Closed-loop identification using direct approach and high order ARX/GOBF-ARX models

Model accuracy plays a key role in the performance of advanced, model predictive control algorithms. Model fidelity is usually affected by routine operating condition changes, which necessitate reidentification. From several theoretical and practical considerations, it is recommended that such re-identification be performed under closed-loop conditions. The direct approach for closed-loop identification, owing to its simplicity, is better suited for MPC. In order to yield unbiased and consistent parameter estimates, however, this approach requires the noise model to be sufficiently parameterized. Towards this objective, high order ARX models are the most suitable candidates from the viewpoint of ease of parameter estimation. For multivariable systems, however, the identification of high order ARX models would require longer experiments to be performed. This being undesirable from a practical viewpoint, there is a need for a parsimonious parameterization that would retain the benefits of high order ARX models. In this work, we propose to use generalized orthonormal basis filters (GOBFs) to achieve this parsimonous parameterization. Further, we propose an approach to obtain reduced order models by emphasizing important frequencies so as to suitably shape the bias. We also show that the choice of the GOBF parameterization has another important merit, viz. their ability to perform well even with minimal perturbation data or short experiment times. The efficacy of the proposed approach is demonstrated via simulations on the benchmark Shell Control Problem and a laboratory quadruple tank setup.     

Application of VPRS model with enhanced threshold parameter selection mechanism to automatic stock market forecasting and portfolio selection

This study proposes a technique based upon Fuzzy C-Means (FCM) classification theory and related fuzzy theories for choosing an appropriate value of the Variable Precision Rough Set (VPRS) threshold parameter (β) when applied to the classification of continuous information systems. The VPRS model is then combined with a moving Average Autoregressive Exogenous (ARX) prediction model and Grey Systems theory to create an automatic stock market forecasting and portfolio selection mechanism. In the proposed mechanism, financial data are collected automatically every quarter and are input to an ARX prediction model to forecast the future trends of the collected data over the next quarter or half-year period. The forecast data are then reduced using a GM(1, N) model, classified using a FCM clustering algorithm, and then supplied to a VPRS classification module which selects appropriate investment stocks in accordance with a pre-determined set of decision-making rules. Finally, a grey relational analysis technique is employed to weight the selected stocks in such a way as to maximize the rate of return of the stock portfolio. The validity of the proposed approach is demonstrated using electronic stock data extracted from the financial database maintained by the Taiwan Economic Journal (TEJ). The portfolio results obtained using the proposed hybrid model are compared with those obtained using a Rough Set (RS) selection model. The effects of the number of attributes of the RS lower approximation set and VPRS β-lower approximation set on the classification are systematically examined and compared. Overall, the results show that the proposed stock forecasting and stock selection mechanism not only yields a greater number of selected stocks in the β-lower approximation set than in the RS approximation set, but also yields a greater rate of return.     

用ARX进行变径岔管曲面CAD开发

讨论了利用ＡＲＸ在ＡｕｔｏＣＡＤＲ１４上进行变径二岔 管和三岔管曲面ＣＡＤ二次的方法,文中讨论了的方法可用于其它类似的基于ＡｕｔｏＣＡＤ的ＣＡＤ系统的二次开发。     

VC^＋＋环境下利用SQL Server与Object ARX开发智能参数化刀具实体模型库

对VC^ ,SQL Server和AutoCAD相互通讯的技术进行深入研究,在此基础上利用AutoCAD的二次开发工具Object ARX完成了对刀具的参数化生成、模糊化选刀和智能化管理的刀具实体模型库系统的开发。     

解决MFC与ARX在图形变换中冲突的方法

本文针对ＡｕｔｏＣＡＤ中常用图形变换方法与ＭＦＣ的冲突,提出利用ＡＲＸ的ＡｃＧｅ库的图形“先变换后显示”,不仅能解决上述冲突,还加快了绘图速度,增加了编程与显示的灵活性。     

ARX在岔管过渡段曲面CAD中的应用

ＡＲＸ是基于ＡｕｔｏＣＡＤ进行ＣＡＤ软件开发的新一代开发工具。本文讨论了利用ＡＲＸ在ＡｕｔｏＣＡＤ ＲＭ上进行岔管过渡段曲面ＣＡＤ开发的方法。     

ObjectARX技术在电网CAD应用中的研究

介绍了面向对象的设计思想和对象的抽象机理在电网 CAD( PWCAD)系统中的应用以及 Object ARX编程技术。阐述了通过利用 Auto CAD核心数据库的开放结构和 Object ARX提供的基类及类的继承、派生机制定义专业对象的过程以及建模系统的数据交换技术 ,并由此建立了 PWCAD的对象模型。     

用Visual J++实现ARX应用程序的动态自动加载

利用AutoCAD提供的COM接口,在Visual J 6.0环境下开发了一个Java应用程序,实现了AutoCAD的动态加载以及ARX应用程序和相应的菜单、工具条的动态自动加载.     

曲柄连杆式飞剪机减速器CAD系统设计

针对曲柄连杆式飞剪机减速器进行了研究.以AutoCAD2002作为开发平台,以VC 6.0为编程环境进行的二次开发,开发出了与AutoCAD自身风格一致的用户接口,人机交互界面友好,操作简单便捷.实现了曲柄连杆式减速器传动机构的常规设计、校核计算、优化设计和参数化绘图一体化.该系统常规设计正确,优化设计结果合理,具有很高的工程使用价值.     

水力机组辅助设备元件图应用程序的开发

利用AutoCAD开发工具ARX ,在VisualC ++5 .0环境下编程开发水力机组辅助设备元件图ARX应用程序 ,并将它装入AutoCADR1 4软件中 ,直接作为AutoCAD的命令使用