Search results for "General Computer Science"
showing 10 items of 895 documents
Dynamical features of forest interactions
2000
Abstract The 3D computer simulations presented here were developed to study at the mesoscopic scale the formation of junctions and their impact on hardening of crystals. The simulations consider the evolution of a dislocation interacting with immobile dislocations in a fcc single crystal of copper where we incorporate well known dislocation interaction mechanisms. From these studies, we deduced a `breaking angle' which characterize the strength of the junctions.
Car sequencing versus mixed-model sequencing: A computational study
2014
Abstract The paper deals with the two most important mathematical models for sequencing products on a mixed-model assembly line in order to minimize work overload the mixed-model sequencing (MMS) model and the car sequencing (CS) model. Although both models follow the same underlying objective, only MMS directly addresses the work overload in its objective function. CS instead applies a surrogate objective using so-called sequencing rules which restrict labor-intensive options accompanied with the products in the sequence. The CS model minimizes the number of violations of the respective sequencing rules, which is widely assumed to lead to minimum work overload. This paper experimentally co…
An evolutionary approach to multi-objective scheduling of mixed model assembly lines
1999
In this paper a multi-objective genetic algorithm for the scheduling of a mixed model assembly line is proposed, pursuing the line stop time minimisation together with the component usage smoothing. Specific features of the developed GA are step by step random selection of diversified crossover and mutation operators, population control for the substitution of duplicate chromosomes, and in-process updating of GA control parameters. Three different formulation of the fitness function were been tested with some distinct line configurations.
Using Internet videos to learn about controversies: Evaluation and integration of multiple and multimodal documents by primary school students
2020
Abstract In many Internet videos authors appear in front of the camera to present their particular view on a topic. Given the high consumption rate of Internet videos by teenagers, we explored the pros and cons of using these videos to learn about complex topics, compared to learning from textual web pages. Specifically, we studied how 207 primary school students (grades 4–6) evaluated and integrated multiple and multimodal web pages (text or video) while learning about the pros and cons of bottled water. Results showed no major role of modality in students' source memory, as measured by citations in their responses to an integration question and their memory for sources. Nevertheless, moda…
A Detailed Account of The Inconsistent Labelling Problem of Stutter-Preserving Partial-Order Reduction
2021
One of the most popular state-space reduction techniques for model checking is partial-order reduction (POR). Of the many different POR implementations, stubborn sets are a very versatile variant and have thus seen many different applications over the past 32 years. One of the early stubborn sets works shows how the basic conditions for reduction can be augmented to preserve stutter-trace equivalence, making stubborn sets suitable for model checking of linear-time properties. In this paper, we identify a flaw in the reasoning and show with a counter-example that stutter-trace equivalence is not necessarily preserved. We propose a stronger reduction condition and provide extensive new correc…
Verification of Well-Formed Communicating Recursive State Machines
2008
AbstractIn this paper we introduce a new (non-Turing equivalent) formal model of recursive concurrent programs called well-formed communicating recursive state machines (CRSM). CRSM extend recursive state machines (RSM) by allowing a restricted form of concurrency: a state of a module can be refined into a finite collection of modules (working in parallel) in a potentially recursive manner. Communication is only possible between the activations of modules invoked on the same fork. We study the model-checking problem of CRSM with respect to specifications expressed in a temporal logic that extends CaRet with a parallel operator (ConCaRet). We propose a decision algorithm that runs in time ex…
Scatter Search—Wellsprings and Challenges
2006
I came up with the idea of editing this volume in the summer of 2002 while working on the book "Scatter search methodologies and implementations in C" with Manuel Laguna in the University of Colorado at Boulder. There, Fred Glover kindly let me use his office, where I found a copy of the "Tabu Search Methods for Optimization" special issue that he edited in 1988 for the European Journal of Operational Research. This encounter made me realize that Scatter Search has reached a level of maturity as an optimization method that has parallels with what Tabu Search was experiencing in the late eighties. So I thought that the moment was perfect to embark on this project, which has been supported en…
Star-free trace languages
1992
Abstract Generalizing a classical result of Schutzenberger to free partially commutative monoids, we prove that the family of star-free trace languages coincides with the family of aperiodic trace languages.
Avoiding patterns in irreducible permutations
2016
We explore the classical pattern avoidance question in the case of irreducible permutations, <i>i.e.</i>, those in which there is no index $i$ such that $\sigma (i+1) - \sigma (i)=1$. The problem is addressed completely in the case of avoiding one or two patterns of length three, and several well known sequences are encountered in the process, such as Catalan, Motzkin, Fibonacci, Tribonacci, Padovan and Binary numbers. Also, we present constructive bijections between the set of Motzkin paths of length $n-1$ and the sets of irreducible permutations of length $n$ (respectively fixed point free irreducible involutions of length $2n$) avoiding a pattern $\alpha$ for $\alpha \in \{13…
Multiple-attribute decision support system based on fuzzy logic for performance assessment
2005
Abstract This paper deals with the problem of assessing the performance of a set of production units, simultaneously considering different kinds of information, yielded by a Data Envelopment Analysis, a qualitative data analysis and an expert assessment. The tool for integrating heterogeneous data is a model that applies fuzzy logic to decision support systems. The results obtained are a holistic performance assessment of each unit of the set and a ranking order of the units.