乙炔法氯乙烯反应器一维二维模型对比

根据氯乙烯合成反应的动力学机理,运用化工过程系统模拟方法,对乙炔法合成氯乙烯的固定床反应器分别建立一维和二维数学模型。针对2种模型的形式和特点,采用适当的数值计算方法,对现有设备进行模拟,得出反应器的床层轴向温度和转换率分布图。在改变进料量的情况下,对比研究2种模型对反应器的特征表达有何异同,分析了各种模型优劣。     

原位脱碳流化床煤气化反应器的数值模拟

为了减少温室效应,对于煤气化过程中CO_2的减排与零排放技术的研究成为必要。本文建立了全面的煤气化反应器的数值模型,对以CaO作为吸收剂的原位脱碳的流化床煤气化反应器进行了数值模拟。模拟以简化结构的二维反应器为求解域,应用标准k-ε模型描述气相湍动,EDC模型描述反应器中湍流与反应的偶合,EDC模型将详细的化学动力学融入到湍流混合中。讨论了反应器中温度、气速、压力及气体产物的分布。     

光气合成反应器动态仿真

该文对光气合成管式反应器的动态仿真技术进行了研究.根据物料及焓守恒方程建立了管式反应器的动态机理模型,并根据模型的形式和特点选择了适当的数值计算方法,开发了光气反应器的动态模拟程序模块.模块应用结果表明,达到稳态时的结果能比较真实地反映生产实际情况,动态过程能很好地反映生产的变化趋势,并能完成对非正常工况的模拟.该模型对光气合成反应器动态特性和控制方式的研究以及光气合成相关工艺仿真培训系统软件的开发等都有重要的意义.     

Lurgi型甲醇合成反应器的动态模拟

为了能更好地预测甲醇合成系统的动态特性、合成与分析控制系统、模拟开停车及事故和培训操作人员等,对Lurgi型甲醇合成反应器的模型化与动态模拟技术进行了研究。根据物料及热量守恒方程建立了Lurgi型甲醇合成固定床反应器的动态模型,并根据模型的形式和特点选择了适当的数值计算方法,开发了动态模拟程序模块,并据此通过模拟计算获得了适宜的操作参数范围,这对于优化合成工艺,提高甲醇产量有明确的指导意义。应用结果表明,达到稳态时的结果能真实地反映生产实际情况,动态过程能很好地反映生产变化趋势。该模型对Lurgi型甲醇合成反应器动态特性和控制方案的研究,以及甲醇合成相关工艺仿真培训系统软件的开发等都有重要的意义。     

基于简化模型的T型微反应器设计

分析T型微反应器内流体混合程度和反应产物收率的常用方法:是建立计算流体动态模型,也就是CFD模型,可是这种模型不适用于微反应器的优化设计,因为利用CFD模型进行优化计算需要的大量的计算时间。本研究开发了一个描述T型微反应器流体流动状态的简化模型,通过假设边界条件和假设扩散系数的设定来计算微反应器内反应产物收率。其中假设边界条件用来描述强混合效果在反应通道入口处的流动状态,假设扩散系数用来描述混合效果在流动路径上的变化。本研究依据此简化模型,确立了一种优化设计方法:,用来设计具有最优尺寸的T型微反应器。优化问题的目标函数是最大反应产物收率,优化约束包括反应通道尺寸约束和操作压力约束。在求解过程中,首先建立尺寸约束边界条件下的CFD模型,然后依据CFD模型计算结果:,求解简化模型中的未知参数。将建好的简化模型作为优化问题的等式约束,最后求出最优的T型微反应器。简化模型和优化设计方法:的有效性通过一个快速平行串联反应在微反应器中的反应过程来验证。简化模型的优化设计结果:和CFD模型验证结果:高度一致。     

基于EMMS模型的聚乙烯流化床流体力学模拟

目前,针对气-固流化床的数值模拟多采用欧拉-欧拉双流体模型(TFM)。而传统的TFM基于均匀拟流体假设,不能准确描述流化床内流态化的非均匀性及介观尺度的性质,如颗粒团聚。本文采用基于能量最小多尺度方法(EMMS)的双流体模型(EFM)来研究聚乙烯流化床流体动力学,模拟结果证明EFM较好把握了流化床内的非均匀性以及介观尺度性质,更能准确描述聚乙烯流化床反应器内部的流体动力学。EFM模型的应用可以为聚乙烯生产过程中流化床结构改进以及"热点"的避免提供更有说服力的模拟验证。     

以光合工厂理论为基础的微藻生长动力学模型的优化研究

以光合成工厂为思想基础的生长动力学模型是从机理上描述微藻光生化反应的一个重要模型,其模型的拟合程度关系到微藻浓度的准确预测。本文通过对实验数据进行合理分组,对其进行了进一步优化;另外,将管式反应器局部光强与光生长动力学相关联,建立了新的生长动力学模型。研究结果表明,优化后模型的判定系数明显增大,与局部光强相关且合理分组得到的数学模型与实验吻合程度最高,明显提高了微藻浓度预测的准确性。     

乙苯脱氢反应器的动态建模与分析

建立了乙苯脱氢反应器的一维拟均相动态模型来模拟实际反应器。以实际工厂数据为基础,用差分进化算法拟合出了反应动力学模型参数和催化剂失活模型参数。模拟结果表明建立的反应器模型精度较高适合于工业应用。同时考虑到实际的开车过程耗时较长,文中设计了一种反应器开车方案,并通过计算机模拟验证了该方案的可行性。     

光气合成反应器一维二维模型的对比研究

基于光气合成反应的动力学机理,分别建立了管式光气合成反应器的一维和二维数学模型。对两种数学模型分别采用不同的数值计算方法,得出反应器的床层温度和氯气转化率分布图。改变进料流量和催化剂的装填量,研究两种模型的特征表达和变化规律,对比分析两种模型计算结果。     

乙炔法氯乙烯合成固定床反应器的建模及分析

针对我国广泛应用的乙炔法氯乙烯合成固定床反应器,结合氯乙烯合成的反应动力学、催化剂的失活动力学,同时引入了传热方程,建立了完整的列管式氯乙烯合成固定床反应器的数学模型。将该模型用于工业生产,模拟了传热系数沿管长的变化,列管内反应温度沿管长的变化并与生产数据对比,验证了模型的正确性。最后分析了乙炔空速、冷却水温度对管内温度分布和乙炔转化率的影响。     

Microsoft repository version 2 and the open information model

Microsoft Repository is an object-oriented meta-data management facility that ships in Microsoft Visual Studio and Microsoft SQL Server. It includes two main components:

• •• A repository engine that implements a set of object-oriented interfaces on top of a SQL database system. A developer can use these interfaces to define information models (i.e., schemas) and manipulate instances of the models.
• •• The Open Information Model, which is a set of information models that cover object modeling, database modeling, and component reuse.

The repository system is designed to meet the persistent storage needs of software tools. Its main technical goals are:

• •• Compatibility with Microsoft's Component Object Model (COM) architecture
• •• Extensibility by customers and independent software vendors, so they can add behavior to objects stored by the repository engine and extend information models provided by Microsoft and others.
• •• Flexible and efficient versioning, configuration management, and checkout/checkin to support team-oriented activities.

This paper describes the programming interface and implementation of the repository engine and the Open Information Model.     

Using model transformation to refactor use case models based on antipatterns

Use Case modeling is a popular technique for documenting functional requirements of software systems. Refactoring is the process of enhancing the structure of a software artifact without changing its intended behavior. Refactoring, which was first introduced for source code, has been extended for use case models. Antipatterns are low quality solutions to commonly occurring design problems. The presence of antipatterns in a use case model is likely to propagate defects to other software artifacts. Therefore, detection and refactoring of antipatterns in use case models is crucial for ensuring the overall quality of a software system. Model transformation can greatly ease several software development activities including model refactoring. In this paper, a model transformation approach is proposed for improving the quality of use case models. Model transformations which can detect antipattern instances in a given use case model, and refactor them appropriately are defined and implemented. The practicability of the approach is demonstrated by applying it on a case study that pertains to biodiversity database system. The results show that model transformations can efficiently improve quality of use case models by saving time and effort.     

新型模糊神经网络模型

分析了已有模糊神经网络模型结构与学习算法的特点,针对它们收敛速度慢、全局逼近能力差等不足,提出了一种新型的模糊神经网络模型,其在模糊化层实现了隶属函数的合成,且结构简单、推理层只有两个节点。实验结果表明该模型具有收敛速度快、全局逼近能力强的优点,具有一定的实用价值。     

RASES: A database supported framework for structured model base management

Structured management of model base has placed demands on some kind of computer based frameworks with highly structured formalisms. This paper proposes a new framework, called the relational algebraic system entity structure (RASES), which is based on the system entity structure (SES) formalism and the relational algebra (RA) formalism. These formalisms provide a conceptual basis for the structured model base management. Within the framework, structural knowledge of a system is represented in a hierarchical structure and saved in a database. Furthermore, several operations can be formulated in terms of relational algebra which can be coded in a standard query language such as the SQL. The framework can be easily implemented on, and fully utilize the functionality of, relational database management system (RDBMS). With the help of the implemented framework, simulation models can be systematically synthesized from the models in the model base through the following processes. First, a family of hierarchical structures of a system is organized in the form of entity structure by the entity structuring process. Then, candidate models of the system which meet design objectives are synthesized from the entity structure through the pruning process. Finally, designers can conduct appropriate experiment with the models for design verification and performance measure.     

Partitioned model-based IMC design using JITL modeling technique

A partitioned model-based internal model control (PM-IMC) design strategy is proposed for a class of nonlinear systems that can be described by just-in-time learning (JITL) modeling technique. The PM-IMC scheme consists of a conventional IMC controller augmented by an auxiliary loop to account for nonlinearities in the system. Two alternative implementations of the JITL are discussed and compared via simulation studies of an industrial polymerization reactor and an isothermal reactor exhibiting inverse response. It is shown that PM-IMC using the database-updating JITL is more desirable owing to the relative ease in collecting the process data required to construct its initial database, while achieving comparable control performance as that obtained by PM-IMC using the JITL with fixed-database, which requires process data collected over the entire operating region to construct its database. In addition, a comparison is made between PM-IMC and its linear counterpart.     

Computer aided model building and CAL

Model building has become an educational objective at the tertiary and the secondary level. There are reservations in regard to the suitability of computer simulations for integrating modelling into the education process. Interactive simulation systems can be designed to meet educational requirements, presenting a preprogrammed simulation environment which only has to be supplied with the model itself. The model can be supplied as a set of statements (“missinglink” program) or as a block diagram representing the structure of the system. Examples are presented for both possibilities and their respective characteristics are discussed.     

模型驱动构架中模型信息交换研究

模型是OMG提出的模型驱动构架中的核心。探讨怎样利用XMI标准为不同模型之间搭起信息交换的桥梁是该文的重点。介绍了模型驱动构架,讨论了模型信息交换的必要性。接着探讨了怎样利用XMI标准描述遵从MOF规范的模型,提出了模型差异的概念,并给出了基于XMI标准的实现。     

飞机电源系统保护控制的仿真研究

针对某型飞机电源系统保护控制的仿真需求,在飞机主电源和二次电源的Saber模型基础上,提出了器件库模型、模型构建工具Model Architect中的模型以及MAST语言编程模型相结合的方法,详细论述了Saber仿真器中过压保护和过流保护控制模型的建模过程,从工程应用的角度建立了相应的混合信号仿真模型,并对控制模型的功能进行仿真验证。仿真结果表明,该方法能准确、可靠地实现电源系统模型的保护控制功能,为今后运用Saber仿真器建立控制模型提供了有益参考。     

Continuous-time control model validation using finite experimentaldata

The application of robust control theory requires models containing unknown, bounded perturbations and unknown, bounded input signals. Model validation is a means of assessing the applicability of a given model with respect to experimental data. This paper develops a theoretical framework, and a computational solution, for the model validation problem in the case where the model, including unknown perturbations and signals, is given in the continuous time domain, yet the experimental datum is a finite, sampled signal. The continuous nature of the unknown components is treated directly with a sampled data lifting theory. This gives results which are valid for any sample period and any datum length. Explicit calculation of whether sufficient data for invalidation has been obtained arises naturally in this framework. A common class of robust control models is treated and leads to a convex matrix optimization problem. A simulation example illustrates the approach     

基于ExSpect的维修保障联邦成员开发

分析了ExSpect的建模方法和软件接口,建立了基于ExSpect的维修保障仿真模型。开发了仿真对象模型（SOM）,并对其信息接口进行了改造,从而实现了Petri网仿真模型与RTI运行支撑环境的无缝连接,为后续开发高层体系结构（HLA）环境下的Petri网仿真模型集成环境进行了初步的探索工作。