共查询到18条相似文献,搜索用时 125 毫秒
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利用定影粉配制成浓度连续变化的溶液,来模拟大气中密度连续变化的空气,实验获得了良好的海市蜃楼"上现蜃景"效果;另外,用不同浓度的蔗糖溶液配制成的梯度溶液,实现了"两个上现蜃景"的效果。通过对这两种体系的成像效果的研究,加深了对海市蜃楼这一神秘自然景观的认识和理解。 相似文献
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目前实验室的海市蜃楼演示装置需要多人操作,且演示周期长,实验现象不稳定.针对这些问题,对该装置进行了改进,增加了3层隔水薄膜,通过抽水机向装置内缓慢注水.改进后的装置演示现象直观、清晰,且实验现象保持的时间较长. 相似文献
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分析了配制传统模拟海市蜃楼溶液的方法的不足,提出了新的配制溶液的方案,推导出了所配制的溶液浓度梯度随高度的分布公式,从而使实验过程中配液的时间大大缩短,实验现象更加明显,提高了实验的成功率. 相似文献
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综合初中物理教材中“光的折射”设计理念,自制了实验装置.通过该实验装置可以开展折射规律、趣味捕鱼、虚像位置真实呈现、全反射、生活中折射现象扩展解释、海市蜃楼模拟等实验,并能够体现视觉表征学习方法,变抽象为形象,从而培养学生的建模能力. 相似文献
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置于以窗口连接的分隔仓中振动驱动的颗粒气体会出现颗粒在两仓中布居分聚现象,被形象地称为麦克斯韦妖现象.通量模型的建立是理解麦克斯韦妖现象的关键问题.Eggers以颗粒气体动力学为基础得出了简化的理论模型.该模型可以很好地得到分仓中颗粒的布居分聚现象,然而似乎无法用于预测两种颗粒在分仓体系中的布居振荡现象.通过实验研究,测量了颗粒气体的流通量曲线,改进了Eggers模型.改进的模型可以很好地得到两种颗粒在分仓体系中的布居振荡现象.
关键词:
颗粒气体
耗散
通量模型 相似文献
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光在介质中的传播规律遵循费马原理,如:在均匀介质中,光沿直线传播.在非均匀介质中,光的传播轨迹比较复杂,与非均匀介质的状态有密切关系.尽管海市蜃楼和沙漠幻影是大自然中能够看到的光在非均匀介质中的传播现象,但只有在一定条件下才能出现,不是随时可以看到的.为了能在光学教学中让学生能够看到光在非均匀介质中的传播,本文利用白糖溶液和水之间扩散形成的浓度非均匀区域,实现了光线的非直线传播.通过光线实际传播的路径,计算了非均匀区域液体折射率的相对变化.这一演示实验取材简单,容易实现,对学生思维训练具有一定的借鉴意义. 相似文献
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A microscopic theory is developed for the projection (quantum mirage) of the Kondo resonance from one focus of an elliptic quantum corral to the other focus. The quantum mirage is shown to be independent of the size and the shape of the ellipse, and experiences lambdaF/4 oscillations ( lambdaF is the surface-band Fermi wavelength) with an increasing semimajor axis length. We predict an oscillatory behavior of the mirage as a function of a weak magnetic field applied perpendicular to the sample. 相似文献
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The thermal diffusivity h of a thin film on a substrate is measured by using the mirage technique. The photothermal deflection of the probe beam is caused by the heat field and the substrate, heated by the pump beam. From the experimental data a two-dimensional algorithm is proposed to obtain the measurements of the diffusivity of film and substrate in one set of mirage detection. 相似文献
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We present exact results for magnetic impurities in nanoscopic systems with focusing properties. We analyze the spectroscopic and magnetic properties of Kondo, intermediate valence, and magnetic impurities on a sphere with a metallic surface. Exact calculations show the occurrence of spectroscopic and magnetic mirages at the antipodes of the impurity location. Comparison with calculations performed using effective models validates previous calculations of spectroscopic mirages. Our results predict the existence of a strong magnetic mirage in the experimentally realizable elliptic corral. 相似文献
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Fiete GA Hersch JS Heller EJ Manoharan HC Lutz CP Eigler DM 《Physical review letters》2001,86(11):2392-2395
We explain the origin of the Kondo mirage seen in recent quantum corral scanning tunneling microscope experiments with a scattering theory of electrons on the surfaces of metals. Our theory, combined with experimental data, provides a direct observation of a single Kondo atom phase shift. The Kondo mirage observed at the empty focus of an elliptical quantum corral is shown to arise from multiple electron bounces off the corral wall adatoms. We demonstrate our theory with direct quantitive comparison to experimental data. 相似文献
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We summarize the approach to brane cosmology known as mirage cosmology and use it to determine the Friedmann equation on a 3-brane embedded in different bulk spacetimes all with one or more extra dimensions. Usually, when there is more than one extra dimension the junction conditions, central to the usual brane world scenarios, are difficult to apply. This problem does not arise in mirage cosmology because the brane is treated as a test particle in the background spacetime. We discuss in detail the dynamics of a brane embedded in two specific 10D bulk spacetimes, namely Sch-AdS5 × S5 and a rotating black hole, and from the dynamics—which are now rather more complicated since the brane can move in all the extra dimensions—determine the new dark fluid terms in the brane Friedmann equation. Some of these, such as the cosmological constant term, are seen to be bulk dependent. We then show explicitly how this mirage cosmology approach matches with the familiar junction condition approach when there is just one extra dimension. The issue of a varying speed of light in mirage cosmology is addressed and we find a scenario in which c
eff always increases, tending asymptotically to c
0 as the universe expands. Finally some comments are made regarding brane inflation and limitations of the mirage cosmology approach are also discussed. 相似文献
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The phenomena of remote projection and quantum mirages are investigated using standard quantum mechanics. The information inherent in delocalized wave functions in the vicinity of the Fermi level, including contributions from localized states, is available wherever the waves propagate coherently and have a non-vanishing amplitude and therefore can be probed remotely. This can explain the observation of a "quantum mirage" by Manoharan et al.: Nature 403, 512 (2000), i.e., the Kondo antiresonance due to a single adsorbed Co atom on Cu (111) far from the location of the cobalt atom. Similar quantum effects can give rise to "mirage" features in the scanning tunnelling spectrum (STS) both on clean and adsorbate-covered metal surfaces, features which are not resolved in other surface-sensitive spectroscopies (IPES, 2PPE). Within a theory based on a many-particle treatment of the tunnelling phenomena in STS and in scanning tunnelling microscopy (STM), the unexpected features in the scanning tunnelling spectra are associated with the spectral weight of transient ion-resonance states generated in the process of electron injection. They transport in a coherent way the information from the tip towards the sample and vice versa over distances of the order of 10 Å or more, generating spectroscopic structures. These "mirage" states are important for the tunnelling current and the imaging properties. 相似文献