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991.
Optimal Conditions for Preparing Ultra-Fine CeO2 Powders in A Submerged Circulative Impinging Stream Reactor 总被引:1,自引:0,他引:1
Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3·6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 0.25 and 0.3 mol·L-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g·L-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r·min-1, 80 ℃, 20 min, 5~6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8~2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point group was O5H-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR). 相似文献
992.
993.
994.
对EDGE技术进行了介绍,并对EDGE技术的现网测试进行了说明,对于EDGE技术的功能特点及现网应用的模型、性能指标进行了研究和探讨。 相似文献
995.
996.
The authors have proposed some modifications of the reduced update Kalman filter (RUKF) as applied to filtering of images corrupted by additive noise. They have reduced the computational complexity by reducing the state dimensionality. By doing so, it is shown that the computational requirement is reduced by an order of magnitude while the loss of performance is only marginal. Next, the RUKF is modified using the score function based approach to accommodate non-Gaussian noise. The image is modeled as a nonstationary mean and stationary variance autoregressive Gaussian process. It is shown that the stationary variance assumption is reasonable if the nonstationary mean is computed by an edge and detail preserving efficient estimator of local nonstationary mean. Such an estimator, called the hybrid multistage medium D (HMSMD) filter, is also described. Detailed experimental results are provided which indicate the success of the new filtering scheme 相似文献
997.
万安水利枢纽底孔坝段中隔墙流激振动响应分析 总被引:3,自引:0,他引:3
研究了万安水利枢纽底孔坝段中隔墙在水流脉动壁压作用下的结构随机振动问题,进行了一种泄流工况下的隔墙结构流激振动响应统计量的理论计算,模拟计算了隔墙-水流-基础耦合系统固有频率对流激振动响应的影响,并对水流脉动壁压随机荷载作用下的结构动力可靠度进行了理论分析。 相似文献
998.
Horng-Wen Wu Mign-Che Liu 《International Communications in Heat and Mass Transfer》1996,23(8):1163-1172
Experiments were performed to investigate the effect of relative humidity on heat transfer characteristics in source arrays for different airflow velocities. The source arrays were heat-generating, block-like elements affixed to an insulation substrate. Nusselt number distribution of components exhibited stronger dependence on velocity and same dependence on the row number and relative humidity. The correlations for the effects of Reynolds number and relative humidity on Nusselt number in different regions are presented. The fittness of the correlations are indicated from a comparison with experimental data. 相似文献
999.
量子卡诺制冷机制冷率与熵产率的协调优化性能 总被引:3,自引:2,他引:1
研究了内可逆谐振子量子卡诺制冷机的整体最优性能。得到了协调优化目标函数E最大时量子制冷机的制冷系数以及最佳制冷率和熵产率。 相似文献
1000.
This paper presents a new formulation useful for modeling waveguides constructed from lossy inhomogeneous anisotropic media. Our approach is based on a pair of Sturm-Liouville type wave equations that have been derived to handle inhomogeneous, diagonalized complex permittivity and permeability tensors. The method of lines is then applied to these wave equations, and related field equations, creating an indirect eigenvalue problem that correctly models this class of structure. Some refinements to the method of lines are also proposed, particularly, regarding the construction of the modal matrices found in the eigenvalue problem. Using our approach, modal dispersion curves have been computed for millimeter-wave and optical structures. Comparisons made with results available from the literature validate our approach 相似文献