COSMO-SAC模型预测含丙三醇体系的汽液相平衡

流体相平衡性质是产品提纯、装备设计、操作优化等过程不可或缺的基本物性数据。借助COSMO-SAC模型,对丙三醇+水、甲醇、乙醇、丙醇和丁醇二元体系的汽液相平衡进行了预测,结果显示考虑氢键作用的模型预测精度较高;针对丙三醇分子结构特点,采用分子模拟软件对其分子结构进行了重新优化,并获得新的COSMO文件,据此预测的相平衡数据精度得到进一步提高;最后根据含丙三醇二元混合体系的汽液平衡数据,给出了新的COSMO-SAC模型参数,并成功预测含丙三醇三元汽液相行为。     

甲酸-水-N-甲基吡咯烷酮体系等压汽液平衡的研究

在常压下测试甲酸-水、甲酸-N-甲基吡咯烷酮、水-甲酸-N-甲基吡咯烷酮的汽液平衡数据。考虑甲酸在汽相中的缔合效应,用维里方程和Hayden-O'connell关联式修正了汽相的非理想性,并用非线性最小二乘法关联前2对二元体系的汽液平衡数据,得NRTL和Wilson方程的模型参数。以NRTL模型参数预测三元体系汽液平衡数据,温度平均偏差为1.76℃,甲酸的汽相平均偏差为0.032 2,水的汽相平均偏差为0.040 4;以Wilson模型参数预测三元体系汽液平衡数据,温度平均偏差为1.66℃,甲酸的汽相平均偏差为0.027 5,水的汽相平均偏差0.011 6,可见2个模型预测值均与实验值吻合良好,而Wilson模型的关联精度较高。     

盐酸-水-盐体系的汽液平衡预测

电解质溶液汽液平衡的预测和计算是加盐萃取精馏模拟的基础,准确计算电解质溶液的汽液平衡有重要的理论和实际意义。本文应用Chen的电解质溶液NRTL模型,根据电解质-水二元体系的汽液平衡数据回归的二元参数．对盐酸-水-氯化钙与盐酸-水-氯化镁两种体系的汽液平衡进行了预测,温度的平均绝对误差分别为0．32(K)和0．39(K),汽相摩尔分数的平均绝对误差分别为0．0080和0．0070。计算结果与文献数据比较一致。     

计算机处理二元汽液平衡法

本文介绍一种不同于常规的汽液平衡数据关联法。定义溶液相对挥发系数概念,提出一个半理论半经验的双组分汽液平衡公式,该式适用于等温或等压下的各种非理想溶液的平衡体系,包含恒沸点,分层或缔合的体系。选取了47组二元汽液平衡实验数据,利用非线性最小二乘法(高斯牛顿法和Marquardt法)拟合模型参数,拟合结果表明比常规法简单且精度有所提高。     

101.33kPa下N-甲基乙酰胺+醋酸+水汽液相平衡研究

用改进式Rose釜测定了101.33kPa下N-甲基乙酰胺 醋酸二元体系和N-甲基乙酰胺 醋酸 水三元体系的汽液平衡数据。对N-甲基乙酰胺 醋酸体系VLE数据进行了面积法热力学一致性检验,用NRTL、Wilson、UNIQUAC模型关联得到了相应的模型参数。最后用二元体系的NRTL模型参数推算了所测N-甲基乙酰胺 醋酸 水三元体系的汽液平衡数据。推算结果中,温度的平均偏差为0.94℃,水在汽相中的平均偏差为0.0137。     

甲基三氯硅烷-二甲基二氯硅烷-苯体系中二元体系的汽液平衡数据推算

在预测卤化硅烷体系性能时,通过改变溶液的混合规则来确定预测方案。估算了甲基三氯硅烷、二甲基二氯硅烷、苯相互之间组成的二元体系在恒压101.325 kPa下的相互作用参数,这种估算是基于把汽相看成理想溶液来实现的,而且采用matlab优化工具箱中的非线性最小二乘法用Wison模型关联了实验数据,预测结果比文献更逼近实验数据。这些二元体系汽液平衡数据为卤硅烷的生产提供了理论依据。     

乙酸乙酯-乙醇-水与甘油体系的液液平衡数据测定及关联

液液平衡数据的测定及热力学模型的研究是化学工程中的重要内容之一,虽然目前已有大量的液液平衡数据发表,但仍有很多物系的相平衡数据有待于人们来测定和研究.本研究选取甘油作为乙酸乙酯液液萃取分离的萃取剂.采用色谱法测定乙醇在甘油中的无限稀释活度系数,并采用单参数法关联UMQUAC方程中的模型参数;采用液液平衡釜测定乙酸乙酯-水、乙酸乙酯-甘油二元体系和乙酸乙酯-乙醇-甘油、乙酸乙酯-水-甘油、乙酸乙酯-乙醇-水三元体系LLE数据,采用最小方差法关联UNIQUAC方程中的模犁参数,并关联二元及三元LLE数据;利用六对模型参数模拟四元LLE数据,并与实验值相比较,实验与计算误差均小于5%.实验值与模拟值吻合较好,精度满足要求,从而可以为液液萃取的工艺改进模拟计算提供可靠的热力学基础数据.另外该体系的液液相平衡数据对于乙酸乙酯的提纯有实际的应用价值.     

常压下丙醛-水-甘油体系汽液平衡测定与关联

采用单循环汽液平衡釜测定了常压条件下丙醛-水的二元以及丙醛-水-甘油三元汽液平衡数据。运用MATLAB中求解非线性最小二乘法问题的函数Lsqnonli,结合丙醛-水的二元汽液平衡实验据,迭代出了Margules、Vanlaar、Wilson和UNIQAC四个方程的二元模型参数。通过计算值和实验值的比较,Wilson方程的相对误差均小于5%,故选择Wilson方程为本体系的适合模型。将测定的丙醛-水-甘油三元汽液平衡数据与模型参数带入Wilson方程求得的三元汽液平衡数据相比较,相对误差均小于5%,由此验证了本文Wilson模型参数的可靠性。本文的测定结果和计算结果为丙醛-水-甘油体系的萃取精馏模拟选择了合适的模型,关联得到的Wilson模型参数,为萃取精馏过程的模拟计算打下基础,同时也为丙醛和水混合液的有效分离提供了一定基础数据。     

苯基二氯化膦-三氯化磷和苯基膦酰二氯-三氯氧磷体系汽液平衡的研究

本文分别测定了苯基二氯化膦和苯基膦酰二氯的饱和蒸气压(其温度范围分别为349．26～426．06k和377．15～457.65k)。采用安托因方程拟合了蒸气压数据并与文献值作了比较。测定了两种二元系在101．325kPa下的沸点一液相组成数据,基于实测数据,采用Wilson活度系数模型关联了模型参数,相互作用参数关联为温度的线性函数,在此基础上推算了上述两个二元系在极低压力(1333Pa)的汽液平衡。     

甲醇-环己酮二元体系汽液平衡的测定与关联

用改进的Ellis汽液平衡釜测定甲醇-环己酮二元体系常压汽液平衡数据,并校验实验数据的Herington热力学一致性,结果表明实验数据满足热力学一致性要求.以汽相组成的误差平方和作为目标函数,分别用Willson和NRTL方程关联实验数据,得两热力学方程的模型参数.汽相组成的模型计算值与实验值的平均相对偏差分别为0.56%和1.10%.     

改进精馏塔模型用于空分塔模拟计算

在传统的机理模型（三对角矩阵法中的泡点法）基础上,将体系压力（P）,平衡液相组成（x1,x2,x3)为输入节点;体系温度（T）,平衡汽相氮组成（y1)及氩、氧的相平衡常数（k2,k3)为输出节点的神经网络液体空气汽液平衡计算模型,取代三对角矩阵法中泡点计算,从而建立精馏塔模型,改进模型用于空分塔的模拟计算,不仅计算速度快,计算结果与机理模型结果非常接近,且符合设计要求,对实现产品质量的在线监控具有一定的指导意义。     

Hybrid multilevel programming with uncertain random parameters

Multilevel programming is developed for modeling decentralized decision-making processes. For different management requirements and risk tolerances of different-level decision-makers, the decision-making criteria applied in different levels cannot be always the same. In this paper, a hybrid multilevel programming model with uncertain random parameters based on expected value model (EVM) and dependent-chance programming (DCP), named as EVM–DCP hybrid multilevel programming, is proposed. The corresponding concepts of Nash equilibrium and Stackelberg–Nash equilibrium are given. For some special case, an equivalent crisp mathematical programming is proposed. An approach integrating uncertain random simulations, Nash equilibrium searching approach and genetic algorithm is designed. Finally, a numerical experiment of uncertain random supply chain pricing decision problem is given.     

WSN中利用贝叶斯博弈的数据传递策略

在无线传感器网络中,数据的传递策略对网络的能量损耗具有重要的影响,为此,提出了一个基于贝叶斯博弈的数据传递模型。在该模型中网络节点为了获取最大的收益,在考虑自身能量水平的基础上,适当的调整发送/转发的数据量。当节点发送/转发的数据满足一定条件时,网络存在均衡状态。仿真结果表明,该基于博弈论的数据传递策略在均衡状态下能够明显降低能量损耗,延长网络的使用寿命。     

Existence and uniqueness of the Nash equilibrium in the non-cooperative QoS routing

Researchers dealing with game theoretic issues are well aware that the definition of a model capturing some physical behaviours such as the routing, the pricing, the flow and congestion control, the admission control just to mention some examples in the telecommunication field, is a difficult task, but it is only half of the overall effort. As a matter of fact, a key aspect is the analysis of the equilibrium (or equilibria) towards which the game will (hopefully) converge. The existence, the uniqueness, the efficiency and the structure of the equilibrium are some of the typical properties which are investigated. In this article, we propose a game theoretic model for quality of service (QoS) routing in networks implementing a Differentiated Service model for the QoS support. In particular, we focus on a parallel link network model and we consider a non-cooperative joint problem of QoS routing and dynamic capacity allocation. For this model, we demonstrate that the Nash equilibrium exists, so overcoming a typical problem in the existence proofs appeared in many papers in the area of routing game since 1990s, and we explicitly obtain a suitable set of relations characterising its structure. Moreover, we prove that Nash equilibrium uniqueness cannot be guaranteed in general.     

Visualizing the dynamical behavior of Wonderland

The article concentrates on the visualization of a four dimensional continuous dynamical system, the Wonderland model. This system poses some interesting analysis challenges. Its temporal evolution, for example, is characterized by slow-fast dynamics. This means that some of the system variables vary much faster than others. The velocity varies by two magnitudes and thus makes visualization difficult. Due to the underlying slow-fast dynamics, some equilibrium surfaces play an essential role in the model's analysis. We consider equilibrium surfaces on which the derivative of the fast system variable equals zero. Due to their definition, these equilibrium surfaces do not describe stream surfaces, which means that trajectories intersect and cross them. For these surfaces we cannot use visualization techniques designed for stream surfaces, which are based on the assumption that a flow starting on the surface will stay within it. Econometrics research typically uses only elementary visualization techniques such as still images, simple line drawings, and 2D projections or cross-sections of higher dimensional phase spaces. Color use is scarce. We collaborated with econometricians to apply more sophisticated visualization techniques and adaptations to the Wonderland model using standard visualization software (AVS by Advanced Visual Systems). The visualizations provided new insights into the system's slow-fast dynamics. Using a commercial rendering package (Autodesk's 3D Studio), we also turned the visualizations into high quality images for presentations     

分子筛合成过程中三聚铝硅酸盐生成机理的DFT研究

采用密度泛函理论研究了在分子筛合成的碱性环境中铝硅酸盐三聚体的生成机理.在B3LYP/6-31 G(d,p)计算水平上对反应物、过渡态和产物分别进行了几何结构的全优化和频率计算,通过内禀反应坐标的方法验证了反应路径,并计算了反应的活化能.采用COSMO-RS模型考虑了溶剂效应.结果表明,二聚硅酸分子SiOSi(OH)6和单体铝酸根离子Al(OH)**的缩聚反应可以按照协同方式进行,SiO-Al桥键的形成与水分子的脱除同时发生,最终生成铝硅酸盐的三聚体.计算得到的缩聚反应活化能为80.1 kJ/mol.     

Commercial property and the location decision

A theoretical model of the commercial property market is developed which takes account of the firm's choice between alternative forms of occupancy (owner-occupancy or tenancy) and locations (centre or periphery), and which assumes that equilibrium rents and prices are determined by a set of simultaneous market-clearing conditions in sub-markets for the different occupancy types and locations. The model suggests that under some conditions, there may be unexpected movements in rents and prices in response to exogenous factors such as changes in interest rates and transport costs.     

Stochastic models of mob control

This paper explores the following model of agents’ threshold behavior. Making binary decisions (choosing between “activity” and “passivity”), agents consider the choice of other members in a group. We formulate and solve an associated control problem, i.e., the random choice problem for the initial states of some agents in order to vary the number of agents preferring “passivity” in an equilibrium.     

Structural shape sensitivity analysis for nonlinear material models with strain softening

This paper describes some considerations around the analytical structural shape sensitivity analysis when the structural behaviour is computed using the finite element method with a nonlinear constitutive material model. Traditionally, the structural sensitivity analysis is computed using an incremental approach based on the incremental procedures for the solution of the structural equilibrium problem. In this work, a direct (nonincremental) formulation for computing these structural sensitivities, that is valid for some specific nonlinear material models, is proposed. The material models for which the presented approach is valid are characterized by the fact that the stresses at any timet can be expressed in terms of the strains at the timet and, in some cases, the strains at a specific past timet ^u (t ^u <t). This is the case of elasticity (linear as well as nonlinear), perfect plasticity and damage models. A special strategy is also proposed for material models with strain softening.For the cases where it is applicable, the sensitivity analysis proposed here allows us to compute the structural sensitivities around any structural equilibrium point after finishing the solution process and it is completely independent of the numerical scheme used to solve the structural equilibrium problem. This possibility is particularized for the case of a damage model considering a strain-softening behaviour. Finally, the quality and reliability of the proposed approach is assessed through its application to some examples.     

基于精确罚函数的一类广义非线性神经网络模型

针对一般的非线性优化问题定义了一种2次非线性罚函数,证明了在一定条件下对应的罚优化问题的精确罚定理,由此引进了一种广义非线性神经网络模型,并证明了这种网络的平衡点与能量函数之间的联系,在一定条件下对应的平衡点收敛到原问题的最优解.这种神经网络模型对于求解许多优化问题具有重要的作用.