共查询到20条相似文献,搜索用时 93 毫秒
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初中物理:“水的热膨胀的特点”的演示在我数年的教学中一直没有做过,这主要是因为:当堂演示太费时间又和讲课配合不好,如让学生等着看实验结果,则大部同学感到索然无味,如不等结果而先讲其他内容,则又打乱了课堂的系统性。加以有些学校根本没有水的最大密度演示器,因之过去讲这一节时,往往只用挂图一讲了事。但后来在物理通报上看到一些老师对这个演示采取了各种不同的方法,从而取得了较好的成绩。为了提高教学质量,我把通报上前后所介绍的几种方法都做了几遍,从不断变换着的操作中给了我新的启示,我又用了 相似文献
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初中物理学上册第三章第35节大气压的一个实验是:水由喷嘴向压强较低的玻璃管中喷入(见原书图55)。这个实验如果没有抽气机,就很难做。我 相似文献
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气体的压强与体积的关系的实验设计陈银潭(江苏兴化市合塔中学225742)实验目的探索气体的压强与体积的关系.方法一实验器材50ml玻璃注射器一只,彩色橡皮膜一块(或小气球).器材装置(图1)图1实验步骤h用橡皮膜做成直径约Zem的小气球,扎紧口后放人... 相似文献
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《Neutron News》2012,23(4):28-31
SNS Construction Continues and Collaborations Grow, by Allen E. Ekkebus J-PARC Construction Proceeds, by Shoji Nagamiya and Yujiro Ikeda Dr. Nicholas Stephen Rosov (1959-2004), by Pat Gallagher, Dan Neumann, and Jeff Lynn FRM-II Reaches Full 20 MW Power, by Juergen Neuhaus 相似文献
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《Neutron News》2012,23(2):22-30
Obituary: Bertram Neville Brockhouse (1918-2003), by E. C. Svensson and J. M. Rowe J. Michael Rowe Receives 2004 Clifford G. Shull Prize of the NSSA, Robert M. Briber BENSC Gets New Neutron Guide Hall, D. Clemens and P. Piwnicki SNS Instrument Installation Begins, Allen E. Ekkebus FRM-II Startup Underway, Jÿrgen Neuhaus Recent Progress on the J-PARC Project, Shoji Nagamiya and Masa Arai 相似文献
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在超导磁约束系统中,超导磁体与射频场、磁场、声场、电场等复合场的兼容耦合是系统稳定运行的关键。探讨了在13.56 MHz频率下的Shoji型天线产生的高频电磁波对超导磁体的影响,高频电磁波会在超导磁体表面产生涡流损耗,进而产生功率损耗并生成热量,导致超导磁体失超。为避免失超现象的发生,在超导磁体室温孔内采用金属屏蔽层进行防护。利用COMSOL软件对整个电磁-射频非线性耦合场进行建模仿真分析,完成了屏蔽层结构的优化选择。基于计算结果,分析讨论了屏蔽层厚度和高度变化对超导磁体上涡流损耗功率的变化影响。通过对超导磁体涡流损耗功率随屏蔽层参数变化进行拟合,最终得到了优化后的屏蔽层参数。 相似文献
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In this article, a structure that employs a Faraday shield between the Shoji antenna and the dielectric tube, which aims to reduce the dielectric wall sputtering, is investigated for the helicon wave plasma (HWP) sources. Faraday shield is usually used between the antenna and the reaction chamber to reduce the radiation from the high electromagnetic field generation, as well as to prevent the sputtering of the antenna material from polluting the reaction chamber during the discharge. Here, the influence of the Faraday shield on the longitudinal and radial electric field of the antenna is analysed through COMSOL MultiphysicsTM. Significant attenuations of both the longitudinal and radial fields are observed in the presence of the shield. In addition, by comparing the electric field distribution under two different shielding parameters, it is found that the shielding effects are not the same. Therefore, a detailed study of two kinds of design (pitch and gap) for the shield was carried out. The results show that the pitch has a little impact on the overall shielding effect when the gap is unaltered. The best shielding performance appears when we set the pitch at T of 8 and 10. In addition, the shielding effect also becomes worse as the gap increases while the pitch remains unchanged. A relatively good shielding effect can be produced by setting the gap to the value of 4–8 mm (a gap/pitch ratio of 2/15–4/15). This work provides a theoretical basis for designing a Faraday shield structure between the antenna and the dielectric tube, which is helpful to realize stable and controllable HWP discharges. 相似文献
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S. Koretune 《Zeitschrift fur Physik C Particles and Fields》1988,39(2):199-202
An Altarelli-Parisi type evolution equation which incorporates kinematical target-mass effects is given by separating out purely kinematical parts from ones given by the perturbative QCD. Based on this separation, a simple method for an analysis of kinematical target-mass effects on the structure function is given. 相似文献
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Some new conservation laws for the transient heat conduction problem for heat transfer in a straight fin are constructed. The thermal conductivity is given by a power law in one case and by a linear function of temperature in the other. Conservation laws are derived using the direct method when thermal conductivity is given by the power law and the multiplier method when thermal conductivity is given as a linear function of temperature. The heat transfer coefficient is assumed to be given by the power law function of temperature. Furthermore, we determine the Lie point symmetries associated with the conserved vectors for the model with power law thermal conductivity. 相似文献
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We study number of spin I states for bosons in this paper. We extend Talmi's recursion formulas for number of states with given spin I to boson systems, and we prove empirical formulas for five bosons by using these recursions. We give number of states with given spin I and isospin F for three and four bosons by using sum rules of six-j and nine-j symbols. We also present formulas of states with given spin I and given F-spin for three and four single-l bosons. 相似文献
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A. Zhubr 《Russian Journal of Mathematical Physics》2014,21(1):123-129
We consider abelian groups formed by simply connected closed oriented smooth 6-manifolds with given 2-dimensional homology and given 2-dimensional Stiefel-Whitney class. In particular, an effective presentation of these groups is given. 相似文献
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本文讨论引力场中局部区域的能量问题。这里提出了一个新的引力场总能量-动量赝张量密度,它所表示的引力场局部空间区域中的能量对纯空间坐标变换是不变量,因而引力场的局部区域能量具有确定的物理意义。关于Schwarzschild场的能量和动量,新的赝张量给出的结果要比现有广义相对论文献中的其他形式的赝张量所给出的结果较为合理。文中还讨论了在引力理论中质量与能量的关系问题。
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We study deviation of ergodic averages for dynamical systems given by self-similar tilings on the plane and in higher dimensions. The main object of our paper is a special family of finitely-additive measures for our systems. An asymptotic formula is given for ergodic integrals in terms of these finitely-additive measures, and, as a corollary, limit theorems are obtained for dynamical systems given by self-similar tilings. 相似文献