A mobile satellite communication system (MSCS) is a device installed on a moving carrier for mobile satellite communication. It can eliminate disturbance and maintain continuous satellite communication when the carrie...A mobile satellite communication system (MSCS) is a device installed on a moving carrier for mobile satellite communication. It can eliminate disturbance and maintain continuous satellite communication when the carrier is moving. Because of many advantages of mobile satellite communication, the MSCSs are becoming more and more popular in modern mobile communication. In this paper, a typical ship-mounted MSCS is studied. The dynamic model of the system is derived using the generalized Lagrange method both in the joint space and in the workspace. Based on the dynamic model, a nonlinear computed torque controller with trajectory planning is designed to track an aimed satellite with a satisfied transient response. Simulation results in two different situations are presented to show the tracking performance of the controller.展开更多
With the significant advancement in emerging processor, memory, and networking technologies, exascale systems will become available in the next few years （2020 2022）. As the exascale systems begin to be deployed and...With the significant advancement in emerging processor, memory, and networking technologies, exascale systems will become available in the next few years （2020 2022）. As the exascale systems begin to be deployed and used, there will be a continuous demand to run next-generation applications with finer granularity, finer time-steps, and increased data sizes. Based on historical trends, next-generation applications will require post-exascale systems during 2025-2035. In this study, we focus on the networking and communication challenges for post-exascale systems. Firstly, we present an envisioned architecture for post-exascale systems. Secondly, the challenges are summarized from different perspectives： heterogeneous networking technologies, high-performance eonmmnication and synchronization protocols, integrated support with accelerators and field-programmable gate arrays, fault-tolerance and quality-of-service support, energy-aware communication schemes and protocols, software- defined networking, and scalable communication protocols with heterogeneous memory and storage. Thirdly, we present the challenges in designing efficient programming model support for high-performance computing, big data, and deep learning on these systems. Finally, we emphasize the critical need for co-designing runtime with upper layers on these systems to achieve the maximum performance and scalability.展开更多
Information and communication technology （ICT） and systems are essential for every business. They can be used in retail, manufacturing and other industries. Nevertheless, new and innovative ideas and solutions are c...Information and communication technology （ICT） and systems are essential for every business. They can be used in retail, manufacturing and other industries. Nevertheless, new and innovative ideas and solutions are constantly emerging and introducing new possibilities for the reorganization of traditional logistics processes. Particularly, attention is given to basic concept of CC （cloud computing） service models and opportunities in logistics. This paper provides comprehensive review and comparison of different ICT solutions and CC applications. As a new and cutting-edge technology, CC is changing the form and function of information technology infrastructures making supply chain information collaboration easy and feasible. It can also be an enabler of fully electronic logistics management systems. Adoption of CC concept involves strong hardware support, good internet connectivity and implied reorganization of traditional business activities.展开更多
The message passing interface (MPI) has become a de facto standard for programming models of highperformance computing, but its rich and flexible interface semantics makes the program easy to generate communication de...The message passing interface (MPI) has become a de facto standard for programming models of highperformance computing, but its rich and flexible interface semantics makes the program easy to generate communication deadlock, which seriously affects the usability of the system. However, the existing detection tools for MPI communication deadlock are not scalable enough to adapt to the continuous expansion of system scale. In this context, we propose a framework for MPI runtime communication deadlock detection, namely MPI-RCDD, which contains three kinds of main mechanisms. Firstly, MPI-RCDD has a message logging protocol that is associated with deadlock detection to ensure that the communication messages required for deadlock analysis are not lost. Secondly, it uses the asynchronous processing thread provided by the MPI to implement the transfer of dependencies between processes, so that multiple processes can participate in deadlock detection simultaneously, thus alleviating the performance bottleneck problem of centralized analysis. In addition, it uses an AND⊕OR model based algorithm named AODA to perform deadlock analysis work. The AODA algorithm combines the advantages of both timeout-based and dependency-based deadlock analysis approaches, and allows the processes in the timeout state to search for a deadlock circle or knot in the process of dependency transfer. Further, the AODA algorithm cannot lead to false positives and can represent the source of the deadlock accurately. The experimental results on typical MPI communication deadlock benchmarks such as Umpire Test Suit demonstrate the capability of MPIRCDD. Additionally, the experiments on the NPB benchmarks obtain the satisfying performance cost, which show that the MPI-RCDD has strong scalability.展开更多
The Global/Regional Assimilation and PrEdiction System（GRAPES）is a new-generation operational numerical weather prediction（NWP）model developed by the China Meteorological Administration（CMA）.It is a grid-point m...The Global/Regional Assimilation and PrEdiction System（GRAPES）is a new-generation operational numerical weather prediction（NWP）model developed by the China Meteorological Administration（CMA）.It is a grid-point model with a code structure different from that of spectral models used in other operational NWP centers such as the European Centre for Medium-Range Weather Forecasts（ECMWF）,National Centers for Environmental Prediction（NCEP）,and Japan Meteorological Agency（JMA）,especially in the context of parallel computing.In the GRAPES global model,a semi-implicit semi-Lagrangian scheme is used for the discretization over a sphere,which requires careful planning for the busy communications between the arrays of processors,because the Lagrangian differential scheme results in shortened trajectories interpolated between the grid points at the poles and in the associated adjacent areas.This means that the latitude-longitude partitioning is more complex for the polar processors.Therefore,a parallel strategy with efficient computation,balanced load,and synchronous communication shall be developed.In this paper,a message passing approach based on MPI（Message Passing Interface）group communication is proposed.Its key-point is to group the polar processors in row with matrix-topology during the processor partitioning.A load balance task distribution algorithm is also discussed.Test runs on the IBM-cluster 1600 at CMA show that the new algorithm is of desired scalability,and the readjusted load balance scheme can reduce the absolute wall clock time by 10% or more.The quasi-operational runs of the model demonstrate that the wall clock time secured by the strategy meets the real-time needs of NWP operations.展开更多
基金supported by National Natural Science Foundation of China (Nos. 61074023 and 60975075)Natural Science Foundation of Jiangsu Province of China (No. BK2008404)+1 种基金Science and Technology Pillar Program of Jiangsu Province of China (No. BE2009160)Innovation Project of Graduate Students of Jiangsu Province of China (No. CXZZ 0254)
文摘A mobile satellite communication system (MSCS) is a device installed on a moving carrier for mobile satellite communication. It can eliminate disturbance and maintain continuous satellite communication when the carrier is moving. Because of many advantages of mobile satellite communication, the MSCSs are becoming more and more popular in modern mobile communication. In this paper, a typical ship-mounted MSCS is studied. The dynamic model of the system is derived using the generalized Lagrange method both in the joint space and in the workspace. Based on the dynamic model, a nonlinear computed torque controller with trajectory planning is designed to track an aimed satellite with a satisfied transient response. Simulation results in two different situations are presented to show the tracking performance of the controller.
基金Project supported by the National Science Foundation of the USA(Nos.IIS-1447804 and CNS-1513120)
文摘With the significant advancement in emerging processor, memory, and networking technologies, exascale systems will become available in the next few years （2020 2022）. As the exascale systems begin to be deployed and used, there will be a continuous demand to run next-generation applications with finer granularity, finer time-steps, and increased data sizes. Based on historical trends, next-generation applications will require post-exascale systems during 2025-2035. In this study, we focus on the networking and communication challenges for post-exascale systems. Firstly, we present an envisioned architecture for post-exascale systems. Secondly, the challenges are summarized from different perspectives： heterogeneous networking technologies, high-performance eonmmnication and synchronization protocols, integrated support with accelerators and field-programmable gate arrays, fault-tolerance and quality-of-service support, energy-aware communication schemes and protocols, software- defined networking, and scalable communication protocols with heterogeneous memory and storage. Thirdly, we present the challenges in designing efficient programming model support for high-performance computing, big data, and deep learning on these systems. Finally, we emphasize the critical need for co-designing runtime with upper layers on these systems to achieve the maximum performance and scalability.
文摘Information and communication technology （ICT） and systems are essential for every business. They can be used in retail, manufacturing and other industries. Nevertheless, new and innovative ideas and solutions are constantly emerging and introducing new possibilities for the reorganization of traditional logistics processes. Particularly, attention is given to basic concept of CC （cloud computing） service models and opportunities in logistics. This paper provides comprehensive review and comparison of different ICT solutions and CC applications. As a new and cutting-edge technology, CC is changing the form and function of information technology infrastructures making supply chain information collaboration easy and feasible. It can also be an enabler of fully electronic logistics management systems. Adoption of CC concept involves strong hardware support, good internet connectivity and implied reorganization of traditional business activities.
基金This work was supported by the National Key Research and Development Program of China under Grant No. 2017YFB0202003。
文摘The message passing interface (MPI) has become a de facto standard for programming models of highperformance computing, but its rich and flexible interface semantics makes the program easy to generate communication deadlock, which seriously affects the usability of the system. However, the existing detection tools for MPI communication deadlock are not scalable enough to adapt to the continuous expansion of system scale. In this context, we propose a framework for MPI runtime communication deadlock detection, namely MPI-RCDD, which contains three kinds of main mechanisms. Firstly, MPI-RCDD has a message logging protocol that is associated with deadlock detection to ensure that the communication messages required for deadlock analysis are not lost. Secondly, it uses the asynchronous processing thread provided by the MPI to implement the transfer of dependencies between processes, so that multiple processes can participate in deadlock detection simultaneously, thus alleviating the performance bottleneck problem of centralized analysis. In addition, it uses an AND⊕OR model based algorithm named AODA to perform deadlock analysis work. The AODA algorithm combines the advantages of both timeout-based and dependency-based deadlock analysis approaches, and allows the processes in the timeout state to search for a deadlock circle or knot in the process of dependency transfer. Further, the AODA algorithm cannot lead to false positives and can represent the source of the deadlock accurately. The experimental results on typical MPI communication deadlock benchmarks such as Umpire Test Suit demonstrate the capability of MPIRCDD. Additionally, the experiments on the NPB benchmarks obtain the satisfying performance cost, which show that the MPI-RCDD has strong scalability.
基金Supported by the National S&T Infrastructure Program for the 11th Five-Year Period under Grant No.2006BAC02B00the National Natural Science Foundation of China under Grant Nos.40575050 and 40775073
文摘The Global/Regional Assimilation and PrEdiction System（GRAPES）is a new-generation operational numerical weather prediction（NWP）model developed by the China Meteorological Administration（CMA）.It is a grid-point model with a code structure different from that of spectral models used in other operational NWP centers such as the European Centre for Medium-Range Weather Forecasts（ECMWF）,National Centers for Environmental Prediction（NCEP）,and Japan Meteorological Agency（JMA）,especially in the context of parallel computing.In the GRAPES global model,a semi-implicit semi-Lagrangian scheme is used for the discretization over a sphere,which requires careful planning for the busy communications between the arrays of processors,because the Lagrangian differential scheme results in shortened trajectories interpolated between the grid points at the poles and in the associated adjacent areas.This means that the latitude-longitude partitioning is more complex for the polar processors.Therefore,a parallel strategy with efficient computation,balanced load,and synchronous communication shall be developed.In this paper,a message passing approach based on MPI（Message Passing Interface）group communication is proposed.Its key-point is to group the polar processors in row with matrix-topology during the processor partitioning.A load balance task distribution algorithm is also discussed.Test runs on the IBM-cluster 1600 at CMA show that the new algorithm is of desired scalability,and the readjusted load balance scheme can reduce the absolute wall clock time by 10% or more.The quasi-operational runs of the model demonstrate that the wall clock time secured by the strategy meets the real-time needs of NWP operations.
