基于层次Petri网的复杂装备保障流程分析方法

针对复杂装备保障流程约束条件多、动态性强、耦合严重、层次结构复杂的特点,提出了一种基于层次Petri网的流程分析方法;首先,分析了保障流程的层次化结构,采用着色时间约束Petri网,建立了包含保障人员、保障设备、保障空间等保障资源库所的层次化Petri网流程模型;然后,采用流程基本模型起始时间——流程子网起始时间——流程总时间的层次方法,设计了流程时间参数统计算法;最后,以某复杂装备系统保障流程为例,进行了实例分析,并通过与ExSpect软件Monte Carlo仿真对比验证了算法的有效性。     

基于锁存器路径的静态时序分析在第三方验证中的应用

随着可编程逻辑门阵列（FPGA）设计规模的扩大,静态时序分析可有效减轻时序仿真的负担,缩短项目周期。常见的静态时序分析(STA)多是基于触发器（FF_Based STA）,对触发器的STA算法研究已经比较成熟。但FPGA综合后网表可能会产生锁存器,而锁存器的STA与触发器的STA在算法上存在差异。为保证在FPGA产品第三方验证工作中对STA路径分析覆盖率达到100%,有必要对基于锁存器的时序分析（Latch_Based STA）做研究。阐述了锁存器“时间借入”与“时间借出”的概念。分析了“锁存器宽裕时间(slack time)”特性,绘制了其函数图。在某FPGA第三方验证项目中使用STA 工具Prime Time（一种计算机模型分析工具）,分别对由“时间借入”、“时间借出”而导致“时序松弛”和“时序收紧”两种情况做了计算和分析,对STA路径分析覆盖率达到了100%,满足了第三方验证要求。     

基于帧频信号的图像存储时序控制方法

针对长时间服役光学设备图像存储系统性能退化和可靠性降低的问题,设计了新的图像存储系统结构。提出了一种基于帧频信号的时序控制方法,以帧频信号为基准驱动系统软硬件工作,结合秒信号、帧频信号与串口时间生成绝对时间,实现了四路独立数据流的同步采集,通过两级缓存机制保证数据采集-打包-存储之间的速率冗余匹配,对图像转移时间误差进行了修正。检测结果表明,系统时序得到了有效控制,长时间采集存储数据稳定可靠不丢帧,时间同步精度优于1ms。     

民航大涵道比涡扇发动机总体性能参数敏感性分析

由于人为误操作和数据库系统异步因素,电力系统监控数据存在错误风险,需要对监控数据进行多点校核来保障其一致性和正确性,可靠的监控数据保证电力系统的安全运转。然而多点校核业务流复杂且对数据精度要求高,目前的人工校核方法不仅成本高,且精度和效率低,不能保证整个监控数据的实时校核工作。为自动化监控数据多点校核过程,需要对整个业务流建模,针对该问题,提出一种基于Petri网的监控数据多点校核动态建模方法。首先将监控系统的校核业务背景形式化Petri网中的具有不同约束的节点;然后使用工作流Petri方法对校核的业务流程进行形式化定义、并将该业务流程用Petri网建模成为网状模型;最后,针对该模型提出一种化简技术对其进行化简,并证实该化简方法的有效性和该模型能拟合监控数据多点校核的整个流程。     

基于Petri网的电力系统监控数据多点校核方法

由于人为误操作和数据库系统异步因素,电力系统监控数据存在错误风险,需要对监控数据进行多点校核来保障其一致性和正确性,可靠的监控数据保证电力系统的安全运转;然而多点校核业务流复杂且对数据精度要求高,目前的人工校核方法不仅成本高,且精度和效率低,不能保证整个监控数据的实时校核工作;为自动化监控数据多点校核过程,需要对整个业务流建模,针对该问题,提出一种基于Petri网的监控数据多点校核动态建模方法;首先将监控系统的校核业务背景形式化Petri网中的具有不同约束的节点;然后使用工作流Petri方法对校核的业务流程进行形式化定义、并将该业务流程用Petri网建模成为网状模型;最后,针对该模型提出一种化简技术对其进行化简,并证实该化简方法的有效性和该模型能拟合监控数据多点校核的整个流程。     

基于IODELAY原语SAR载荷模拟器延迟单元设计

针对星载合成孔径雷达中数传分系统接收数据时序拉偏测试需求,本文提出一种基于FPGA原语的SAR载荷模拟器延时单元设计与实现。该延迟单元采用IODELAY原语,通过时序约束实现正反向时钟拉偏功能。仿真与试验结果表明,该延迟单元时序调整范围可达-6ns至6ns,步进1ns,系统运行稳定,满足设计要求。     

基于有色Petri网的机械系统故障诊断研究

故障诊断对于机械系统的使用与维护起着重要的作用;为了提高机械系统故障诊断的效率以及直观性,提出了一种使用基于知识的故障诊断方法,即使用有色Petri网诊断方法建立一种通用机械系统故障诊断模型并进行分析。针对数控机床液压元件故障这一案例,首先获取其故障来源建立故障树;其次在故障树基础上运用有色Petri网建模工具CPNTools建立有色Petri网模型;最后对模型进行了仿真分析以模拟故障的传递,进行状态空间分析以判断模型安全性,结果表明所提出的建模方法能够使得故障传递更加直观化,快速了解故障的发展趋势,并表明此模型有着较强的易用性以及通用性。     

一种飞行试验FC航电系统的采集网络时延测试方法

针对飞行试验FC总线测试的特点，文章提出了一种飞行试验FC航电系统的采集网络时延测试方法，在不影响原航电系统信息传输结构与特性的前提下，测试到通信消息从航电子系统端口发出的精准时刻，解决了航电FC采集网络时延测试难题；通过对某试验机的FC采集网络时间延迟测试，提高了飞行试验某航电子系统的试验计算精度，证明了该方法在工程中的有效性。     

脉冲快热中子分析时序优化理论研究

源中子脉冲的脉宽和滞空是脉冲快热中子分析技术的两个关键时序参数,但目前国内外还没有针对上述参数的量化评估及设置方法的相关文献报道。针对这一现状,定义了时序优化的量化评估函数,进而建立了一种时序参数优化的理论解析模型,并通过将待测目标物与周边介质等效为线性时不变系统,简化了计算过程。从数学上证明了基于该模型获取的中子脉冲的最优脉宽和滞空应相等。以美国研制的脉冲中子元素分析仪应用于地雷探测时的场景为例,获取了该场景下的最优时序参数,并论证了该模型对环境介质、探测布局的适应性。结果表明,该理论模型能快速有效地获取特定应用场景下的最优时序参数,且对探测背景、探测布局均具有较强的适应性。提出的理论模型可为脉冲快热中子分析技术应用于物料分析、违禁品探测、地雷探测等领域提供参考。     

基于Android的综合航电数据监控平台的研制

为实现对某型综合航电系统进行地面在线监控,研制了一款基于嵌入式的数据监控平台.本平台采用Arm处理器,通过以太数据方式,采集航电系统中一系列飞行参数,按照算法进行分析和处理,最终实现了对综合航电系统的工作状态监控.在硬件设计基础上,开发了Android系统下的测试设备驱动及相应应用程序.从工程应用结果表明,该平台能够实现综合航电系统状态的定期检测以及组件故障判断.     

ARINC659总线桥接的设计及对总线同步的影响分析

ARINC659总线因其在时间和空间上均提供了完备的故障冗余和操作健壮性,已经逐渐在对数据通信确定性及故障沉默和屏蔽要求较高的航天领域中展开应用。为了使ARINC659总线能够更好的适应航天器综合电子系统的高度冗余容及分布式控制的需求,对一种能够在不同设备中ARINC659总线之间相互桥接的技术进行了研究,进而实现分布式综合电子系统中所有硬件模块的统一时序规划和通信调度,可以显著提升系统中的资源共享、并行处理、故障冗余及分布式控制能力,同时也为关键系统中不同设备中的硬件模块间实现严格的时序关系操作提供了一种解决方案。最后就桥接对ARINC659总线同步机制的影响进行了分析,据此提出了桥接设计的约束和实现规则。     

Control of coexisting attractors via temporal feedback

We propose a method for controlling coexisting attractors in multistable dynamical systems. In this method, the feedback for an initial duration of time can drive the system to the desired state. We have illustrated this method by considering temporal feedback in autonomous as well as non-autonomous dynamical systems. The experimental realisation of the proposed method is also presented.     

光学系统时间传递函数的研究

随着瞬态光学的快速发展,光学系统的时间特性越来越引起人们的关注,时间特性评价方法也随之发展起来.时间光学传递函数作为评价光学系统时间特性最确切、最全面的一种方法,是时间特性评价方法的发展方向.本文重点论述了时间传递函数的理论依据、色权因子的选择、复色光时间线扩散函数的技术处理、时间传递函数的计算方法及其软件计算实例.     

基于有色Petri网的工作流故障诊断方法

工作流系统的故障自动诊断和定位是云计算环境提供持续服务的基础。为了提高工作流系统的故障诊断准确性,本文提出了一种基于有色Petri网的故障诊断方法。首先,用开放世系模型对工作流进行建模。然后,提出了一种基于有色Petri网的故障模型。最后,将工作流的开放世系模型转化为有色Petri网故障模型,并提出了相应的多故障诊断方法。实验表明,本文提出的方法不仅故障定位的准确率和执行效率高于相关算法,还能有效的识别系统中的多个故障。     

Iterative two-step temporal phase-unwrapping applied to high sensitivity three-dimensional profilometry

Although temporal phase unwrapping method can be applied to solve some problems to measure an object with steep shapes, isolated parts or fringe undersampling in three-dimensional (3D) shape measurement, it needs to acquire and process a sequence of fringe pattern images which would take much time. Servin et al. proposed a 2-step temporal phase unwrapping algorithm, which only needs the 2 extreme phase-maps to achieve exactly the same results as standard temporal unwrapping method. But this method is only validated by computer simulation, shortage of experimental demonstration, its sensitivity coefficient G is limited, and it cannot be used when the G value is larger. We proposed an iterative two-step temporal phase-unwrapping algorithm which is an extension of Servin׳s method. First, add a fringe pattern with an intermediate sensitivity, project the fringe patterns of different sensitivity onto the tested object’s surface, and collect deformed fringe patterns with a CCD camera. Then we obtain the unwrapped phase with larger sensitivity coefficient G by cascading the sensitivity coefficients. And we derive the initial phase conditions of the 2-step temporal phase unwrapping algorithm. Finally, the experimental evaluation is conducted to prove the validity of the proposed method. The results are analyzed and compared with Servin׳s method. The experimental results show that the proposed method can achieve higher sensitivity and more accurate measurement, and it can overcome the main disadvantages encountered by Servin׳s method.     

Threshold model of cascades in empirical temporal networks

Threshold models try to explain the consequences of social influence like the spread of fads and opinions. Along with models of epidemics, they constitute a major theoretical framework of social spreading processes. In threshold models on static networks, an individual changes her state if a certain fraction of her neighbors has done the same. When there are strong correlations in the temporal aspects of contact patterns, it is useful to represent the system as a temporal network. In such a system, not only contacts but also the time of the contacts are represented explicitly. In many cases, bursty temporal patterns slow down disease spreading. However, as we will see, this is not a universal truth for threshold models. In this work we propose an extension of Watts’s classic threshold model to temporal networks. We do this by assuming that an agent is influenced by contacts which lie a certain time into the past. I.e., the individuals are affected by contacts within a time window. In addition to thresholds in the fraction of contacts, we also investigate the number of contacts within the time window as a basis for influence. To elucidate the model’s behavior, we run the model on real and randomized empirical contact datasets.     

PageRank centrality for temporal networks

In this paper, we propose a new centrality measure for ranking the nodes and time layers of temporal networks simultaneously, referred to as the f-PageRank centrality. The f-PageRank values of nodes and time layers in temporal networks are obtained by solving the eigenvector of a multi-homogeneous map. The existence and uniqueness of the proposed centrality measure are also guaranteed by existing results, under some reasonable conditions. The numerical experiments on a synthetic temporal network and two real-world temporal networks (i.e., Email-Eu-core and CollegeMsg temporal networks) show that the proposed centrality outperforms some existing centrality measures.     

Background suppression for cloud clutter using temporal difference projection

To remove high intensity cloud clutter in infrared image sequence containing point target with high velocity, based on the optimal log-likelihood ratio detector test (LLRDT) together with exploratory temporal data analysis, a method called standardized maximum projection of temporal difference on adjacent frames (SMPTDAF) is proposed. First, cloud scenario is classified and analysis according to temporal features. Second, mathematical difference models of adjacent frames for all regions are presented. Third, to obtain the optimal temporal performance under LLRDT operator, based on the models, projection method after differencing and its simplified method for practical application are established. Finally in the paper, we compared the proposed method against classical temporal suppression method named Moving Target Indicator (MTI) and wavelet method by test image sequence. Experimental results show that the average SCR gain exceeds 11 when the target SCR is from 1.0 and 3, which is better than results of some representative multi-frame filters mentioned above.