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101.
The electrochemical properties of an electrochemical double-layer capacitor electrode based on an ultra-long (500 μm), aligned, carbon nanotube array (ACNTA) in Et4NPF6/propylene carbonate electrolyte are examined. The specific capacitance of the ACNTA electrode in an organic electrolyte is 24.5 F g−1, which is larger than that obtained in an aqueous electrolyte. The results of ac impedance measurements show that the ACNTA electrode gives a high power density and an excellent rate capability in an organic electrolyte. It is shown that the ACNTA electrode has a lower equivalent series resistance and a better rate capability than activated carbon electrode. This is due to the fact that ACNTA possesses a larger pore size and a more a regular pore structure. Both these features are conformed by scanning electron microscopic and nitrogen gas adsorption studies. 相似文献
102.
The effect of magnetic field on OH radical distribution in a hydrogen-oxygen diffusion flame was experimentally and numerically investigated to explore the possibility of combustion control by magnetic force. In experiments, a coaxial type of burner was set between the magnet pieces. Two-dimensional (2D) cross-section distributions of OH* chemiluminescence intensity and OH fluorescence intensity were obtained with spectroscopic techniques using a CCD camera and a Planar Laser-Induced Fluorescence (PLIF) system, respectively. It was clearly seen that the high-density regions of OH* and OH radicals axisymmetrically migrated toward the central axis of the flame due to the influence of the magnetic field. In numerical simulations, such a phenomenon was qualitatively reproduced by solving the equations of reactive gas dynamics and magnetism. As a result, it was found that the magnetic force does not directly and selectively induce the diffusion velocity (the relative velocity) of OH itself. Alternatively, the magnetic force acting on O2, whose mass density and magnetic susceptibility are much larger than those of other chemical species, causes the change in the mean velocity (the mass-average velocity) of mixture gas to transport the OH radical distribution indirectly and passively. 相似文献
103.
Chestnuts were dehydrated by using a combined method of osmotic dehydration followed by air drying. Samples were osmotically pretreated with sucrose (60% w/w) and glucose (56% w/w) for 8 h, air-dried at temperatures of 45, 55, and 65°C, at a relative humidity of 30% and at a velocity of 2.7 m·s-1 and the experimental data of the drying kinetics were obtained. Whole samples were dried with different peelings: (a) removal of endocarp and pericarp (peeled) and (b) additionally the internal rough surface (cut). In all cases, cut chestnuts show greater drying rates than peeled samples, indicating that a significant mass transfer resistance in the layer nearest to the surface takes place. Peeled samples pretreated with sucrose solutions behave in a similar way to untreated samples. For the rest of the samples, the cut samples osmotically treated with sucrose solutions and all the samples treated with the glucose solution, the drying rates decrease during drying. Drying kinetics are successfully modeled by employing a diffusional model that takes the shrinkage into account. The effective coefficient of water diffusion was evaluated and correlated with temperature. The quality of the final product was monitored by color change. In spite of the fact that the total color difference is not modified by the osmotic treatment, the L*, a*, and b* color coordinates of cut samples treated with sucrose and glucose solutions do undergo changes; the L* and a* coordinates change less than the b*. 相似文献
104.
J.M.P.Q. Delgado 《Journal of Phase Equilibria and Diffusion》2007,28(5):427-432
Molecular (or tracer) diffusion coefficient data were obtained for 2-naphthol, benzoic acid, salicylic acid, camphor, and
cinnamic acid in water at temperatures that differ significantly from ambient value. Experimental values were determined for
the dissolution of 2-naphthol in water at 283 to 368 K, of benzoic acid in water at 283 to 338 K, of salicylic acid in water
at 283 to 343 K, of camphor in water at 283 to 318 K, and of cinnamic acid in water at 283 to 318 K. Empirical correlations
are presented for the prediction of molecular diffusion coefficient over the entire range of temperatures studied, and they
are shown to predict the obtained data with very good accuracy. 相似文献
105.
Li Weilian 《石油科学(英文版)》2007,4(4):17-22
The caprock is one of the key factors for a reservoir, especially for a gas reservoir. Whether the caprocks can block off the gas is of significance for the accumulation and preservation of the gas reservoir. In this paper, we use the Amplitude versus offset (AVO) seismic technique to determine the lateral extension of the hydrocarbon concentration sealing caprocks. The essence of this technique is to detect the variations of the reservoir bed physical properties by monitoring the variations of the reflection coefficient of seismic waves upon the interfaces between different lithologies.Generally it is used to indicate hydrocarbon directly. For the hydrocarbon concentration sealing caprocks, the change of hydrocarbon concentration may cause the change of physical properties of the caprocks. Therefore it is possible to evaluate the hydrocarbon concentration sealing ability of the caprocks by AVO. This paper presents a case study using AVO to determine the lateral extension of the hydrocarbon concentration sealing caprocks. The result shows that this method is helpful for the exploration of the region. 相似文献
106.
程控电话交换机过电流保护元件用高性能PTC陶瓷的研制 总被引:3,自引:0,他引:3
阐述了高性能PTC陶瓷材料制备的基本要点,并以基方固溶体化学组成、原材料选择、复合添加物改性以及特定烧结工艺等方面开展工作,制得了居里温度为90℃左右、室温体积电阻率为30Ω·cm,电阻率突变ρνmax/ρνmin>105、电阻率温度系数α≈15%/℃、耐电压强度≥150V/mm的高性能PTC陶瓷材料。此材料制得的元件能满足程控电话交换机过电流保护的要求。 相似文献
107.
108.
焊前处理方式对LF6铝合金扩散焊的影响 总被引:4,自引:0,他引:4
利用Gleeble-1500热/力模拟试验机,研究了LF6铝合金的扩散焊工艺,通过对焊接温度、压力、时间的调整和选用不同的料前处理方法,确定了最佳的扩散规范,研究结果表明:在一定的温度和时间范围内,LF65铝合金扩散焊接头的剪切哟度随焊接温度和时间的增加而提高;化学浸蚀法比机械打磨法能更有效的去除铝合金表面的氧化膜;在现有试验条件下,得到LF6铝合金扩散焊的最佳规范参数,搭接试扩散焊接头的剪切强度 相似文献
109.
Anatoly M. Dolgonosov Ruslan Kh. Khamizov Anna N. Krachak Andrei G. Prudkovsky 《Reactive and Functional Polymers》1995,28(1)
A model for multispecies ion-exchange kinetics based on the Nernst-Planck equation is suggested. It is analyzed in comparison with the “locally-determinate” model described by Hwang and Helfferich [1]. The model makes possible simple computation. The conditions for the occurrence of unusual kinetic curves with a maximum are clarified. The proposed model is developed for different types of kinetic problems and verified by the experimental investigation of a kinetics in ternary systems. 相似文献
110.
采用扫描电镜、能谱分析、X射线衍射和示差扫描量热分析研究了具有较大负混合焓的Al_xCu_(1-x)对称扩散系合金的高能球磨固态合成反应。高能球磨时组元晶粒细化达纳米级,造成纳米晶界亚互溶,为室温固态合成反应创造了条件,球磨强度对反应进程影响显著,在x=0.3~0.7范围内仅形成一种金属间化合物。 相似文献