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131.
132.
The schlieren interferograms used to be analyzed in a qualitative way. In this paper, by means of the powerful computational
ability and the large memory of computer; the image processing method is investigated for the digitalization of an axisymmetric
schlieren interferogram and the determination of the density field. This method includes the 2-D low-pass filtering, the thinning
of interferometric fringes, the extraction of physical information and the numerical integration of the density field. The
image processing results show that the accuracy of the quantitative analysis of the schlieren interferogram can be improved
and a lot of time can be saved in dealing with optical experimental results. Therefore, the algorithm used here is useful
and efficient. 相似文献
133.
本文应用谱分析理论研究了剪切湍流场中的压力脉动,包括功率谱、均方值等.通过对压力脉动Possion方程的Fourier变换,首先将压力脉动谱表示成速度脉动谱的形式.利用Navier-Stokes方程的形式解及准正态分布假设,可以进一步将压力脉动功率谱表达式中所包含的速度脉动的三阶相关与四阶相关表示成速度脉动的二阶相关(功率谱).最后,引入高雷诺数流的速度脉动功率谱模型,导出了由湍动e0,耗散ε,雷诺应力-iuj>及时均速度梯度表示的压力脉动均方值的湍流模式,并同现有数据进行了比较. 相似文献
134.
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136.
All-solid-state sodium batteries with poly(ethylene oxide) (PEO)-based electrolytes have shown great promise for large-scale energy storage applications. However, the reported PEO-based electrolytes still suffer from a low Na+ transference number and poor ionic conductivity, which mainly result from the simultaneous migration of Na+ and anions, the high crystallinity of PEO, and the low concentration of free Na+. Here, we report a high-performance PEO-based all-solid-state electrolyte for sodium batteries by introducing Na3SbS4 to interact with the TFSI− anion in the salt and decrease the crystallinity of PEO. The optimal PEO/NaTFSI/Na3SbS4 electrolyte exhibits a remarkably enhanced Na+ transference number (0.49) and a high ionic conductivity of 1.33 × 10−4 S cm−1 at 45 °C. Moreover, we found that the electrolyte can largely alleviate Na+ depletion near the electrode surface in symmetric cells and, thus, contributes to stable and dendrite-free Na plating/stripping for 500 h. Furthermore, all-solid-state Na batteries with a 3,4,9,10-perylenetetracarboxylic dianhydride cathode exhibit a high capacity retention of 84% after 200 cycles and superior rate performance (up to 10C). Our work develops an effective way to realize a high-performance all-solid-state electrolyte for sodium batteries.A high-performance all-solid-state PEO/NaTFSI/Na3SbS4 electrolyte for sodium batteries is realized owing to the electrostatic interaction between TFSI− in the salt and Na3SbS4, which immobilizes TFSI− anions and promotes the dissociation of NaTFSI. 相似文献
137.
A new simple optical system based on optical beam deflection combining the holophote corner cube was developed in order to study the dynamics of laser-induced shock waves in air. In this method, we adopt a He-Ne laser beam as the detection beam. The He-Ne laser beam, reflected by corner cube, intersects the propagating shock wave at two successive positions. The measurement of the shock wave velocity benefits from the double peak signals induced by the same acting laser pulse, which is calculated from the time interval between the corresponding oscilloscope signals and the distance of the two He-Ne laser beams. By virtue of this setup, we are also able to determine the pressure of the generated shock waves. It is shown that this method is simple with a fairly good precision and is much easier than the conventional methods used for this task. 相似文献
138.
X. Ni G. V. Naik A. V. Kildishev Y. Barnakov A. Boltasseva V. M. Shalaev 《Applied physics. B, Lasers and optics》2011,103(3):553-558
Spontaneous emission patterns of electric and magnetic dipoles on different metallic surfaces and a hyperbolic metamaterial
(HMM) surface were simulated using the dyadic Green’s function technique. The theoretical approach was verified by experimental
results obtained by measuring angular-dependent emission spectra of europium ions on top of different films. The results show
the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces. The results of numerical calculations
agree well with experimental data. 相似文献
139.
An analytical formula for the average intensity of cosh-Gaussian (ChG) beams diffracted by an aperture in turbulent atmosphere
is derived and some limiting cases are discussed. By using the average intensity formula, some numerical simulation comparisons
are made and some special cases are studied, especially the influences of the ChG beam parameter (Ω0), the propagation distance, the aperture and its size on the average normalized intensity distribution. It is determined
that the evolution properties of the average normalized intensity profile in turbulent atmosphere with aperture are different
not only from those of free space with aperture but also from those in turbulent atmosphere without aperture.
PACS 42.68.Bz; 42.79.Ag; 42.25.Fx 相似文献
140.
Hierarchical Na2FeP2O7 spheres with nanoparticles were successfully fabricated by a facile spray drying method. A relatively low drying temperature was introduced in order to form a carbon layer on the surface. As a cathode material for sodium-ion batteries, it delivered a reversible capacity of 84.4 mAh g?1 at 0.1 C and showed excellent cycling and rate performance (64.7 mAh g?1 at 5 C). Furthermore, a full sodium battery was fabricated using SP-Na2FeP2O7 as the cathode and hard carbon as the anode, suffering almost no capacity loss after 400 cycles at 1 C. Due to its superior electrochemical property and the low materials cost, Na2FeP2O7 is becoming a promising cathode material for large-scale energy storage systems. 相似文献