基于多元线性回归分析的焦炭质量预测研究

利用某焦化厂2014—2015年生产中配合煤与焦炭质量指标的实际数据,从数学角度出发,选取配合煤的主要指标,建立数学模型,通过曲线回归拟合以及多元线性回归法建立预测方程,并对方程进行残差分析和显著性检验;应用检验结果表明,所得方程预测效果良好,可以采用该模型预测焦炭质量。     

水-乙醇-甲基异丁基甲酮体系液液相平衡数据的测定与关联

在常压下测定了水-乙醇-甲基异丁基甲酮体系在308.15,318.15,328.15 K的液液相平衡数据。用Hand方程和Othmer-Tobias方程对实验数据进行拟合,结果表明:Hand方程拟合效果优于Othmer-Tobias方程。采用NRTL模型和UNIQUAC模型对实验数据进行了关联,回归得到了该三元物系的二元交互参数;并对此物系的相平衡数据进行了预测,由模型计算值和实验值的均方根偏差知,NRTL模型能更好地与实验数据吻合。     

APG工艺用环氧树脂体系的固化及流变模型

研究了自动压力凝胶工艺用环氧树脂混合体系在动态升温过程中的固化反应,采用Malek法确定了动力学模型并预测了相应的参数。该体系符合两参数自催化SB模型。用旋转流变仪测定了该体系在动态升温过程中黏度相对于温度的变化曲线,采用WLF和Macosko混合方程描述该体系的化学流变模型,用非线性拟合方法预测了模型中的参数。模型预测与实验数据比较吻合。     

基于不同状态方程预测气体水合物相平衡条件

气相逸度的计算结果会直接影响气体水合物相平衡条件的预测精度。基于Chen-Guo模型,选取RK、SRK、PR以及PT四种状态方程计算逸度,分别对甲烷、乙烷以及二氧化碳三种不同气体水合物在不同温度范围内的相平衡条件进行计算。结果表明：纯水条件下,RK方程最适合预测甲烷水合物相平衡条件,而PR方程更适合预测乙烷及二氧化碳水合物相平衡条件;对于冰中,SRK方程适合预测甲烷水合物的相平衡条件,PR方程适合预测乙烷水合物的,而RK方程更适合二氧化碳水合物的;对于甲烷水合物,低于218.2 K的预测是导致模型预测精度偏低的原因;对于乙烷水合物,需要提高低于230.2 K的预测精度;对二氧化碳水合物而言,提高对低于270.7 K的预测可以进一步提高模型预测精度。     

基于回归分析和GA-BP神经网络算法的3D打印件弯曲性能预测

为进一步探究熔融沉积成型(FDM) 3D打印参数和制件弯曲性能之间的关系,创建合理的FDM 3D打印制件弯曲强度预测模型。根据正交试验L16 (45)的设计原则和神经网络算法模型的构建要求,按照不同分层高度、填充密度、打印温度、打印速度以及外壳厚度五种因素,制备25组试验试样,并进行弯曲性能检测。随后通过建立GA-BP神经网络模型、传统BP神经网络模型以及多元回归方程模型,分别对FDM 3D打印制件弯曲性能进行预测,并将预测数据与试验测试数据进行对比。通过对比发现,GA-BP神经网络模型预测数据与试验测试数据更为接近,其平均误差为3.71%,且误差值整体波动最小,BP神经网络模型与多元回归方程模型预测精度相差不大,BP神经网络模型预测平均误差为8.05%,多元回归方程模型预测平均误差为9.07%,但多元回归方程误差值整体波动最大。因此,采用GA遗传算法优化后的BP神经网络模型在进行FDM 3D打印制件弯曲性能预测方面具有更高的精度和更良好的稳定性。     

基于不同状态方程预测气体水合物相平衡条件

气相逸度的计算结果会直接影响气体水合物相平衡条件的预测精度。基于Chen-Guo模型,选取RK、SRK、PR以及PT四种状态方程计算逸度,分别对甲烷、乙烷以及二氧化碳三种不同气体水合物在不同温度范围内的相平衡条件进行计算。结果表明:纯水条件下,RK方程最适合预测甲烷水合物相平衡条件,而PR方程更适合预测乙烷及二氧化碳水合物相平衡条件;对于冰中,SRK方程适合预测甲烷水合物的相平衡条件,PR方程适合预测乙烷水合物的,而RK方程更适合二氧化碳水合物的;对于甲烷水合物,低于218.2 K的预测是导致模型预测精度偏低的原因;对于乙烷水合物,需要提高低于230.2 K的预测精度;对二氧化碳水合物而言,提高对低于270.7K的预测可以进一步提高模型预测精度。     

制冷剂比定压热容的计算分析

利用精确度高的P-R状态方程和M-H81状态方程,采用余函数法对制冷剂的比定压热容进行了理论推算和比较分析。文中选用了10种纯制冷剂和4种混合制冷剂进行了详细的计算和比较,计算结果表明:在气相区,2个状态方程模型的计算精度均在3%左右;在液相区,M-H81型方程模型明显优于P-R方程,其计算精度在10%以内。M-H81型方程模型比P-R方程优越,能更好地预测更宽广温度和压力范围的流体比定压热容。文中的工作初步验证了利用状态方程推算实际流体比定压热容的可行性,为其他基础物性的理论预测提供了坚实的理论思路。     

丙烯酰胺类水溶性聚合物共混水溶液黏度模型

针对丙烯酰胺类水溶性聚合物共混水溶液的黏度特点,结合流变仪测量数据,提出了一种半理论半经验模型,用于预测此类共混水溶液的黏度.基于Eyring绝对速率方程的黏度机理构建模型,使用Flory-Huggins方程(FH方程)反映共混过程的混合熵变化,再引入基团贡献模型和静电作用模型以表达混合焓变化.采用遗传算法对未知相互作...     

化工计算传质学的一个改进模型

计算传质学模型由浓度输运方程及其封闭方程和相应的计算流体力学模型组成。使用这一模型可同时计算出湍流传质扩散系数、三维浓度场和速度场分布。但刘伯潭提出的传质封闭方程c2-cε模式,形式复杂而且其模型常数均直接借鉴于传热研究;此外,由于计算流体力学模型对最终浓度场的预测结果有着重要的影响,所以有对其进一步改进的必要。文中对传质封闭方程进行了简化并重新确定了模型常数,而且对计算流体力学模型进行了改进使其预测结果与文献中的实验值符合得更好。通过与文献中的湍流传质扩散系数及浓度值的比较,证明了这一简化的可行性。     

基于主成分分析和PLS算法的弧线管污垢特性研究

搭建了弧线管污垢特性实验平台,用于测量相应的污垢参数。基于主成分分析理论和偏最小二乘算法(PLS)建立了弧线管的污垢特性方程。该方程以弧线管的出入口温度、壁温及流速等参数作为模型的自变量,以污垢热阻值作为因变量。利用交叉验证原则以提取最佳主成分个数。通过对预测方程的检验,结果表明:所建5自变量预测方程能较好地实现对弧线管污垢特性的预测,而且明显优于6自变量模型。     

Control of multivariable systems containing time delays using a multivariable smith predictor

A multivariable version of the classical Smith predictor is applied to a double effect evaporator containing time delays in the control variables and some of the output variables. As in the classical approach, the multivariable Smith predictor eliminates time delays from the characteristic equation of the closed-loop system. Simulation and experimental results for the pilot-scale evaporator are quite promising and demonstrate the feasibility of the multivariable Smith predictor for practical control problems.     

Economic model predictive control of nonlinear time‐delay systems: Closed‐loop stability and delay compensation

Closed‐loop stability of nonlinear time‐delay systems under Lyapunov‐based economic model predictive control (LEMPC) is considered. LEMPC is initially formulated with an ordinary differential equation model and is designed on the basis of an explicit stabilizing control law. To address closed‐loop stability under LEMPC, first, we consider the stability properties of the sampled‐data system resulting from the nonlinear continuous‐time delay system with state and input delay under a sample‐and‐hold implementation of the explicit controller. The steady‐state of this sampled‐data closed‐loop system is shown to be practically stable. Second, conditions such that closed‐loop stability, in the sense of boundedness of the closed‐loop state, under LEMPC are derived. A chemical process example is used to demonstrate that indeed closed‐loop stability is maintained under LEMPC for sufficiently small time‐delays. To cope with performance degradation owing to the effect of input delay, a predictor feedback LEMPC methodology is also proposed. The predictor feedback LEMPC design employs a predictor to compute a prediction of the state after the input delay period and an LEMPC scheme that is formulated with a differential difference equation (DDE) model, which describes the time‐delay system, initialized with the predicted state. The predictor feedback LEMPC is also applied to the chemical process example and yields improved closed‐loop stability and economic performance properties. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4152–4165, 2015     

EXACT LEAST SQUARES MULTI-STEP PREDICTION FROM NONLINEAR AUTOREGRESSIVE MODELS

Abstract. We obtain an integral equation recurrence relation for the optimal least squares predictor of a nonlinear autoregressive time series model. Numerical solutions are given for a first order threshold model up to three steps ahead.     

精制剂用量的计算方法

经过数学推导,得出了根据化盐水中的ＮａＣｌ质量浓度来计算精制剂用量的配碱公式,并作了修正,分析了配碱公式的操作弹性。     

Nonlinear state estimation and control of a batch reactive distillation

This paper deals with the advanced adaptive control of a batch reactive distillation (RD) column for the production of ethyl acetate. The nonlinear adaptive control law consists of the generic model controller (GMC) and an adaptive state estimator (ASE). In the first part of the present work, the design approach of the ASE scheme in two different forms, namely ASE1 and ASE2, has been addressed for a batch reactive rectifier. The predictor model of both the ASE estimators includes only a component mole balance equation around the condenser-reflux drum system and an extra state equation having no dynamics, and therefore, there is a large process/predictor mismatch. In presence of this structural discrepancy, the adaptive estimation schemes compute the imprecisely known parameters quite accurately based on the measured distillate composition under initialization error, disturbance and uncertainty. In the subsequent part, the adaptive GMC–ASE1 control structure has been formulated for the sample reactive column. This nonlinear control strategy shows comparatively better closed-loop performance than the gain-scheduled proportional integral (GSPI) controller due to the exponential error convergence capability of the estimation scheme and the high-quality control of the GMC law.     

A chaos‐based iterated multistep predictor for blast furnace ironmaking process

The prediction and control of the inner thermal state of a blast furnace, represented as silicon content in blast furnace hot metal, pose a great challenge because of complex chemical reactions and transfer phenomena taking place in blast furnace ironmaking process. In this article, a chaos‐based iterated multistep predictor is designed for predicting the silicon content in blast furnace hot metal collected from a pint‐sized blast furnace. The reasonable agreement between the predicted values and the observed values indicates that the established high dimensional chaotic predictor can predict the evolvement of silicon series well, which conversely render the strong indication of existing deterministic mechanism ruling the dynamics of complex blast furnace ironmaking process, i.e., a high‐dimensional chaotic system is suitable for representing the blast furnace system. The results may serve as guidelines for characterizing blast furnace ironmaking process, an extremely complex but fascinating field, with chaos in the future investigation. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

应力敏感油藏中考虑启动压力和二次梯度的非线性渗流模型

从质量守恒原理出发,详细推导出了应力敏感油藏中考虑启动压力梯度和二次压力梯度非线性不稳定渗流偏微分方程。并通过变量代换,将渗流方程拟线性化,最后利用Douglas-Jones预估一校正法求得模型的数值解。讨论了不同参数变化时井底压力的变化规律,做出了典型压力曲线图版。曲线在形态和特征上与线性模型曲线明显不同,不再遵循“0．5线”规则和“单位斜率”规则。启动压力梯度因子影响压力降落曲线晚期上翘段的斜率,该因子越大,曲线上翘程度越大,当其很小时,压力导数曲线出现水平直线段。     

煤矸石灰分与发热量的回归分析及其运用

利用回归分析法对煤矸石的灰分和发热量进行分析,求得它们的线性回归方程,对回归方程的显著性进行检验,从而证明推导出的回归方程运用于生产实践中的置信度。     

高效液相色谱法测定异菌脲悬浮剂的含量

介绍了采用反相高效液相色谱法,使用C18色谱柱,以乙腈一水为流动相,流速为1．0min／mL,在吸收波长为220nm下,外标法定量检测异菌脲的含量。本方法的线性方程为：y=38608824x＋107628,R2=0．9986,相对标准偏差为0．11％,回收率在98．2％-100．9％之间。     

全氟丁基乙烯气相色谱分析方法研究

以气相色谱法分析全氟丁基乙烯的含量,通过采用封口顶空瓶装液体样,进样针液体直接进样,考察了色谱柱、色谱柱柱温等条件对PFBE分析的影响.结果表明,使用SPB-5毛细管柱,柱温40℃保持2min,以5℃/min升至150℃,保持5min;进样量在0.1-0.4μL内,方程呈良好的线性关系,相对标准偏差0.017%,数据稳...