浸没式浮筒对系泊缆松弛-张紧特性的影响研究

为了研究浸没式浮筒对悬链线系泊缆松弛-张紧特性的影响,本文基于集中质量法建立了下端锚固、上端做简谐运动的带浮筒悬链线系缆运动微分方程。运用Newton-Raphson法和Howbolt差分法,求解了系缆的运动特性和动张力值。通过与无浮筒悬链线系泊系统的对比,分析了几种不同参数的浮筒对系泊缆松弛-张紧现象及冲击放大系数两个方面的影响。结果表明:附加一定大小的浸没式浮筒能有效抑制系泊缆松弛-张紧现象的出现,并且减小系缆运动过程中动张力的冲击放大系数;但当附加浮筒的净浮力过大时,在极端海况下,会助长系泊缆上端出现松弛-张紧现象,进而影响系泊物的稳定性。     

在激光下几种磷酸盐溶液的折光规律

研究了KH₂PO₄、KD₂PO₄、NH₄H₂PO₄溶液、H₂和D₂O对激光的折光性。测定了它们对He-Ne激光和钠光的折光率温度系数及色散能力。确定了不同溶液折光指数与浓度的关系。单独给出了几种饱和溶液的折光规律,并用激光纹影法精确测定了相应溶液的饱和度数据。     

初中“经验型”数学活动实践研究

对基本活动经验的学习,在教材中常常是体现在综合与实践部分,也就是课本上的数学活动.在新课程改革的背景下,加强数学活动部分的学习,提高学生的实际动手能力,保证活动和实践的开展,激发学生的学习兴趣,培养学生运用数学知识解决实际问题的能力和意识.在本文中,将对经验型的数学活动进行相关的探讨,目的是与大家交流如何增强学生的基本活动经验,开展好经验型的数学活动,提高学生的综合能力.     

Wildly Tunable,High-Efficiency MgO：PPLN Mid-IR Optical Parametric Oscillator Pumped by a Yb-Fiber Laser

We demonstrate a wildly tunable, high-eFficiency mid-infrared （mid-IR） output-coupled single resonant optical parametric oscillator （OC-SRO） pumped by a Yb-fiber laser. The compact mid-infrared source employs a 50- mm-long, multi-grating MgO-doped periodically poled lithium niobate （MgO-PPLN） crystal, providing as much as 1.73 W idler power at 3.012#m, and 1.27W signal power at 1645nm, corresponding to an overall conversion efficiency of 41.7% and a slope efficiency of 77.9%. In particular, the mid-infrared output power of 1.03 W and 0.67W are obtained at 3.7μm and 3.9μm, respectively, with an optical-to-optical conversion efficiency of 14.3% and 9.3%. Furthermore, the idler light is tunable from 3 μm to 3.9 μm by changing the periods from 31 to 28.5μm, with the output power 〉1 W over 78% of the tuning range. Our experimental results are pump power limited and further mid-IR power and conversion efficiency could be obtained with a suitable high-power pump source. The total OC-SRO output power rms at 2.6 W is about 0.6% during 2 h measurement.