基于小波包能量谱的管道缺陷磁记忆检测信号特征研究

现有磁记忆检测技术判定准则,只能指示应力集中位置,无法进一步获取应力集中信息。为获取应力集中信息,提出一种基于小波包能量谱的磁记忆信号分析方法,进行试件拉伸试验。拉伸应力为200 MPa时,信号小波包能量谱分布较为均匀,各频带能量占总能量之比均小于15%,不存在集中分布的频带范围。拉伸应力为410 MPa时,信号小波包能量谱最大值分布在1,3,4频带,1~4频带能量之和占总能量的73.8%,小波包能量主要集中在低频段。试件屈服后,信号小波包能量谱最大值分布在1,2频带,能量谱分布极为分散,能量主要集中在低频段的1,2频带,1~3频带能量之和占总能量的87.3%。管道试件应力集中程度与磁记忆信号的小波包能量谱分布特征有关,应力集中程度越低,小波包能量谱分布越均匀;应力集中程度越高,小波包能量谱分布越集中,能量主要向低频段集中。     

战时装备保障过程建模仿真研究

目前战时装备保障方案制定,多是依靠基本原则和经验,过程描述随意性大,同时保障活动的组织缺乏有效的手段,导致方案缺乏科学性、可操作性差。为此借鉴过程管理的思想,应用IDEF3方法建立装备保障准备阶段过程模型,形成规范的、易于交流的保障流程,依据过程模型采用离散事件仿真的方法对不同活动组合的过程效率进行了分析,改变以往根据排队理论经过大量计算分析效率的方式,实现战时快速准确优化过程的目的,为装备保障方案的形成提供方法支持。     

Holmes’ front: constructing a new face of battle for America’s Civil War

ABSTRACT

In his seminal study of the changing nature of warfare between Agincourt and the Somme, military historian John Keegan proposed that future historians might consider combatants’ emotions in their assessments of the impact and nature of conflict. Recent years have witnessed the emergence of the history of emotions as an analytical approach, but rarely, if ever, is this directed toward the study of military history, far less the history of insurgencies and counter-insurgencies. This paper examines America’s civil war (1861–1865) as a case study of the ways in which an emotional history approach might illuminate not the physical experiences of but rather the immediate and longer-term reactions to counter-insurgency conflict through a focus on one specific individual, the future Supreme Court Justice Oliver Wendell Holmes, Jr. It proposes that Holmes, whilst not a man of the ranks, nevertheless can reveal the wider ramifications of civil war and its emotional impact, both individually and culturally. As a relatively limited internecine war, one not fought by professional armies but by volunteer forces, America’s civil war highlights the ways in which the soldier’s response points us toward the kind of emotional revolution that has, to date, mainly been located within the European nations.