高性能计算和数据中心融合网络研究综述

随着高性能计算、大数据处理、云计算和人工智能计算呈融合发展趋势,高性能计算网络和数据中心网络的融合网络成为互连网络发展的重要趋势。分析当前融合网络研究现状;针对当前最具代表性的融合网络进行详细阐述,全面展示该领域的最新技术和动态;提出融合网络面临的技术挑战;基于技术挑战对融合网络的发展趋势进行展望,包括融合网络协议栈设计中融合与分化并存、基于在网计算实现融合网络性能加速、面向新兴应用需求优化融合网络性能。     

电磁脉冲对高频结构的热效应分析

对于Cerenkov型器件,由高频结构温升引发的热脱附会造成的射频击穿,进而导致输出功率降低和脉冲缩短。基于此,研究了电磁脉冲对高频结构的加热温升效应,推导了高频结构的温升公式,指出了理论公式的适用范围,并给出了数值求解试件温升的方法。以二周期1 MV·cm^-1的高频结构为例,进行了温升的数值计算和仿真研究。结果表明,脉宽100 ns的单脉冲对不锈钢试件的温升效应明显高于其他材料。当系统工作在高重频时,电磁脉冲的温升作用可能使金属材料达到气体脱附的阈值从而引发气体脱附形成局部高压。该研究可为高功率微波源中的气体脱附以及射频击穿等研究提供参考。     

火箭出口面积对RBCC发动机引射模态影响规律分析

火箭基组合循环发动机引射模态飞行状态复杂,为了提高发动机的整体性能,研究了火箭出口面积对发动机引射模态的影响规律。通过数值模拟研究,引射流量在低飞行马赫数条件下,主要受引射性能影响,火箭出口面积越大,引射性能越好。然而,随着飞行马赫数的提升,引射空气的动能提升,隔离段内出现壅塞情况,引射流量主要受限于隔离段几何尺寸,与火箭出口面积无关。在亚声速工况下,火箭出口面积越小,发动机比冲越低,且出口无量纲面积为3.15时,火箭羽流膨胀撞壁,会引起性能骤减,需要予以避免;在超声速工况下,选择面积较小的火箭出口面积,燃烧室内压越高,发动机性能提升越明显。     

Many‐server loss models with non‐poisson time‐varying arrivals

This article proposes an approximation for the blocking probability in a many‐server loss model with a non‐Poisson time‐varying arrival process and flexible staffing (number of servers) and shows that it can be used to set staffing levels to stabilize the time‐varying blocking probability at a target level. Because the blocking probabilities necessarily change dramatically after each staffing change, we randomize the time of each staffing change about the planned time. We apply simulation to show that (i) the blocking probabilities cannot be stabilized without some form of randomization, (ii) the new staffing algorithm with randomiation can stabilize blocking probabilities at target levels and (iii) the required staffing can be quite different when the Poisson assumption is dropped. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 177–202, 2017     

A survey of performance issues in defence innovation

This article reviews innovation processes in defence. It analyses the way and the context under which these processes are carried out. The article covers the features of defence goods with impact on innovation, the development of a new good, the institutional arrangements that support these processes and the effect of innovation on industrial market. The analysis helps to identify the causes of facts observed in practice, such as poor performance in terms of product quality, cost or delivery time, as well as to assess potential remedies. Some policy implications, which can be derived from this analysis, are finally outlined.     

并行程序运行故障原因识别

高性能计算系统的复杂性和规模的不断增长使得系统的平均无故障时间越来越短,因此系统的硬软件故障导致并行程序运行出错的概率随之增加。此外,并行程序本身可能存在的编程错误也会导致运行出错。由于处理上述两类故障原因的措施迥异,所以在程序运行出现故障时,用户需要关注故障原因的类别。针对这一问题,设计和实现了一种基于作业管理系统Slurm的并行程序运行故障原因识别系统。通过对Slurm进行扩展,监控作业状态,重提交和重运行作业。根据作业运行结果,区分故障原因类别。故障注入方式进行的实验表明,该系统具有较高的识别准确率。     

可调喷油规律下柴油机性能随喷油提前角的影响

为获取可调喷油规律条件下,喷油提前角对柴油机性能的影响规律及成因机理。在实现可调喷油规律喷射的基础上,基于Fire软件建立了柴油机工作过程计算模型,并通过试验对模型中的主要参数进行了标定,进而利用模型分析了靴形喷油规律下柴油机性能随喷油提前角的变化。结果表明：随着增压时刻的滞后,喷油规律由矩形过渡到斜坡形再到靴形,实现了灵活可调的喷油规律。在靴形喷油规律条件下,存在一个最佳的喷油提前角,使柴油机的动力性和经济性均达到最优。同时,随着喷油提前角的增大,柴油机缸内压力、缸内温度以及放热率均逐渐升高,且到达各自最大值的时刻前移,而NOx排放量和碳烟排放量则分别呈现出增加和减小的趋势。     

The investigation of NTO/HMX-based plastic-bonded explosives and its safety performance

3-nitro-1,2,4-triazol-5-one (NTO) is the main component of insensitive munitions (IM) formulation because of its outstanding insensitive properties.In this paper,a series of NTO/HMX-based composite explosives were prepared and characterized.The study focuses on the effect of NTO on the performance of the formulations,especially the safety performance.The results revealed that the mechanical sensi-tivity of formulations was associated with NTO content,as well as the thermal conductivity,specific heat capacity and Arrhenius parameters.Then,the high amount of NTO using in formulation was proved to be helpful for NTO/HMX-based formulation to exhibit good thermal safety.Besides,by accelerating rate calorimeter (ARC) and a modified cook-offequipment,the pressure and pressure rise rate were proved as the important indicator for judging the thermal safety performance in confined spaces.Finally,the numerical simulation was used as a credible method for predicting the respond temperature of cook-off experiment.     

海拔对离心泵吸入性能的影响

海拔对离心泵吸入性能影响较大,但对应关系不明确。为定量分析海拔与离心泵吸入性能的关系,需进行泵高原工作吸入性能实验。海拔与真空度关系密切,利用控制泵吸入口真空度的方法,开展泵高原工作吸入性能模拟实验,获取各工况下泵吸入口持液率数据,并绘制曲线图。实验结果表明：海拔每升高500 m,泵吸入口持液率下降2%~5%;随着海拔的提升,泵吸入性能下降速率加快,工作状态趋于不稳定。     

舰艇编队防空过程建模及分析

防空作战是大型水面舰艇编队的主要作战样式之一。运用PEPA(性能评价过程代数)方法对舰艇编队防空作战全过程进行有效建模,形式化描述了预警探测、情报传递、命令下达、防空拦截等作战主要过程。建立的PEPA模型具有层次化结构,考虑了要素间相互协作,体现了编队防空作战分布、并发的特点。通过对建立的PEPA模型进行性能指标选择和稳定状态分析,得到了不同因素对编队能力发挥的影响情况,获得了防空作战的基本要素组成,从而提供了一种解决舰艇编队问题的新方法。