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61.
从微小内尺度测量角度出发,研究了针孔尺寸、探测器位置、透镜的数值孔径、放大倍率和杂散光等对自聚焦共焦式探测系统轴向分辨率的影响。结果表明,为提高系统的轴向分辨率,需将有效针孔尺寸控制在≤2.5;探测器需配以精密微调整装置以实现横向精确定位;选用差动共焦光路及大数值孔径和大放大倍率的自聚焦透镜,同时,偏振光路的使用将有效的提高系统的信噪比。 相似文献
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R. Thomas conjectured, 20 years ago, that the presence of a positive circuit in the interaction graph of a dynamical system is a necessary condition for the presence of several stable states. Recently, E. Remy et al. stated and proved the conjecture for Boolean dynamical systems. Using a similar approach, we generalize the result to discrete dynamical systems, and by focusing on the asynchronous dynamics that R. Thomas used in the course of his analysis of genetic networks, we obtain a more general variant of R. Thomas’ conjecture. In this way, we get a necessary condition for genetic networks to lead to differentiation. 相似文献
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Xiaoming Zhou Martin Jacobsson Henk Uijterwaal Piet Van Mieghem 《International Journal of Communication Systems》2008,21(6):643-663
Although packet delay and loss are two important parameters of the Internet performance, to the best of our knowledge, the evolution of large‐scale IPv6 delay and loss performance has previously not been studied. In this paper, we analyze more than 600 end‐to‐end IPv6 paths between about 26 testboxes of RIPE Network Coordination Centre over two years, and compare the delay and loss performance over time with their IPv4 counterparts. We present and discuss the measurement methodologies and show that IPv6 paths have a higher delay and loss than their IPv4 counterparts. The main reason for the worse performance stems from IPv6‐in‐IPv4 tunnels rather than from native IPv6 paths and such tunnels are still widely used today. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Gel polymer electrolyte (GPE) films comprising of poly(vinylidenefluoride), propylene carbonate, ethylene carbonate and zinc trifluoromethane sulfonate are prepared and characterized. The composition of GPE is optimized to contain minimum liquid components with a maximum specific conductivity of 3.94×10−3 S cm−1 at (25±1) °C. A detailed investigation on the properties such as ionic conductivity, transport number, electrochemical stability window, reversibility of Zn/Zn2+ couple and Zn/gel electrolyte interfacial stability have been carried out. The ionic conductivity follows a VTF behaviour with an activation energy of about 0.0014 eV. Cationic transport number varies from 0.51 at 25 °C to 0.18 at 70 °C. Several cells have been assembled with GPE as the electrolyte, zinc as the anode, γ-MnO2 as the cathode and their charge–discharge behaviour followed. Capacity values of 105, 82, 64 and 37 mAh/g of MnO2 have been achieved at 10, 50, 100 and 200 μA/cm2 discharge current densities, respectively. The discharge capacity values are almost constant for about 55 cycles for all values of current densities. Cyclic voltammetric study of MnO2 electrode in Zn/GPE/MnO2 cell clearly shows intercalation/deintercalation of Zn2+. 相似文献
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F-H实验仪与光栅光谱仪连用观测253.7nm谱线 总被引:1,自引:0,他引:1
通过F-H实验仪和光栅光谱仪的连用,可实时观测汞原子从6s6s1So态激发到6s6sSP1态,退激时,辐射出能量为4.9eV的光量子,其波长为253.7nm. 相似文献