排序方式： 共有26条查询结果，搜索用时 228 毫秒
1.
SAR图像舰船尾迹检测不仅能够反演运动舰船的航速航向信息，也有助于发现图像中弱小的舰船目标。现有的舰船尾迹检测方法对于简单背景SAR图像的检测效果较好，但复杂背景下的检测效果难以满足使用要求。提出一种基于能量泛函极小化的复杂背景SAR图像舰船尾迹检测方法。该方法采用相对全变分技术将图像分解为包含舰船尾迹的光滑成分和海背景纹理成分，通过剪切波变换高频系数重构增强光滑成分，再通过Radon变换检测光滑成分中的尾迹线。比对实验结果表明，本文所提方法对于复杂背景SAR图像的舰船尾迹检测效果明显优于现有的方法。 相似文献
2.
Steffen Pacholak Stefan Hochstein Alexander Rudert Christoph Brücker 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(2):176-194
The undulatory underwater sequence is one of the most important phases in competitive swimming. An understanding of the recurrent vortex dynamics around the human body and their generation could therefore be used to improve swimming techniques. In order to produce a dynamic model, we applied human joint kinematics to three-dimensional (3D) body scans of a female swimmer. The flow around this dynamic model was then calculated using computational fluid dynamics with the aid of moving 3D meshes. Evaluation of the numerical results delivered by the various motion cycles identified characteristic vortex structures for each of the cycles, which exhibited increasing intensity and drag influence. At maximum thrust, drag forces appear to be 12 times higher than those of a passive gliding swimmer. As far as we know, this is the first disclosure of vortex rings merging into vortex tubes in the wake after vortex recapturing. All unsteady structures were visualized using a modified Q-criterion also incorporated into our methods. At the very least, our approach is likely to be suited to further studies examining swimmers engaging in undulatory swimming during training or competition. 相似文献
3.
4.
To find out the detailed characteristics of the coherent structures and associated particle dispersion in free shear flow, large eddy simulation method was adopted to investigate a two-dimensional particle-laden wake flow. The well-known Sub-grid Scale mode introduced by Smagorinsky was employed to simulate the gas flow field and Lagrangian approach was used to trace the particles. The results showed that the typical large-scale vortex structures exhibit a stable counter rotating arrangement of opposite sign, and alternately form from the near wall region, shed and move towards the downstream positions of the wake with the development of the flow. For particle dispersion, the Stokes number of particles is a key parameter. At the Stokes numbers of 1.4 and 3.8 the particles concentrate highly in the outer boundary regions. While the particles congregate densely in the vortex core regions at the Stokes number of 0.15, and the particles at Stokes number of 15 assemble in the vortex braid regions and the rib regions between the adjoining vortex structures. 相似文献
5.
彭晓东 《内江师范学院学报》2006,21(2):63-65
主要介绍了远程唤醒技术及其在机房管理中的应用,包括远程唤醒技术的基本原理、实现远程唤醒所需的软硬件条件及对系统所需的基本设置。并给出了一个基于de lph i的远程唤醒程序的主要代码。 相似文献
6.
以Iwan改进的尾流振子模型为基础,给出了剪切流中水中悬浮隧道锚索横向涡激振动的工程分析方法,分析了悬浮隧道重浮比以及剪切流特性对锚索涡激响应的影响。计算结果表明,悬浮隧道重浮比的改变,使锚索各阶模态的频锁区域分布发生变化,从而改变了结构的涡激振动响应;剪切流陡度参数的增大会使锚索涡激响应的幅值减小,若使用均匀流场代替剪切流场计算悬浮隧道锚索的涡激振动,会过高估计其响应幅值。 相似文献
7.
田显忠 《牡丹江教育学院学报》2010,(1):3-4
作为中国现代文学史上第一篇现代白话短篇小说,《狂人日记》塑造的狂人形象是一个多种形象的复合体：是患病者,是怀疑者,是发现者,也是批判者。与狂人形象所具有的丰富内涵相一致,小说也同样有着深厚的主题意蕴,其中饱含着希望与绝望的矛盾交织,绝望而又反抗绝望的倔强与坚持。 相似文献
8.
针对空中编队的尾流规避问题进行研究,分析尾流的成因和特性,介绍大编队飞行中规避尾流的几种方法,并对误入尾流后的判断和特情处置方法进行详细的说明. 相似文献
9.
10.
射箭实时反馈系统在实际训练中应用的研究 总被引：1，自引：0，他引：1
旨在研究改装过的射箭实时反馈系统在实际训练中的应用,通过对"八一"队五名健将级运动员瞄准时尾迹的长度、尾迹的上下、左右的晃动,击发前不同时刻的瞄准轨迹的上下、左右晃动,上靶方向等参数进行了比较分析、研究,以最直观、最简单和最快的速度对运动员现场进行反馈.这些指标和参数不但可以衡量每一只箭的好坏,而且可以作为队员个人的纵向比较和队员之间的横向比较资料,为射箭的训练提供了科学的依据. 相似文献