The Experts below are selected from a list of 5319 Experts worldwide ranked by ideXlab platform
D. Bonvin - One of the best experts on this subject based on the ideXlab platform.
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Convergence analysis of iterative identification and optimization schemes
Proceedings of the 2003 American Control Conference 2003., 2003Co-Authors: B. Srinivasan, D. BonvinAbstract:The use of measurements to compensate for model uncertainty has received increasing attention in the context of process optimization. The idea consists of iteratively using the measurements for identifying model parameters and the updated model for optimization. This paper investigates the convergence of various iterative identification and optimization schemes in the presence of model mismatch. The optimization can be model-based, data-based or of mixed nature. Based on the advantages and drawbacks of the various approaches, a novel scheme is proposed, by which the optimization is model-based so as to ensure fast improvement and finishes as a data-based approach so as to converge towards the true optimum. The performance improvement obtained with the proposed methodology is illustrated via the simulation of a semi-Batch Reaction system.
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Interplay between identification and optimization in run-to-run optimization schemes
Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301), 2002Co-Authors: B. Srinivasan, D. BonvinAbstract:The use of measurements to compensate for model uncertainty and disturbances has received increasing attention in the context of process optimization. The standard procedure consists of iteratively using the measurements for identifying the model parameters and the updated model for optimization. However, in the presence of model mismatch, this scheme suffers from lack of synergy between the identification and optimization problems. This paper investigates the performance of run-to-run optimization schemes and proposes to modify the objective function of the identification problem so as to include the cost function and the constraints of the optimization problem. The weights of the various terms in the extended objective function axe based on Lagrange multipliers. The performance improvement obtained with the proposed methodology is illustrated via the simulation of a semi-Batch Reaction system.
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Optimization of a semi-Batch Reaction system under safety constraints
1999 European Control Conference (ECC), 1999Co-Authors: O. Ubrich, B. Srinivasan, F. Stoessel, D. BonvinAbstract:Maximizing the yield of a second-order Reaction by manipulating the inlet flow rate is considered in both the isoperibolic and isothermal modes. For safety considerations, constraints on (i) the amount of heat produced, and (ii) the temperature under cooling failure are imposed. The optimal solution is discontinuous and is first obtained numerically. Analytical expressions for (i) the evolution of the input between the discontinuities, and (ii) the switching times are obtained. Using the analytical characterization of the optimal solution, an efficient feedback implementation strategy is designed.
Junting Xu - One of the best experts on this subject based on the ideXlab platform.
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ethylene 1 hexene copolymerization with mgcl2 supported ziegler natta catalysts containing aryloxy ligands part i catalysts prepared by immobilizing ticl3 oar onto mgcl2 in Batch Reaction
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Zhisheng Fu, Biao Huang, Junting XuAbstract:Abstract Novel aryloxy-containing MgCl2-supported Ziegler–Natta catalysts were prepared by treating TiCl3(OAr) (Ar = C6H5-, 2,6-Me2C6H3-, 2,6-i-Pr2C6H3-, 2,6-t-Bu2C6H3-) with MgCl2 in Batch Reaction. The influences of aryloxy group on the titanium content and aryloxy/Ti molar ratio in the catalysts was investigated. Because of ligand exchanges between the immobilized titanium species and TiCl3(OAr) in the solution, the aryloxy/Ti molar ratio in these catalysts were less than 1. Using triethylaluminum (TEA) or triisobutylaluminum (TIBA) as cocatalyst, these catalysts showed different catalytic behaviors in ethylene-1-hexene copolymerization. Using TIBA as cocatalyst, the aryloxy-containing catalysts showed higher activity than a TiCl4/MgCl2 blank catalyst. Although the total 1-hexene incorporation of the copolymers prepared by the novel catalysts were lower than that of the blank system, the difference in 1-hexene content between the boiling n-heptane soluble part and the insoluble part was markedly lower, and the blockiness of comonomer sequence distribution was evidently higher. The TIBA activated aryloxy-containing catalysts were found to produce poly(ethylene-co-1-hexene) with more uniform chemical composition distribution.
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Ethylene/1-hexene copolymerization with MgCl2-supported Ziegler–Natta catalysts containing aryloxy ligands. Part I: Catalysts prepared by immobilizing TiCl3(OAr) onto MgCl2 in Batch Reaction
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Zhisheng Fu, Biao Huang, Junting XuAbstract:Abstract Novel aryloxy-containing MgCl2-supported Ziegler–Natta catalysts were prepared by treating TiCl3(OAr) (Ar = C6H5-, 2,6-Me2C6H3-, 2,6-i-Pr2C6H3-, 2,6-t-Bu2C6H3-) with MgCl2 in Batch Reaction. The influences of aryloxy group on the titanium content and aryloxy/Ti molar ratio in the catalysts was investigated. Because of ligand exchanges between the immobilized titanium species and TiCl3(OAr) in the solution, the aryloxy/Ti molar ratio in these catalysts were less than 1. Using triethylaluminum (TEA) or triisobutylaluminum (TIBA) as cocatalyst, these catalysts showed different catalytic behaviors in ethylene-1-hexene copolymerization. Using TIBA as cocatalyst, the aryloxy-containing catalysts showed higher activity than a TiCl4/MgCl2 blank catalyst. Although the total 1-hexene incorporation of the copolymers prepared by the novel catalysts were lower than that of the blank system, the difference in 1-hexene content between the boiling n-heptane soluble part and the insoluble part was markedly lower, and the blockiness of comonomer sequence distribution was evidently higher. The TIBA activated aryloxy-containing catalysts were found to produce poly(ethylene-co-1-hexene) with more uniform chemical composition distribution.
Zhisheng Fu - One of the best experts on this subject based on the ideXlab platform.
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Ethylene/1-hexene copolymerization with supported ziegler-natta catalysts prepared by immobilizing TiCl3(OAr) onto MgCl2
Journal of Applied Polymer Science, 2015Co-Authors: Hongrui Yang, Zhisheng Fu, Biao Huang, Zhiqiang FanAbstract:ABSTRACT: Five titanium complexes TiCl3(OAr) (Ar5C6H5A, 2,6-Me2C6H3A, 2,6-i-Pr2C6H3A, 2,6-t-Bu2C6H3A, 4-Me-2,6-t- Bu2C6H3A) were immobilized, respectively, on MgCl2 in semiBatch Reaction to form supported catalysts for olefin polymerization. Comparing with the catalysts prepared by immobilizing TiCl3(OAr) onto MgCl2 in Batch Reaction, the catalysts prepared by semi- Batch Reaction have lower titanium content and higher ArO/Ti ratio. The aryloxy-containing catalysts studied in this work showed higher ethylene/1-hexene copolymerization activity and higher 1-hexene incorporation rate than the blank catalyst when activated by triisobutylaluminum. Similar effects of the aryloxy ligand were observed when the copolymerization is conducted in the presence of hydrogen. Introducing aryloxy ligand in the catalysts either by semiBatch or Batch Reaction caused similar effects of enhancing copoly- merization activity and a-olefin incorporation rate. Mechanism of the effects of aryloxy ligand has been discussed. V C 2014 Wiley Period- icals, Inc. J. Appl. Polym. Sci. 2015, 132, 41329. KEYWORDS:
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ethylene 1 hexene copolymerization with mgcl2 supported ziegler natta catalysts containing aryloxy ligands part i catalysts prepared by immobilizing ticl3 oar onto mgcl2 in Batch Reaction
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Zhisheng Fu, Biao Huang, Junting XuAbstract:Abstract Novel aryloxy-containing MgCl2-supported Ziegler–Natta catalysts were prepared by treating TiCl3(OAr) (Ar = C6H5-, 2,6-Me2C6H3-, 2,6-i-Pr2C6H3-, 2,6-t-Bu2C6H3-) with MgCl2 in Batch Reaction. The influences of aryloxy group on the titanium content and aryloxy/Ti molar ratio in the catalysts was investigated. Because of ligand exchanges between the immobilized titanium species and TiCl3(OAr) in the solution, the aryloxy/Ti molar ratio in these catalysts were less than 1. Using triethylaluminum (TEA) or triisobutylaluminum (TIBA) as cocatalyst, these catalysts showed different catalytic behaviors in ethylene-1-hexene copolymerization. Using TIBA as cocatalyst, the aryloxy-containing catalysts showed higher activity than a TiCl4/MgCl2 blank catalyst. Although the total 1-hexene incorporation of the copolymers prepared by the novel catalysts were lower than that of the blank system, the difference in 1-hexene content between the boiling n-heptane soluble part and the insoluble part was markedly lower, and the blockiness of comonomer sequence distribution was evidently higher. The TIBA activated aryloxy-containing catalysts were found to produce poly(ethylene-co-1-hexene) with more uniform chemical composition distribution.
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Ethylene/1-hexene copolymerization with MgCl2-supported Ziegler–Natta catalysts containing aryloxy ligands. Part I: Catalysts prepared by immobilizing TiCl3(OAr) onto MgCl2 in Batch Reaction
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Zhisheng Fu, Biao Huang, Junting XuAbstract:Abstract Novel aryloxy-containing MgCl2-supported Ziegler–Natta catalysts were prepared by treating TiCl3(OAr) (Ar = C6H5-, 2,6-Me2C6H3-, 2,6-i-Pr2C6H3-, 2,6-t-Bu2C6H3-) with MgCl2 in Batch Reaction. The influences of aryloxy group on the titanium content and aryloxy/Ti molar ratio in the catalysts was investigated. Because of ligand exchanges between the immobilized titanium species and TiCl3(OAr) in the solution, the aryloxy/Ti molar ratio in these catalysts were less than 1. Using triethylaluminum (TEA) or triisobutylaluminum (TIBA) as cocatalyst, these catalysts showed different catalytic behaviors in ethylene-1-hexene copolymerization. Using TIBA as cocatalyst, the aryloxy-containing catalysts showed higher activity than a TiCl4/MgCl2 blank catalyst. Although the total 1-hexene incorporation of the copolymers prepared by the novel catalysts were lower than that of the blank system, the difference in 1-hexene content between the boiling n-heptane soluble part and the insoluble part was markedly lower, and the blockiness of comonomer sequence distribution was evidently higher. The TIBA activated aryloxy-containing catalysts were found to produce poly(ethylene-co-1-hexene) with more uniform chemical composition distribution.
B. Srinivasan - One of the best experts on this subject based on the ideXlab platform.
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Convergence analysis of iterative identification and optimization schemes
Proceedings of the 2003 American Control Conference 2003., 2003Co-Authors: B. Srinivasan, D. BonvinAbstract:The use of measurements to compensate for model uncertainty has received increasing attention in the context of process optimization. The idea consists of iteratively using the measurements for identifying model parameters and the updated model for optimization. This paper investigates the convergence of various iterative identification and optimization schemes in the presence of model mismatch. The optimization can be model-based, data-based or of mixed nature. Based on the advantages and drawbacks of the various approaches, a novel scheme is proposed, by which the optimization is model-based so as to ensure fast improvement and finishes as a data-based approach so as to converge towards the true optimum. The performance improvement obtained with the proposed methodology is illustrated via the simulation of a semi-Batch Reaction system.
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Interplay between identification and optimization in run-to-run optimization schemes
Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301), 2002Co-Authors: B. Srinivasan, D. BonvinAbstract:The use of measurements to compensate for model uncertainty and disturbances has received increasing attention in the context of process optimization. The standard procedure consists of iteratively using the measurements for identifying the model parameters and the updated model for optimization. However, in the presence of model mismatch, this scheme suffers from lack of synergy between the identification and optimization problems. This paper investigates the performance of run-to-run optimization schemes and proposes to modify the objective function of the identification problem so as to include the cost function and the constraints of the optimization problem. The weights of the various terms in the extended objective function axe based on Lagrange multipliers. The performance improvement obtained with the proposed methodology is illustrated via the simulation of a semi-Batch Reaction system.
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Optimization of a semi-Batch Reaction system under safety constraints
1999 European Control Conference (ECC), 1999Co-Authors: O. Ubrich, B. Srinivasan, F. Stoessel, D. BonvinAbstract:Maximizing the yield of a second-order Reaction by manipulating the inlet flow rate is considered in both the isoperibolic and isothermal modes. For safety considerations, constraints on (i) the amount of heat produced, and (ii) the temperature under cooling failure are imposed. The optimal solution is discontinuous and is first obtained numerically. Analytical expressions for (i) the evolution of the input between the discontinuities, and (ii) the switching times are obtained. Using the analytical characterization of the optimal solution, an efficient feedback implementation strategy is designed.
Brian J. Marquardt - One of the best experts on this subject based on the ideXlab platform.
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moffat swern oxidation of alcohols translating a Batch Reaction to a continuous flow Reaction
Journal of Flow Chemistry, 2015Co-Authors: Olav Bleie, Michael F. Roberto, Thomas I. Dearing, Charles W. Branham, Olav M. Kvalheim, Brian J. MarquardtAbstract:The Moffatt-Swern oxidation (MSO) is a multistep, versatile, metal-free Reaction by which alcohols are transformed into aldehydes and ketones. Batch MSO requires low temperatures (−70 °C) due to a highly exothermic Reaction step that generates intermediates. This work shows that a rigorous investigation of the MSO in Batch can be used as a stepping-stone to its implementation in a continuous-flow reactor (CFR). This work has two parts: the first part details the investigation of MSO in Batch; the second covers the translation of the knowledge derived from Batch to a CFR. The MSO Batch Reaction was performed under cryogenic conditions with real-time process monitoring. The Reaction was monitored with Raman spectroscopy and could be tracked throughout the Reaction. All concentrations were validated using offline high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Two configurations of the CFR were produced. Configuration 1 used the traditional Batch methodology in...
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Moffat-Swern Oxidation of Alcohols: Translating a Batch Reaction to a Continuous-Flow Reaction
Journal of Flow Chemistry, 2015Co-Authors: Olav Bleie, Michael F. Roberto, Thomas I. Dearing, Charles W. Branham, Olav M. Kvalheim, Brian J. MarquardtAbstract:The Moffatt-Swern oxidation (MSO) is a multistep, versatile, metal-free Reaction by which alcohols are transformed into aldehydes and ketones. Batch MSO requires low temperatures (−70 °C) due to a highly exothermic Reaction step that generates intermediates. This work shows that a rigorous investigation of the MSO in Batch can be used as a stepping-stone to its implementation in a continuous-flow reactor (CFR). This work has two parts: the first part details the investigation of MSO in Batch; the second covers the translation of the knowledge derived from Batch to a CFR. The MSO Batch Reaction was performed under cryogenic conditions with real-time process monitoring. The Reaction was monitored with Raman spectroscopy and could be tracked throughout the Reaction. All concentrations were validated using offline high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Two configurations of the CFR were produced. Configuration 1 used the traditional Batch methodology in terms of reagent addition and Reaction conditions. Configuration 2 used the information derived from the Batch Reaction, changing the order of the reagent addition and increasing the temperature of the reactor. Real-time quantitative monitoring of chemical yield in the CFR was demonstrated via Raman spectroscopy and partial least squares (PLS) regression modeling. Reaction yield was accurately predicted every 15 s, reducing the need for chromatographic validation once the model was built. Configuration 2 was shown to perform comparably to configuration 1 at low temperature and far outperforming it at higher temperatures. Both CFR configurations performed significantly better than the Batch setup in terms of temperature and yield, as was expected.
