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排序方式： 共有138条查询结果，搜索用时 15 毫秒
1.
质子交换膜中的传质分析 总被引：1，自引：0，他引：1
质子交换膜燃料电池是最有应用前景的汽车动力替代系统。质子交换膜中的传质是质子交换膜燃料电池性能的控制因素之一。论文从宏观和微观角度分析了质子交换膜中的质子和水分的传递机理,分析了操作参数对质子在质子交换膜中传递的影响。研究发现:外载荷对质子和水分在质子交换膜中的传递有很大影响;（H5O2）+是水合质子的主要结构形式;通过（H5O2）+中氢氧键不断形成与断裂,电荷在质子交换膜中得以传递。研究结果对理解质子交换膜中的传质机理及其推广应用具有积极意义。 相似文献
2.
《International Journal of Solids and Structures》1999,36(21):3215-3237
This work presents a novel formulation of the scaling function of the intrinsic timescale. The new formulated scaling function and the rate-sensitivity function are used in theendochronic theory to simulate the rate-dependent elasto-plastic behaviors of materials. Severalcases of rate-dependent elasto-plastic material responses are discussed separately. Experimentaldata found in literature of 304 stainless steels and Ti7Al2Cb1Tatitanium alloy for rate-dependent elasto-plastic responses are used for comparison. It is shownthat the theory adequately simulates the experimental results. 相似文献
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With the reduction of crude oil throughout the world, enhance oil recovery technology has become a major oil research topics, which can greatly increase the recovery ratio of the crude oil before the dawning of renewable energy era. Near-well ultrasonic processing technology, as one new method, has attracted more attention for Enhanced Oil Recovery due to its low cost, good applicability and no environmental pollution in recent rears. There are two important relevant aspects about Near-well ultrasonic processing technology: (a) how to enhance the oil flow through the rocks into the pumping pool and (b) how to reduce the oil viscosity so that it can be easier to pump. Therefore, how to design a high-power ultrasonic equipment with excellent performance is crucial for Near-well ultrasonic processing technology. In this paper, recent new high-power ultrasonic transducers for Near-well ultrasonic processing technology are summarized. Each field application of them are also given. The purpose of this paper is to provide reference for the further development of Near-well ultrasonic processing technology.With the reduction of crude oil throughout the world, enhance oil recovery technology has become a major oil research topics, which can greatly increase the recovery ratio of the crude oil before the dawning of renewable energy era. Near-well ultrasonic processing technology, as one new method, has attracted more attention for Enhanced Oil Recovery due to its low cost, good applicability and no environmental pollution in recent rears. There are two important relevant aspects about Near-well ultrasonic processing technology: (a) how to enhance the oil flow through the rocks into the pumping pool and (b) how to reduce the oil viscosity so that it can be easier to pump. Therefore, how to design a high-power ultrasonic equipment with excellent performance is crucial for Near-well ultrasonic processing technology. In this paper, recent new high-power ultrasonic transducers for Near-well ultrasonic processing technology are summarized. Each field application of them are also given. The purpose of this paper is to provide reference for the further development of Near-well ultrasonic processing technology 相似文献
6.
The electronic properties of SiC nanotubes (SiCNTs) under external transverse electric field were investigated using density functional theory. The pristine SiCNTs were semiconductors with band-gaps of 2.03, 2.17 and 2.25 eV for (6,6), (8,8) and (10,10) SiCNTs, respectively. It was found the band gaps was reduced with the external transverse electric filed applied. The (8,8) and (10,10) SiCNTs changed from semiconductor to metals as the intensity of electric field reached 0.7 and 0.5 V/Å. The results indicate that the electronic properties of SiCNTs can be tuned by the transvers electric field with integrality of the nanotubes. 相似文献
7.
From a microscopic point of view, the real contact area between two rough surfaces is the sum of the areas of contact between facing asperities. Since the real contact area is a fraction of the nominal contact area, the real contact pressure is much higher than the nominal contact pressure, which results in plastic deformation of asperities. As plasticity is size dependent at size scales below tens of micrometers, with the general trend of smaller being harder, macroscopic plasticity is not suitable to describe plastic deformation of small asperities and thus fails to capture the real contact area and pressure accurately. Here we adopt conventional mechanism-based strain gradient plasticity (CMSGP) to analyze the contact between a rigid platen and an elasto-plastic solid with a rough surface. Flattening of a single sinusoidal asperity is analyzed first to highlight the difference between CMSGP and J2 isotropic plasticity. For the rough surface contact, besides CMSGP, pure elastic and J2 isotropic plasticity analysis is also carried out for comparison. In all cases, the contact area A rises linearly with the applied load, but with a different slope which implies that the mean contact pressures are different. CMSGP produces qualitative changes in the distributions of local contact pressures compared with pure elastic and J2 isotropic plasticity analysis, furthermore, bounded by the two. 相似文献
8.
《Chemical physics letters》1987,134(4):379-384
The influence of viscosity on the electronic relaxation of pinacyanol in alcoholic solutions has been determined by recording, with picosecond and nanosecond resolution, the fluorescence decay at various temperatures. The results are interpreted with the aid of a model of electronic relaxation implying a molecular conformational change with no internal potential barrier and with a Boltzmann equilibrium distribution of the initial configuration. Furthermore, fluorescence depolarization analysis indicates that the reorientational relaxation of the molecule takes place on a time scale much greater than that characterizing the intramolecular geometrical change. 相似文献
9.
《Chemical physics letters》1986,125(3):246-250
Intrapolymer electron transfer from the higher excited to the neighbouring ground states of pyrenyl chromophores occurs rapidly in polyesters. This charge separation process is characteristic of polymers and was not observed in the studies on bichromophoric model compounds. Relative geometrical structures of the relevant chromophores are discussed by comparing the results with those of polypeptides having the same chromophore. 相似文献
10.
Nonlinear Dynamics - Piezoelectric ceramic actuators show nonlinear hysteresis characteristics due to material properties. In order to modify the inverse piezoelectric effect as an ideal linear... 相似文献