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将口袋式仪表Analog Discovery 2及其配套控制软件WaveForms引入巨磁阻效应实验,替代直流电源、信号发生器、示波器、数字信号控制器等传统仪表,完成信号的激发、采集以及处理.由Analog Discovery 2驱动螺线管、巨磁阻传感器、直流电机和步进电机等部件,可以实现巨磁阻传感器R-B基本特征曲线和高速转动转速的快速测量,还可以结合齿轮状铁磁体,实现低速转动的准确测量及微小角位移的定标和测量.各主要部件采用三维调整架固定,偏置永磁铁也配备了不同形状的导磁头,方便学生观察不同条件下的实验现象,完成更具有开放性和创新性的实验内容. 相似文献
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Fluid simulation of the pulsed bias effect on inductively coupled nitrogen discharges for low-voltage plasma immersion ion implantation 下载免费PDF全文
Planar radio frequency inductively coupled plasmas(ICP) are employed for low-voltage ion implantation processes,with capacitive pulse biasing of the substrate for modulation of the ion energy. In this work, a two-dimensional(2D) selfconsistent fluid model has been employed to investigate the influence of the pulsed bias power on the nitrogen plasmas for various bias voltages and pulse frequencies. The results indicate that the plasma density as well as the inductive power density increase significantly when the bias voltage varies from 0 V to-4000 V, due to the heating of the capacitive field caused by the bias power. The N+fraction increases rapidly to a maximum at the beginning of the power-on time, and then it decreases and reaches the steady state at the end of the glow period. Moreover, it increases with the bias voltage during the power-on time, whereas the N_2~+ fraction exhibits a reverse behavior. When the pulse frequency increases to 25 kHz and40 kHz, the plasma steady state cannot be obtained, and a rapid decrease of the ion density at the substrate surface at the beginning of the glow period is observed. 相似文献
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The inflexion point of electron density and effective electron temperature curves versus radio-frequency (RF) bias voltage is observed in the H mode of inductively coupled plasmas (ICPs). The electron energy probability function (EEPF) evolves first from a Maxwellian to a Druyvesteyn-like distribution, and then to a Maxwellian distribution again as the RF bias voltage increases. This can be explained by the interaction of two distinct bias-induced mechanisms, that is: bias- induced electron heating and bias-induced ion acceleration loss and the decrease of the effective discharge volume due to the sheath expansion. Furthermore, the trend of electron density is verified by a fluid model combined with a sheath module. 相似文献
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In this paper the use of the mixed finite element method forstress analysis of reinforced conical branch pipe junctionssubjected to internal water pressure is presented,branchpipe junction being considered as an intersection body oftwo thin conical shells.For the purpose of computing alarge number of branch pipe junctions with different geome-trical varieties,an automatical meshing routine has beenput up in the mixed FEM program with 3 geometrical parame-ters of the junctions to be varied,i.e.,the angle includedbetween axes of the main pipe and the branch pipe,the thick-ness of the wall of the shell and that of the reinforcingpad and the ratio of diameters of the branch pipe to thatof the main pipe.The computer program has been providedfunctions to distinguish 8 kinds of different meshes and12 sorts of elements,and to lay automatically coordinatesof nodes as well as different boundary conditions of ele-ments.In this way,stress analyses of 101 junctions havebeen carried out and results of computations ar 相似文献
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开放性的创新实践平台是培养学生创新精神和实践能力的重要基础条件.受人员、经费等客观因素的限制,该类平台的资源往往难以被充分利用,可持续性发展也无法得到保证.针对这些问题,以组织和指导学生参与大学生物理学术竞赛系列赛事为契机,大连理工大学基础物理实验中心在物理创新平台的建设和发展方面做了一些有益的尝试.首先,充分挖掘人力资源,分别建立了教师和学生功能团队,有效的保证了平台各层面的有效运行;其次,依靠购置和资源梳理,充实了创新平台的的硬件条件,解决了创新活动的场地和器材问题.最后,通过规范的形式和科学的设计提高了创新实践教育的培养质量. 相似文献
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In this paper the use of the mixed finite element method for stress analysis of reinforced conical branch pipe junctions subjected to internal water pressure is presented, branch pipe junction being considered as an intersection body of two thin conical shells. For the purpose of computing a large number of branch pipe junctions with different geometrical varieties, an automatical meshing routine has been up in the mixed FEM program with 3 geometrical parameters of the junctions to be varied, i.e., the angle included between axes of the main pipe and the branch pipe, the thickness of the wall of the shell and that of the reinforcing pad and the ratio of diameters of the branch pipe to that of the main pipe. The computer program has been provided functions to distinguish 8 kinds of different meshes and 12 sorts of elements, and to lay automatically coordinates of nodes as well as different boundary conditions of element. In this way, stress analyses of 101 junctions have been carried out and results of computations are excellent. 相似文献