Showing papers in "Computers & Chemical Engineering in 1991"

TL;DR: In this paper, it is shown that qualitative knowledge in process synthesis that can be expressed in prepositional logic form has an equivalent representation as linear equations and inequalities, which can be applied to chemical process synthesis problems.

TL;DR: In this article, a single optimization problem is proposed to solve simultaneously the optimal utility consumption level, matches and network configuration, which can be applied to both pseudo-pinch and strict pinch design problems.

TL;DR: In this article, the authors instead minimize an objective function that is constructed using maximum likelihood principle to construct a new distribution function, which takes into account both contributions from random and gross errors.

TL;DR: The need for a modeling environment like ASCEND to aid the design process is discussed, comparing its functional requirements to earlier approaches and an informal definition of the syntax and associated semantics for the language is presented.

TL;DR: In this article, it was shown that a blind application of generalized Benders decomposition to nonconvex problems does not always lead to the global optimum for these problems; it may not even lead to a local optimum.

TL;DR: In this article, a mixture of large biochemicals can exhibit complex chromatographic behavior, in addition to mass transfer mechanisms, in the presence of nonequilibrium adaption.

TL;DR: A computational scheme based on valid outer-approximations of the nonlinear part of the problem is proposed to strengthen the bounds of the master problem and therefore achieve fast convergence.

TL;DR: A large number of planning and scheduling problems can be formulated as multi-period MILP models which often require substantial computational expense f and often require large computational overhead f as mentioned in this paper,.

TL;DR: A general optimization framework for discrete and continuous problems based on genetic algorithmic techniques is presented and the proposed framework exhi is presented.

TL;DR: In this article, the authors introduce the subject of heat recovery between areas of integrity and give a procedure for finding the required heat flows between areas, where the results are made available as targets, before any network design.

TL;DR: In this paper, a new stochastic modeling capability implemented in the ASPEN process simulator is presented, which provides a useful tool for design, analysis and decision-making in the face of uncertainties.

TL;DR: This paper proposes the use of Petri nets as a modeling tool for the analysis and control of discrete-event systems, and shows how the graphical model can be translated to a system of linear equations and constraints.

TL;DR: The effectiveness of SA in solving complex problems of noncontinuous plant design is demonstrated and several forms of simulated annealing algorithms are evaluated using illustrative problems, and results are compared with results from existing algorithms.

TL;DR: In this paper, numerical integration nested within a nonlinear programming algorithm was employed within the proposed nonlinear dynamic error-in-variables method (NDEVM) for on-line and off-line parameter estimation.

TL;DR: The individua band profiles obtained for binary mixtures are more accurate than those derived using one of several possible finite difference methods, and the advantage of the better accuracy is compensated by a considerably higher computation time.

TL;DR: In this article, it is shown that in certain cases only local minima may be found, whereas in other cases not even convergence to local optima can be achieved, and a criterion to identify whether the converged value is a candidate for being a local minimum is provided.

TL;DR: To solve nonlinear optimal control problems, the problems are here transformed into finite dimensional optimization problems, which can then be solved as discussed by the authors, where the problem is then transformed into a nonlinear optimization problem.

TL;DR: It is shown that it may not in practice be useful to attempt the solution of intractable index problems, as these may differ substantially from the behaviour of an achievable control system.

TL;DR: In this article, the same authors compared the performance of two different methods: (1) simultaneous solution after linearization; and (2) the inside-outside method, a tearing algorithm.

TL;DR: In this paper, the authors consider the problem of intermediate storage utilization in multi-stage batch processes and propose a solution to solve it by using unstable intermediate intermediates in the scheduling of multistep batch processes.

TL;DR: The moving finite element method (MFEM) as mentioned in this paper uses polynomial approximations of arbitrary degree in each of the finite elements, obtained by the Lagrange interpolation polynomials, with the interior nodes optimized as in the orthogonal collocation method.

TL;DR: GRAES is shown to be a good technique for fast computation of NPS solutions, although the quality of solutions obtained by SA is better, which is dependent on the range of processing times and also on the size of the problem.

TL;DR: In this article, a discussion of the advantages of the discrete weighted residuals method (DWRM) and an application to polymerization reactions is presented. But the authors do not discuss the application of DWRM to the simulation of polymers.

TL;DR: In this article, a relatively rapid solution method is proposed which utilizes the Newton's technique to directly solve for the cyclic profiles in catalytic reactor ope. But this method is limited to the case of catalytic engines.

TL;DR: This approach performs very well on a number of small problems and has been implemented within a large-scale modelling system (GAMS), but it should be mentioned that this algorithm can fail when the LP yields a zero search direction at a nonsolution point.

TL;DR: In this article, an algorithm which combines orthogonal collocation for the pellet equations and a backward difference method for the bulk phase equations was derived to enable an efficient numerical solution of the reactor model.

TL;DR: The focus of this paper is the way SPLIT addresses the presynthesis problem, i.e. the generation of a reasonable set of alternative separation processes, which may be incorporated in a superstructure in order to determine the best solution.

TL;DR: In this paper, the design of an extractant molecule for use in liquid-liquid extraction, traditionally a combinatorial optimization problem, has been solved using continuous optimization and the UNIFAC model was used as the basis for all calculation.

TL;DR: This powerful and comprehensive package is expected to be computationally more efficient than existing packages and has been extensively tested with benchmark cases involving binary and multicomponent systems, with nonideal behavior and in columns with appreciable holdup effects.

TL;DR: Overall, the frontal codes developed here significantly outperform the usual general sparse code, LU1SOL, and show considerable promise for the solution of large EB flowsheeting matrices on advanced computer architectures.