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121.
122.
以氮气为气相、蒸馏水为液相、铜粉为固相构建了的气-液-固三相流化床冷态实验装置,流化床反应器内径为50 mm、高为500 mm.采用Hilbert-Huang Transform分析了布风板上表面处压力脉动信号,考察了布风板压差和床内两固定测点间压差随气体流速的变化关系,使用降速法得到了气-液-固三相流化床的最小流化速度,并通过同步图像采集验证了该最小流化速度.结果表明:气体流速为14.85 mm/s时,固体颗粒之间碰撞剧烈,气、液、固三相混合均匀;随着气体流速的增加,两固定测点间压降呈现先降低,后增加,最后又降低的变化趋势;气-液-固三相流化床的最小流化速度约为17.4 mm/s. 相似文献
123.
Yonggang Wang Xinfu Pang Zailin Piao Jingjing Fang Jun Fu Tianyou Chai 《中国化学工程学报》2015,23(12):2075-2086
The control objective of the forced-circulation evaporation process of alumina production is not only to avoid large fluctuations of the level, but also to ensure the product density to track its setpoint quickly. Due to the existence of strong coupling between the level loop and the product density loop, and high nonlinearities in the process, the conventional control strategy cannot achieve satisfactory control performance, and thus the production demand cannot bemet. In this paper, an intelligent decoupling PID controller including conventional PID controllers, a decoupling compensator and a neural feedforward compensator is proposed. The parameters of such controller are determined by generalized predictive control law. Real-time experiment results show that the proposed method can decouple the loops effectively and thus improve the evaporation efficiency. 相似文献
124.
Mei Jing Piao Kyoung Ah Kang Rui Zhang Dong Ok Ko Zhi Hong Wang Keun Hwa Lee Weon Young Chang Sungwook Chae Youngheun Jee Taekyun Shin Jae Woo Park Nam Ho Lee Jin Won Hyun 《Food chemistry》2009
The antioxidant potential of 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG), isolated from Elaeocarpus sylvestris var. ellipticus, was investigated by various established systems based on cell-free and cell system experiments, such as radical detection, antioxidant enzyme assay, lipid peroxidation detection, and cell viability assay. PGG was found to quench the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and intracellular reactive oxygen species. PGG recovered the cellular antioxidant enzyme activities of superoxide dismutase, catalase, and glutathione peroxidase, which were reduced by H2O2 treatment, thereby resulting in the inhibition of lipid peroxidation. Cytoprotective effects of PGG were based on the results of DNA fragmentation, mitochondrial membrane potential (Δψ), apoptotic body formation, and caspase-3 activity. The results suggest that PGG protects cells against H2O2-induced cell damage via antioxidant properties. 相似文献
125.
126.
Zhang A Piao D 《Journal of the Optical Society of America. A, Optics, image science, and vision》2012,29(7):1445-1458
Part IV examines frequency-domain photon diffusion in a homogeneous medium enclosed by a "concave" circular cylindrical applicator or enclosing a "convex" circular cylindrical applicator, both geometries being infinite in the longitudinal dimension. The aim is to assess by analogical and finite-element methods the changes of AC amplitude, modulation depth, and phase with respect to the line-of-sight source-detector distance for a source and a detector located along the azimuthal or longitudinal direction on the concave or convex medium-applicator interface. By comparing to their counterparts along a straight line on a semi-infinite medium-applicator interface, for the same line-of-sight source-detector distance, it is found that: (1) the decay-rate of AC photon fluence is smaller along the azimuthal direction and greater along the longitudinal direction on the concave interface, (2) the decay-rate of AC photon fluence is greater along the azimuthal direction and smaller along the longitudinal direction on the convex interface, (3) the modulation depth along both azimuthal and longitudinal directions decays more slowly on the concave interface and faster on the convex interface, and (4) the phase along both azimuthal and longitudinal directions increases more slowly on the concave interface and faster on the convex interface. 相似文献
127.
针对采用静态检测手段对机床回转误差的检测精度不高,本文提出把误差分离技术用于机床主轴回转误差的检测,把工件的圆度误差从误差中分离出来,从而提高了机床回转误差的检测精度。 相似文献
128.
Zhong-yu Piao Bin-shi Xu Hai-dou Wang Dong-hui Wen 《Fusion Engineering and Design》2013,88(11):2933-2938
The objective of the present study is to characterize the Fe-based alloy coating deposited by the supersonic plasma spraying process. The condition of the melting particles was in situ monitored. The microstructure of the coating was examined by scanning electron microscope and high resolution transmission electron microscope. The phase composition was examined by X-ray diffraction. The microhardness and porosity were also measured, respectively. Results show the prepared coatings have excellent properties, such as few oxides, high microhardness and a low porosity amount. At the same time, a mass of amorphous/nanocrystalline phases was found in the coating. The mechanism of the formation of amorphous/nanocrystalline phases was investigated. The appropriate material composition of spraying material and flash set process of plasma spraying are the key factors. Moreover, the mechanism for oxidation resistance is also investigated, where the separation between melting metal and oxygen by the formation of SiO2 films is the key factor. 相似文献
129.
As one form of the energy resources, coal is becoming more and more important. Due to the particularity in coal mine production, mine accidents some time occur in countries all over the world, which result in large casualties and economic losses. As equipment that can provides the miners with an emergency shelter when the coal mine accidents occur, the underground coal mine refuge chamber is paid more and more attention by coal mine enterprises, and the application of the refuge chamber is increasingly widespread. The general functions, the classification, and the successful applications of the underground coal mine refuge chamber are illustrated first, and the research significance on the underground coal mine refuge chamber is stated. Following, the development status quo at home and abroad for the refuge chamber is introduced. Then, the implementation methods for the key functions of the underground coal mine refuge chamber are demonstrated. Finally, the prospect for the development of the underground coal mine refuge chamber is stated. 相似文献
130.
In this study, transesterification of soybean oil to biodiesel using CaO as a solid base catalyst was studied. The reaction mechanism was proposed and the separate effects of the molar ratio of methanol to oil, reaction temperature, mass ratio of catalyst to oil and water content were investigated. The experimental results showed that a 12:1 molar ratio of methanol to oil, addition of 8% CaO catalyst, 65 °C reaction temperature and 2.03% water content in methanol gave the best results, and the biodiesel yield exceeded 95% at 3 h. The catalyst lifetime was longer than that of calcined K2CO3/γ-Al2O3 and KF/γ-Al2O3 catalysts. CaO maintained sustained activity even after being repeatedly used for 20 cycles and the biodiesel yield at 1.5 h was not affected much in the repeated experiments. 相似文献