网格环境下的航空发动机集成设计与分布仿真研究

建立了一个开发航空发动机分布仿真的系统环境．该环境中子模型具有自治性,子模型的设计者可以根据自己的需要选择所使用的工具,定义变量以及他们与其他设计者之间的关系．应用新兴的网格技术建立了一个集成设计和分布仿真的环境框架,它可以灵活地建立和修改基于部件对象模型建立起来的航空发动机模型,并尝试解决仿真中存在的多学科耦合以及大计算量的问题．该框架具有图形化界面,可以方便地更改发动机的参数和结构,其所具有网格技术的易扩展性也为今后建立更复杂的发动机模型提供了良好的平台．研究人员可以应用该系统提供的可扩展设计和仿真环境,灵活地组建新的航空发动机模型并进行仿真．     

航空发动机控制系统故障检测仿真平台研究

通过分析目前航空发动机控制系统故障检测仿真软件缺乏通用性、模块化的问题,将发动机建模、故障检测和组件开发技术相结合,提出并设计了航空发动机控制系统故障检测仿真平台,分析该平台的设计目标、软件总体架构与主要功能.针对某型涡扇发动机为研究对象,给出传感器与执行机构典型故障的模式分析和检测逻辑,在飞行包线设计点进行仿真计算.实践表明该平台能够准确实时仿真发动机控制系统典型故障,具有功能可靠、易扩展、工程化程度高的特点.     

基于SOA的柔性分布式仿真框架的设计

为了使分布式仿真系统能够适应复杂仿真中的实现技术、部署位置和仿真流程等不确定因素,提出了一个基于SOA的柔性分布式仿真框架,在分布式环境下,满足跨地域、跨平台的异构仿真单元的集成和交互,并实现仿真流程动态配置与切换。框架基于SOA架构、仿真组件化思想、采用Web服务技术实现仿真服务化封装;在仿真服务接口层为仿真客户端和远程仿真服务提供统一的、基于标准的程序级的调用方法;用仿真服务总线实现对仿真服务的灵活的集成和交互;利用动态加载和实时配置的方法对仿真服务进行管理。经实践证明,框架适用于跨地域的异构平台下流程复杂且多变的仿真需求。     

航空发动机机械液压控制器建模及仿真技术研究

以流量连续方程和力平衡方程为基础，研究了航空发动机机械液压控制器典型部件的建模方法以及系统中存在的北线性环节的描述方法。对某型航空发动机慢车转速燃油控制系统进行了建模和数字仿真研究，结果与工程实践中现场的情况一致，效果优于常规的仿真方法。工程实践已经验证了仿真研究给出的主要的控制器参数改变的建议是正确的，使控制系统的性能达到了设计要求。这表明所提出的航空发动机机械液压控制器建模和仿真方法是正确、有效的。     

A knowledge-based simulation environment for hierarchical flexiblemanufacturing

This article presents an approach to embedding expert systems within an object oriented simulation environment. The basic idea is to create classes of expert system models that can be interfaced with other model classes. An expert system shell is developed within a knowledge-based design and simulation environment which combines artificial intelligence and systems modeling concepts. In the given framework, interruptible and distributed expert systems can be defined as components of simulations models. This facilitates simulation modeling of knowledge-based controls for flexible manufacturing and many other autonomous intelligent systems. Moreover, the structure of a system can be specified using a recursive system entity structure (SES) and unfolded to generate a family of hierarchical structures using an extension of SES pruning called recursive pruning. This recursive generation of hierarchical structures is especially appropriate for design of multilevel flexible factories. The article illustrates the utility of the proposed framework within the flexible manufacturing context     

基于一种改进型逆凸不等式的混合攻击下多区域时滞电力系统的分布式控制

本文研究了混合攻击下多区域时滞电力系统的分布式协调控制问题。首先,考虑了一种基于混合攻击下（包括拒绝服务攻击和欺骗攻击）的多区域时滞电力系统,在拒绝服务攻击下,时滞电力系统的各个区域之间的通信将恶化为一种切换残余拓扑结构,它的时间特性建模成了模型依赖的平均停留时间的模型。在以负反馈控制为目标的欺骗攻击下,将其建模成了基于符号函数的模型。然后,为了在低惯性和混合攻击下获得时滞电力系统的弹性性能,采用了负荷频率控制与虚拟惯性控制相结合的弹性分布式策略,并将时滞电力系统的负荷频率控制问题转换为切换非线性切换系统控制问题。再通过采用合适的Lyapunov-Krasovskii泛函、改进型逆凸不等式、线性矩阵不等式技术以及切换系统方法,得到了多区域时滞电力系统的稳定性定理。并基于此定理,设计了负荷频率控制和虚拟惯性控制下的分布式控制增益。最后,建立仿真,针对三区域电力系统进行了仿真,仿真结果体现了本文所提出来的稳定性定理和设计的分布式控制增益的优势和有效性。     

Genetic algorithm-based identification of transfer function parameters for a rectangular flexible plate system

This paper focuses on an identification technique based on genetic algorithms (GAs) with application to rectangular flexible plate systems for active vibration control. A real coded GA with a new truncation-based selection strategy of individuals is developed, to allow fast convergence to the global optimum. A simulation environment characterizing the dynamic behavior of a flexible rectangular plate system is developed using the central finite difference (FD) techniques. The plate thus developed is excited by a uniformly distributed random disturbance and the input–output data of the system acquired is used for black-box modeling the system with the GA optimization using an autoregressive model structure. Model validity tests based on statistical measures and output prediction are carried out. The prediction capability of the model is further examined with unseen data. It is demonstrated that the GA gives faster convergence to an optimum solution and the model obtained characterizes the dynamic system behavior of the system well.     

A criterion on inclusion of stress stiffening effects in flexible multibody dynamic system simulation

This paper presents a criterion on inclusion of stress stiffening effects in dynamic simulation of flexible multibody systems. The proposed criterion examines numerically the eigenvalue variation of the total modal stiffness matrix that is a combination of the modal stress stiffness matrix and the conventional linear modal stiffness matrix prior to actual dynamic simulation. If the variation is sufficiently large for any flexible body in the multibody system, then stress stiffening effects must be included in dynamic simulation of flexible multibody systems for accurate prediction of dynamic behavior. Since the criterion uses the most general stress stiffness matrix contributed from applied and constraint reaction loads as well as from a system of 12 inertial loads, this criterion is applicable to any general flexible multibody dynamic system. Several numerical results are presented to show the effectiveness of the proposed criterion.     

基于SSH和LDAP的分布式安全文件系统*

如何为文件系统提供更完备和更强伸缩性的安全保障是安全文件系统研究的重要方面。基于LDAP技术和SSH协议设计了一个分布式安全文件系统,为文件系统提供了灵活而强大的安全策略保护,介绍了分布式安全文件系统的框架、原理以及安全设计以及分析。     

一种用户行为分析的动态备份机制

目前大多数分布式存储系统采用静态备份机制保证系统的高可靠性,灵活性差,不适合系统规模及用户访问量不断变化的存储系统．因此提出一种基于用户行为分析的动态备份机制,通过分析用户行为获得相关信息来动态改变备份数量及确定备份位置,具有较强的灵活性,适合大规模的分布式存储系统;实现动态备份系统将其应用于已建立的科技信息数据中心．通过实验分析表明,该动态备份机制能提高系统的可靠性。     

分布式集群协同仿真研究

分布式集群协同仿真是指地域上分布、系统上异构的多个节点群为实现某一复杂的仿真目的而进行互连并进行内容级的互操作的一种复杂、大型、综合的协同仿真。其中每一个节点为一个仿真系统(或仿真器)或控制系统或服务器,多个节点互连形成为节点群构成具有明确仿真目标的综合仿真系统,井且这些节点群综合仿真系统种类多样(虚拟仿真系统、实物仿真系统、构造仿真系统等)、具有层次结构(如军事上战略仿真、战役仿真、战术仿真、装备仿真等)、地理上,“域分布(WAN或INTERNT环境)而且它们之间的连接关系较为复杂(一对一、一对多、多对一、多对多等)。该文提出了“分布式集群协同仿真”与“双时仿真”的概念与构想;研究并设计了分布式集群协同仍真的体系结构;建立了多节点分布集群协同仿真时间管理策略;构建了几类典型协间仿真系统运行控制的算法。分布式集群协同仿真由于具有分布、异构、广域、多粒、层差等特性,因此,分布式集群协同仿真研究既足一个实践课题,同时也是一个理论课题。该文的研究,主要集中在分布集群协同仿真层次的多节点复杂大系统的应刚领域,属实践课题研究。     

飞翼布局无人作战飞机自动着陆控制系统设计

飞翼飞机是一种先进的飞行结构.但由于气动外形的特殊,无垂直尾翼的飞翼飞机在着陆阶段,极易受到侧风的干扰,而使其偏离航线;根据飞翼飞机的气动参数,建立了飞翼飞机的非线性数学模型,设计了飞翼无人机的着陆轨迹和控制方案;针对飞翼飞机的特性,采用不同于常规飞机的控制律,设计了抗侧风自动着陆控制系统;设计的控制系统经过非线性仿真试验,结果显示,飞机抗侧风着陆性能达到了设计要求,从而验证了设计方案的可行性.     

Implementation of real-time distributed control for discrete event robotic systems using Petri nets

This article presents a systematic method of modeling and implementing real-time control for discrete-event robotic systems using Petri nets. Because, in complex robotic systems such as flexible manufacturing systems, the controllers are distributed according to their physical structure, it is desirable to realize real-time distributed control. In this article, the task specification of robotic processes is represented as a system control-level net. Then, based on the hierarchical approach, it is transformed into detailed subnets, which are decomposed and distributed into the local machine controllers. The implementation of real-time distributed control through communication between the system controller and the machine controllers on a microcomputer network is described for a sample robotic system. The proposed implementation method is sufficiently general, and can be used as an effective prototyping tool for consistent modeling, simulation, and real-time control of large and complex robotic systems.     

Non-centralised control strategies for energy-efficient and flexible manufacturing systems

The manufacturing industry is transforming towards smart, energy-efficient, and flexible manufacturing systems. In this regard, this work deals with the design of non-centralised control architectures to improve the energy efficiency of such systems and to promote their flexibility. Based on both the configuration of manufacturing systems and their coupling dynamics, these systems are divided into sub-systems, from which smaller control problems can be stated. Thus, control/management strategies can also be modularised to confer more flexibility to manufacturing systems. Then, by using suitable distributed optimisation techniques, and properly defining the consensus stages among the local controllers, the outputs from such controllers are optimally coordinated to minimise the total energy consumption of the whole system. The proposed control strategies are tested in simulation for a typical process line of automotive parts manufacturing industry, in which the main processing units are machine tools. Based on the obtained results, manufacturing systems and their control strategies could be suitably modularised using non-centralised control schemes, from which a closed-loop performance similar to its centralised counterpart can be achieved.     

.NET Remoting在分布式建模与仿真环境中的应用

.NET Remoting作为一种新的分布式解决方案较Web Service等其他分布式开发技术具有效率高、功能强大、配置灵活等特点。融合.NET Remoting技术的分布式建模与仿真环境可以实现网络环境下以浏览器作为系统入口进行复杂系统的多学科协同建模和仿真应用。文章介绍了一种基于.NET Remoting的分布式建模与仿真环境的设计与实现。     

基于ZYNQ的航空发动机传感器仿真系统设计

针对航空发动机传感器地面仿真实验中存在的缺陷进行了深入研究,提出了一种采用硬件在环仿真的全新模式,解决了传统实验操作复杂、易受干扰、扩展性差等不足。仿真系统基于可扩展处理平台Zynq[1],移植了适合嵌入式系统的小型TCP/IP协议栈LwIP[2],可接入综合实验网络。对于不同的实验要求,只需调整接入网络的设备数量,大幅提高了可扩展性,便于系统集成。用户无需进入实验室,就能完成模型仿真、参数验证、数据测试等一系列操作。实际使用效果表明,新型仿真系统的综合性能大幅优于传统模式。在航空发动机的仿真与测试方面,提供了一种高效便利的解决方案,可提升实验效率30%以上。目前已被成功应用到多型航空发动机综合实验中。     

动态网络环境下的多Agent移动合作系统

多Agent移动合作系统为分布式系统提供了灵活、高效的解决方案,但针对动态网络环境,当前的一些研究工作还存在局限性,以多Agent移动合作系统模型为基础,考虑到动态环境中Agent知识的不确定性、影响力和Agent间可能客观存在的矛盾,提出了Agent模糊知识表达与交换的思想、理论模型及算法,较好地考虑并解决了Agent的模糊信念合成及矛盾处理等关键问题,通过仿真研究,将所提出的理论与模型应用于解决动态网络拓扑发现问题,结果证明了该模型是可行、高效的。     

分布式卫星系统仿真支撑框架设计

分布式卫星系统是卫星技术发展的一个重要方向,但分布式卫星系统的复杂性也给传统的仿真技术提出了挑战.为降低仿真开发的难度,为分布式卫星系统仿真从模捌建立、仿真定义到仿真运行设计了支撑软件框架.基于支持实时分布式条件下通信的数据分发服务实现.并定义了进程间和进程内两层仿真支撑框架,使得可以根据仿真成员的特性灵活布置仿真成员.提高分布式仿真的计算效率.分布式卫星系统仿真支撑框架提高了仿真开发的灵活性和效率,并能满足分布式卫星系统仿真在仿真成员互操作性和可重用性方面的需求.     

FlexiFrag: A design pattern for flexible file sharing in distributed collaborative applications

The need for flexible file sharing in distributed systems is increasing in applications such as calendar management, collaborative editing of documents, collaborative software developments etc. The file sharing policies required in these applications are often very different from the traditional read/write policies. Hence, a flexible way of specifying and implementing sharing policies on individual files in file systems is required. We propose a distributed object-based system model of constructing file systems. The object-based system model is based on a pattern called FlexiFrag. We show how a distributed object-based system and in particular distributed file system can be constructed using the pattern in a flexible way.     

Adaptive fault‐tolerant control for a nonlinear flexible aircraft wing system

Fault‐tolerant control problems have been extensively studied in all kinds of control systems. However, there is little work on fault‐tolerant control for distributed parameter systems. In this paper, a novel adaptive fault‐tolerant boundary control scheme is proposed for a nonlinear flexible aircraft wing system against actuator faults. The whole system is regarded as a distributed parameter system, and the dynamic model of the flexible wing system is described by a set of partial differential equations (PDEs) and ordinary differential equations (ODEs). The proposed controller is designed by using the Lyapunov's direct method and adaptive control strategies. Based on the online estimation of actuator faults, the adaptive controller parameters can update automatically to compensate the actuator faults of the system. Besides, a fault‐tolerant controller is also developed for this system in the presence of external disturbances. Differing from existing works about adaptive fault‐tolerant control, the adaptive controller presented in this paper is designed for a distributed parameter system. Finally, numerical simulations are carried out to illustrate the effectiveness of the proposed control scheme.