RIBBING INSTABILITY IN COATING FLOWS: EFFECT OF POLYMER ADDITIVES

Data are presented which show the effect of dilute addition of polymer on the ribbing instability in coating flows. A qualitative model which treats the growth of a disturbance as an extensional flow suggests that elasticity is a destabilizing factor, in agreement with the observations.     

基于神经网络的容错控制方法在CSTR中的应用研究

针对一个连续搅拌釜式反应器,将容错控制(FTC)与故障诊断(FDD)方法相结合,提出了一种关于传感器故障的容错控制方法。用RBF神经网络建立传感器故障模型,对系统的状态和故障参数进行在线估计,将故障参数与修正的Bayes分类算法相结合,进行传感器故障的在线检测、分离和估计。当传感器发生故障时,认为是系统处于不同的工作模式,利用估计出的状态值在线训练神经网络控制器的参数,使网络适应系统新的(故障)状态,维持系统性能。仿真结果表明,方法具有很强的关于传感器故障的容错能力。     

ADAPTIVE CONTROL OF A CSTR WITH INPUT CONSTRAINTS

Control of a nonisothermal CSTR with input constraints has been developed. The control system is a multivariable nonlinear one. Indirect adaptive control is applied. An algorithm based on an output direction vector is proposed for determining the constrained input vector. By using the proposed method, it is possible to operate the reactor at an unstable steady state within a stable limit cycle.     

ON THE GLOBAL STABILIZATION OF nth-ORDER REACTIONS

It is shown that n^th-order reactions (n ≥ 0) are globally stabilized by employing a reference model controller.     

Treatment of landfill leachate by Fenton's reagent in a continuous stirred tank reactor

The treatment of landfill leachate by Fenton process was carried out in a continuous stirred tank reactor (CSTR). The effect of operating conditions such as reaction time, hydraulic retention time, pH, H(2)O(2) to Fe(II) molar ratio, Fenton's reagent dosage, initial COD strength, and temperature on the efficacy of Fenton process was investigated. It is demonstrated that Fenton's reagent can effectively degrade leachate organics. Fenton process reached the steady state after three times of hydraulic retention. The oxidation of organic materials in the leachate was pH dependent and the optimal pH was 2.5. The favorable H(2)O(2) to Fe(II) molar ratio was 3, and organic removal increased as dosage increased at the favorable H(2)O(2) to Fe(II) molar ratio. Temperature gave a positive effect on organic removal.     

D002强酸性离子交换树脂催化醇醛缩合生产甲缩醛的工艺模拟

基于连续搅拌反应器(CSTR),对D002离子交换树脂作催化剂反应合成甲缩醛的过程进行了模拟。在确定了参数的甲缩醛反应动力学模型的基础上,用Aspen Plus软件建立了CSTR流程。在甲醇进料流量为2kmol/h、甲醛进料流量为1kmol/h、水进料流量为4.44mol/h的条件下研究了催化剂用量、反应温度、反应器体积、反应器操作压力等因素对甲缩醛收率的影响。得到的优化工艺条件如下:催化剂质量分数为10%,反应温度为100℃,反应器体积为10m3,醇醛物质的量比为2:1,反应器操作压力为常压。采用优化的工艺参数后甲缩醛收率可达58.0%。     

Impact of 5-hydroxy methyl furfural on continuous hydrogen production from galactose and glucose feedstock with periodic recovery

A continuous stirred tank reactor (CSTR) was operated for more than 120 days with fixed hydraulic retention time of 6 h at mesophilic temperature along with a periodic recovery phase towards hydrogen production and stimulated by the existence of 5-hydroxy methyl furfural concentration (5-HMF). Interestingly, CSTR mixed with a small amount of 5-HMF, range of 0.3–0.6 g/L showed at least 50% higher hydrogen production rate than control without 5-HMF. However, when 5-HMF concentration was higher than 0.6 g/L, the performance was significantly inhibited. The bacterial community shifted by 5-HMF from Clostridium-dominated to Lactobacillus-dominated population. Regardless of the remain 5-HMF concentration in CSTR, the microbial community and hydrogen producing performance were restored by stop mixing the 5-HMF from the feedstock. The high-rate hydrogen production of 20.0 ± 1.8 L H₂/L/d was achieved in the presence of 5-HMF using the threshold information and recovery strategy.     

基于粒子群优化的神经网络容错控制算法

针对一类非线性系统的传感器故障,将故障诊断与容错控制方法相结合,提出了一种容错控制方法。用BP网络建立传感器故障模型,并用粒子群算法来训练BP网络的参数,在线估计系统的状态和故障参数。然后将故障参数与修正的Bayes分类算法相结合,对传感器故障在线检测、分离和估计,通过补偿算法,实现容错控制。对连续搅拌釜式反应器（CSTR）的仿真结果表明,该方法收敛性好,对传感器故障具有很强的容错能力。     

CMAC神经元网络在CSTR系统建模中的应用

目前正在兴起和发展的人工智能和人工神经网 络的研究,为复杂非线性系统的控制开辟了一条新路．本文将CMAC神经元网络用于CSTR系统 的建模,取得了很好的仿真效果．     

有色噪声条件下的子空间辨识改进方法及应用

针对工业生产过程中噪声往往为有色噪声的情况,提出一种改进的子空间辨识方法。传统的子空间辨识方法在系统存在有色噪声时辨识效果不佳,改进方法则采用变换系统模型形式来克服有色噪声对系统的影响,在辨识时直接利用变换系统模型后的数据得到系统较为准确的状态空间模型,实践证明,状态空间模型更适用于工业过程。连续搅拌反应釜（CSTR）系统是一类典型的工业生产系统,将子空间辨识方法应用于CSTR过程的仿真实验,通过比较改进前和改进后的系统预测误差,验证了所提方法的有效性。