-performance computing(HPC)is an innovative paradigm to speed up the efficiency of AI research and development.However,building and operating an HPC/AI converged system require broad knowledge to leverage the latest computing,networking,and storage technologies.Moreover,an HPC-based AI computing environment needs an appropriate resource allocation and monitoring strategy to efficiently utilize the system resources.In this regard,we introduce a technique for building and operating a high-performance AI-computing environment with the latest technologies.Specifically,an HPC/AI converged system is configured inside Gwangju Institute of Science and Technology(GIST),called GIST AI-X computing cluster,which is built by leveraging the latest Nvidia DGX servers,high-performance storage and networking devices,and various open source tools.Therefore,it can be a good reference for building a small or middlesized HPC/AI converged system for research and educational institutes.In addition,we propose a resource allocation method for DL jobs to efficiently utilize the computing resources with multi-agent deep reinforcement learning(mDRL).Through extensive simulations and experiments,we validate that the proposed mDRL algorithm can help the HPC/AI converged cluster to achieve both system utilization and power consumption improvement.By deploying the proposed resource allocation method to the system,total job completion time is reduced by around 20%and inefficient power consumption is reduced by around 40%.展开更多
27 February 2013, Shenzhen-ZTE Corporation today announced that its converged FDD/TDD solution the Global TD-LTE Initiative （GTI） Innovation Award at the Mobile World Congress in Barcelona. GTI Night is held each y...27 February 2013, Shenzhen-ZTE Corporation today announced that its converged FDD/TDD solution the Global TD-LTE Initiative （GTI） Innovation Award at the Mobile World Congress in Barcelona. GTI Night is held each year to recognize outstanding achievements in telecommunications. This year＇ was selected by a GTI steering committee comprising multiple operators. GTI Night 2013 was attended than 30 global operators and several industry partners. has won s winner by more展开更多
The convergence of telecom networks requires an improved Quality of Service (QoS) solution. The introduction of the QoS resource control architecture based on the IP Multimedia Subsystem (IMS) framework is a way to so...The convergence of telecom networks requires an improved Quality of Service (QoS) solution. The introduction of the QoS resource control architecture based on the IP Multimedia Subsystem (IMS) framework is a way to solve QoS problems in the converged networks. Services,QoS guarantee,resource control and accounting functions are integrated into this IMS-based QoS control architecture. It is a solution to the problems currently facing the fixed network operators,helping them offer more QoS-guaranteed multimedia services such as 3D games,and make a transition from bandwidth providers to genuine telecom services providers.展开更多
February 4, 2014--ZTE Corporation has launched the world＇s first converged intelligent videoconferencing solution at Integrated Systems Europe, Amsterdam. The solution transforms existing video conferencing terminals...February 4, 2014--ZTE Corporation has launched the world＇s first converged intelligent videoconferencing solution at Integrated Systems Europe, Amsterdam. The solution transforms existing video conferencing terminals from functional ma- chines into smart machines. Due to restrictions in system convergence, traditional videoconferencing can no longer meet the requirements of rapidly developing technologies and markets. The development of video codec technology and the extensive use of wireless technol- ogies such as LTE are also raising people＇ s expectations for higher video resolution and more flexible video communica- tions. This converged intelligent videoconferencing solution uses an open video communication interface, provides a univer- sal platform, and supports convergence with third-party applications, quickly meeting different user requirements. The sys- tem has pre-installed common conferencing software and supports plug and play USB flash disks and portable hard disks for easy sharing of electronic documents. With integrated functions such as E-whiteboard, data conferencing and muhi- touch, the system supports simple and intuitive operations.展开更多
ZTE Corporation launched its zVOA solution on February 21. This solution enables operators to deploy a unified control network for voice, video and multimedia services over any existing mobile and fixed access network...ZTE Corporation launched its zVOA solution on February 21. This solution enables operators to deploy a unified control network for voice, video and multimedia services over any existing mobile and fixed access network infrastructure.展开更多
The current telecom target network architecture with IP Multimedia Subsystem (IMS) as the core lacks the actual verification of existing large-scale networks and faces the stiff competition from Internet technologies....The current telecom target network architecture with IP Multimedia Subsystem (IMS) as the core lacks the actual verification of existing large-scale networks and faces the stiff competition from Internet technologies. In the process of promoting the commercial usage of IMS services, the Service Delivery Platform (SDP) is evolving into a more convergent and open Service Delivery Environment (SDE) and will become the mainstream of the next generation Telecom Service Network. ZTE’s concept of the Converged Service Network (CSN) is to integrate various network service capabilities to realize the unification of data, service, capability and management and thus the fast provisioning of various Value-Added Services (VASs), which helps the carriers to maintain a leading position in the value chain, meeting the telecom carriers ’ requirements for service network development.展开更多
Acknowledgments Thanks for assistance and support, which is provided by State Grid Corporation of China and State Grid Communication Information ＆ Telecommunication Company, for the project in the process of researc...Acknowledgments Thanks for assistance and support, which is provided by State Grid Corporation of China and State Grid Communication Information ＆ Telecommunication Company, for the project in the process of research and development. Fibrlink Communications Co., Ltd will keep exerting itself to innovating, which aims for making more contribution of the smart grid on energy reduction and environment protection.展开更多
As Moore’s law approaching its end,electronics is hitting its power,bandwidth,and capacity limits.Photonics is able to overcome the performance limits of electronics but lacks practical photonic register and flexible...As Moore’s law approaching its end,electronics is hitting its power,bandwidth,and capacity limits.Photonics is able to overcome the performance limits of electronics but lacks practical photonic register and flexible control.Combining electronics and photonics provides the best of both worlds and is widely regarded as an important post-Moore’s direction.For stability and dynamic operations considerations,feedback tuning of photonic devices is required.For silicon photonics,the thermooptic effect is the most frequently used tuning mechanism due to the advantages of high efficiency and low loss.However,it brings new design requirements,creating new design challenges.Emerging applications,such as optical phased array,optical switches,and optical neural networks,employ a large number of photonic devices,making PCB tuning solutions no longer suitable.Electronic-photonic-converged solutions with compact footprints will play an important role in system scalability.In this paper,we present a unified model for thermo-optic feedback tuning that can be specialized to different applications,review its recent advances,and discuss its future trends.展开更多
Converged communication and radar sensing systems have attained increasing attention in recent years.The development of converged radar-data systems is reviewed,with a special focus on millimeter/terahertz systems as ...Converged communication and radar sensing systems have attained increasing attention in recent years.The development of converged radar-data systems is reviewed,with a special focus on millimeter/terahertz systems as a promising trend.Firstly,we present historical development and convergence technology concept for communication-radar systems,and highlight some emerging technologies in this area.We then provide an updated and comprehensive survey of several converged systems operating in different microwave and millimeter frequency bands,by providing some selective typical communication and radar sensing systems.In this part,we also summarize and compare the system performance in terms of maximum range/range resolution for radar mode and Bit Error Rate(BER)/wireless distance for communication mode.In the last section,the convergence of millimeter/terahertz communication-radar system is concluded by analyzing the prospect of millimeter-wave/terahertz technologies in providing ultrafast data rates and high resolution for our smart future.展开更多
To evaluate the trail potential of converged heterogeneous network （CHN） market, the logistic method for adoption modeling of CHN is used. User growth ＆ penetration have been taken as two variants to find saturatio...To evaluate the trail potential of converged heterogeneous network （CHN） market, the logistic method for adoption modeling of CHN is used. User growth ＆ penetration have been taken as two variants to find saturation condition in market. Model is continuous in time but modifications are done for discrete recurrence equation, commonly known as logistic map. Dynamic and static phases are taken into consideration while penetration decay is not covered in this model.展开更多
This article discusses a possible approach for telecom operators to achieve converged telecom and Internet services. It involves integrally developing telecom networks and Internet businesses through the convergence o...This article discusses a possible approach for telecom operators to achieve converged telecom and Internet services. It involves integrally developing telecom networks and Internet businesses through the convergence of their instant news and social networking services. Some background, benefits for telecom operators, and possible challenges are analyzed. A new service convergence approach such as this can also facilitate triple-screen and multi-screen convergence in the future.展开更多
In this article, a novel cooperative wireless localization scheme based on information fusion is proposed. The scheme combines large-scale arrival time and small-scale distance measurements obtained from the next-gene...In this article, a novel cooperative wireless localization scheme based on information fusion is proposed. The scheme combines large-scale arrival time and small-scale distance measurements obtained from the next-generation converged networks. The maximum likelihood （ML） estimate of the terminal＇s position is derived with closed-form solution, and the Cramer-Rao lower bound （CRLB） of the estimate error is investigated. Both theoretical analysis and simulation results verify that the proposed localization scheme can significantly enhance the location precision. Moreover, the mean square error of position estimate approximates the CRLB when the number of reference stations increases, which indicates that the proposed ML estimator is asymptotically efficient.展开更多
In this paper,an adaptive cubic regularisation algorithm based on affine scaling methods(ARCBASM)is proposed for solving nonlinear equality constrained programming with nonnegative constraints on variables.From the op...In this paper,an adaptive cubic regularisation algorithm based on affine scaling methods(ARCBASM)is proposed for solving nonlinear equality constrained programming with nonnegative constraints on variables.From the optimality conditions of the problem,we introduce appropriate affine matrix and construct an affine scaling ARC subproblem with linearized constraints.Composite step methods and reduced Hessian methods are applied to tackle the linearized constraints.As a result,a standard unconstrained ARC subproblem is deduced and its solution can supply sufficient decrease.The fraction to the boundary rule maintains the strict feasibility(for nonnegative constraints on variables)of every iteration point.Reflection techniques are employed to prevent the iterations from approaching zero too early.Under mild assumptions,global convergence of the algorithm is analysed.Preliminary numerical results are reported.展开更多
The organization of biological neuronal networks into functional modules has intrigued scientists and inspired engineers to develop artificial systems.These networks are characterized by two key properties.First,they ...The organization of biological neuronal networks into functional modules has intrigued scientists and inspired engineers to develop artificial systems.These networks are characterized by two key properties.First,they exhibit dense interconnectivity(Braitenburg and Schüz,1998;Campagnola et al.,2022).The strength and probability of connectivity depend on cell type,inter-neuronal distance,and species.Still,every cortical neuron receives input from thousands of other neurons while transmitting output to a similar number of neurons.Second,communication between neurons occurs primarily via chemical or electrical synapses.展开更多
The investigation of converged twisted beams with a helical phase structure has a remarkable impact on both fundamental physics and practical applications.Geometric metasurfaces consisting of individually orientated m...The investigation of converged twisted beams with a helical phase structure has a remarkable impact on both fundamental physics and practical applications.Geometric metasurfaces consisting of individually orientated metal/dielectric meta-atoms provide an ultracompact platform for generating converged vortices.However,it is still challenging to simultaneously focus left-handed and right-handed circularly polarized incident beams with pure geometric phase modulation,which hinders the independent operation on topological charges between these two helical components.Here we propose and experimentally demonstrate an approach to design terahertz geometric metasurfaces that can generate helicity-independent converged vortices with homogeneous polarization states by the superposition of two orthogonal helical vortices with identical topological charges.Furthermore,the multiplexing of polarization-rotatable multiple vortices in multiple dimensions,i.e.,in both longitudinal and transverse directions,and a vortex with an extended focal depth is confirmed by embedding polarization modulation into the geometric metasurfaces.The demonstrated approach provides a new way to simultaneously manipulate orthogonal helical components and expand the design dimension,enabling new applications of geometric metasurface devices in polarization optics,twisted-beam related image and edge detection,high capacity optical communication,and quantum information processing,to name a few.展开更多
Bursty traffic and thousands of concurrent flows incur inevitable network congestion in datacenter networks(DCNs)and then affect the overall performance.Various transport protocols are developed to mitigate the networ...Bursty traffic and thousands of concurrent flows incur inevitable network congestion in datacenter networks(DCNs)and then affect the overall performance.Various transport protocols are developed to mitigate the network congestion,including reactive and proactive protocols.Reactive schemes use different congestion signals,such as explicit congestion notification(ECN)and round trip time(RTT),to handle the network congestion after congestion arises.However,with the growth of scale and link speed in datacenters,reactive schemes encounter a significant problem of slow responding to congestion.On the contrary,proactive protocols(e.g.,credit-reservation protocols)are designed to avoid congestion before it occurs,and they have the advantages of zero data loss,fast convergence and low buffer occupancy.But credit-reservation protocols have not been widely deployed in current DCNs(e.g.,Microsoft,Amazon),which mainly deploy ECN-based protocols,such as data center transport control protocol(DCTCP)and data center quantized congestion notification(DCQCN).And in an actual deployment scenario,it is hard to guarantee one protocol to be deployed in every server at one time.When credit-reservation protocol is deployed to DCNs step by step,the network will be converted to multi-protocol state and will face the following fundamental challenges:1)unfairness,2)high buffer occupancy,and 3)heavy tail latency.Therefore,we propose Harmonia,aiming for converging ECN-based and credit-reservation protocols to fairness with minimal modification.To the best of our knowledge,Harmonia is the first to address the trouble of harmonizing proactive and reactive congestion control.Targeting the common ECN-based protocols-DCTCP and DCQCN,Harmonia leverages forward ECN and RTT to deliver real-time congestion information and redefines feedback control.After the evaluation,the results show that Harmonia effectively solves the unfair link allocation,eliminating the timeouts and addressing the buffer overflow.展开更多
In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradien...In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.展开更多
基金supported by the Special Funds for Key Program of the China No.2009ZX01039-002-001-07,No.2010ZX03005-001-03Ministry of Education infrastructure construction project(2-5-2)
文摘An open architecture for converged Internet of Things (IoT) is proposed in this paper.By using this model,the various and huge amount of data can be converted into converged data and then encapsulated as service packages.Moreover,a Representational State Transfer (REST) platform has been implemented in the lab environment.The merit of this architecture is the enhancement of data efficiency.Experimental results are provided to show the benefits of the proposed architecture.
文摘As the complexity of deep learning(DL)networks and training data grows enormously,methods that scale with computation are becoming the future of artificial intelligence(AI)development.In this regard,the interplay between machine learning(ML)and high-performance computing(HPC)is an innovative paradigm to speed up the efficiency of AI research and development.However,building and operating an HPC/AI converged system require broad knowledge to leverage the latest computing,networking,and storage technologies.Moreover,an HPC-based AI computing environment needs an appropriate resource allocation and monitoring strategy to efficiently utilize the system resources.In this regard,we introduce a technique for building and operating a high-performance AI-computing environment with the latest technologies.Specifically,an HPC/AI converged system is configured inside Gwangju Institute of Science and Technology(GIST),called GIST AI-X computing cluster,which is built by leveraging the latest Nvidia DGX servers,high-performance storage and networking devices,and various open source tools.Therefore,it can be a good reference for building a small or middlesized HPC/AI converged system for research and educational institutes.In addition,we propose a resource allocation method for DL jobs to efficiently utilize the computing resources with multi-agent deep reinforcement learning(mDRL).Through extensive simulations and experiments,we validate that the proposed mDRL algorithm can help the HPC/AI converged cluster to achieve both system utilization and power consumption improvement.By deploying the proposed resource allocation method to the system,total job completion time is reduced by around 20%and inefficient power consumption is reduced by around 40%.
文摘27 February 2013, Shenzhen-ZTE Corporation today announced that its converged FDD/TDD solution the Global TD-LTE Initiative （GTI） Innovation Award at the Mobile World Congress in Barcelona. GTI Night is held each year to recognize outstanding achievements in telecommunications. This year＇ was selected by a GTI steering committee comprising multiple operators. GTI Night 2013 was attended than 30 global operators and several industry partners. has won s winner by more
文摘The convergence of telecom networks requires an improved Quality of Service (QoS) solution. The introduction of the QoS resource control architecture based on the IP Multimedia Subsystem (IMS) framework is a way to solve QoS problems in the converged networks. Services,QoS guarantee,resource control and accounting functions are integrated into this IMS-based QoS control architecture. It is a solution to the problems currently facing the fixed network operators,helping them offer more QoS-guaranteed multimedia services such as 3D games,and make a transition from bandwidth providers to genuine telecom services providers.
文摘February 4, 2014--ZTE Corporation has launched the world＇s first converged intelligent videoconferencing solution at Integrated Systems Europe, Amsterdam. The solution transforms existing video conferencing terminals from functional ma- chines into smart machines. Due to restrictions in system convergence, traditional videoconferencing can no longer meet the requirements of rapidly developing technologies and markets. The development of video codec technology and the extensive use of wireless technol- ogies such as LTE are also raising people＇ s expectations for higher video resolution and more flexible video communica- tions. This converged intelligent videoconferencing solution uses an open video communication interface, provides a univer- sal platform, and supports convergence with third-party applications, quickly meeting different user requirements. The sys- tem has pre-installed common conferencing software and supports plug and play USB flash disks and portable hard disks for easy sharing of electronic documents. With integrated functions such as E-whiteboard, data conferencing and muhi- touch, the system supports simple and intuitive operations.
文摘ZTE Corporation launched its zVOA solution on February 21. This solution enables operators to deploy a unified control network for voice, video and multimedia services over any existing mobile and fixed access network infrastructure.
文摘The current telecom target network architecture with IP Multimedia Subsystem (IMS) as the core lacks the actual verification of existing large-scale networks and faces the stiff competition from Internet technologies. In the process of promoting the commercial usage of IMS services, the Service Delivery Platform (SDP) is evolving into a more convergent and open Service Delivery Environment (SDE) and will become the mainstream of the next generation Telecom Service Network. ZTE’s concept of the Converged Service Network (CSN) is to integrate various network service capabilities to realize the unification of data, service, capability and management and thus the fast provisioning of various Value-Added Services (VASs), which helps the carriers to maintain a leading position in the value chain, meeting the telecom carriers ’ requirements for service network development.
文摘Acknowledgments Thanks for assistance and support, which is provided by State Grid Corporation of China and State Grid Communication Information ＆ Telecommunication Company, for the project in the process of research and development. Fibrlink Communications Co., Ltd will keep exerting itself to innovating, which aims for making more contribution of the smart grid on energy reduction and environment protection.
基金This work was supported by the National Key Research and Development Program of China(No.2018YFA0704400).
文摘As Moore’s law approaching its end,electronics is hitting its power,bandwidth,and capacity limits.Photonics is able to overcome the performance limits of electronics but lacks practical photonic register and flexible control.Combining electronics and photonics provides the best of both worlds and is widely regarded as an important post-Moore’s direction.For stability and dynamic operations considerations,feedback tuning of photonic devices is required.For silicon photonics,the thermooptic effect is the most frequently used tuning mechanism due to the advantages of high efficiency and low loss.However,it brings new design requirements,creating new design challenges.Emerging applications,such as optical phased array,optical switches,and optical neural networks,employ a large number of photonic devices,making PCB tuning solutions no longer suitable.Electronic-photonic-converged solutions with compact footprints will play an important role in system scalability.In this paper,we present a unified model for thermo-optic feedback tuning that can be specialized to different applications,review its recent advances,and discuss its future trends.
基金supported in part by National Natural Science Foundation of China(NSFC)under Grant No.61771424in part by Natural Science Foundation of Zhejiang Province under Grant No.LZ18F010001.
文摘Converged communication and radar sensing systems have attained increasing attention in recent years.The development of converged radar-data systems is reviewed,with a special focus on millimeter/terahertz systems as a promising trend.Firstly,we present historical development and convergence technology concept for communication-radar systems,and highlight some emerging technologies in this area.We then provide an updated and comprehensive survey of several converged systems operating in different microwave and millimeter frequency bands,by providing some selective typical communication and radar sensing systems.In this part,we also summarize and compare the system performance in terms of maximum range/range resolution for radar mode and Bit Error Rate(BER)/wireless distance for communication mode.In the last section,the convergence of millimeter/terahertz communication-radar system is concluded by analyzing the prospect of millimeter-wave/terahertz technologies in providing ultrafast data rates and high resolution for our smart future.
基金Supported by the National Natural Science Foundation of China(60772066)
文摘To evaluate the trail potential of converged heterogeneous network （CHN） market, the logistic method for adoption modeling of CHN is used. User growth ＆ penetration have been taken as two variants to find saturation condition in market. Model is continuous in time but modifications are done for discrete recurrence equation, commonly known as logistic map. Dynamic and static phases are taken into consideration while penetration decay is not covered in this model.
文摘This article discusses a possible approach for telecom operators to achieve converged telecom and Internet services. It involves integrally developing telecom networks and Internet businesses through the convergence of their instant news and social networking services. Some background, benefits for telecom operators, and possible challenges are analyzed. A new service convergence approach such as this can also facilitate triple-screen and multi-screen convergence in the future.
基金supported by the Program for New Century Excellent Talents in University (NCET-05-0116)the Hi-Tech Research and Development Program of China (2006AA01Z283, 2007AA01Z261)+1 种基金the National Natural Science Foundation of China (60702051)the Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP-20070013028)
文摘In this article, a novel cooperative wireless localization scheme based on information fusion is proposed. The scheme combines large-scale arrival time and small-scale distance measurements obtained from the next-generation converged networks. The maximum likelihood （ML） estimate of the terminal＇s position is derived with closed-form solution, and the Cramer-Rao lower bound （CRLB） of the estimate error is investigated. Both theoretical analysis and simulation results verify that the proposed localization scheme can significantly enhance the location precision. Moreover, the mean square error of position estimate approximates the CRLB when the number of reference stations increases, which indicates that the proposed ML estimator is asymptotically efficient.
基金Supported by the National Natural Science Foundation of China(12071133)Natural Science Foundation of Henan Province(252300421993)Key Scientific Research Project of Higher Education Institutions in Henan Province(25B110005)。
文摘In this paper,an adaptive cubic regularisation algorithm based on affine scaling methods(ARCBASM)is proposed for solving nonlinear equality constrained programming with nonnegative constraints on variables.From the optimality conditions of the problem,we introduce appropriate affine matrix and construct an affine scaling ARC subproblem with linearized constraints.Composite step methods and reduced Hessian methods are applied to tackle the linearized constraints.As a result,a standard unconstrained ARC subproblem is deduced and its solution can supply sufficient decrease.The fraction to the boundary rule maintains the strict feasibility(for nonnegative constraints on variables)of every iteration point.Reflection techniques are employed to prevent the iterations from approaching zero too early.Under mild assumptions,global convergence of the algorithm is analysed.Preliminary numerical results are reported.
基金supported in part by the Rosetrees Trust(#CF-2023-I-2_113)by the Israel Ministry of Innovation,Science,and Technology(#7393)(to ES).
文摘The organization of biological neuronal networks into functional modules has intrigued scientists and inspired engineers to develop artificial systems.These networks are characterized by two key properties.First,they exhibit dense interconnectivity(Braitenburg and Schüz,1998;Campagnola et al.,2022).The strength and probability of connectivity depend on cell type,inter-neuronal distance,and species.Still,every cortical neuron receives input from thousands of other neurons while transmitting output to a similar number of neurons.Second,communication between neurons occurs primarily via chemical or electrical synapses.
基金National Key Research and Development Program of China(2017YFA0701005)National Natural Science Foundation of China(61722111,61871268)+4 种基金"Shuguang"Program of Shanghai Education Commission(19SG44)Program of General Administration of Customs of the People’s Republic of China(2019HK006)Shanghai International Joint Laboratory Project(17590750300)111 Project(D18014)Interdisciplinary Scientific and Educational School of Moscow University"Photonic and Quantum Technologies.Digital Medicine"。
文摘The investigation of converged twisted beams with a helical phase structure has a remarkable impact on both fundamental physics and practical applications.Geometric metasurfaces consisting of individually orientated metal/dielectric meta-atoms provide an ultracompact platform for generating converged vortices.However,it is still challenging to simultaneously focus left-handed and right-handed circularly polarized incident beams with pure geometric phase modulation,which hinders the independent operation on topological charges between these two helical components.Here we propose and experimentally demonstrate an approach to design terahertz geometric metasurfaces that can generate helicity-independent converged vortices with homogeneous polarization states by the superposition of two orthogonal helical vortices with identical topological charges.Furthermore,the multiplexing of polarization-rotatable multiple vortices in multiple dimensions,i.e.,in both longitudinal and transverse directions,and a vortex with an extended focal depth is confirmed by embedding polarization modulation into the geometric metasurfaces.The demonstrated approach provides a new way to simultaneously manipulate orthogonal helical components and expand the design dimension,enabling new applications of geometric metasurface devices in polarization optics,twisted-beam related image and edge detection,high capacity optical communication,and quantum information processing,to name a few.
基金supported by the National Key Research and Development Program of China under Grant No.2018YFB0204300the National Postdoctoral Program for Innovative Talents under Grant No.BX20190091Excellent Youth Foundation of Hunan Province(De-Zun Dong).
文摘Bursty traffic and thousands of concurrent flows incur inevitable network congestion in datacenter networks(DCNs)and then affect the overall performance.Various transport protocols are developed to mitigate the network congestion,including reactive and proactive protocols.Reactive schemes use different congestion signals,such as explicit congestion notification(ECN)and round trip time(RTT),to handle the network congestion after congestion arises.However,with the growth of scale and link speed in datacenters,reactive schemes encounter a significant problem of slow responding to congestion.On the contrary,proactive protocols(e.g.,credit-reservation protocols)are designed to avoid congestion before it occurs,and they have the advantages of zero data loss,fast convergence and low buffer occupancy.But credit-reservation protocols have not been widely deployed in current DCNs(e.g.,Microsoft,Amazon),which mainly deploy ECN-based protocols,such as data center transport control protocol(DCTCP)and data center quantized congestion notification(DCQCN).And in an actual deployment scenario,it is hard to guarantee one protocol to be deployed in every server at one time.When credit-reservation protocol is deployed to DCNs step by step,the network will be converted to multi-protocol state and will face the following fundamental challenges:1)unfairness,2)high buffer occupancy,and 3)heavy tail latency.Therefore,we propose Harmonia,aiming for converging ECN-based and credit-reservation protocols to fairness with minimal modification.To the best of our knowledge,Harmonia is the first to address the trouble of harmonizing proactive and reactive congestion control.Targeting the common ECN-based protocols-DCTCP and DCQCN,Harmonia leverages forward ECN and RTT to deliver real-time congestion information and redefines feedback control.After the evaluation,the results show that Harmonia effectively solves the unfair link allocation,eliminating the timeouts and addressing the buffer overflow.
基金Supported by the Science and Technology Project of Guangxi(Guike AD23023002)。
文摘In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.
