关键

For the realization of Chinas railway technology and equipment modernization, to achieve the introduction, digestion, absorption and innovation of key technologies and parts, in this paper, the high-strength aluminum alloy used for axle box of high-speed train is studied as research background.

为实现中国铁路技术装备现代化以及对关键技术及关键零部件的引进、消化吸收、再创新，本文以高速列车轴箱体用高强度铝合金为研究背景，开展应用于我国铁道车辆关键零部件的高强度铸造铝合金的研究。

Video abstraction are composed of the shot key fames according to the time order.

然后对候选关键帧按照相邻帧间交互信息量的比较来提取镜头关键帧，最后将镜头关键帧按时序排列在一起形成视频摘要。

To choose a key is easy; to choose a strong key is a bit harder; to remember such a key is the hardest thing.

要选择的关键是容易，选择一个强大的，关键是有些困难，要记住这样一个关键是最难thing。

Accordingly, an optimistic data consistency maintenance method based on key-attributes is proposed. In the method, the update of key-attributes is separated from user update requests. Key-Updates are propagated by latency-overlay update propagation model, that is, updates are always propagated to the nodes having maximum or minimum latency, and assured and uncertain propagation paths of updates are all taken into account. Based on classifying key-update conflicts, a double-level reconciling mechanism including buffer preprocessing and update-log processing is applied to detect and reconcile conflicts, and then conflicts are solved by policies as last-writer-win and divide-and-rule. Lastly, update-log management method and maintenance method brought by node failure and network partitioning are discussed for the above is deployed based on the information storied in update-log.

在该方法中，首先分离出用户提交的更新请求中关于关键属性的更新；然后采用基于延迟-覆盖的更新传播模型进行更新传播，即基于副本间的网络延迟选择具有最大和最小网络延迟的结点转发更新，并在传播过程中记录和综合考虑更新的确定传播和不确定传播两条路径；在对关键更新冲突分类的基础上，采用更新缓冲区和更新日志两层更新协商机制并结合最新写胜出和分而治之规则，优化关键更新冲突的发现和解决；更新日志信息是方法中各种策略开展的基础，讨论了更新日志中信息管理方法以及结点失效和网络划分发生时信息的维护方法。

Perhaps, the heart of youth is readily inattentive; perhaps it cannot anticipate the finale, but since we have fixed our targets, we don't need to appreciate the transient night-blooming cereus along the road to our goals.

也许当我们站立在生命的关键时刻，蓦然回首，我们会发现人生路上关键的只有几步，这关键的几步也因为凝聚了老师的段段师长情和父母的拳拳爱子心而显得那么沉重，然而这份沉重是人生路上辉煌的顿挫，生命因此而显得波澜壮阔，意志也由此而变得坚韧不拔，也许此时的我们才开始学会走路，才开始学会生活。

The Key At Time option opens a Key at Time dialog box figure 19, which lets you set one or more keyframes for the selected properties at any point in time, regardless of the current time.

时间关键帧选项会打开一个当前关键帧对话框（图19），它让你为被选择的属性在任何时间点设置一个或多个关键帧，而不管当前时间。

Department of Neurological Surgery and the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA.

然而，那些移植的细胞接着在某一较后的时间开始了一个新的关键期，且该关键期与植入的年龄不一致的神经元的关键期相一致。

The former firstly establishes state graph of power system, and then, with the use of the adjacency matrix and path matrix of the directed graph, fast finds out the key transmission sections suffering greatly from the outages of overload lines through simple calculation of matrix.

前者根据实时网络拓扑结构和潮流分布状态，在对初始电力网络简化、分区的基础上，利用有向图的邻接矩阵与路径矩阵，通过简单的矩阵运算，快速识别出与过载线路相关的关键输电断面；后者直接利用系统各支路的阻抗，从图论算法的基本思想出发，搜索最易遭受大负荷转移的关键传输路径，从而将安全性分析目标从整个网络缩小到某些关键的输电线路。

The former firstly establishes state graph of power system, and then, with the use of the adjacency matrix and path matrix of the directed graph, fast finds out the key transmission sections suffered greatly from the outages of overload lines through simple calculation of matrix. In the latter, the minimal short transmission path, the length of which is calculated with line impedance, is determined with graph theory to focus on security analysis objects from the whole network to some key transmission lines.

前者根据实时网络拓扑结构和潮流分布状态，在对初始电力网络简化、分区的基础上，利用有向图的邻接矩阵与路径矩阵，通过简单的矩阵运算，快速识别出与过载线路相关的关键输电断面；后者直接利用系统各支路的阻抗，从图论算法的基本思想出发，搜索最易遭受大负荷转移的关键传输路径，从而将安全性分析目标从整个网络缩小到某些关键的输电线路。

The research work presented in this dissertation focused on developing the scheme and techniques of OPCPA. This dissertation gives the results of the theoretical and experimental investigation on OPCPA scheme. The validation of OPCPA at high energy level was demonstrated successfully. And some important results were achieved. Several key techniques related to developing table-top ultra-intense and ultra-short OPCPA laser system were put forward, for example, the generation of femtosecond seeding pulses, the precisely temporal synchronization of the pump and signal pulses, the pulse stretching and recompression, the OPCPA process with high energy conversion efficiency and etc. Based on the integration of these key techniques, a 1.46-TW/153-fs OPCPA table-top ultra-intense and ultra-high laser system has been developed, which, to the best of our knowledge, has generated laser pulses with the shortest pulse duration and the highest peak power among the joule level OPCPA systems in the world.

本学位论文工作主要是瞄准 OPCPA 这一国际上提出不久并处于初级阶段的新概念，重点开展了 OPCPA 新原理的理论模拟、实验验证，以及基于 OPCPA 新原理的小型化超强超短激光系统的研究与发展，创造性地解决关键科学技术问题，建立并发展相关关键科学技术，如超短脉冲种子源的产生、小型化强激光泵浦源的研制及其脉冲的整形、信号光与泵浦光的精确同步、高效率光学参量放大及高保真脉冲展宽与压缩等关键技术，并在单元技术的总体集成方面取得了重大创新性进展与突破性研究成果，获得了国际上高量级泵浦条件下 OPCPA 激光研究中峰值输出功率最高且脉冲宽度最短的总体领先结果。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷