Alessandro Alle | University of Sao Paulo (original) (raw)

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Papers by Alessandro Alle

Research paper thumbnail of A general framework for simultaneous cyclic scheduling and operational optimization of multiproduct continuous plants

Brazilian Journal of Chemical Engineering, 2002

Research paper thumbnail of Modelagem matemática da policondensação no estado sólido do poli(tereftalato de etileno)

Research paper thumbnail of Economic Lot Scheduling under Performance Decay

The aim of this work is to propose a mathematical programming model for the Economic Lot Scheduli... more The aim of this work is to propose a mathematical programming model for the Economic Lot Scheduling Problem (ELSP) with performance decay. The main difficulties related to this model are the nonlinearities and/or nonconvexities associated with the dynamic behavior of the system with time. Firstly, the problem is formulated as a Mixed Integer Non Linear Program (MINLP), which is found to be nonconvex. The model is then transformed into a Mixed Integer Linear Programming (MILP) model through the discretization of cycle time. Therefore, the globally optimal schedule can be obtained. A case study demonstrates the applicability of the MILP model and its potential benefits in comparison with a hierarchical approach.

Research paper thumbnail of The Economic Lot Scheduling Problem under Performance Decay

Industrial & Engineering Chemistry Research, 2004

The aim of this work is to propose a mathematical programming model for the economic lot scheduli... more The aim of this work is to propose a mathematical programming model for the economic lot scheduling problem (ELSP) with performance decay. First, the problem is formulated as a mixed integer nonlinear program (MINLP), which is found to be nonconvex. The model is then transformed into a mixed integer linear programming (MILP) model through the discretization of the cycle time. This model is tested in a wide set of randomly generated problems with various degrees of difficulty. The results show that the MILP model can achieve the optimum within satisfactory CPU times. An illustrative example demonstrates the applicability of the MILP model and its potential benefits in comparison with a hierarchical approach.

Research paper thumbnail of Global Optimization for the Cyclic Scheduling and Operation of Multistage Continuous Plants

Industrial & Engineering Chemistry Research, 2004

Research paper thumbnail of Cyclic production and cleaning scheduling of multiproduct continuous plants

Computer Aided Chemical …, 2002

... 3. Mathematical Model The mathematical formulation is based on a previous continuous-time sch... more ... 3. Mathematical Model The mathematical formulation is based on a previous continuous-time scheduling model for continuous muldproduct plants (Alle and Pinto, 2001 ... i,m,r (11) r /??; ^T^ Vi> (13) r The total demand on final products must be satisfied at the cycle end: W.^>d.Tc ...

Research paper thumbnail of Mixed-Integer Programming Models for the Scheduling and Operational Optimization of Multiproduct Continuous Plants

Industrial & Engineering Chemistry Research, 2002

This paper addresses the problem of the simultaneous scheduling and optimization of the operating... more This paper addresses the problem of the simultaneous scheduling and optimization of the operating conditions of continuous multistage multiproduct plants with intermediate storage. First, an MINLP model, called TSPFLOW, that is based on the TSP formulation for product sequencing is proposed for the scheduling of the operation of such plants. TSPFLOW leads to a significant reduction in the number of constraints and continuous and binary variables from a formulation previously reported (Pinto, J. M.; Grossmann, I. E. Comput. Chem. Eng. 1994, 18, 797) and, consequently, a one-order-of-magnitude reduction in CPU time. Moreover, TSPFLOW solves instances two times as large as those formerly reported. Second, production rates and yields are introduced as additional optimization variables to state the simultaneous problem of scheduling with operational optimization. A linearization approach that employs the discretization of nonlinear variables is presented and compared to the direct solution of the original MINLP. Results show that nonlinear restrictions are more effective than linear discrete restrictions from the points of view of both optimality and computational effort. The tradeoffs involved are very complex, and the development of a straightforward method (general rule) for optimal scheduling of the operation seems to be less effective than the proposed approach.

Research paper thumbnail of Optimal Cyclic Scheduling and Operation of Multistage Multiproduct Continuous Plants with Intermediate Storage

Chemie Ingenieur Technik, 2001

Research paper thumbnail of Optimal Cyclic Scheduling and Operation of Multistage Multiproduct Continuous Plants with Intermediate Storage

Chemie Ingenieur Technik, 2001

Research paper thumbnail of Simultaneous Scheduling and Operational Optimization of Multiproduct, Cyclic Continuous Plants

Brazilian Journal of Chemical Engineering, 2002

... A.Alle and JMPinto * Department of Chemical Engineering, University of Sao Paulo Av. Prof. ..... more ... A.Alle and JMPinto * Department of Chemical Engineering, University of Sao Paulo Av. Prof. ... Constraint (7) states that in processing two consecutive products, the processing of the second starts exactly after the end of the processing of the first plus the transition time. ...

Research paper thumbnail of A general framework for simultaneous cyclic scheduling and operational optimization of multiproduct continuous plants

Brazilian Journal of Chemical Engineering, 2002

Research paper thumbnail of Modelagem matemática da policondensação no estado sólido do poli(tereftalato de etileno)

Research paper thumbnail of Economic Lot Scheduling under Performance Decay

The aim of this work is to propose a mathematical programming model for the Economic Lot Scheduli... more The aim of this work is to propose a mathematical programming model for the Economic Lot Scheduling Problem (ELSP) with performance decay. The main difficulties related to this model are the nonlinearities and/or nonconvexities associated with the dynamic behavior of the system with time. Firstly, the problem is formulated as a Mixed Integer Non Linear Program (MINLP), which is found to be nonconvex. The model is then transformed into a Mixed Integer Linear Programming (MILP) model through the discretization of cycle time. Therefore, the globally optimal schedule can be obtained. A case study demonstrates the applicability of the MILP model and its potential benefits in comparison with a hierarchical approach.

Research paper thumbnail of The Economic Lot Scheduling Problem under Performance Decay

Industrial & Engineering Chemistry Research, 2004

The aim of this work is to propose a mathematical programming model for the economic lot scheduli... more The aim of this work is to propose a mathematical programming model for the economic lot scheduling problem (ELSP) with performance decay. First, the problem is formulated as a mixed integer nonlinear program (MINLP), which is found to be nonconvex. The model is then transformed into a mixed integer linear programming (MILP) model through the discretization of the cycle time. This model is tested in a wide set of randomly generated problems with various degrees of difficulty. The results show that the MILP model can achieve the optimum within satisfactory CPU times. An illustrative example demonstrates the applicability of the MILP model and its potential benefits in comparison with a hierarchical approach.

Research paper thumbnail of Global Optimization for the Cyclic Scheduling and Operation of Multistage Continuous Plants

Industrial & Engineering Chemistry Research, 2004

Research paper thumbnail of Cyclic production and cleaning scheduling of multiproduct continuous plants

Computer Aided Chemical …, 2002

... 3. Mathematical Model The mathematical formulation is based on a previous continuous-time sch... more ... 3. Mathematical Model The mathematical formulation is based on a previous continuous-time scheduling model for continuous muldproduct plants (Alle and Pinto, 2001 ... i,m,r (11) r /??; ^T^ Vi> (13) r The total demand on final products must be satisfied at the cycle end: W.^>d.Tc ...

Research paper thumbnail of Mixed-Integer Programming Models for the Scheduling and Operational Optimization of Multiproduct Continuous Plants

Industrial & Engineering Chemistry Research, 2002

This paper addresses the problem of the simultaneous scheduling and optimization of the operating... more This paper addresses the problem of the simultaneous scheduling and optimization of the operating conditions of continuous multistage multiproduct plants with intermediate storage. First, an MINLP model, called TSPFLOW, that is based on the TSP formulation for product sequencing is proposed for the scheduling of the operation of such plants. TSPFLOW leads to a significant reduction in the number of constraints and continuous and binary variables from a formulation previously reported (Pinto, J. M.; Grossmann, I. E. Comput. Chem. Eng. 1994, 18, 797) and, consequently, a one-order-of-magnitude reduction in CPU time. Moreover, TSPFLOW solves instances two times as large as those formerly reported. Second, production rates and yields are introduced as additional optimization variables to state the simultaneous problem of scheduling with operational optimization. A linearization approach that employs the discretization of nonlinear variables is presented and compared to the direct solution of the original MINLP. Results show that nonlinear restrictions are more effective than linear discrete restrictions from the points of view of both optimality and computational effort. The tradeoffs involved are very complex, and the development of a straightforward method (general rule) for optimal scheduling of the operation seems to be less effective than the proposed approach.

Research paper thumbnail of Optimal Cyclic Scheduling and Operation of Multistage Multiproduct Continuous Plants with Intermediate Storage

Chemie Ingenieur Technik, 2001

Research paper thumbnail of Optimal Cyclic Scheduling and Operation of Multistage Multiproduct Continuous Plants with Intermediate Storage

Chemie Ingenieur Technik, 2001

Research paper thumbnail of Simultaneous Scheduling and Operational Optimization of Multiproduct, Cyclic Continuous Plants

Brazilian Journal of Chemical Engineering, 2002

... A.Alle and JMPinto * Department of Chemical Engineering, University of Sao Paulo Av. Prof. ..... more ... A.Alle and JMPinto * Department of Chemical Engineering, University of Sao Paulo Av. Prof. ... Constraint (7) states that in processing two consecutive products, the processing of the second starts exactly after the end of the processing of the first plus the transition time. ...