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Vibrational mode in a two-dimensional dust monolayer is investigated by considering the finite size of dust grains. Each dust grain is assumed to be a negative point charge and a dipole moment due to the inhomogeneous charge distribution on its surface. The dispersion relation of the vibrational mode is derived. Both the self-excited and externally excited cases are discussed. It is shown that the mode is sensitive to the direction of the dipole moment. 相似文献
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介绍单片微型计算实验教学改革的一些做法.自制实验设备,改革实验内容和方法,开放实验室,进行实验考试等.大大地提高了教学质量,增强了学生实验操作能力,科学研究能力和解决问题等方面的能力. 相似文献
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正An academician of Chinese Academy of Sciences (CAS),Professor Changxuan Yu,a long-time professor of plasma physics at the University of Science and Technology of China (USTC),Hefei,China,passed away in Hefei on May 23,2017.Professor Yu was born on July 7,1941,in Java Island,Indonesia,and then moved back to China in 1948 with his parents.He finished his high school 相似文献
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Numerical simulations based on the finite-difference-time-domain (FDTD) approximation to multi-fluid equations for positive ions, negative ions and electrons are used to study high frequency electromagnetic wave propagation and absorption in an unmagnetized plasma layer. The interaction between the incident high frequency wave and the plasma layer shows that the existence of negative ions and the nonlinear effect reduces the power absorption capability of the plasma. Parameter dependences of the effects are calculated and discussed. 相似文献
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强流脉冲离子束(IPIB)及其在靶材中沉积的能量是研究束流与靶材作用的基础.根据三束材料改性国家重点实验室从俄罗斯引进TEMPⅡ型加速器实测的磁绝缘二极管(MID)的加速电压波形及法拉第杯检测到的MID焦点处离子流密度波形,对其进行拟合得到高斯脉冲分布模型,以此为基础采用Monte Carlo方法模拟了离子在铝靶内沉积的能量,得到了一个脉冲内靶材内沉积的能量的时空演化规律.计算了单能离子束以20°~40°角入射铝靶情形.不同能量的单能H+束和C+束以一定角度入射时的最大射程比垂直入射时都要小,表面处单位长度沉积的能量随入射角的增加而增多.IPIB入射铝靶时变化规律同单能离子束.同时对H+和C+二维入射靶材情况也进行了模拟研究. 相似文献
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在温度场和应力场计算的基础上建立了强流脉冲电子束轰击作用下的扩散模型,并给出了数值方法及其数值解。该模型与方法同样适用于其它高能束流作用下的扩散过程。计算表明,浓度扩散流仍然是影响扩散的主要因素;而轰击超过一定次数后,扩散的作用将减弱;当边界条件为表面扩散时,扩散进行较快,这是表面涂覆加脉冲电子束后处理快速表面合金化工艺的理论基础。对实验结果和理论结果的对比分析表明,在脉冲轰击下,扩散激活能随空位浓度的增加而下降,从而加速扩散过程;在表面有熔化的情况下,则液态时的对流混合作用是主导因素。 相似文献