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J. A. Spim

Other affiliations: State University of Campinas
Bio: J. A. Spim is an academic researcher from Universidade Federal do Rio Grande do Sul. The author has contributed to research in topics: Continuous casting & Casting (metalworking). The author has an hindex of 13, co-authored 23 publications receiving 610 citations. Previous affiliations of J. A. Spim include State University of Campinas.

Papers
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Journal ArticleDOI
TL;DR: Using the numerical model linked to a search method and the knowledge base, results can be produced for determining optimum settings of casting conditions, which are conducive to the best strand surface temperature profile and metallurgical length.

129 citations

Journal ArticleDOI
TL;DR: In this article, a numerical model for the two-dimensional solidification problem in the twin-roll continuous casting system was presented by using a finite difference technique, and the thermal analysis results gave valuable insight into the thermal characteristics of solidification and processing for the strip casting.

74 citations

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TL;DR: In this paper, the authors present an algorithm, which incorporates heuristic search techniques for direct application in metallurgical industries, particularly those using continuous casting process for the production of steel billets and slabs.

63 citations

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TL;DR: In this article, a numerical model capable of predicting the solute redistribution at any stage of a multi-pass zone refining is proposed, which can establish an optimum combination of initial long zones followed by shorter ones, providing improvement in purification efficiency.

51 citations

Journal ArticleDOI
TL;DR: In this paper, heat transfer coefficients along different cooling zones of a continuous caster billet machine were determined during casting of low and medium carbon steels, and the effects of casting parameters, such as machine characteristics, the ingot dimension, mold, sprays zones, radiant cooling, melt composition, and casting temperature were correlated with heat transfer coefficient.
Abstract: In the present work, heat transfer coefficients (h) along different cooling zones of a continuous caster billet machine were determined during casting of low and medium carbon steels. The effects of casting parameters, such as machine characteristics, the ingot dimension, mold, sprays zones, radiant cooling, melt composition, and casting temperature were investigated and correlated with heat transfer coefficients. By using industrial measured billet surface temperatures, linked with a numerical solution of the solidification problem, ingot/cooling zones heat transfer coefficients were quantified based on the solution of the inverse heat conduction problem (IHCP). The experimental temperatures were compared with simulations furnished by an explicit finite difference numerical model, and an automatic search has selected the best theoretical–experimental fit from a range of values of h. The computer software algorithm has been developed to simulate temperature profiles, solid shell growth, phase transformati...

41 citations


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08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a review of various investigations made by researchers in different stages of investment casting and highlight their importance, such as pattern wax properties, effects of blending, additives and fillers.

307 citations

Journal ArticleDOI
01 Jun 2010
TL;DR: A Knowledge-Based Ant Colony Optimization (KBACO) algorithm is proposed in this paper for the Flexible Job Shop Scheduling Problem (FJSSP) and results indicate that the proposed KBACO algorithm outperforms some current approaches in the quality of schedules.
Abstract: A Knowledge-Based Ant Colony Optimization (KBACO) algorithm is proposed in this paper for the Flexible Job Shop Scheduling Problem (FJSSP). KBACO algorithm provides an effective integration between Ant Colony Optimization (ACO) model and knowledge model. In the KBACO algorithm, knowledge model learns some available knowledge from the optimization of ACO, and then applies the existing knowledge to guide the current heuristic searching. The performance of KBACO was evaluated by a large range of benchmark instances taken from literature and some generated by ourselves. Final experimental results indicate that the proposed KBACO algorithm outperforms some current approaches in the quality of schedules.

285 citations

Journal ArticleDOI
TL;DR: In this article, the authors focused on the determination of transient mold-environment and metal-mold heat transfer coefficients during solidification using the expedient of comparing theoretical and experimental thermal profiles and applied both to pure metals and metallic alloys.

190 citations

Journal ArticleDOI
TL;DR: Genetic algorithms (GAs) are biologically inspired computing techniques, which tend to mimic the basic Darwinian concepts of natural selection, and are highly robust and efficient for most engineering optimising studies as mentioned in this paper.
Abstract: Genetic algorithms (GAs) are biologically inspired computing techniques, which tend to mimic the basic Darwinian concepts of natural selection. They are highly robust and efficient for most engineering optimising studies. Although a late entrant in the materials arena, GAs based studies are increasingly making their presence felt in many different aspects of this discipline. In recent times, GAs have been successfully used in numerous problems in the areas of atomistic material design, alloy design, polymer processing, powder compaction and sintering, ferrous production metallurgy, continuous casting, metal rolling, metal cutting, welding, and so on. The present review attempts to present the state of the art in this area. It includes three broad sections given as: fundamentals of genetic algorithms, genetic algorithms in materials design, and genetic algorithms in materials processing. The first section provides the reader with the basic concepts and the intricacies associated with this novel tec...

182 citations