三元分子体系氨基酸+蛋白质变性剂+水的密度预测

以298．15K时α-氨基酸 水和蛋白质变性剂 水二元实验数据为基础,利用改进的逆传播算法训练神经网络,构造混合物组成与密度关系的模型,用于对α-氨基酸(甘氨酸、DL—α-丙氨酸、DL—α-氨基正丁酸、DL-α-缬氨酸和DL-α-亮氨酸)-蛋白质变性剂(乙酸钠,丁酸钠,己酸钠和辛酸钠)-水三元混合物体系的密度进行预测,所得预测结果与实验值进行了对比。结果表明,神经网络作为三元混合物体系密度的预测是令人满意的。     

神经网络用于三元分子混合物密度与粘度的预测

以二元系实验为基础，利用反向转播算法训练神经网络，构造混合物组成，温度等与物性关系的模型，用于对４个三元混合物体系（１）邻二甲苯－间二甲苯－对二甲苯；（２）四氯化碳－环己烷－２－丙醇；（３）甲醇－丙酮－水；（４）水－甲醇－乙二醇的密度和５个三元混合物体系（１）信甲苯－间二甲苯－对二甲苯；（２）四氯化碳－环己烷－２－丙醇；（３）氯仿－２－丙醇－２－丁醇；（４）甲醇－丙酮－水；（５）乙醇－甲醇－水的粘     

含临界区流体混合物的统计缔合理论研究

含临界区流体混合物汽液平衡等热力学性质的研究是化工热力学的一个难题。本文用改进的统计缔合流体理论方程(SAFT-CP)^[1,2]结合范德华单流体混合规则(vdWl)计算了含临界点的二元混合物的汽液平衡。与原始的SAFT方程^[3/4]相比，SAFT-CP方程以非球形的硬体项作为参考流体，代替原来的硬球项，考虑了分子成链对色散作用的影响，对于极性流体，考虑了分子的偶极-偶极相互作用而忽略了缔合作用。本文计算的二元体系包括非极性-非极性体系：二氧化碳-丙烷、二氧化碳-丁烷和二氧化碳-戊烷，以及非极性～极性体系：硫化氢-戊烷、甲烷-丙酮和二氧化碳-甲醇。含临界点在内的计算结果与文献实验值符合很好，表明该方程适用于二元混合物含临界区的相平衡计算，具有广阔的应用前景。     

正己烷-甲基环戊烷-邻苯二甲酸二丁酯三元体系汽液平衡研究

测量了不同压力下正己烷-甲基环戊烷-邻苯二甲酸二丁酯三元体系等压汽液平衡数据，确定了该体系Wilson方程模型参数，并以Wilson方程为汽液平衡模型，采用微机模拟计算了以邻苯二甲酸二丁酯为溶剂，萃取精馏分离正己烷-甲基环戊烷混合物的分离结果，结果表明，萃取精馏分离该混合物效果良好。     

计算机辅助三元体系组成分析

本文提出一个计算机辅助三元体系组成分析方法。三元混合物的物理性质可从三个相应的二元体系用按比例内插法计算得到，借助于计算机分析三元体系物性与组成的关系获取三元体系的组成。本方法能有效地消除人为影响造成的误差，具有较高的精确度。只要某组分的某一物理性质与其它一个组分相差较大，一般不小于０．０７５，而不一定要求两条组成曲线之间很接近，也不要求相差较小的两组分间的组成曲线具有较好的线性。适应性强，应...     

小波神经网络结合紫外光谱用于四种维生素混合体系的同时测定

首次实现了小波网络多节点输出,表明该网络在且分混合物的定量分析问题上有独到的优点。运用小波神经网络对Ｂ族维生素的混保体系进行了测定。结果良好。     

二氧化碳与2-丁醇二元体系在高压下的亨利系数和偏摩尔体积性质计算

利用固定体积可视高压釜测量出的在323K~353K温度范围内的CO2与2-丁醇二元体系在高压下的汽液相平衡数据,根据Krichevsky-Kasarnovsky方程建立了CO2在液相中的溶解度模型,得到了该二元体系在高压下的亨利系数和CO2在无限稀释溶液中的偏摩尔体积等性质。同时根据偏摩尔体积性质和Peng-Robinson状态方程及Van der Waals-2混合规则来计算该体系在平衡状态下的气、液相的偏摩尔体积。结果表明CO2在2-丁醇中的亨利系数和CO2在无限稀释溶液中的偏摩尔体积均为温度的函数,CO2在2-丁醇中的亨利系数随温度的升高而降低。CO2在无限稀释溶液中的偏摩尔体积∞1V在研究温度下均为负值,其中随温度升高,其绝对值下降。在平衡状态下的气、液相的偏摩尔体积计算结果表明:平衡状态下,液相中CO2与2-丁醇的偏摩尔体积均为正值。气相中不同温度下CO2的偏摩尔体积均为负值,且其绝对值随着压力的增加而越来越大,2-丁醇的偏摩尔体积均为正值。此研究为该体系超临界萃取条件的确立和指导工业化生产提供了理论依据。     

基于神经网络的高压输电线路单端测距方法

针对单端行波故障测距第二个行波波头性质辨识问题,提出一种将小波模极大值方法和神经网络算法相结合的测距方法。采集故障波头时间差和极性等信息作为样本,利用神经网络的非线性拟合能力对样本进行训练、测试,从而建立相应的故障测距神经网络模型。将故障信息代入神经网络模型得到初步测距结果,根据初测结果和波头极性、时间差等性质的关系,对第二个行波波头进行正确辨识,从而得到优化的测距结果。经Matlab/Simulink仿真验证,该方法有较高的可靠性和精确性。     

利用神经网络推算二元混合物体系的过量焓

以第一组分的摩尔分数和第二组分分子中碳原子数目的差异来表征二元分子体系利用具有三层拓扑结构的神经网络模型，推算了２８个体系的过量焓，其中内插１６个体系，外推１２个体系，所有体系的相对误差均在５％左右，最大相对误差为７．６８％，最小相对误差为２．２９％。     

利用神经网络推算二元混合物体系的过量

以第一组分的摩尔分数和第二组分分子中碳原子数目的差异来表证二元分子体系，利用具有三层拓扑结构的神经网络模型，推算了２８个体系的过量焓，其中内插１６个体系，外推１２个体系，所有体系的相对误差均在５％左右，最大相对误差为７．６８％，最小相对误差为２．２９％。     

Computer-aided thermodynamics of fcc solid ternary Fe–Co–Cr alloys by Knudsen cell mass spectrometry

The fcc solid ternary Fe–Co–Cr alloys have been investigated thermodynamically by means of computer-aided Knudsen cell mass spectrometry. The “Digital Intensity Ratio” (DIR) method has been applied for the determination of the thermodynamic excess properties. The ternary thermodynamically adapted power (TAP) series concept is used for the algebraic representation of the molar excess properties. The corresponding TAP parameters as well as the values of the molar excess Gibbs energies G^E, of the molar heats of mixing H^E, of the molar excess entropies S^E, and of the thermodynamic activities at 1673 K are presented.     

CALPHAD modelling of the unmixing of transition metal carbide phases

Phase separation in a pseudo-binary solid solution of the form (M₁,M₂)C where M₁ and M₂ are chosen among minor addition in 9% Cr, martensitic-ferritic steels such as Nb, V, Ta and other transition elements such as Hf and Zr has been studied using the Calphad-Thermocalc approach. Ternary excess parameters accounting for phase equilibria in pseudo-binary sections have been optimised using suitable combinations of already published excess parameters which have been calculated on a physical basis. The ternary parameters obtained by optimisation were checked, when possible, with experimental information on isothermal ternary sections.     

Using spline functions for obtaining accurate partial molar volumes in binary mixtures

A numerical method for obtaining accurate partial molar volumes of binary mixtures from density measurements is presented. The method makes use of cubic spline functions for smoothing of data, given easy-to-handle analytical representations of the excess molar volume of the mixture. Moreover, the method is very fast and easy to implement on a laboratory microcomputer for research and/or teaching purposes. A user-friendly program is given that performs all the calculations needed, including as an output the input code for plotting the results using Mathematica®.     

An optimal method to calculate the viscosity of simple liquid ternary alloys from the measured binary data

An optimal method to calculate the viscosity of simple liquid ternary alloys from the measured binary data is investigated in this paper. In order to find a relationship which describes the ternary viscosity data from binary data most adequately, a comparison was made between three different approaches tested on the example of the Au–Ag–Cu system. The optimal method turned out to be the extension of the Redlich–Kister polynomial to excess viscosity without any ternary term. This optimal method was applied further on the Fe–Ni–Co system. The estimation of viscosities for liquid Fe–Ni–Co alloys was done in different sections with molar ratio of two components equal to 1:1, 1:3 and 3:1. A diagram showing iso-viscosity lines was constructed at the investigated temperature of 1873 K.     

Prediction of the thermodynamic properties for the Ga–Sb–Pb ternary system

The results of some thermodynamic prediction methods applied to the Ga–Sb–Pb ternary system are presented in this paper. The Chou general solution model and the traditional models of Kohler and Toop were included in the calculation for the comparison and discussion. Integral enthalpy of mixing and integral excess Gibbs energy dependences on composition for the 15 investigated cross sections at 973 K and 1073 K, respectively, were obtained according to the applied models. The comparison between the results of the three models shows good mutual agreement. Obtained results were used for the further calculation of partial molar quantities for every component of the investigated ternary system. Calculated activity values at 1073 K for all components are given in the form of isoactivity diagrams.     

The equilibrium phase diagram of the pentaerythritol-pentaglycerine-2-amino-2methyl-1,3, propanediol (PE-PG-AMPL) system

Polyalcohols and amines have been considered as potential thermal energy storage materials, owing to their energetic solid-solid phase transitions. In this paper, we present equilibrium phase diagram of Pentaerythritol (PE)–Pentaglycerine (PG)– 2-amino-2methyl-1,3, propanediol (AMPL) ternary system that has been thermodynamically assessed using the CALPHAD method. A special class of, so called, “Plastic Crystals” have tetrahederally configured molecules with O–H⋯O or N–H⋯O layered or chained bonds in the low temperature phase, and store latent heat of transformation during solid-solid phase change in orientationally disordered crystals at higher temperatures. For example, in polyalcohols, there are O–H⋯O bond rotations around the C–C bonds that are responsible for storing large amounts of solid state phase change energy. Several binary equilibrium phase diagrams of polyalcohols, amines and combination thereof have been calculated and experimentally validated. We only know of three ternary phase diagram of these plastic crystals reported, to the best of knowledge. In the thermodynamic calculations of thePE-PG-AMPL system, we used the binary phase diagram experimental data for the optimization and calculation of excess energies. The binary systems have been optimized using regular and sub-regular solution models. The binaries as well as the ternary system have been calculated from room temperature to the liquid phase. The solution phases are modeled as substitutional solutions, in which the excess Gibbs energies are expressed by the Redlich–Kister–Muggianu polynomial. There is a very good agreement between previously reported experimental data and the calculated phase diagrams.     

A general “geometric” thermodynamic model for multicomponent solutions

Several “geometric” models have been proposed for estimating thermodynamic properties of a ternary solution from optimized data for its binary subsystems. The most common are the Kohler, Muggianu, Kohler/Toop, and Muggianu/Toop models. The latter two are “asymmetric” in that one component is singled out, whereas the first two are “symmetric”. The use of a symmetric model when an asymetric model is more appropriate can often give rise to errors. There are 64 possible simple geometric models for a ternary system. Equations are developed to calculate the thermodynamic properties of an N-component solution (N>3) in a rational manner while permitting complete flexibility to choose any of the 64 possible geometric models for any ternary subsystem. An improved general functional form for “ternary terms” in the excess Gibbs energy expression is also proposed.     

A thermodynamic analysis of the Mo-V and Mo-V-C system

A new thermodynamic evaluation of the binary Mo-V system and the ternary Mo-V-C system using thermodynamic models for the Gibbs energy of individual phases is presented. The CALPHAD method has been used, with predictions of unknown thermodynamic quantities, to optimize a set of thermodynamic parameters taking related experimental information into consideration. The predictions are based on regularities in bonding properties and vibrational entropy of 3d-transition metal carbides. The results are summarized in tables of thermodynamic parameters, calculated binary phase diagrams and isothermal sections of the ternary phase diagram compared with experimental information. Finally the influence of ternary interaction parameters, especially in the fcc phase, on calculations of equilibria in multicomponent systems is discussed.     

Equilibrium between MB2 (M=Ti,Zr,Hf) UHTC and Ni: A thermodynamic database for the B-Hf-Ni-Ti-Zr system

MB₂ (M=Ti,Zr,Hf) Ultra High Temperature Ceramics (UHTCs) are characterised by melting temperatures in excess of 3000 °C and have structural, physical, transport, and thermodynamic properties suitable for use as thermal barriers in extreme environments. It is then necessary to investigate interactions of the diborides with the materials they are supposed to protect. To this end it has been developed a CALPHAD thermodynamic database for the calculation of phase equilibria and thermodynamic properties in the quinary system B-Ni-Ti-Zr-Hf. The database contains thermodynamic parameters for all the phases included in the 10 binary and 10 ternary sub-systems of B-Ni-Ti-Zr-Hf. A few binary systems (B-Hf, B-Ti, B-Zr, Hf-Ni, Ni-Zr) have been slightly modified with respect to the previous assessments and several ternary systems (B-Hf-Ni, B-Ni-Ti, B-Ni-Zr, B-Hf-Zr, B-Ti-Zr, Hf-Ni-Ti, Hf-Ni-Zr, Hf-Ti-Zr, Ni-Ti-Zr) have been completely assessed or re-assessed in this work with particular attention to the self-consistency of the models adopted.