共查询到20条相似文献,搜索用时 78 毫秒
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讨论了用绳拉船靠岸的速度,介绍和比较了两种求解方法:微分求导数和速度合成与分解法,提供并较详细分析了第三种求解方法:作功和能量方法,阐述了第四种求解方法:几何学方法,提出了两个值得认真思考和讨论的问题 相似文献
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本文给出了气体分子方均根速率求解的三种方法,论述了查表法和Γ函数法的根据,特别是用分部积分法和物理条件求得了解答,与目前采用的方法相比,这样求解,不仅方法简单,适合学生的数学基础,而且突出了物理意义. 相似文献
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利用级数展开的Z扫描理论分析 总被引:6,自引:0,他引:6
利用级数展开的方法,对薄介质的Z扫描理论进行了分析,并对于通常所采用的级数展开和菲涅耳衍射分析方法进行了讨论,证明了在分析利用高斯光束对薄介质进行Z扫描测量时,即使对于大的非线性相移,高斯分解方法和菲涅耳衍射积分方法仍具有等效性,澄清了人们认识上的一些误解。同时分析了远场小孔的归一化透射率与积分限的关系,并对采用高斯分解方法时级数求和的振荡原因进行了分析和讨论,给出了消除振荡所需的最小求和数的判据。针对高斯分解方法和菲涅耳衍射积分方法的使用场合,也进行了讨论。根据所得结论,可以在具体的实验和理论分析中,正确地选择更高效的分析方法。 相似文献
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在流形元的基础上,提出了非协调数值流形方法,非协调数值流形方法的优点是在不增加广义节点自由度的前提下,大大提高数值流形方法的计算精度和计算效率.利用内部自由度静力凝聚处理,推导了消除内参后的单元应变矩阵和单元刚度矩阵.在Hilbert空间内,从最小势能原理出发对非协调数值流形方法的稳定性和收敛性进行了分析和讨论,得到了保证非协调流形元解唯一存在和收敛的基本条件,完善了非协调数值流形方法的理论基础.数值试验表明,新单元构造过程简单,有较高的精度,从而证明了本方法的可行性. 相似文献
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介绍了在酿酒工业陈化过程中所用到的八种物理学方法,它们是静电,磁场,红外线,微波,X射线,γ射线,光学和电子综合催陈方法,并对每种方法的工作原理,使用条件设备和效果简单地作了介绍。 相似文献
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本文介绍了激光滋共振光谱方法近几年来的新发展,其中包括实验系统的改进,以及采用磁旋转方法、双调制方法、双共振方法和时间分辨方法的激光磁共振新技术.用这些方法对许多自由基分子、离子分子和激发态分子作了测量,同时也介绍了它们的一些应用. 相似文献
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自加热式铜蒸气激光器的热气体透镜研究 总被引:1,自引:1,他引:0
本文分析了自加热式铜蒸气激光器放电管内的热气体透镜效应,并指出不同的铜蒸气激光器在稳定工作时可能等效为正透镜,也可能等效为负透镜。在实验部分,本文给出了热气体透镜焦距与输入功率、缓冲气体压强的关系,描绘了热气体透镜从负透镜变化到正透镜的动态过程。 相似文献
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Qinghong Zhou 《Optics Communications》2011,284(18):4207-4214
With the FEA and matrix methods, the thermal lenses induced by the thermooptic effect, thermally induced mechanical strain and end face bulging in a Ti:sapphire crystal are analyzed. The results show that there is an unignorable strain-induced lens in a high pump power region. With the thermal lens effect, an injection-locked cw Ti:sapphire laser is numerically simulated. We find that the poor mode matching between the lasing and pump beams due to thermal lens will cause the slope efficiency decreasing. The calculated results agree with the reported experimental data, and we also predict that the thermal lens is obviously active at a certain pump power level. 相似文献
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热透镜效应下的克尔透镜锁模 总被引:2,自引:1,他引:1
讨论了在增益介质与克尔介质分离情况下热透镜效应对克尔透镜锁模的影响,计算了克尔透镜锁模在热不敏感腔中需满足的条件,结果表明,通过适当地调整激光腔参数,有可能实现热不敏感的克尔透镜锁模。最后通过计算机数值模拟获得了对典型振荡腔设计参量的修正。 相似文献
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针对热容激光器的热透镜效应,给出了棒状钕玻璃热容激光器的热透镜公式表达式。理论上分析了热透镜焦距自平衡补偿方法的基本原理。在考虑了棒状钕玻璃热容激光器的具体特性的基础上,设计了一种简单的热透镜焦距自平衡补偿方法,使光抽运钕玻璃热容激光器在热透镜焦距变化情况下,可以使激光输出光斑大小稳定。为了解棒状热容激光器热透镜焦距的影响,利用自研的光栅型曲率传感器测量了热容激光器总的热透镜等效焦距的大小,结果表明热传导在抽运光发射完20 s左右后才建立热平衡产生了明显的热透镜效应; 随着抽运脉冲个数的增加,热透镜效应随之变大。 相似文献
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The thermally induced lensing effects of a diode-pumped Nd:YVO4 laser amplifier in a grazing incidence bounce geometry are carefully measured experimentally. Measurements of the thermal effects are interpreted by considering the diode-pumped amplifier region as a thick lens. A more detailed modeling was made of a quadratic refractive index lens duct for the normal to the bounce plane distribution. Due to the asymmetric pumping the thermal lens shows significant astigmatism. The ratio between dioptric powers in the plane normal to bounce and in the bounce plane is measured to be approximately 20. A nonlinear component of the power dependence of the lens is observed and related to the nonlinear heating induced by energy transfer upconversion. Measurements made under non-lasing conditions are used to infer thermal lensing behavior under lasing conditions and this allows optimization of optical resonator design. 相似文献
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The thermal lens effects in Tm:YAP laser are analyzed by solving the Poisson equation with finite difference method. The thermal focal lengths measured are in the range of 40-90 mm at the pump power of 16-34 W, consistent with the simulation results. The temperature contribution coefficient (the linear coefficient between the maximum temperature in the laser crystal and the pump power) of 1.19 K/W is also obtained. The convex lens and plano-concave mirror thermal lens compensation methods are proposed and applied to a high power pumped Tm:YAP laser. 相似文献
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To decrease the performance difference between the actual microscanning thermal imager and the theoretical value, a germanium lens (placed at a certain angle between the infrared focal plane array and infrared lens) dip angle model of flat optical component microscanning is introduced in this letter. The model is the basis for choosing the dip angle of the germanium lens, which is used in the microscanning thermal imager. In addition, the actual dip angle of the germanium lens is chosen according to the model, the infrared lens parameters of the thermal imager, and the germanium lens parameters of manufacture and installation. Only in this manner can the optimal performance of the microscanning thermal imager based on the flat optical component be obtained. Results of the experiments confirm the accuracy of the conclusions above. 相似文献