Showing papers in "Computers & Chemical Engineering in 1997"

TL;DR: The proposed branch and bound type algorithm attains finite ϵ-convergence to the global minimum through the successive refinement of a convex relaxation of the feasible region and/or of the objective function and the subsequent solution of a series of nonlinear convex optimization problems.

TL;DR: A non-linear modeling framework that supports model development in between empirical and mechanistic modeling and a flexible computer aided modeling tool that supports modeling within this framework are presented.

TL;DR: In this article, an orthogonal collocation method based on moving finite elements has been developed for simulating fixed-bed adsorbers, where the movement of the grid is calculated explicitly before starting the integration of the discretized equations, using the results of the equilibrium theory for wave transitions and the shock layer theory for shock transitions.

TL;DR: The M-SIMPSA algorithm, which does not require feasible initial points or any problem decomposition, was tested with several functions published in the literature, and results were compared with those obtained with a robust adaptive random search method.

TL;DR: In this paper, the authors proposed GLOPEQ (GLobal OPtimization for the phase and chemical EQuilibrium problem), which is a combined algorithm to find a globally stable equilibrium solution using the tangent plane stability criterion.

TL;DR: Genetic Programming is proposed as a method for developing input-output process models from experimental data that can discriminate between relevant and irrelevant process inputs, yielding parsimonious model structures that accurately represent process characteristics.

TL;DR: Two new methodologies for the global optimization of MINLP models, the Special structure Mixed Integer Nonlinear αBB,SMIN-αBB, and the General structure MixedInteger Nonlinear βBB,GMIN-βBB, are presented.

TL;DR: A new nonparametric regression method for high-dimensional data, nonlinear partial least squares (NLPLS), which is motivated by projection-based regression methods, e.g. PLS, projection pursuit regression and feedforward neural networks is proposed.

TL;DR: An Integrated Computer Aided System, which is particularly suitable for solving problems related to integrated design of chemical processes, is presented and a case study involving the separation of binary azeotropic mixtures is highlighted.

TL;DR: In this paper, the authors present three "rolling horizon" algorithms that are formally based on the rigorous aggregated Resource-Task Network (RTN) formulation presented by Wilkinson (1996).

TL;DR: Model robustness is shown to be significantly improved as a direct consequence of using multiple neural network representations and confidence bands for the neural network model predictions also result directly from the application of the bootstrap technique.

TL;DR: A modified version of the reformulation/spatial branch-and-bound algorithm of Smith and Pantelides (1996) for the solution of nonconvex MINLP problems arising from process engineering applications is presented.

TL;DR: A general framework for preventive maintenance optimization that combines Monte Carlo simulation with a genetic algorithm that overcomes demonstrated shortcomings with analytic or Markov techniques in terms of solution accuracy, versatility, and tractability is proposed.

TL;DR: The solution of the two-stage fixed recourse problem is considered, for which a sensitivity-based successive disaggregation algorithm is proposed, and several example problems are solved where the certainty equivalent problem involves millions of variables and constraints.

TL;DR: In this paper, the authors extend the Petlyuk columns to separations of four components, although extensions to more components is straightforward, and discuss alternative column arrangements from the literature, which allow for implementation in a single shell using dividing walls or vertical partitions.

TL;DR: In this article, a predictive control strategy for nonlinear processes based on radial basis function models is proposed, which provides excellent setpoint tracking and disturbance rejection when compared to conventional PI control.

TL;DR: In this paper, a general theory for the flow and the generation of potential environmental impact through a chemical process has been developed, which defines six potential impact indexes that characterize the generated potential impact within a process, and the output of potential impact from a process.

TL;DR: In this article, a two-stage approach is proposed that requires the solution of MILP subproblems coupled with a shortest path algorithm, resulting in orders of magnitude reduction in computation time as compared to a direct MILP solution.

TL;DR: A novel disturbance diagnosis approach is presented based on angle discriminants that is successful in cases where distance based discrimination is not very accurate and compared with the diagnosis utilizing distance based algorithms.

TL;DR: In this article, the authors compared three modeling approaches, viz. the conventional mechanistic approach, formulations based on different artificial neural network (ANN) topologies and a hybrid mechanistic-ANN structure.

TL;DR: A methodology for incorporating ecological considerations in the optimal design and scheduling of batch/semi-continuous processes is presented in this article, which embeds principles from Life Cycle Analysis (LCA) within a general multi-objective formulation for the design of multipurpose batch plants, with process economics and environmental impact as distinct design objectives.

TL;DR: A signed directed graph (SDG) based algorithm for multiple fault diagnosis (MFD) is developed and implemented in Gensym's expert system shell, G2.

TL;DR: A novel approach is presented in this paper which uses intrinsically dynamic neurons inspired from biological control systems as the processing elements in network architectures, which results in a network which incorporates dynamic elements with continuous feedback.

TL;DR: A flexible formulation for handling a wide range of short-term scheduling problems arising in multi-product/multipurpose batch chemical plants is presented in this article, where time is directly used to model events arising in the schedule and thus use of binary variables over periods during which no changes in system state occur is avoided.

TL;DR: The Environmental Hazard Index (EHI) as discussed by the authors ranks routes by the estimated environmental impact of a total release of chemical inventory, and the lower the EHI the more environmentally friendly is the route.

TL;DR: In this paper, the authors propose a control algorithm for fixed bed bioreactors which are based on the nonlinear distributed parameter model of the process and analyze the influence of the position of the internal sensors on the observability in order to determine the best observability possible in practice.

TL;DR: In this article, a nonlinear adaptive controller with an extended Kalman filter is proposed for temperature control of semi-batch polymerization reactors, which is based on differential geometric concepts.

TL;DR: A hybrid framework in which different diagnostic methods perform collective problem solving shows a lot of promise, and combines causal model-based diagnosis with statistical classifiers and syntactic pattem recognition, called DKit is proposed.

TL;DR: In this article, a methodology is presented which identifies the in-plant water reuse opportunities, resulting in significant freshwater consumption reductions, illustrated with a case study based on the food industry.

TL;DR: In this paper, the authors describe the theory behind LOGMIP, a new computer code for disjunctive programming and MINLP, and discuss a hybrid modeling framework which combines both approaches, allowing binary variables and disjunctions for expressing discrete choices.