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排序方式: 共有228条查询结果,搜索用时 15 毫秒
1.
The effect of mixing on Co‐precipitation and evolution of microstructure of Cu‐ZnO catalyst
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Xin Jiang Xiangfei Qin Chen Ling Zhiyong Wang Jiangang Lu 《American Institute of Chemical Engineers》2018,64(7):2647-2654
The influence of feeding point in conventional stirred tank reactor and flow characteristics in micro‐reactor on the microstructure of Cu‐ZnO catalyst was studied. Cu‐Zn distribution in co‐precipitate was characterized by EDS and Zn fraction in zincian malachite was estimated from the 20 peak shift in XRD pattern. The theory analysis and experimental results, combining with measurement of segregation index, show that the contact pattern and mixing of reactants in precipitation process determine the uniformity of Cu‐Zn distribution in initial co‐precipitates at the micro‐scale. The uniform Cu‐Zn distribution is favorable for the formation of zincian malachite with higher Zn fraction, whereas the uneven distribution could lead to either zincian malachite with lower Zn fraction or aurichalcite‐like nonmalachite. These differences in the precursor structure act on subsequent calcination and reduction, as well as their products. Along this path, mixing affects the evolution of the catalyst microstructure by means of Cu‐Zn distribution. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2647–2654, 2018 相似文献
2.
Zhuokai Zhuang Jingtian Yan Chenglang Sun Haiqiang Wang Yuejun Wang Zhongbiao Wu 《中国化学工程学报》1982,28(9):2438-2446
For the nitrogen oxide removal processes, high performance gas mixer is deeply needed for the injection of NH3 or O3. In this study, a new type of double swirl static mixer in gas mixing was investigated using computational fluid dynamics (CFD). The results obtained using Particle Image Velocimetry (PIV) correlated well with the results obtained from simulation. The comparisons in pressure loss between the experimental results and the simulation results showed that the model was suitable and accurate for the simulation of the static mixer. Optimal process conditions and design were investigated. When L/D equaled 4, coefficient of variation (COV) was <5%. The inlet velocity did not affect the distributions of turbulent kinetic energy. In terms of both COV and pressure loss, the inner connector is important in the design of the static mixer. The nozzle length should be set at 4 cm. Taking both COV and pressure loss into consideration, the optimal oblique degree is 45°. The averaged kinetic energy changed according to process conditions and design. The new static mixer resulted in improved mixing performance in a more compact design. The new static mixer is more energy efficient compared with other SV static mixers. Therefore, the double swirl static mixer is promising in gas mixing. 相似文献
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针对一类具有范数有界不确定性的连续系统和二次矩阵不等式区域,
考虑系统具有方差和区域极点约束 的输出反馈控制器设计问题.
为此首先导出闭环系统区域稳定的充分必要条件.
然后用线性矩阵不等式方法给出输出反馈控制器存在的一个充分条件.
在此充分条件下闭环系统是鲁棒区域稳定的且具有H-infinity性能以及当干扰为白噪声信号时其稳态状态方差有限.
接下来用矩阵分解方法给出输出反馈控制器增益矩阵的求解过程.
最后通过一个仿真实例说明本文所提出的控制器设计方法的有效性. 相似文献
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涡街流量计是目前发展势头十分良好的流量计,在管道流量测量中得到广泛应用,并已跻身通用流量计之列.但涡街流量计尚属发展中流量计,其理论基础和实践经验较薄弱,在使用中,还会出现一些预想不到的问题.为解决这些问题,国内外科研工作者进行了大量的研究工作,并取得了一定进展.从涡街流量计中旋涡分离、涡街发生体形状、涡街信号检测方法及涡街信号分析和处理几方面对国内外研究现状进行了综述,指出研究中存在的难点及今后的研究方向,并提出一种利用涡街原理的新质量流量测量方法. 相似文献
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Inspired by the biological RNA, a circular genetic operators based RNA genetic algorithm (cRNA-GA) is proposed to estimate the model parameters of the proton exchange membrane fuel cell (PEMFC). To maintain the population diversity and avoid premature convergence, we design the novel genetic operator of the double-loop crossover operator. To allow the algorithm to jump out of local optima, the adaptive mutation probabilities are presented and the stem-loop mutation operator is adopted with the other mutation operators. The simulated annealing method is also incorporated into the cRNA-GA to improve local search ability. Performance tests conducted on some typical benchmark functions have witnessed the validity of cRNA-GA. The cRNA-GA is also applied to estimate the parameters of the PEMFC model and the satisfactory results have shown its effectiveness. 相似文献
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Based on our recent study on probability distributions for evolution in extremal optimization (EO),we propose a modified framework called EOSAT to approximate ground states of the hard maximum satisfia... 相似文献
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This paper proposes a practical generalized predictive control(GPC)algorithm based on online least squares support vector machines(LS-SVM)which can deal with nonlinear systems effectively.At each sampling period the algorithm recursively modifies the model by adding a new data pair and deleting the least important one out of the consideration on realtime property.The data pair deleted is determined by the absolute value of lagrange multiplier from last sampling period.The paper gives the recursive algorithm of model parameters when adding a new data pair and deleting an existent one,respectively,and thus the inversion of a large matrix is avoided and the memory can be controlled by the algorithm entirely.The nonlinear LS-SVM model is applied in GPC algorithm at each sampling period.The experiments of generalized predictive control on pH neutralizing process show the effectiveness and practicality of the proposed algorithm. 相似文献
10.
A novel optimal Finite Word Length (FWL) controller design is proposed in the framework of μ theory. A computationally tractable close-loop stability measure with FWL implementation considerations of the controller is derived based on the μ theory, and the optimal FWL controller realizations are obtained by solving the resulting optimal FWL realization problem using linear matrix inequality techniques. 相似文献