28 resultados para 33-318


Relevância:

20.00% 20.00%

Publicador:

Resumo:

对低雷诺数旋转振动圆柱绕流问题运用低维Galerkin方法将N-S方程约化为一组非线 性常微分方程组.运用打靶法数值求解了这组方程的周期解,并用 Floquet理论对周期解的稳 定性进行了分析,研究了流动失稳的机制.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

介绍了一种基于3×3和2×2光纤耦合器构成的非平衡马赫-曾德尔干涉仪的波长解调方案。理论分析和数据对比表明,相对于由两个2×2光纤耦合器构成的马赫-曾德尔干涉仪,本干涉仪具有宽谱的灵敏度、能跟踪波长的变化方向和相位展开的优点,实验方案用于测量固定在悬臂梁上的传感光纤布拉格光栅(FBG)的峰值波长变化,获得了±1pm的静态波长解调精度,在10Hz处的动态分辨率为27nε/√Hz。相位展开算法使得应变测量范围达到了2014με,对应的相位变化为3.22π。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The early life-history of Chinese rock carp Procypris rabaudi was investigated during a 56-day rearing period: 318 artificially propagated P. rabaudi larvae were reared throughout metamorphosis in a small-scale recirculation system (345 L water volume, 10 x 18 L rearing tanks, 150 L storage and filter compartment with bioballs, 20-30 larvae L-1) at the Institute of Hydrobiology, Wuhan, Hubei Province, China. The newly hatched larvae had an initial total length of 8.93 +/- 0.35 mm SD (n = 10) at 3 days post-hatch and reached an average total length of 33.29 mm (+/- 1.88 mm SD, n = 10) 56 days after hatching. Length increment averaged 0.45 mm day(-1), resulting in a mean growth of 24.4 mm within the 56-day period. High mortality rates of up to 92% derived from an introduced fungus infection and subsequent treatment stress with malachite green. Our results indicate that Chinese rock carp can be raised successfully from artificially fertilized eggs. We therefore assume this species to be a candidate for commercial aquaculture.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

本发明公开了一种基于3×3耦合器两路输出的波长解调系统及方法,系统包括:高通滤波模块,对接收自3×3耦合器的任意两路干涉条纹进行高通滤波,滤去直流项后得到两路输出信号;乘法交叉相减模块,对两路信号进行乘法交叉相减,得到包含信号的正弦项和余弦项;微分平方相加模块,对信号进行消去包含信号的正弦和余弦项,得到信号微分的平方项;开方判断正负模块,对信号微分的平方项进行开根号运算,然后再对得到的结果进行正负的判断,得到信号的微分项;中值滤波积分模块,对信号的微分项进行中值滤波,滤去坏点后再经过积分器积分,得到最后的解调结果。本发明具有精度高,动态范围大,成本低,算法简单,容易实现组网的优点。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

国家863计划(2007AA03Z415)

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

研究了基于3×3耦合器的非平衡迈克耳孙干涉仪的相位特性。由光纤耦合器的散射矩阵理论,推导出了当3×3耦合器分光比不均匀时,干涉仪三路输出信号相位差的表达式。根据实际使用的3×3耦合器各通道的插入损耗,经计算与修正得到其散射矩阵,并求出干涉仪三路输出信号的相位差分别为120.21°、120.77°和119.02°,与理想值120°的偏差在1°以内。实验测得的干涉仪三路输出信号的相位差随时间随机变化,经分析是由光偏振态随机变化引起的。相位差与理想值120°的偏离均在1°以内,符合理论分析得到的结论。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

采用3×3耦合器的光纤光栅激光传感系统(FBGLS)的波长解调结果依赖于3×3耦合器的物理特性,解调结果会因3×3耦合器三路输出的直流项、干涉条纹可见度和相位差参数的不稳定而发生一定程度的失真。理论推导给出了标定参数的方法并实现了计算机编程,能够在较大信号时实时给出标定结果,同时给出了相应的解调方案。计算机模拟发现采用上述方法消除了由3×3耦合器三路输出的参数不稳定带来的谐波,实验中解调结果的对比表明该方法带来一定程度的改善,和标准参考传感器测量结果有很高的相关性,此外基于该解调方案的光纤光栅激光传感系统具有较高的分辨率、动态范围和线性度。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Continuous wave operation of a semiconductor laser diode based on five stacks of InAs quantum dots (QDs) embedded within strained InGaAs quantum wells as an active region is demonstrated. At room temperature, 355-mW output power at ground state of 1.33-1.35 microns for a 20-micron ridge-waveguide laser without facet coating is achieved. By optimizing the molecular beam epitaxy (MBE) growth conditions, the QD density per layer is raised to 4*10^(10) cm^(-2). The laser keeps lasing at ground state until the temperature reaches 65 Celsius degree.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

于2010-11-23批量导入

Relevância:

20.00% 20.00%

Publicador:

Resumo:

在不同角度测得的 33 4MeV/u17N +9Be反应中 ,发射中子的能谱具有复杂的形式 ,而且随着角度的增大显示出有规律的变化 发射中子至少来源于靶弹核间的核子 -核子碰撞、17N的破裂反应以及熔合热核的统计蒸发三种不同起源 分析结果表明 :反应体系三种起源的发射中子截面分别为 4 4 9,0 4 4和 5 5b