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131.
Jun‐Wei Wang Huai‐Ning Wu Han‐Xiong Li 《American Institute of Chemical Engineers》2013,59(7):2366-2378
The guaranteed cost distributed fuzzy (GCDF) observer‐based control design is proposed for a class of nonlinear spatially distributed processes described by first‐order hyperbolic partial differential equations (PDEs). Initially, a T–S fuzzy hyperbolic PDE model is proposed to accurately represent the nonlinear PDE system. Then, based on the fuzzy PDE model, the GCDF observer‐based control design is developed in terms of a set of space‐dependent linear matrix inequalities. In the proposed control scheme, a distributed fuzzy observer is used to estimate the state of the PDE system. The designed fuzzy controller can not only ensure the exponential stability of the closed‐loop PDE system but also provide an upper bound of quadratic cost function. Moreover, a suboptimal fuzzy control design is addressed in the sense of minimizing an upper bound of the cost function. The finite difference method in space and the existing linear matrix inequality optimization techniques are used to approximately solve the suboptimal control design problem. Finally, the proposed design method is applied to the control of a nonisothermal plug‐flow reactor. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2366–2378, 2013 相似文献
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Simulation of gas exothermic chemical reaction in porous media reactor with lattice Boltzmann method
Exothermic reactor is the main part in a chemical heat pump. It involves complex multi-component exothermal chemical reaction in catalyst-filled porous media. The lattice Boltzmann method (LBM) is developed to simulate the characteristics of fluid flow, heat and mass transfer coupling chemical reaction in the exothermic reactor of the isopropanol/acetone/hydrogen chemical heat pump system. Fractal theory is used to structure a porous medium model in the reactor. The simulation results show that LBM is suitable for the simulation and the conversion has an optimal value with different inlet velocities. 相似文献
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An experimental study of flow and heat transfer of supercritical carbon dioxide in multi-port mini channels under cooling conditions 总被引:1,自引:0,他引:1
This paper presents the fluid flow and heat transfer characteristics of supercritical CO2 in a horizontal multi-port extruded aluminum test section consisting of 10 circular channels with an inner diameter of 1.31 mm. Both local and average pressure drop and heat transfer coefficients were measured as CO2 was cooled in the multi-port circular channels with pressures ranging from 7.4 to 8.5 MPa, inlet fluid temperatures ranging from 22 to , and mass velocity ranging from 113.7 to 418.6 kg/m2 s. The results indicate that the operating pressure, the mass velocity and the temperature of CO2 had significant effects on fluid flow and heat transfer characteristics. The pressure drop and the average heat transfer coefficient increased greatly with increasing the average temperatures of CO2 in the near-critical region; the average heat transfer coefficient attained a peak value near the corresponding pseudocritical temperature; and the maximum heat transfer coefficient decreased as the pressure increased. Both the pressure drop and the heat transfer coefficient increased with the mass velocity, but decreased with the operating pressure. The measured average heat transfer coefficients were compared with the experimental data reported in the literatures and a large discrepancy was observed. Based on the experimental data collected in the present work, a new correlation was developed for forced convection of supercritical CO2 in horizontal multi-port mini channels under cooling conditions. 相似文献
136.
Wenbo Li Hongxue Zhang Liping Wang Canbin Ouyang Xiaokang Ding Hui Cao Huai Yang 《应用聚合物科学杂志》2007,105(4):2185-2189
Polymer‐dispersed liquid crystal (PDLC) films were prepared by the ultraviolet‐light‐induced polymerization of photopolymerizable monomers in nematic liquid crystal/monomer/chiral dopant composites, and the effect of the chiral dopant on the electro‐optical properties of the PDLC films was studied. It was demonstrated that the addition of a small amount of the chiral dopant increased the driving voltage somewhat but decreased the turn‐off time significantly. Furthermore, the transmittance of ultraviolet, visible, and near‐infrared light of the off state of PDLC films showing light scattering increased with increasing content of the chiral dopant, and the optimum electro‐optical properties of the PDLC films were obtained when the content of the chiral dopant was not more than 2 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
137.
利用金相显微镜、扫描电镜及透射电镜等测试手段研究了挤压温度对固溶态Mg-2.0Zn-0.5Zr-3.0Gd镁合金显微组织的影响。同时,采用浸泡实验和电化学测试等方法研究了合金在模拟体液中的腐蚀行为。结果表明:挤压态合金主要由大的变形晶粒和动态再结晶晶粒组成,析出相由纳米级的棒状(Mg, Zn)3Gd相和颗粒状的Mg2Zn11相组成。挤压温度在340~360 ℃时,合金中动态再结晶晶粒的体积分数随着挤压温度的升高而增加,腐蚀速率随着挤压温度的升高而降低。当挤压温度为360 ℃时,合金发了完全动态再结晶,具有较好的耐腐蚀性,静态腐蚀速率为0.527 mm/y,腐蚀形式为均匀腐蚀。当温度升高至380 ℃时,部分动态再结晶晶粒发生异常长大现象,导致腐蚀速率随着挤压温度的升高而升高。 相似文献
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溶血磷脂的制备及其性能研究 总被引:1,自引:1,他引:1
溶血磷脂可通过磷脂酶A_2的催化而获得。酶浓度、钙离子浓度、温度和pH对溶血磷脂转化率都有影响.对溶血磷脂性能的研究表明,溶血磷脂的乳化能力、乳化液在高温和低温下、在不同pH条件下的稳定性都明显高于普通磷脂,并且具有较强的广谱抗菌能力. 相似文献
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