共查询到20条相似文献,搜索用时 718 毫秒
1.
1989年是照片诞生后的第150周年.自从第一次将光影与化学结合起来用于从大自然中获得永恒的图片后,自然风光摄影就倍受争议.不管怎样,无论艺术还是科学,技艺还是职业,摄影都是产生于客观性与选择性之间,创造性与现实性之上的一种档案媒介.在最新的一次统计后,国家档案馆现今保存有1500万以上的照片档案.不管是百年前拍摄的还是上个星期刚刚拍摄的,照片所要传递出的要素通常是些非常独特的信息.无论照片、底片和幻灯片,是黑白的还是彩色的,无论旧与新,不管是退色了的还是色彩艳丽的,单独的还是成集合的,最为关键的是它们都见证了加拿大历史与社会的发展与兴衰. 相似文献
2.
3.
中国电影资料馆珍藏着大量早期影片,其中许多具有珍贵的保存价值.1936年由蔡楚生编导、任光谱曲的<迷途的羔羊>是我国第一部以流浪儿童为题材的影片,也是我国儿童影片中的第一部有声片.此片在思想和艺术上都取得了突破,尤其是以童谣形式演唱的主题歌<月光光歌>感人至深,充分发挥了音乐的魅力,增强了整部影片的感染力.影片公映后,深受广大观众的欢迎和电影工作者的赞扬.七十多年过去了,当我们准备再次让它同观众见面时,却发现能够最真实、最原始记录影音效果的原底、声底片却出现了许多问题,给复制工作带来了空前的难度,这是我们从事资料影片复制工作三十多年来从未遇到过的难题.主要有以下几方面问题: 相似文献
4.
5.
通过加热碳纳米管和强酸的混合物,使碳纳米管的憎水表面发生氧化.加热含经处理的碳纳米管的悬浮液,使之脱水,得到自组装的碳纳米管圆片,该圆片可直接分散.扫描电镜图显示该圆片由局部规则排列的碳纳米管构成;红外光谱和光电子谱分析表明在化学处理过程中,碳纳米管的表面产生了含氧官能团;虽然拉曼谱测出处理过程增加了缺陷,但是X射线衍射结果表明碳纳米管类似石墨的层状结构得到保留;同时研究了经处理的碳纳米管的热稳定性.这种自组装且可分散的碳纳米管圆片为研究碳纳米管结构材料和碳纳米管复合材料提供了有效途径. 相似文献
6.
钢琴被称为乐器之王,可以演奏出美妙的音乐,这种有键盘的乐器,似乎比别的乐器都好学,任何人都可以从上面摸出音阶来,它的音律准确,声音悦耳,绝不像初学小提琴者在琴上"锯"出来的声音难听又不准.但是要在钢琴上得心应手地弹奏出好听乐曲,绝不是一件简单的事.仅仅当一个一般水平的专业演奏者,就需要投入大量的劳动,有人估计以每天7小时的练习时间计,他需要10年.而且只有大量的练习还是不够的,同时还需要科学的演奏法.…… 相似文献
7.
8.
9.
10.
11.
12.
13.
14.
J. J. MARAIS K. C. MISTRY 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(10):931-938
This paper discusses the monitoring of the condition of the OREX ore export line rails in South Africa. Ultrasonic testing is widely used to monitor defect development and growth as well as to plan and manage programs to ensure a high level of rail integrity. An overview of the performance and history of the line is given in terms of rail defect levels and derailments due to rail failures in relation to traffic volumes. Some of the inherent characteristics of the rails are discussed and related to the defect development. From the available data it is clear that the rails are degrading in a ‘wear‐out mode’, with increasing defect rates. The use of high technology ultrasonic testing equipment has enhanced the level of knowledge of the condition of the rails tremendously and has led to programs that actually improved the overall condition of the line and eliminated derailments due to rail defects. 相似文献
15.
樊玲 《制冷与空调(四川)》2004,18(2):61-63
本文讨论了进口轻轨车辆应用于我国轻轨系统时,由于气候条件的不同,车载空调系统冷负荷不能满足要求时,乘客的舒适性感觉.提出了在此种不利情况下的一些改善措施. 相似文献
16.
Anjum Naweed Mark S. Young Jeanette Aitken 《Theoretical Issues in Ergonomics Science》2013,14(6):731-762
AbstractThe last 15?years has witnessed a surge in rail-related human factors research but little has examined the Track Worker role. Track work often takes place whilst trains are running under the protection of Lookouts who provide warning of approaching trains. Despite—or perhaps because of—these measures, there is a notable prevalence of incidents involving Lookouts, warranting a closer look at the nature of their task and the wider sociotechnical system (STS) to identify what may be learned for railway safety management. A systematic review of incident reports involving Lookouts was undertaken on Australian and UK rail incidents from 2006 to mid-2018 with a qualitative meta-analysis (n?=?31) revealing nine factors corresponding with STS dimensions at the organisational, social, task and individual level. Much of the risk lay in the set up and implementation of Lookout working, and in Track Worker group dynamics—factors endemic to working whilst trains are running—rather than specific to the Lookout, with such factors arguably applicable across other Track Worker groups. Findings point to a need for more targeted research into the STS aspects of track working, as well as improving the training and/or procedures of those managing the Lookout protection system of work. 相似文献
17.
通过对轨道交通噪声源的分析,结合我国现状,降低轮轨噪声是轨道交通减振降噪的关键.从声源的控制,隔振,吸振三方面着手,提出轨道结构方面的减振措施. 相似文献
18.
19.
某城际高速铁路开通运营仅约半年,使用的U71MnG60kg/m热轧钢轨在某车站列车进站端的半径为600m的一曲线路段上随机出现多处严重轨头踏面掉块伤损。经对钢轨伤损状态的分析以及化学成分分析、拉伸性能测试和金相检验对掉块伤损的原因进行了分析。结果表明:钢轨轨头踏面的掉块伤损是由其表层的马氏体组织造成,而马氏体组织的产生则是因列车车轮对钢轨的严重摩擦所引起的。 相似文献
20.
Information is provided about a new device for measuring the wave-like wear of railway rails. 相似文献