The Mechanical Behaviour of Polyimide/Copper Laminates Part 2: Peel Energy Measurements

The mechanical peel behaviour of laminates consisting of polyimide films adhered to copper foil using a modified acrylic adhesive has been studied over a wide range of test rates and temperatures. The laminates were prepared from polyimide films which had been subjected to either a “high-thermal history” or a “low-thermal history” treatment during the production of the film. The measured peel energies of the laminates could be superimposed to give a master curve of peel energy versus the reduced rate of peel test, Ra_T, where R is the rate of peel test and a_T is the time-temperature shift factor. The appropriate shift factors were a function of the test temperature and were mainly deduced from tensile tests conducted on the bulk adhesive. The “high-thermal history” laminates gave higher peel energies and the locus of failure of the laminates was mainly by cohesive fracture through the adhesive layer. At low values of log₁₀ Ra_T, i.e. Low rates of peel and high test temperatures, the “low-thermal history” laminates also failed in the adhesive layer and possessed similar peel energies to those measured for the “high-thermal history” laminates. However, at high log₁₀ Ra_T values, the peel energies measured for the “low-thermal history” laminates were lower and showed a wider scatter. These arose from a different locus of failure occurring in these “low-thermal history” laminates when tested under these conditions. Namely, it was found that most of these laminates failed in a weak boundary layer in the outer regions of the “low-thermal history” polyimide film.     

Failure to diverge in African Great Lakes: The case of Dolicirroplectanum lacustre gen. nov. comb. nov. (Monogenea,Diplectanidae) infecting latid hosts

Speciation of fish in the African Great Lakes has been widely studied. Surprisingly, extensive speciation in parasites was only recently discovered in these biodiversity hotspots, notably in monogeneans (Platyhelminthes) from Lake Tanganyika. Diplectanum is a monogenean genus of which only a single species is known from the Great Lakes: Diplectanum lacustre (Diplectanidae) living on lates perches (Latidae) of Lake Albert. Despite their primary marine origin, latids have diversified in African freshwaters including several Great Lakes. In better-studied marine diplectanid species, incongruence between morphological and genetic differentiation was documented. As freshwater systems provide more opportunities for speciation than the marine realm, we ask whether diplectanids of Lates spp. of the Great Lakes underwent similar diversification as their hosts. Fresh and museum specimens of five African latid species (Lates angustifrons, L. mariae, L. microlepis, L. niloticus, L. stappersii) were examined for the presence of monogenean gill parasites. Monogeneans were characterised morphologically via morphometrics of sclerotised structures and genetically using nuclear and mitochondrial markers. Continuous morphological variation was documented in these parasites. In addition, the genetic distance, based on the COI region, between parasites of geographically isolated host species did not reach the level typically associated with distinct diplectanid species. Therefore, a single species of a newly described genus, Dolicirroplectanum lacustre gen. nov. comb. nov. is suggested to infect latid species in the examined basins. We discuss this parasite’s failure to diverge in the light of the congruence between the rate of molecular evolution in COI and host historical distribution.     

移动列车作用下大直径顶管群和路基的动力变形和应力

大直径顶管下穿重要铁路干线时,路基的承载力和动力特性必将发生改变,铁路部门要求列车运行时顶管上方竖向动位移与顶管施工前相比变化量≤5 mm。对列车驶过顶管群上方铁路的过程进行了数值模拟,给出路基瞬时竖向位移和顶管附加动应力等结果。采用三维有限元Newmark动力时程分析法和seed等效线性法模拟路基的振动软化,按照实际工程考虑6根直径4.7 m的顶管群下穿京沪铁路,计算列车速度分别为100,200 km/h。计算结果表明,在管道埋深12 m时,路基最大竖向动位移增加1.3 mm,顶管受到的附加拉(压)动应力为0.14 MPa左右,顶管群对铁路运行的影响在容许范围内。     

SFT中的因素作用路径与作用历史

为了描述SFT中系统或元件在不同工作环境状态下经历变化的特征,提出了因素作用路径和作用历史的概念。作用路径描述系统或元件在不同工作状态变化过程中所经历状态的集合。作用历史描述经历作用路径过程中的可积累状态量。给出使用作用路径和作用历史分析问题的步骤。列举一例子,计算在设定条件下的元件维护成本。计算作用路径分别为AB和ACB两种,作用历史中使元件故障概率等于20%的维护成本,该维护成本是通过调整使用时间t和使用温度c产生的。最后给出以实例为背景的作用历史计算方法的不足、面临的问题和可能的解决方法。     

史学讲座与职校学生人文素质的提高

职校学生由于受到多方面因素的影响,在思想上普遍存在"四缺"现象,而长期的应试教育造成学生人文素质降低是其重要原因,因此,人文素质教育必须成为职业教育的重要内容之一。历史学讲座以其轻松的氛围、灵活的选题、广大的受众、特殊的教师队伍,既可以补充职校学生史学知识常识的不足,而且是提高学生人文素质的有效渠道之一。     

青岛市即墨鳌山卫镇的历史文化资源保护策略

在城市化快速发展的今天,很多普通小城镇的历史文化被漠视,城镇建设缺少地方特色,造成人文资源、自然资源的破坏.在鳌山卫镇快速建设的今天,亟待一套完整、科学的历史文化保护策略,以缓解城镇历史文化的延续与新城镇建设之间的矛盾,实现城镇建设的可持续发展.     

更宽泛时空视角下的美国城市变迁史

跳出美国200多年的历史和美国本土的空间范围,以更长的历史视角与更宽泛的空间视角对这美国城市变迁过程进行分析.从15世纪资本主义萌芽从欧洲诞生起,资本作用从欧洲热那亚地区扩展到整个欧洲国家,再通过英帝国的殖民地扩张,发展到北美大陆;而二战后的布雷顿森林体系则奏响了资本全球化的前奏.美国早期城市人口的集中背后的动力是资本不断积累的历史过程.二战后所谓的"郊区化"同样伴随着资本的力量在全球的扩张.在全球范围内,资本生产过程中对环境破坏与污染的问题并没有得到解决,只是通过跨国公司在全球的生产链分工,从美国转移到了亟需资本投资的第三世界国家中.     

“天下”观与秦皇汉武时代的美术史——《秦始皇至汉武帝时代对“天下”观念的视觉艺术形塑》导论

本文从东周至秦汉中期政治与社会转型的视角出发,在细致回顾与评析学界对＂天下＂观念进行研究的基础上,从美术史视角通过分析这一时期衍生的带有皇权建构与空间表现特征的美术材料,从而提出对该课题进行重新研讨的可行性。     

民国词中的圆明园镜像

自1860年至1900年,圆明园两次遭受入侵外敌的毁坏。历尽劫难的圆明园,在民国时期,成了民国词人文学创作的表现题材。民国词人将自己游览圆明园时的所见所闻、所思、所感,运用多种艺术手法加以表现。这些呈现在民国词中的圆明园镜像,体现了民国词人对历史与社会变迁的关注,丰富了词的情感内涵,具有重要的词史意义。     

考虑扭转效应的平面不规则大底盘单塔楼减震性能分析

对平面不规则大底盘单塔楼进行隔震分析,分别将层间隔震支座及基础隔震支座应用于此类结构,分别建立层间隔震及基础隔震以及传统的抗震结构模型,利用有限元软件SAP2000对某单塔楼结构在罕遇地震作用下进行动力时程分析.通过楼层剪力,层间位移以及楼层加速度对比,表明采用隔震装置结构的减震效果明显,同时表明由结构平面布置不规则所导致的扭转效应引起我们高度重视.