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电子经过介质时,将介质极化,本工作的目的是研究较低能量的电子经过不同介质时,由于这种极化效应对于电子能量损耗的影响。利用灌氢气的膨胀式云雾室测量了能量为0.3—1.0Mev的电子经过铍、炭及铝片的平均能耗及最大可几能耗。实验指出:在此能量范围内的电子,经过某些介质,它们的传导电子数与全部电子数的比值f0以及电阻系数ρ都大,如铍及炭,其能量损耗由于介质被极化而显著减少。电子经过铍的能耗实验结果显著比考虑了介质极化影响的Helpern及Hall与电子能量损耗有显著减少Sterneimer的理论为小;电子经过炭的能耗实验结果是介于此二理论之间。 相似文献
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高载流子迁移率和可调直接带隙是低维电子器件应用的两个关键特性.但目前发现的此类二维材料稀少.鉴于此在第一性原理计算的基础上,本文系统研究了In2(PS3)3单层的稳定性、电子结构性质和机械性质.研究结果表明,In2(PS3)3单层是具有直接带隙的半导体材料(1.58 eV).在-3%到3%应变下,In2(PS3)3单层的带隙是可以调节的(1.3~1.8 eV).声子谱、分子动力学和弹性常数的计算结果表明,In2(PS3)3单层是热力学、动力学和机械稳定的.此外,In2(PS3)3单层的剥离能(0.21 J m-2)小于石墨烯的剥离能(0.36 J m-2),有望像石墨烯一样机械剥离得到.这些优异的的性能使得In 相似文献
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讨论了电话用按键按力的概念及其测试方法,指出了GB12196、GB12198标准中有关条款的内容与硅橡胶按键结构设计和制造的实际要求的不同之处,并提出了修改标准的具体建议。 相似文献
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In this paper a new finite element method is presented.in which complex functions arechosen to be the finite element model and the partitioning concept of the generalizedvariational method is utilized.The stress concentration factors for a finite holed platewelded by a stiffener are calculated and the analytical solutions in series form are obtained.From some computer trials it is demonstrated that the problem of displacementcompatibility and continuity of tractions between the holed plate and the stiffener issuccessfully analysed by using this method.Since only three elements need to beformulated.relatively less storage is required than the usual finite element methods.Furthermore,the accurary of solutions is improved and the computer time requirements areconsiderably reduced.Numerical results of stress concentration factors and stresses alongthe welded-line which may be referential to engineers are shown in tables. 相似文献
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为研究波长对连续激光晶化非晶硅(a-Si) 薄膜过程的影响,利用连续Ar+-Kr+激光对a-Si薄膜晶 化,在5ms固定照射时间下,改变激光波长,采用拉曼光谱测试技术和场发射扫描电子显微 镜(SEM)研究在不同 激光功率密度下薄膜晶化后的特性。结果表明,a-Si薄膜的晶化阈值随着波长的 增大而增大,当波长为 458nm时薄膜晶化阈值为13.2kW/cm2,波长 为647nm时,晶化阈值为19.2kW/cm2;在激光功率密度范 围为0~27.1kW/cm2内,薄膜的最大晶化率受波长的影响相对较小 ,但总体也随着波长的增大而呈增大 趋势,当波长为647nm时,在激光功率密度26.5kW/cm2处,晶化率达到最大值75.85%。 相似文献
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非视距被动声定位与跟踪方法 总被引:1,自引:1,他引:0
非视距声信号通过短程线路径绕射到达基阵,将信号传播所得的短程线离散化,通过离散点之间的迭代关系,对绕射信号进行了射线寻迹.针对非视距情况下被动声定位及跟踪技术的特点,基于射线寻迹的原理,提出了对被动声源进行非视距定位的方法,然后利用卡尔曼滤波分别对静止和移动目标进行跟踪.仿真结果表明,当障碍物为非对称几何体时,能够对非视距声源位置及速度进行有效估计. 相似文献
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在高考结束后,我被学校派去新疆参加"南京·伊宁"教育研讨会,其中活动之一是同课异构活动,这次选择的高二选修4-5《不等式选讲》中的不等式证明的第一课时《比较法证明不等式》.我和伊宁的一位老师同时上这一课,我把伊宁地区用的人教A版教材认真学习了一下,发现这一节课数学知识很少,常规是按照习题课的形式上.我在准备这一节课时从归纳提升、应用巩固、发现问题、探究解法、 相似文献
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In this paper a new finite element method is presented, in which complex functions are chosen to be the finite element model
and the partitioning concept of the generalized variational method is utilized. The stress concentration factors for a finite
holed plate welded by a stiffener are calculated and the analytical solutions in series form are obtained. From some computer
trials it is demonstrated that the problem of displacement compatibility and continuity of tractions between the holed plate
and the stiffener is successfully analysed by using this method. Since only three elements need to be formulated, relatively
less storage is required than the usual finite element methods. Furthermore, the accuracy of solutions is improved and the
computer time requirements are considerably reduced. Numerical results of stress concentration factors and stresses along
the welded-line which may be referential to engineers are shown in tables. 相似文献