446 research outputs found

    A decision support system for TV self-promotion scheduling

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    This paper describes a Decision Support System (DSS) that aims to plan and maintain the weekly self-promotion space for an over the air TV station. The self-promotion plan requires the assignment of several self-promotion advertisements to a given set of available time slots over a pre-specified planning period. The DSS consists of a data base, a statistic module, an optimization module, and a user interface. The input data is provided by the TV station and by an external audiometry company, which collects daily audience information. The statistical module provides estimates based on the data received from the audiometry company. The optimization module uses a genetic algorithm that can find good solutions quickly. The interface reports the solution and corresponding metrics and can also be used by the decision makers to manually change solutions and input data. Here, we report mainly on the optimization module, which uses a genetic algorithm (GA) to obtain solutions of good quality for realistic sized problem instances in a reasonable amount of time. The GA solution quality is assessed using the optimal solutions obtained by using a branch-and-bound based algorithm to solve instances of small size, for which optimality gaps below 1% are obtained.This research had the support of COMPETE-FEDERPORTUGAL2020-POCI-NORTE2020-FCT funding via grants POCI-01-0145-FEDER 031447 and 031821, NORTE-01-0145-FEDER-000020, and PTDC-EEI-AUT-2933-2014|16858–TOCCATA

    A decision support system for planning promotion time slots

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    We report on the development of a Decision Support System (DSS) to plan the best assignment for the weekly promotion space of a TV station. Each product to promote has a given target audience that is best reached at specific time periods during the week. The DSS aims to maximize the total viewing for each product within its target audience while fulfilling a set of constraints defined by the user. The purpose of this paper is to describe the development and successful implementation of a heuristic-based scheduling software system that has been developed for a major Portuguese TV station.Fundação para a Ciência e a Tecnologia (FCT)- FCT/POCI 2010/FEDER, Projecto POCTI/MAT/61842/2004Estação de Televisão SI

    A genetic algorithm approach for the TV self-promotion assignment problem

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    We report on the development of a Genetic Algorithm (GA), which has been integrated into a Decision Support System to plan the best assignment of the weekly self-promotion space for a TV station. The problem addressed consists on deciding which shows to advertise and when such that the number of viewers, of an intended group or target, is maximized. The GA proposed incorporates a greedy heuristic to find good initial solutions. These solutions, as well as the solutions later obtained through the use of the GA, go then through a repair procedure. This is used with two objectives, which are addressed in turn. Firstly, it checks the solution feasibility and if unfeasible it is fixed by removing some shows. Secondly, it tries to improve the solution by adding some extra shows. Since the problem faced by the commercial TV station is too big and has too many features it cannot be solved exactly. Therefore, in order to test the quality of the solutions provided by the proposed GA we have randomly generated some smaller problem instances. For these problems we have obtained solutions on average within 1% of the optimal solution value

    Fatigue laws for Brazilians asphalt rubber mixtures obtained in 4 point bending tests

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    The majority of Brazilian roadpavements consistsof thin pavement structures unable to resist the damage caused by heavy loads and an increasing traffic demand. The main structural distress modes found in Brazilians asphalt layers is fatigue cracking. One of the prom-ising techniques to improve the pavement performance is through asphalt rubber mixtures, which make use of crumb rubber from scrap tires to modify and enhance the properties of the asphalt. The inexistence of fatigue laws for asphalt rubber mixtures to be applied in road design encouraged the study presented in this paper, aiming at the development of prediction models for fatigue and dynamic modulus from the results obtained in laboratory tests. Four mixtures (gap and dense graded) containing Brazilian terminal blend asphalt rubbers were assessed through four point bending tests to evaluate their fatigue and stiffness properties

    Desempenho de misturas betuminosas com betume modificado com borracha através do processo húmido

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    Este trabalho apresenta os resultados da avaliação de desempenho mecânico de misturas betuminosas produzidas com betume modificado com borracha de pneus usados através do processo húmido, utilizando o sistema terminal blend e o sistema continuous blend. Os betumes modificados com borracha através dos dois sistemas foram caracterizados através dos seguintes ensaios: (i) penetração; (ii) ponto de amolecimento (método anel e bola); (iii) resiliência; (iv) viscosidade Brookfield. A avaliação do comportamento mecânico das misturas betuminosas inclui a resistência à fadiga, através do ensaio de flexão em quatro pontos e da deformação permanente utilizando o ensaio de corte simples repetido à altura constante (RSST-CH). Para este estudo foram produzidas misturas betuminosas com dois tipos de granulometria: (i) granulometria densa (Instituto do Asfalto Faixa IV) com betume borracha terminal blend; (ii) granulometria descontínua tipo gap graded (Caltrans ARHM-GG), com betume borracha continuous blend. As misturas com betume borracha foram comparadas com a mistura de referência denominada concreto asfáltico usinado a quente (DNIT 031/2006), preparada com betume convencional. Os resultados mostraram que a mistura com betume modificado com borracha através do sistema terminal blend apresentou o melhor desempenho, com maior vida à fadiga e maior resistência às deformações permanentes.Programa de Bolsas de Alto Nível da União Europeia para a América Latina (Programa ALβAN) - bolsa nº E04D040507BRConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ

    Consideração da propagação de trincas em camadas de reforço com misturas com asfalto-borracha

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    A restauração de pavimentos flexíveis trincados através da execução de uma camada de reforço ou da fresagem parcial do revestimento existente e a colocação de uma camada asfáltica convencional são soluções frequentemente adotadas pelos órgãos rodoviários brasileiros. No entanto, tal prática tem mostrado que nem sempre o objetivo proposto é alcançado, uma vez que a camada executada não atinge a vida de projeto prevista devido ao aparecimento prematuro de trincas que têm como origem a propagação das trincas existentes no revestimento antigo. Assim, em pavimentos em que o trincamento predominantemente ocorre de baixo para cima, com a fresagem parcial do revestimento a patologia não é de todo eliminada. Desta forma, ao se executar uma camada de revestimento novo sobre esta superfície, as trincas existentes se comportam como pontas de uma trinca. A elevada concentração de tensões na extremidade das trincas existentes, provocadas pelos movimentos dos seus bordos, é resultante das seguintes ações: (i) tráfego, (ii) variações de temperatura; (iii) variações de umidade no subleito; (iv) qualidade de construção. Para mitigar o problema da propagação de trincas, várias soluções têm sido pesquisadas em diversos países. Dentre elas, misturas asfálticas modificadas com asfalto-borracha têm sido desenvolvidas com o objetivo de inibir a propagação de trincas, além de retardar o aparecimento de patologias como o trincamento por fadiga e o afundamento, comumente encontradas em rodovias brasileiras. No presente trabalho apresenta-se uma simulação numérica utilizando um modelo de propagação de trincas, através de técnica de elementos finitos, para avaliar o dano provocado em uma camada de reforço de um pavimento devido à ação do tráfego e das variações de temperatura. O modelo determina os níveis de extensão desviatória de Von Misses a que uma camada de reforço fica submetida quando assente sobre uma superfície trincada e, utilizando-se as leis de fadiga das misturas pesquisadas, obtidas no ensaio de fadiga por flexão alternada em 4 pontos, avalia-se a vida de fadiga desta camada em termos de seu trincamento. Os resultados mostraram que as misturas com asfalto-borracha prolongam consideravelmente a vida da camada de reforço, em termos de propagação de trincas, em relação a uma mistura convencional

    Comparação do desempenho de asfaltos produzidos através dos sistemas continuous blend e terminal blend

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    O processo de fabricação de um asfalto modificado pela adição de borracha de pneus insersíveis é um dos principais fatores que influencia suas propriedades de desempenho. No presente trabalho, a incorporação de borracha de pneus ao asfalto foi feita através do processo úmido (wet process), no qual a borracha foi adicionada asfalto convencional e resultou em um novo produto, o asfalto modificado com borracha ou asfalto-borracha. O estudo investigou o comportamento dos asfaltos modificados com borracha de pneus usados obtidos através dos sistemas continuous blend e terminal blend. Na produção do asfalto-borracha continuous blend utilizou-se o asfalto convencional CAP 50/70 e a borracha de pneus obtida no sistema ambiente. Inicialmente, o estudo comparou as características do asfalto-borracha do sistema continuous blend através da variação da percentagem de borracha e do tempo de digestão, e identificou o asfalto-borracha otimizado. A investigação conduzida em laboratório avaliou o desempenho dos asfaltos-borracha (continuous e terminal blend) através dos seguintes ensaios: (i) penetração; (ii) ponto de amolecimento; (iii) resiliência; (iv) viscosidade Brookfield. Foram produzidas misturas asfálticas com os dois tipos de asfalto-borracha e com o asfalto convencional. O desempenho das misturas foram comparadas através da vida de fadiga obtida por meio de ensaio de flexão em 4 pontos. O resultado mostrou que as misturas produzidas com o asfalto-borracha proveniente do sistema terminal blend possui um desempenho superior quando comparado com as outras misturas confeccionadas com o ligante convencional e proveniente do sistema continuous blend.The production process of modified asphalt by the addition of crumb rubber from waste tires is one of the main factors that have been influenced the asphalt properties. In this present study, the incorporation of crumb rubber into the asphalt was made by wet process, in which one the crumb rubber was added into conventional asphalt and resulted in a new product, the asphalt modified with rubber or asphalt-rubber. The study investigated the performance of the asphalts-rubber, obtained through continuous blend system and terminal blend system. The conventional asphalt CAP 50/70 was used to produce the continuous blend asphalt-rubber, and the rubber from waste tires was obtained in the ambient system. Initially, the study compared the characteristics of the asphalt-rubber produced in continuous blend system through the variation of these variables: crumb rubber percentage and digestion time, in order to identify the optimized asphalt-rubber. The evaluation of the asphalt rubber (terminal blend and continuous blend) was done through following tests: (i) penetration; (ii) softening point; (iii) resilience; (iv) apparent viscosity using a Brookfield viscometer. Asphalt mixtures were produced using two types of asphalt-rubber and the conventional asphalt one. All mixtures were evaluated through fatigue test (four-points flexural beam tests). The results showed that the mixture prepared from terminal blend system presented better performance than the mixtures produced with conventional asphalt and asphalt rubber from continuous blend system

    Improvement of the functional pavement quality with asphalt rubber mixtures

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    Skid resistance and texture are important safety characteristics which need to be considered in flexible pavement design, maintenance and rehabilitation. The main objective of this paper is to optimize surface texture characteristics in asphalt rubber pavements, mainly macrotexture to reduce splash, spray and hydroplaning and microtexture to increase friction at low and high speeds. The objective was accomplished by measuring the friction surface with two different tests: (i) British pendulum; (ii) Volumetric Method. The specimens prepared in the laboratory represent the as-constructed pavement surface. In this study, two different mixtures grading (dense and gap) were produced using three types of binders: (i) conventional asphalt; (ii) asphalt rubber using terminal blend process; (iii) asphalt rubber using continuous blend process. The binder content influence in functional quality was tested by using the same configuration for mixtures with more 1% of asphalt rubber content. The results of this study were carried out to evaluate the effect of asphalt rubber production process and mixtures gradation on the pavement surface characteristics. The results showed that the mixture with gap grading exhibit higher texture in comparison of mixtures with a dense grade gradation. The asphalt rubber mixtures improved the skid resistance compared to conventional mixtures. This research indicates that the CRM (crumb rubber modified) production with rubber from the different processes have significant differences in pavement surface characteristics.União Europeia (UE) - Programme Alban (E04D040507BR)

    Defense behavior and tail loss in the endemic lizard Eurolophosaurus nanuzae (Squamata, Tropiduridae) from southeastern Brazil

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    Defense behavior of the endemic tropidurid lizard Eurolophosaurus nanuzae was studied in an area of rocky outcrops at Serra do Cipó, Minas Gerais State, southeastern Brazil. Tail loss aspects of this species were also studied in lizards from three populations (Diamantina, Serra do Cipó, and Serro, Minas Gerais State, Brazil). Lizards relied primarily on crypsis to avoid detection by predators. Secondary defense strategies involved a complex set of behaviors. Mean maximum distance of flight was 1.68 ± 1.70 m. When captured,individuals attempted to flee, lifted the tail, produced distress calls, discharged the cloacal contents, waived their tails, and bit. Frequency of tail autotomy was 13.2% (n = 53) in Diamantina, 11.9% (n = 42) in Serra do Cipó, and 4.1% (n = 49) in Serro. Tail autotomy frequency did not differ among the three populations (X2 = 3.3, DF =2, p = 0.19). Tail autotomy did not vary between the years of the study (X2 = 1.32, p = 0.35) and did not differ between males and females among the studied populations
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