Dynamic characteristics analysis of deployable space structures considering joint clearance

The clearance in joints influences the dynamic stability and the performance of deployable space structures (DSS). A virtual experimental modal analysis (VEMA) method is proposed to deal with the effects of joint clearance and link flexibility on the dynamic characteristics of the DSS in this paper. The focus is on the finite element modeling of the clearance joint, VEMA and the modal parameters identification of the DSS. The finite element models (FEM) of the clearance joint and the deployable structure are established in ANSYS. The transient dynamic analysis is conducted to provide the time history data of excitation and response for the VEMA. The fast Fourier transform (FFT) technique is used to transform the data from time domain to frequency domain. The frequency response function is calculated to identify the modal parameters of the deployable structure. Experimental verification is provided to indicate the VEMA method is both a cost and time efficient approach to obtain the dynamic characteristics of the DSS. Finally, we analyze the effects of clearance size and gravity on the dynamic characteristics of the DSS. The analysis results indicate that the joint clearance and gravity strongly influence the dynamic characteristics of the DSS.     

A formal approach using SysML for capturing functional requirements in avionics domain

In this work, a Model-Based Systems Engineering approach based on SysML is proposed. This approach is used for the capture and the definition of functional requirements in avionics domain. The motivation of this work is triple: guide the capture of functional requirements, validate these functional requirements through functional simulation, and verify efficiently the consistency of these functional requirements. The proposed approach is decomposed into several steps that are detailed to go from conceptual model of avionics domain to a formal functional model that can be simulated in its operating context. To achieve this work, a subset of SysML has been used as an intermediate modelling language to ensure progressive transformation that can be understood and agreed by system stakeholders. Formal concepts are introduced to ensure theoretical consistency of the approach. In addition, transformation rules are defined and the mappings between concepts of ARP4754A civil aircraft guidelines and SysML are formalized through meta-model. The resulting formalization enables engineers to perform functional simulation of the top-level functional architecture extracted from operational scenarios. Finally, the approach has been tested on an industrial avionics system called the Onboard Maintenance System.     

对建立工业快速动员体系的探讨

本文介绍了美国快速动员体系的基本情况，对建立我国的快速动员体系提出了几点建议。     

高强度钢Domex700MCD焊接性能研究

分析了Domex700MCD焊接性,并通过试验及数据分析表明,在焊接工艺中,采用混合气体保护焊、低合金结构钢焊丝ER69-3,通过控制焊接线能量,运用合理的焊接规范,可获得良好的焊缝机械性能。     

螺栓预紧方式工艺研究

采用液压拉伸螺栓预紧的方法,通过模拟某产品平台螺栓安装预紧的工艺试验研究,优选并确定了工艺的实际操作方法、步骤,以及所需要的工艺参数,为各种大型结构件的螺栓安装提供了技术支持。     

构建数学模型 优化贴装过程

贴装优化问题直接关系到表面贴装工艺的效率。本文以JUKI．2010／2020贴片机为试验平台，根据该机型结构及贴装过程，把贴装优化问题的描述为最小权重匹配问题（MWMP）以及非对称旅行商（TSP）问题，构建了一种新的优化模型：把时间优化转化为距离优化，并应用启发式算法进行软件编程。通过生产企业的6块PCB板的对比实验，证明了该数学模型和算法是合理的。     

运载火箭姿态系统自适应神经网络容错控制

针对运载火箭姿态系统跟踪问题,考虑干扰、执行器故障和模型不确定因素的影响,设计了一种基于自适应神经网络的非线性容错控制律。该控制算法结合了连续的终端滑模控制,径向基神经网络和自适应控制方法。首先,基于滑模控制理论,设计了一种快速终端滑模面,保证系统跟踪误差能够在有限时间收敛至零。然后,在终端滑模面基础上,提出了一种基于自适应径向基神经网络估计的终端滑模控制律。利用自适应参数的神经网络逼近系统参数并提高抗干扰性能,采用平滑连续控制策略消除了终端滑模中的颤动现象。通过李雅普诺夫的分析方法证明了闭环系统的收敛性和全局稳定性。采用数值仿真,验证了提出的基于自适应径向基神经网络的终端滑模控制律具有较好的跟踪性能和精度。     

F-22战斗机管理创新研究

F-22项目是一个典型的国防武器采办项目,其管理工具和方法确保了F-22项目能够成为有序的、管理良好的项目并取得成功.本文主要介绍了F-22项目的团队组成及职责、阶段划分及任务管理、创新管理和存在的问题等,以期能为我国武器装备项目管理提供一些有益的参考,促进我国武器装备事业的发展.     

汽车车速传感器的电磁兼容设计

电磁兼容性作为汽车电器可靠性参数日益受到重视。针对汽车车速传感器所面临的电磁兼容问题提出了一种设计方案,应用该方案的车速传感器电磁兼容性测试结果符合速度传感器通用技术条件的整体误差标准,并在实际应用中获得了预期的效果。该电磁兼容设计方案对汽车中其他电子设备的电磁兼容性设计同样具有参考意义。     

航天软件中多重中断程序的动态检测方法研究

随着控制系统软硬件平台的设计复杂度不断增加,特别是飞行控制系统中集成的传感器不断增多,中断数量也随之不断增加.本文根据飞控系统的具体特点,使用标记迁移系统对多重中断并发程序进行建模,提出了原子性违背和数据竞争的形式化描述,运用动态偏序化简算法对程序的状态空间进行化简,并设计实现了多重中断控制系统程序的动态检测工具,实验结果表明该检测算法可以在满足对多重中断并发程序错误检测的基础上,大大的缩短检测时间.