1,720,991 research outputs found
BzzOde: a new C++ class for the solution of stiff and non-stiff ordinary differential equation systems
No full textA new code for the solution of ordinary differential equation (ODE) systems was developed in C++ language. Three main aspects were studied: robustness, efficiency and ease of use. BzzOde is a new C++ class intended to solve both stiff and non-stiff ODE problems numerically. Neither FORTRAN 77 nor Fortran 90 was adopted as the reference language. C++ was chosen in order to increase the implementation efficiency and the ease of use and consistency features of the library. Although BzzOde is intended to solve both stiff and non-stiff problems, this paper will only deal with stiff problems since they are the most interesting and commonly occurring ones in everyday chemical problem solving. Several examples taken from both the literature and real life cases, such as chemical kinetics problems, were investigated by comparing the BzzOde performances with state of the art Fortran ODE solvers. The paper describes the robustness feature and performance of BzzOde applied not only to classical problems but also to specific tests that involve medium and large eigenvalue imaginary parts, discontinuous systems and problems with constrained integration variables. Medium-large ODE systems describing real life literature problems analyze and benchmark the efficiency of the ODE solvers tested. New algorithmic techniques for identifying the discontinuity points, for working with constrained variables and for increasing the Jacobian evaluation performance of a sparse ODE system are proposed and critically examined. A detailed description for the benchmark problems and corresponding results is reported in appendixes A and B. (C) 1998 Elsevier Science Ltd. All rights reserved
Buzzi-Ferraris and Manenti Talk About Their New Book
No full textMedia Interview at ChemistryViews.
Wiley-VCH Verlag GmbH & Co. KGa
An Improved Version of a Sequential Design Criterion for Discriminating Among Rival Multiresponse Models
No full textMechanism of drop coalescence at the interface of two immiscible liquids
No full textSeveral industrial processes, in some of their operations, involve the presence of two immiscible liquid phases with dispersed drops surrounded by a continuous phase. The drops tend to coalesce to join to their own continuous phase. This phenomenon occurs in many industrial mixing, separation, as well as in environmental processes. In this paper it is analyzed the problem of the coalescence of a single drop at the planar interface of two immiscible liquids. An original model for coalescence mechanism is proposed. It is then compared with some experimental data obtained by the literature or by the authors. The comparisons are quite satisfactory. The mechanism of single drop coalescence contains the bases for the analysis of more complex interfacial structures like froths, that can be of great importance into many equipments
Stochastic NMPC/DRTO of batch operations: Batch-to-batch dynamic identification of the optimal description of model uncertainty
No full textThe effectiveness of stochastic online process optimization strongly depends on the choice of the uncertain parameters, which are used to characterize the uncertainty embedded in the process model. This contribution presents a framework for rapid identification of the optimal set of uncertain parameters, needed for the formulation of stochastic online optimization problems. This algorithm relies on a combination of approximate statistical analysis, multi-point/global sensitivity analysis and ad-hoc ranking indices, and is tailored for applications in the field of stochastic dynamic optimization/optimal control of campaigns of batch cycles. To demonstrate the potential of the proposed approach, we apply it within the optimization of a batch campaign, in the presence of equipment fouling and of dynamic variations in the campaign targets. The process model, utilized in all of these studies, is a batch adaptation of the Tennessee Eastman Challenge problem
Combined dynamic optimization, optimal control and online runaway detection & prevention under uncertainty
Full text linkIntegral Recovery of Bisphenol from Poly-Bisphenol A Carbonate via Hydrolysis
No full textRecycling of polymer wastes is an important way for recovering valuable chemicals and reducing the environmental impact of human activities. The increasing amount of poly-bisphenol A carbonate (PC) wastes generated by electronical and electrical equipments, automobiles, optical materials, CDs and other products, makes it necessary to develop processes for their recycling. This paper investigates a recovery process based on the hydrolysis of PC with subcritical liquid water. It has been performed at 260-300 °C in a high pressure batch reactor. The effect of temperature, pressure, residence time and reaction conditions has been investigated. The products have been quantitatively and qualitatively characterized showing a substantially integral recovery of the monomer
Stochastic NMPC/DRTO of Batch Operations: Batch-to-Batch Dynamic Identification of the Optimal Description of Model Uncertainty
No full textA Performance-Oriented Robust Framework for the Online Model-Based Optimization and Control of (Fed-)Batch Systems
No full textPyrolysis of Naphtha Feedstocks: Automatic Generation of Detailed Kinetics and Lumping Procedures
No full textThis paper analyses and revises the critical steps in the computer generation of complex reaction schemes for pyrolysis reactions of naphtha feeds. Moving from the pioneering experience of the well known SPYRO kinetic model, the critical steps in the simplification and lumping procedures are explained, critically discussed and partially removed. The availability of parallel processors and always more efficient computer facilities allows enlarging the description details of the overall reacting system. With reference to typical naphtha feedstocks, different description evels of feed characterization and different simplifications of the reaction network can be used. Namely, a large number of branched paraffin isomers are used to characterize the feed and the effect of possible refinery treatments of the naphtha feed are discussed. Moreover, the complex reaction scheme of hydrocarbon pyrolysis needs to be simplified both in terms of decomposition and recombination reactions, in order to avoid an excessive increase of the overall dimension of the mechanism, without significant improvements in the obtained results. As a result of this kinetic study, the SPYRO kinetic scheme is further extended to cover new possible feeds and more complex situations. Several examples illustrate the advantages and the limits of the proposed approach
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