排序方式: 共有66条查询结果,搜索用时 62 毫秒
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K-shell X-ray emission from a Cu nanowire target irradiated by an ultraintense femtosecond laser pulse is studied using an elliptically bent quartz crystal and imaging plate. The designed bent crystal spectrometer has better spectral resolution, which is higher than 1 000. The absolute Kα radiation photon yields are obtained from the experimental results and the Monte-Carlo model. The conversion efficiency of the Cu Kα line is estimated to be 0.019% from the interaction of 4 J, 50-fs laser pulse irradiated on a Cu nanowire target. The high yield of K shell X-ray has important applications in X-ray emission source. 相似文献
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王文涛 《高校应用数学学报(A辑)》2009,24(4)
基于B网扰动和约束优化方法,对n次C-Bézier曲线控制多边形顶点进行扰动,并找到其退化为n-1次次C-Bézier曲线的条件.在满足退化条件的约束下,使n次C-Bézier曲线控制多边形顶点扰动量最小,由此找到降阶为n-1次的C-Bézier曲线,同时也研究了在C~0,C~1连续条件下对n次C-Bézier曲线降阶的B网扰动和约束优化方法.给出了扰动显示格式计算方法和降阶逼近的误差估计式. 相似文献
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Beam quality degradation during the transition from a laser wakefield accelerator to the vacuum is one of the reasons that cause the beam transport distortion, which hinders the way to compact free-electron-lasers. Here,we performed transition simulation to initialize the beam parameters for beam optics transport. This initialization was crucial in matching the experimental results and the designed evolution of the beamline. We experimentally characterized properties of high-quality laser-wakefield-accelerated electron beams, such as transverse beam profile, divergence, and directionality after long-distance transport. By installing magnetic quadrupole lenses with tailored strength gradients, we successfully collimated the electron beams with tunable energies from 200 to 600 MeV. 相似文献
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2011年高考安徽卷的一道选择题,原题如下.
题目:一质量为m的物块恰好在倾角为θ的斜面上.现对物块施加一个竖直向下的恒力F,如图1所示.则物块
A.仍处于静止状态
B.沿斜面加速下滑
C.受到的摩擦力不变
D.受到的合外力增大
本题考查了物体的平衡,主要考查学生的理解能力和推理能力.实际上,我们也可以从另外一个角度去审视此题,即自锁现象.自锁现象是力学中的一种特有现象,当自锁条件满足时,无论施以多大的力都不可能让一个物体与另一个物体之间发生相对运动.
本文详细阐述了水平面、竖直平面和斜面上的三类自锁现象,以及这种现象在生产和生活中的应用. 相似文献
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高能激光光束质量β因子测量装置主要用于强激光系统状态调试和综合性能参数诊断,用于评价激光系统出光性能以及远场光斑可聚焦的能力。针对接近衍射极限光束质量β因子测量过程中被测光斑在面阵相机上所占的像素点太少等缺陷,研究了采用聚焦显微放大与高精度扫描狭缝相结合的光束质量β因子测量方法,并对相关方案进行了分析计算。此外还设计了采用固定像差元件及平行光管光源组合的激光光束质量β因子测量结果验证方案,对研制的高能激光光束质量β因子测量装置进行了不确定度分析,测量不确定度优于10%。 相似文献
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