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Carbon nitride thin films were prepared by electron-beam evaporation
assisted with nitrogen ion bombardment and TiN/CNx composite films were by
unbalanced dc magnetron sputtering, respectively. It was found that the
sputtered films were better than the evaporated films in hardness and
adhesion. The experiments of atomic oxygen action, cold welding, friction
and wearing were emphasized, and the results proved that the sputtered
TiN/CNx composite films were suitable for space application. 相似文献
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气体开关作为脉冲功率装置的关键部件,其自击穿概率以及触发放电延时抖动对整个脉冲功率系统具有至关重要的影响。降低开关工作系数有利于提高开关稳定性,但延时抖动会随之增大。针对用于磁驱动实验的10 MA级大电流装置应用需求,设计了一种具有较高场畸变系数、能在较低工作系数条件下稳定工作的三电极气体开关,并开展了该开关的性能研究。模拟与实验结果表明:在触发电压与充电电压相当的条件下,开关的场畸变系数接近4,开关工作系数高于60%时,开关具有较低的延时抖动,抖动均方根小于3 ns。结合该开关设计了一个两级Marx储能模块,充电电压±50 kV条件下短路放电,模块回路放电电流峰值达到150 kA、周期2μs。上千次放电实验后,开关电极表面未发生明显烧蚀,工作正常。工作系数68.5%时,共计4 000发实验中未出现自放电现象,自击穿概率低于2.5×10-4。上述结果表明该开关可满足300~400只开关同时工作的大电流装置需求。 相似文献
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We propose a catalytically activated duplication model to mimic the
coagulation and duplication of the DNA polymer system under the
catalysis of the primer RNA. In the model, two aggregates of the
same species can coagulate themselves and a DNA aggregate of any
size can yield a new monomer or double itself with the help of RNA
aggregates. By employing the mean-field rate equation approach we
analytically investigate the evolution behaviour of the system. For
the system with catalysis-driven monomer duplications, the aggregate
size distribution of DNA polymers ak(t) always follows a power
law in size in the long-time limit, and it decreases with time or
approaches a time-independent steady-state form in the case of the
duplication rate independent of the size of the mother aggregates,
while it increases with time increasing in the case of the
duplication rate proportional to the size of the mother aggregates.
For the system with complete catalysis-driven duplications, the
aggregate size distribution ak(t) approaches a generalized or
modified scaling form. 相似文献
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为了研究电磁驱动药型罩形成高速成型弹丸的可行性及弹丸成型特性,基于CQ-7脉冲功率装置,开展了电磁驱动线性药型罩形成弹丸技术实验。结合激光多普勒测速技术,实现了电磁驱动药型罩形成弹丸的速度测量和侵彻铝靶验证。同时,基于流体动力学软件和相应电磁仿真模块,建立了电磁驱动弹丸成型的物理模型和数值模拟方法,模拟了弹丸成型和侵彻铝靶的动力学过程,利用实验结果验证了数值模拟方法的可靠性。在此基础上,研究了等壁厚球缺型药型罩的结构参数以及加载能量对弹丸成型参数的影响规律。结果表明:外曲率半径对弹丸的头部速度影响较小,而头部速度会随壁厚的减小和加载能量的增大显著增加;弹丸的长径比随外曲率半径和壁厚的减小、加载能量的增大呈逐渐增加的趋势。最后,利用数值模拟方法预测并验证了利用电磁驱动技术获得高速度和大质量成型弹丸的可行性。 相似文献
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