Modeling and Nonlinear Computed Torque Control of Ship-mounted Mobile Satellite Communication System

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.

计算机失效网络中节点可通信性能建模评估方法

在计算机失效网络中节点可通信性能建模评估时,传统的评估方法没有评估风险度值,因此评估误码率较高。为此,提出计算机失效网络中节点可通信性能建模评估方法。首先建立失效网络节点通信性能评估模型,以失效节点为中心,分析通信需求、通过信息流并导入通信信息,构成立体的交互式评估模型;计算评估节点可通信性能风险度值,直到二次评估能够达到规定的迭代次数或是评估误差控制在规定的范围内为止,获得计算机失效网络中节点可通信性能建模评估结果。实验结果表明,所提方法评估误码率最低可达0.202%,实现对计算机失效网络中节点可通信性能的精准评估。

分布式航电系统架构研究

针对未来体系化作战对航空电子系统提出的平台功能可变、体系快速融入与集成、新技术新能力快速插入等需求,在综合分析了未来航空电子系统架构发展趋势的基础上,提出了以网络为中心的分布式综合模块化航电系统架构.研究了分布式综合模块化航电系统架构的概念、模型和特征,重点分析了分级综合与管理、航电轻量云计算、计算和通信模型等分布式架构工程化应用需解决的核心技术.通过与传统架构进行了对比分析,提出了分布式综合模块化航电系统架构为作战使用带来的好处,为未来航空电子系统设计与研发提出了一种可行的解决方案.

时间触发网络在分布式架构中的应用分析

在分析综合化航电系统架构发展趋势的基础上,重点研究了分布式综合模块化航电(DIMA)系统架构的概念、模型、特点以及对时间触发网络的需求,提出了基于时间触发网络的分布式架构模型,研究了时间触发架构在分布式系统中的应用方法,为下一代航电系统架构选型和实现提供了解决思路。

Networking and communication challenges for post-exascale systems

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.

时间触发网络在机载系统中的应用分析

时间触发技术将是未来机载网络的发展趋势。为了解决时间触发网络在机载系统中的工程化应用问题,分析了时间触发网络的特点和优势、采用时间触发网络为系统设计带来的变革、时间触发网络在机载系统中的应用场景以及为系统带来的益处,可有效解决机载网络系统总体方案论证所关注的问题。

Cloud Computing Applications in Global Logistics Information System Infrastructure

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.

MPI-RCDD: A Framework for MPI Runtime Communication Deadlock Detection

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.

Parallelization Load Balance Strategy for a Global Grid-Point Model

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.