Shiguo Lian, Dimitris Kanellopoulos, Giancarlo Ruffo,
A multimedia communication system enables multimedia data's generation, storage, management, distribution, receiving, consuming, editing, sharing, and so on. In such systems, there are various security issues, which must be considered such as eavesdropping, intrusion, forgery, piracy and privacy, etc. Until now, various security solutions for multimedia communication systems have been reported, while few works have surveyed the latest research advances. This paper gives a thorough review to multimedia ...
Tópico(s): Chaos-based Image/Signal Encryption
2009 - IOS Press | Informatica
Abdelhakim Dahimene, Mohamed Noureddine, Aarab Azrar,
This paper deals with the problem of peak clipped speech. Our basic assumption is that the clipped speech is voiced and can be linearly predicted with a high accuracy. The coefficients of linear prediction are computed using two different algorithms: a least square direct method and a recursive Kalman filter. The speech reconstruction is accomplished using backward prediction. Povzetek: Predstavljen je algoritem za obnavljanje zvocnega signala.
Tópico(s): Advanced Adaptive Filtering Techniques
2008 - IOS Press | Informatica
Produção Nacional
Daniel Lichtnow, Ramiro Saldaña Garin, Luiz A. M. Palazzo, Stanley Loh, Adriana Justin Cerveira Kampff, Tiago Thompsen Primo, José Palazzo Moreira de Oliveira, José Valdeni de Lima,
Este artigo apresenta o SisRecCol – Sistema de Recomendacao para Apoio a Colaboracao. O sistema oferece ferramentas que tem por finalidade apoiar o processo de aprendizagem colaborativa. O sistema segue a perspectiva socio-interacionista de Vygotsky, procurando a partir da identificacao dos perfis interagentes, realizar recomendacoes que possam auxiliar no processo de aprendizado. As recomendacoes sao feitas a partir da analise do comportamento dos usuarios em um web chat e do acesso a uma biblioteca ...
Tópico(s): Business and Management Studies
2006 - | Revista Brasileira de Informática na Educação
We give an algorithm, its correctness proof, and its proof of execution time bound, for finding the sets of equivalent states in a deterministic finite state automaton. The time bound is K · m · n · log n where K is a constant, m the number of input, symbols, and n the number of states. Hopcroft [3] has already published such an algorithm. The main reason for this paper is to illustrate the use of communicating an algorithm to others using a structured, top-down approach. We have also been able to improve ...
Tópico(s): Machine Learning and Algorithms
1973 - Springer Science+Business Media | Acta Informatica
D. Brown, BrendaS. Baker, H.P. Katseff,
Many problems, such as cutting stock problems and the scheduling of tasks with a shared resource, can be viewed as two-dimensional bin packing problems. Using the two-dimensional packing model of Baker, Coffman, and Rivest, a finite list L of rectangles is to be packed into a rectangular bin of finite width but infinite height, so as to minimize the total height used. An algorithm which packs the list in the order given without looking ahead or moving pieces already packed is called an on-line algorithm. ...
Tópico(s): Computational Geometry and Mesh Generation
1982 - Springer Science+Business Media | Acta Informatica
Produção Nacional
Ana Vilma Tijiboy, DEBORA LAURINDO MAÇADA, Lucila Maria Costi Santarosa, Léa da Cruz Fagundes,
Esse trabalho enfatiza a importanciada aprendizagem coopertaiva em ambientes telemáticos e seu potencial para educação na era digital da informática. Assim, o referencial teórico inclui autores que ressaltam a importancia da cooperação na aprendizagem e no desenvolvimento do sujeito. São apresentados como elementos relevates que suportam e propiciam a aprendizagem cooperativa na internet, a postura cooperativa, a estrutura do ambiente e o funcionamento heterarquico do mesmo.
Tópico(s): Open Education and E-Learning
1998 - | Informática na educação teoria & prática
A programming language called Pascal is described which was developed on the basis ofAlgol 60. Compared toAlgol 60, its range of applicability is considerably increased due to a variety of data structuring facilities. In view of its intended usage both as a convenient basis to teach programming and as an efficient tool to write large programs, emphasis was placed on keeping the number of fundamental concepts reasonably small, on a simple and systematic language structure, and on efficient implementability. ...
Tópico(s): Teaching and Learning Programming
1971 - Springer Science+Business Media | Acta Informatica
General correctness, which subsumes partial and total correctness, is defined for both weakest preconditions and strongest postconditions. Healthiness properties for general-correctness predicate transformers are more uniform and complete than those for partial- and total-correctness systems. In fact, the healthiness properties for partial and total correctness are simple restrictions of those for general correctness. General correctness allows simple formulations of the connections between weakest ...
Tópico(s): Formal Methods in Verification
1985 - Springer Science+Business Media | Acta Informatica
Witold Lipski, F. P. Preparata,
A bipartite graph G=(A, B, E) is convex on the vertex set A if A can be ordered so that for each element b in the vertex set B the elements of A connected to b form an interval of A; G is doubly convex if it is convex on both A and B. Letting ¦A¦=m and ¦B¦=n, in this paper we describe maximum matching algorithms which run in time O(m + nA(n)) on convex graphs (where A(n) is a very slowly growing function related to a functional inverse of Ackermann's function), and in time O(m+n) on doubly convex graphs. ...
Tópico(s): Optimization and Search Problems
1981 - Springer Science+Business Media | Acta Informatica
Jan van den Bos, Chris Laffra,
PROCOL is an object-oriented language with distributed delegation. It strongly supports concurrency: many objects may be active simultaneously, they execute in parallel unless engaged in communication. An object has exported operations, called Actions. Only one Action can be active at a time, however special interrupt Actions may interrupt regular Actions. Communication is performed via remote procedure call, or via a one-way synchronous message with short-time binding. In communications both client ...
Tópico(s): Security and Verification in Computing
1991 - Springer Science+Business Media | Acta Informatica
Josep Dı́az, Marı́a Serna, Jacobo Torán,
This paper describes a technique to obtain NC Approximations Schemes for the Maximum Independent Set in planar graphs and related optimization problems. The strategy consists in decomposing the graph into K-outerplanar subgraphs and solve for each K-outerplanar using tree contraction techniques.
Tópico(s): Computational Geometry and Mesh Generation
1996 - Springer Science+Business Media | Acta Informatica
Tópico(s): Service-Oriented Architecture and Web Services
1996 - Springer Science+Business Media | Acta Informatica
Salem M. Al-Ykoob, Hanif D. Sherali,
This paper investigates the problem of partitioning a complete weighted graph into complete subgraphs, each having the same number of vertices, with the objective of minimizing the sum of edge weights of the resulting subgraphs. This NP-complete problem arises in many applications such as assignment and scheduling-related group partitioning problems and micro-aggregation techniques. In this paper, we present a mathematical programming model and propose a complementary column generation approach ...
Tópico(s): VLSI and FPGA Design Techniques
2020 - IOS Press | Informatica
Rajkumar Verma, José M. Merigó,
In this paper, we develop a new flexible method for interval-valued intuitionistic fuzzy decision-making problems with cosine similarity measure. We first introduce the interval-valued intuitionistic fuzzy cosine similarity measure based on the notion of the weighted reduced intuitionistic fuzzy sets. With this cosine similarity measure, we are able to accommodate the attitudinal character of decision-makers in the similarity measuring process. We study some of its essential properties and propose ...
Tópico(s): Optimization and Mathematical Programming
2020 - IOS Press | Informatica
Alptekin Ulutaş, Dragiša Stanujkić, Darjan Karabašević, Gabrijela Popović, Edmundas Kazimieras Zavadskas, Florentín Smarandache, Willem K. Brauers,
The main aim of the article is to propose a new multiple criteria decision-making approach for selecting alternatives, the newly-developed MULTIMOOSRAL approach, which integrates advantages of the three well-known and prominent multiple-criteria decision-making methods: MOOSRA, MOORA, and MULTIMOORA. More specifically, the MULTIMOOSRAL method has been further upgraded with an approach that can be clearly seen in the well-known WASPAS and CoCoSo methods, which rely on the integration of weighted ...
Tópico(s): Optimization and Mathematical Programming
2021 - IOS Press | Informatica
Produção Nacional
Entrevista concedida pela Profa. Dra. Margarete Axt ao N?cleo de Aprendizagem Virtual ñ NAVI ñ da Escola de AdministraÁ„o da UFRGS, em 08 de junho de 2004, integrando o Curso de Extens„ o a Dist‚ncia Gestão Universitária, ministrado para gestores da Universidade.
Tópico(s): Business and Management Studies
2004 - | Informática na educação teoria & prática
Jan Ramon, Maurice Bruynooghe,
Measuring the similarity or distance between sets of points in a metric space is an important problem in machine learning and has also applications in other disciplines e.g. in computational geometry, philosophy of science, methods for updating or changing theories, $\ldots$ . Recently Eiter and Mannila have proposed a new measure which is computable in polynomial time. However, it is not a distance function in the mathematical sense because it does not satisfy the trian gle inequality. We introduce ...
Tópico(s): Digital Image Processing Techniques
2001 - Springer Science+Business Media | Acta Informatica
Alessandro Cimatti, Luke Hunsberger, Andrea Micheli, Roberto Posenato, Marco Roveri,
Temporal networks are data structures for representing and reasoning about temporal constraints on activities. Many kinds of temporal networks have been defined in the literature, differing in their expressiveness. The simplest kinds of networks have polynomial algorithms for determining their temporal consistency or different levels of controllability, but corresponding algorithms for more expressive networks (e.g., those that include observation nodes or disjunctive constraints) have so far been ...
Tópico(s): Logic, Reasoning, and Knowledge
2016 - Springer Science+Business Media | Acta Informatica
Marcello M. Bersani, Matteo Rossi, Pierluigi San Pietro,
Constraint LTL over clocks is a variant of CLTL, an extension of linear-time temporal logic allowing atomic assertions in a concrete constraint system. Satisfiability of CLTL over clocks is here shown to be decidable by means of a reduction to a decidable Satisfiability Modulo Theories (SMT) problem. The result is a complete Bounded Satisfiability Checking procedure, which has been implemented by using standard SMT solvers. The importance of this technique derives from the possibility of translating ...
Tópico(s): Logic, Reasoning, and Knowledge
2015 - Springer Science+Business Media | Acta Informatica
Lorenzo Bettini, Ferruccio Damiani, Ina Schaefer,
Delta-oriented programming is a compositional approach to flexibly implementing software product lines. A product line is represented by a code base and a product line declaration. The code base consists of a set of delta modules specifying modifications to object-oriented programs. A particular product in a delta-oriented product line is generated by applying the modifications contained in the suitable delta modules to the empty program. The product-line declaration provides the connection of the ...
Tópico(s): Formal Methods in Verification
2013 - Springer Science+Business Media | Acta Informatica
Loop is a powerful program construct in classical computation, but its power is still not exploited fully in quantum computation. The exploitation of such power definitely requires a deep understanding of the mechanism of quantum loop programs. In this paper, we introduce a general scheme of quantum loops and describe its computational process. The function computed by a quantum loop is defined, and a denotational semantics and a weakest precondition semantics of a quantum loop are given. The notions ...
Tópico(s): Quantum-Dot Cellular Automata
2010 - Springer Science+Business Media | Acta Informatica
Jan Van Leeuwen, Mark H. Overmars,
We develop a new perspective on trees, that enables us to distinguish and analyse many different subclasses of known classes of (height-)balanced search trees in a uniform manner. The approach shows that a great many different local constraints, including an arbitrary degree of density, can be enforced on everyday balanced search tree models, without losing the O(log n) bound on the time for insertions, deletions and finds. The theory extends known concepts from the study of B-trees.
Tópico(s): Stochastic processes and statistical mechanics
1983 - Springer Science+Business Media | Acta Informatica
Mark H. Overmars, Jan Van Leeuwen,
Tópico(s): Algorithms and Data Compression
1982 - Springer Science+Business Media | Acta Informatica
It is assumed in the π-calculus that communication channels are always noiseless. But it is usually not the case in the mobile systems that developers are faced with in the real life. In this paper, we introduce an extension of π, called πN, in which noisy channels may be present. A probabilistic transitional semantics of πN is given. The notions of approximate (strong) bisimilarity and equivalence between agents in πN are proposed, and various algebraic laws for them are established. In particular, ...
Tópico(s): Logic, Reasoning, and Knowledge
2005 - Springer Science+Business Media | Acta Informatica
Cliff B. Jones, C.A. Middelburg,
Tópico(s): Logic, Reasoning, and Knowledge
1994 - Springer Science+Business Media | Acta Informatica
A. Bijlsma, Philip Matthews, J. G. Wiltink,
A proof rule for the procedure call is proposed that has the property that the precondition it defines is the weakest precondition that can be inferred solely from the procedure's specification. Thus the rule enforces exactly the abstraction introduced by the specification. Gries's proof rule for the procedure call is shown not to have this property in cases when the specification involves so-called specification variables.
Tópico(s): Logic, Reasoning, and Knowledge
1989 - Springer Science+Business Media | Acta Informatica
R.M. Aguilar, J. Torres, Carlos A. Martín,
<p>Uno de los mayores desafíos tecnológicos de la actualidad es la obtención de modelos predictivos de sistemas complejos. En este artículo se propone darle valor a los datos recogidos sobre un proceso utilizándolos para la identificación del mismo mediante el empleo de algoritmos de aprendizaje automático. En concreto, se describe el desarrollo de un proyecto de determinación del modelo predictivo de un sistema, a partir de algoritmos de aprendizaje automático supervisado, usando como ejemplo ...
Tópico(s): Reservoir Engineering and Simulation Methods
2018 - Technical University of Valencia | Revista Iberoamericana de Automática e Informática Industrial RIAI
Cecilia Fernández, Nadia Pantano, Sebastian Alejandro Godoy, Mario Emanuel Serrano, Gustavo Scaglia,
<p>En este trabajo se propone una estrategia de control en lazo cerrado para el seguimiento de perfiles óptimos previamente definidos para un bioproceso fed-batch. La mayor ventaja de este enfoque es que las acciones de control se calculan resolviendo un sistema de ecuaciones lineales, sin tener que linealizar el modelo matemático, lo que permite trabajar en cualquier rango. Además, se plantean tres técnicas para la sintonización de los parámetros del controlador diseñado. Primero se propone ...
Tópico(s): Fault Detection and Control Systems
2018 - Technical University of Valencia | Revista Iberoamericana de Automática e Informática Industrial RIAI
Manuel R. Arahal, Agnieszka Kowal G., Federico Barrerro, M. Castilla,
El control de máquinas de inducción multifásicas avanza con la incorporación de controladores predictivos que actúan directamente sobre el inversor sin mediar moduladores. Se lleva a cabo en tiempo discreto, mediante una optimización exhaustiva de los estados posibles del inversor. La optimización utiliza una función de coste que penaliza desviaciones de la referencia y otros efectos indeseados, por lo que su diseño tiene gran importancia en el comportamiento en bucle cerrado. En este artículo se ...
Tópico(s): Advanced DC-DC Converters
2018 - Technical University of Valencia | Revista Iberoamericana de Automática e Informática Industrial RIAI