超定系统的代谢通量分析算法研究

With the xanthan synthesis in Xanthomonas campestris as an example,two methods for metabilic flux analysis of overdetermined system,the experimental data error minimization method and the equation error minimization method,are compared from their mathematical basis,rationality of the results and the easiness of computation.The results show that the experimental data error minimization method is appropriate in metabolic flux analysis of overdetermined system.     

Investigation of the Metabolic Flux Analysis Method for Overdetermined System

With the xanthan synthesis in Xanthomonas campestris as an example, two methods for metabolic flux analysis of overdetermined system, the experimental data error minimization method and the equation error minimization method, are compared from their mathematical basis, rationality of the results and the easiness of computation. The results show that the experimental data error minimization method is appropriate in metabolic flux analysis of overdetermined system.     

一种用于显著误差检测与数据校正的NT-MT组合算法

An NT-MT combined method based on nodal test （NT） and measurement test （MT） is developed for gross error detection and data reconciliation for industrial application. The NT-MT combined method makes use of both NT and MT tests and this combination helps to overcome the defects in the respective methods. It also avoids any artificial manipulation and eliminates the huge combinatorial problem that is created in the combined method based on the nodal test in the case of more than one gross error for a large process system. Serial compensation strategy is also used to avoid the decrease of the coefficient matrix rank during the computation of the proposed method. Simulation results show that the proposed method is very effective and possesses good performance.     

基于矩法和时间域分析法研究稠密CO2中甲苯和对氯苯在硅胶固定床系统中的吸附和传递性质

Based on chromatographic theory, the moment method and the time-domain fitting analysis were applied to measure and evaluate the adsorption equilibrium constant and mass transfer properties (axial dispersion coefficient and effective intra-particle diffusivity) for toluene and p-dichlorobenzene on silica gel adsorbent in the subcritical and supercritical CO2. An apparatus based on supercritical fluid chromatography was established and the experiments were performed at temperatures of 298.15-318.15 K and pressures of 7.5-17.8 MPa. The two methods have been compared. The results show that for the systems studied here the moment method can give reasonable values for both adsorption equilibrium constant and mass transfer properties, but the time-domain analysis only can obtain the adsorption equilibrium constant. The dependence of adsorption equilibrium constant and mass transfer properties on temperature and pressure was investigated.     

基于矩法和时间域分析法研究稠密CO2中甲苯和对氯苯在硅胶固定床系统中的吸附和传递性质

Based on chromatographic theory, the moment method and the time-domain fitting analysis were applied to measure and evaluate the adsorption equilibrium constant and mass transfer properties (axial dispersion coefficient and effective intra-particle diffnsivity) for toluene and p-dichlorobenzene on silica gel adsorbent in the subcritical and supercritical CO2. An apparatus based on supercritical fluid chromatography was established and the experiments were performed at temperatures of 298.15-318.15 K and pressures of 7.5-17.8 MPa. The two methods have been compared. The results show that for the systems studied here the moment method can give reasonable values for both adsorption equilibrium constant and mass transfer properties, but the time-domain analysis only can obtain the adsorption equilibrium constant. The dependence of adsorption equilibrium constant and mass transfer properties on temperature and pressure was investigated.     

高浓度H2O-NH3-CO2体系汽液平衡计算

A vapor liquid equilibrium model and its related interactive energy parameters based on UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of temperature from 30℃ to 90℃, pressure from 0.1 MPa to 0.4MPa, and the maximum NH3 mass fraction up to 0.4 are provided. This model agrees with experimental data well (average relative error < 1%) and is useful for analysis of industrial urea production.     

基于分片化MPCA模型的多阶段批次过程阶段分析与阶段辨识方法(英文)

Multi-way principal component analysis (MPCA) is the most widely utilized multivariate statistical process control method for batch processes. Previous research on MPCA has commonly agreed that it is not a suitable method for multiphase batch process analysis. In this paper, abundant phase information is revealed by way of partitioning MPCA model, and a new phase identification method based on global dynamic information is proposed. The application to injection molding shows that it is a feasible and effective method for multiphase batch process knowledge understanding, phase division and process monitoring.     

Prediction of Liquid Viscosities of Petroleum Fractions

A general equation is proposed for predicting the liquid viscosities of petroleum fzac-riots based on a generalied pseudocompound method in which pure hydrocarbons and undefined hydrocarbon mixtures or petroleum fractions are treated as a hypothetical pure substance called pseudocompound which is chaxacterized only by a boiling point and a density. The equation is tested by using the liquld viscosities of the petroleum fractlons of typical American crude oils and crude oils from major oil producing sreas. Good agreement between the predicted and experlmental viscosities for the petroleum fractions is obtained.     

混合蒸汽在活性炭上的吸附平衡

The XG equation, which is developed by us previously for describing the adsorption equilibrium of pure vapor on activated carbon, is extended to multi-component system. Verified by experimental data, the extended XG equation was found to be more successful in predicting the adsorption equilibrium of vapor mixture on activated carbon than the extended Langmuir equation, the extended BET equation and the ideal adsorbed solution theory (IAST).     

用人工神经网络方法预测鼓泡塔气含率

A new correlation for the prediction of gas hod up in bubble columns was proposed based on an extensive experimental database set up from the literature published over last 30 years .The updated estimation method relying on artificial neural network,dimensional analysis and phenomenological approaches was used and the model prediction agreed with the experimental data with average relative error less than 10%.     

状态方程在气固相平衡计算中的应用

状态方程法是研究气固平衡的一种常用方法,但是目前仅有SRK和PR方程运用于元素硫沉积机理的研究。采用RK、SRK、PR、PT和LHSS状态方程对含硫天然气气固相平衡进行了计算,并且比较了不同状态方程对计算结果的影响。通过算例分析可知,对含硫天然气气固相平衡进行计算时每种状态方程都会存在误差,而误差主要来源于实验过程中的误差、状态方程参数设置的误差、数值计算方法的误差等。计算结果表明,采用RK和SRK方程计算误差较大,PR和PT方程两者计算误差差别不大,LHSS方程更适合描述含硫天然气的气固相平衡。     

管道泄漏污染物一维迁移的LBM模拟

石油管道泄漏现象时有发生,对环境造成了危害,研究埋地管道石油污染物泄漏尤为关键。在此采用Boltzmann研究方法,通过多尺度技术和局部平衡态分布函数的Chapman-Enskog展开得到运算的平衡态方程,并给出了石油管道污染物泄漏迁移的一维有源扩散方程的格子Boltzmann模型,通过C++软件数值模拟进行运算。最终得出结果与理论解一致,验证了用Boltzmann方法研究污染物泄漏迁移的可行性。     

A mathematical method to estimate the equilibrium melting temperature from growth rate data

The regime transitions analysis is subject to all the limitations of the ordinary least squares method which is generally applied to the linearized form of the Lauritzen-Hoffman equation. Therefore, polymers growth rate has to be measured in a sufficiently wide temperature range to ensure a reliable kinetic analysis based on the secondary nucleation theory. Furthermore, an accurate value of the equilibrium melting temperature has to be used in order to achieve trustworthy thermodynamics outcomes, although this quantity may be affected by a high uncertainty. Here a method is proposed in order to verify directly from growth rate data the use of the most reliable value of the equilibrium melting temperature. The method is based on the comparison between the derivatives of the growth rate functions calculated by the Lauritzen-Hoffman equation using the outcomes of the regime analysis.     

An improved SRK-equation for the estimation of concentrations by inferential measurements

A method is proposed for solving the vapour-liquid equilibrium problem in binary distillation processes, when pressure and temperature are known. Special attention is paid to the applicability of the method for control purposes. Therefore, a comparison between measured and estimated concentrations is included for the case of propane-propylene distillation. The method is based on an improved Soave-Redlich-Kwong equation of state and is easy to implement on a process computer. It yields a close approximation of experimental vapour and liquid volumes. On applying the original SRK-equation at high pressures, an error in excess of 20% is obtained in the liquid volume which is one of the reasons why this equation cannot be used for control where high accuracy is required. In addition, the conventional mixing rule cannot reproduce the mole fractions correctly. Therefore, a new density-dependent mixing rule is put forward for modelling of experimental results.     

Analysis of ultracentrifugation interference patterns with image digitizer: Application to molecular weight determination of SRM 1478 polystyrene

A new method for the analysis of ultracentrifugation interference patterns with the use of a commercial image digitizer is given. The application of the method to the sedimentation equilibrium data for SRM 1478 polystyrene leads to a weight-average molecular weight of 37 400 g mol⁻¹ having a sample standard deviation of 0.7% and an expected systematic error limit of 2%.     

热力学状态方程二元交互作用参数估算模型开发

基于气液平衡理论,建立了热力学状态方程二元交互作用参数估算模型。首先,结合气液平衡理论、状态方程以及相应的混合规则建立气液相平衡数学模型;然后以气相组成误差平方和与压力相对误差平方和之和作为目标函数,并使用计算机编程,利用单纯形法进行优化求解,实现了热力学状态方程二元交互作用参数估算模型的开发;最后,用该模型对5组二元气液平衡体系中的组分二元交互作用参数进行估算,并根据估算出的参数对各体系的气相组成进行预测,结果显示,预测值与实验值的平均相对偏差均小于1％,表明该模型计算结果准确,可应用于气液平衡计算中。     

Errors associated with swelling in the analysis of polymer-solvent diffusion measurements

Sorption curves are generated from a mathematical model which includes the influence of the polymer swelling for unsteady-state sorption of a vapor or liquid by a polymer. To investigate the simultaneous effects of the specific volumes of the polymer-penetrant pair and the difference between the final and initial equilibrium concentrations on the sorption curves, statistical experimental design approach is used. Simulation results obtained from the numerical solution of model equations are utilized to estimate the error that would occur if one simply evaluates the diffusion coefficient using the traditional formulas derived from the analytical solution of the sorption equation. An empirical expression is developed that describes the effects of the difference between the final and initial equilibrium concentrations and the specific volumes of the polymer and the penetrant on the magnitude of error in diffusivity associated with the use of one of these traditional formulas so called the initial slope method. The predictive ability of the regression model is tested by performing additional simulations not used in the regression analysis.     

在共存相中饱和液体及饱和蒸气密度的计算

本文证实了Hanson计算方法的可能性,并应用了跨界压缩因子解决了Hanson方法中存在的缺点.计算饱和液体的密度,其误差在1%以内,本文尚提供了计算饱和蒸气的密度和混合液体的密度的方法.导出了一个计算汽化热的普遍公式.这些结果证明了在两相区域内可以应用对比状态的规律.     

Study of equilibrium,kinetic and thermodynamic parameters about methylene blue adsorption onto natural zeolite

Adsorption equilibrium and kinetic of methylene blue (MB) onto natural zeolite was studied in a batch system. Variables of the system include contact time, pH, salt concentration, temperature, and initial MB concentration. The increase in temperature resulted in a higher MB loading per unit weight of the zeolite. Langmuir, Freundlich, Redlich–Peterson, Koble–Corrigan and Temkin isotherm models were applied to experimental equilibrium data of MB adsorption depending on temperature. The effect of contact time at different temperatures and initial concentration were fitted to pseudo-second-order kinetic model. Linear regressive method and nonlinear regressive method were used to obtain the relative parameters. The error analysis was conducted to find whether linear method or nonlinear method was better to predict the experimental results and which model was better to fit the experimental data. Both methods were suitable to obtain the parameters. The Redlich–Peterson equation was best to fit the equilibrium data. The pseudo-second-order kinetic model can be used to describe the adsorption behavior. The nonlinear method may be better with the absolute error as limited condition. The adsorption process was spontaneous and endothermic.     

LNG接收站蒸发计算状态方程选择

LNG物性参数是LNG接收站模型建立、工艺流程模拟计算及研究必不可少的基础数据。以国外实验数据为基础,采用Aspen HYSYS软件分析评价PR、SRK、LKP、BWRS状态方程对气液相组成、焓、密度等物性参数的预测结果,比选汽液相平衡和热力学参数的计算状态方程,建立了LNG接收站储罐蒸发模型,并比较了四种状态方程的准确度。结果表明：PR方程在汽液相平衡计算方面计算精度最高,相对误差为4.70%;LKP方程计算热力学参数最准确,预测误差为2.59%。综合考虑相平衡参数和热力学参数计算精度,PR方程精度最高,预测误差为3.77%。此外,PR方程对LNG储罐蒸发和储罐压力的模拟计算值与现场数据吻合度最好,因此LNG接收站蒸发计算推荐选用PR方程。研究结果对物性参数和LNG接收站蒸发计算状态方程的选择具有借鉴意义。