Documents disponibles écrits par cet auteur

An Exponentially Weighted Moving Average Method for Identification and Monitoring of / Shyh-Hong Hwang in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8239–8249 Titre : An Exponentially Weighted Moving Average Method for Identification and Monitoring of Type de document : texte imprimé Auteurs : Shyh-Hong Hwang, Auteur ; Ho-Tsen Chen, Auteur ; Chuei-Tin Chang, Auteur Année de publication : 2008 Article en page(s) : p. 8239–8249 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : The  stochasticEWMA  parameter  estimators Résumé : To identify parametric models for stochastic systems, the standard least-squares method tends to yield biased parameter estimates owing to correlated residuals resulting from unknown stochastic disturbances. Although the consistency properties of parameter estimates could generically be secured by instrumental variable methods, the inadequate choices of instruments and prefilters would render them much less efficient. This article establishes a method to identify an ARARX (AutoRegressive AutoRegressive with eXogenous input), an ARMAX (AutoRegressive Moving Average with eXogenous input), or a BJ (Box–Jenkins) model based on the process output data smoothed by the EWMA (Exponentially Weighted Moving Average). The major advantages of the method are 2-fold. First, the proposed off-line and online algorithms often acquire unbiased, efficient, and consistent parameter estimation from identification tests operating in open loop or closed loop. Second, the resultant process plus disturbance model can be easily employed to remove the autocorrelation in process data for accurate statistical process monitoring. Monte-Carlo simulation studies demonstrate that the proposed method provides reliable parametric models for a wide variety of noise characteristics and is highly robust with respect to the sampling period, sample size, and noise-to-signal ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0707218 [article] An Exponentially Weighted Moving Average Method for Identification and Monitoring of [texte imprimé] / Shyh-Hong Hwang, Auteur ; Ho-Tsen Chen, Auteur ; Chuei-Tin Chang, Auteur . - 2008 . - p. 8239–8249. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8239–8249 Mots-clés : The  stochasticEWMA  parameter  estimators Résumé : To identify parametric models for stochastic systems, the standard least-squares method tends to yield biased parameter estimates owing to correlated residuals resulting from unknown stochastic disturbances. Although the consistency properties of parameter estimates could generically be secured by instrumental variable methods, the inadequate choices of instruments and prefilters would render them much less efficient. This article establishes a method to identify an ARARX (AutoRegressive AutoRegressive with eXogenous input), an ARMAX (AutoRegressive Moving Average with eXogenous input), or a BJ (Box–Jenkins) model based on the process output data smoothed by the EWMA (Exponentially Weighted Moving Average). The major advantages of the method are 2-fold. First, the proposed off-line and online algorithms often acquire unbiased, efficient, and consistent parameter estimation from identification tests operating in open loop or closed loop. Second, the resultant process plus disturbance model can be easily employed to remove the autocorrelation in process data for accurate statistical process monitoring. Monte-Carlo simulation studies demonstrate that the proposed method provides reliable parametric models for a wide variety of noise characteristics and is highly robust with respect to the sampling period, sample size, and noise-to-signal ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0707218

Design and maintenance of multichannel protective systems / Yue-Cheng Liao in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11421–11433 Titre : Design and maintenance of multichannel protective systems Type de document : texte imprimé Auteurs : Yue-Cheng Liao, Auteur ; Chuei-Tin Chang, Auteur Année de publication : 2011 Article en page(s) : pp. 11421–11433 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Multichannel  protective  systems Résumé : To mitigate the undesirable effects caused by accidents in chemical plants, it is a common practice to install protective systems on processing units operated under hazardous conditions. Because hardware failures are basically random events, the availability of the protective system is highly dependent on its structural properties and also the maintenance programs. The aim of this study is to improve and generalize the current practice(1) for generating the design specifications and maintenance policies. Specifically, instead of monitoring only a single condition, in this work, the emergency system status is detected according to the measurements of several different process variables (or “alarm channels”) so as to optimize alarm performance. Because each of these channels can be consist of more than one online sensor, a modified version of the spare-supported corrective maintenance policy is also devised in this study to enhance availability. By solving the corresponding mathematical programming model, the optimal configurations of sensors and shutdown units, the best corrective and preventive maintenance procedures, and alarm/shutdown logic can all be identified automatically. Two examples are provided in this article to demonstrate the feasibility and effectiveness of the proposed approach. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901818e [article] Design and maintenance of multichannel protective systems [texte imprimé] / Yue-Cheng Liao, Auteur ; Chuei-Tin Chang, Auteur . - 2011 . - pp. 11421–11433. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11421–11433 Mots-clés : Multichannel  protective  systems Résumé : To mitigate the undesirable effects caused by accidents in chemical plants, it is a common practice to install protective systems on processing units operated under hazardous conditions. Because hardware failures are basically random events, the availability of the protective system is highly dependent on its structural properties and also the maintenance programs. The aim of this study is to improve and generalize the current practice(1) for generating the design specifications and maintenance policies. Specifically, instead of monitoring only a single condition, in this work, the emergency system status is detected according to the measurements of several different process variables (or “alarm channels”) so as to optimize alarm performance. Because each of these channels can be consist of more than one online sensor, a modified version of the spare-supported corrective maintenance policy is also devised in this study to enhance availability. By solving the corresponding mathematical programming model, the optimal configurations of sensors and shutdown units, the best corrective and preventive maintenance procedures, and alarm/shutdown logic can all be identified automatically. Two examples are provided in this article to demonstrate the feasibility and effectiveness of the proposed approach. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901818e

Development of an optimal sensor placement procedure based on fault evolution sequences / Jung Yang Chen in Industrial & engineering chemistry research, Vol. 47 N°19 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7335–7346 Titre : Development of an optimal sensor placement procedure based on fault evolution sequences Type de document : texte imprimé Auteurs : Jung Yang Chen, Auteur ; Chuei-Tin Chang, Auteur Année de publication : 2008 Article en page(s) : p. 7335–7346 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sensor  placement  procedures  SDG-based  strategy Résumé : The diagnostic resolution issues are usually addressed with a quantitative or semiquantitative approach in the reported studies concerning sensor placement procedures. Since the required information for implementing the traditional methods may not be always available, a SDG-based strategy is proposed in this paper to design the sensor networks on the basis of qualitatively predicted fault evolution sequences. To achieve a maximum level of resolution and, at the same time, to ensure observability, the corresponding design problems are formulated as integer programs in this work. Two alternative strategies are also developed for producing the optimal solutions. The feasibility of the proposed method is demonstrated with three examples. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701767v [article] Development of an optimal sensor placement procedure based on fault evolution sequences [texte imprimé] / Jung Yang Chen, Auteur ; Chuei-Tin Chang, Auteur . - 2008 . - p. 7335–7346. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7335–7346 Mots-clés : Sensor  placement  procedures  SDG-based  strategy Résumé : The diagnostic resolution issues are usually addressed with a quantitative or semiquantitative approach in the reported studies concerning sensor placement procedures. Since the required information for implementing the traditional methods may not be always available, a SDG-based strategy is proposed in this paper to design the sensor networks on the basis of qualitatively predicted fault evolution sequences. To achieve a maximum level of resolution and, at the same time, to ensure observability, the corresponding design problems are formulated as integer programs in this work. Two alternative strategies are also developed for producing the optimal solutions. The feasibility of the proposed method is demonstrated with three examples. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701767v

Development of a generalized mixed integer nonlinear programming model for assessing and improving the operational flexibility of water network designs / Chuei-Tin Chang in Industrial & engineering chemistry research, Vol. 48 N° 7 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3496–3504 Titre : Development of a generalized mixed integer nonlinear programming model for assessing and improving the operational flexibility of water network designs Type de document : texte imprimé Auteurs : Chuei-Tin Chang, Auteur ; Bao-Hong Li, Auteur ; Chih-Wen Liou, Auteur Année de publication : 2009 Article en page(s) : pp. 3496–3504 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water  network  Operational  flexibility  Mixed  integer  nonlinear  program Résumé : In designing and operating any water network, a typical issue that must be addressed is concerned with the uncertain process conditions. A systematic procedure is proposed in this paper to enhance the operational flexibility of a given structure. Specifically, two design options have been investigated: (1) relaxation of the allowed maximum freshwater consumption rate in the nominal design and (2) installation of auxiliary pipelines and/or elimination of existing ones. The flexibility index model proposed by Swaney and Grossmann (1985) has been modified and formulated in a generalized format to evaluate the impact of introducing various modifications into an existing network. Since this model is a mixed integer nonlinear program (MINLP), it is in general very difficult to locate the global optima in the iterative solution processes. A simple and effective initialization procedure has also been devised in this work to facilitate successful convergence. The effectiveness of the proposed approach is demonstrated with two examples in this paper. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015363 [article] Development of a generalized mixed integer nonlinear programming model for assessing and improving the operational flexibility of water network designs [texte imprimé] / Chuei-Tin Chang, Auteur ; Bao-Hong Li, Auteur ; Chih-Wen Liou, Auteur . - 2009 . - pp. 3496–3504. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3496–3504 Mots-clés : Water  network  Operational  flexibility  Mixed  integer  nonlinear  program Résumé : In designing and operating any water network, a typical issue that must be addressed is concerned with the uncertain process conditions. A systematic procedure is proposed in this paper to enhance the operational flexibility of a given structure. Specifically, two design options have been investigated: (1) relaxation of the allowed maximum freshwater consumption rate in the nominal design and (2) installation of auxiliary pipelines and/or elimination of existing ones. The flexibility index model proposed by Swaney and Grossmann (1985) has been modified and formulated in a generalized format to evaluate the impact of introducing various modifications into an existing network. Since this model is a mixed integer nonlinear program (MINLP), it is in general very difficult to locate the global optima in the iterative solution processes. A simple and effective initialization procedure has also been devised in this work to facilitate successful convergence. The effectiveness of the proposed approach is demonstrated with two examples in this paper. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015363

Efficient flexibility assessment procedure for water network designs / Bao-Hong Li in Industrial & engineering chemistry research, Vol. 50 N° 7 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 7 (Avril 2011) . - pp. 3763–3774 Titre : Efficient flexibility assessment procedure for water network designs Type de document : texte imprimé Auteurs : Bao-Hong Li, Auteur ; Chuei-Tin Chang, Auteur Année de publication : 2011 Article en page(s) : pp. 3763–3774 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Water  network  designs Résumé : A new nonlinear programming (NLP) formulation of the conventional flexibility index model (Swaney and Grossmann, 1985) has been developed in this work for flexibility analysis of single-contaminant water networks. Since this improved model is constructed on the basis of a single critical point instead of the entire region of uncertain parameters, the iterative optimization process converges at a much faster rate. A systematic flexibility assessment procedure has also been devised to analyze and modify a given network so as to achieve the desired level of operational resiliency. Specific design steps are followed sequentially to check the feasibility of a nominal design and to improve its flexibility index by (1) relaxing the upper limit of freshwater capacity and/or (2) adding new pipelines and/or removing existing ones. The effectiveness of the proposed approach is demonstrated with two examples in this paper. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101329v [article] Efficient flexibility assessment procedure for water network designs [texte imprimé] / Bao-Hong Li, Auteur ; Chuei-Tin Chang, Auteur . - 2011 . - pp. 3763–3774. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 7 (Avril 2011) . - pp. 3763–3774 Mots-clés : Water  network  designs Résumé : A new nonlinear programming (NLP) formulation of the conventional flexibility index model (Swaney and Grossmann, 1985) has been developed in this work for flexibility analysis of single-contaminant water networks. Since this improved model is constructed on the basis of a single critical point instead of the entire region of uncertain parameters, the iterative optimization process converges at a much faster rate. A systematic flexibility assessment procedure has also been devised to analyze and modify a given network so as to achieve the desired level of operational resiliency. Specific design steps are followed sequentially to check the feasibility of a nominal design and to improve its flexibility index by (1) relaxing the upper limit of freshwater capacity and/or (2) adding new pipelines and/or removing existing ones. The effectiveness of the proposed approach is demonstrated with two examples in this paper. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101329v

Heuristic approach to incorporate timesharing schemes in multiperiod heat exchanger network designs / Efrat Sadeli in Industrial & engineering chemistry research, Vol. 51 N° 23 (Juin 2012) 

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Iterative identification of continuous-time hammerstein and wiener systems using a two-stage estimation algorithm / Ho-Tsen Chen in Industrial & engineering chemistry research, Vol. 48 N°3 (Février 2009) 

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Sequential approach to design batch distillation processes for homogeneous azeotropic systems / Vincentius Surya Kurnia Adi in Industrial & engineering chemistry research, Vol. 49 N° 9 (Mai 2010) 

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A simultaneous optimization approach to generate design specifications and maintenance policies for the multilayer protective systems in chemical processes / Kuo-Hwa Liang in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

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Two-tier search strategy to identify nominal operating conditions for maximum flexibility / Vincentius Surya Kurnia Adi in Industrial & engineering chemistry research, Vol. 50 N° 18 (Septembre 2011) 

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