Competition policy costs to firms

The existence of competition policy forces companies to adjust their behaviour. This is also costly. Using a database from a company on contracts, I will try to estimate if a specific competition policy disposition, supply contracts cannot be longer than 60 months, has costs for the coffee suppliers operating in the Portuguese “on-trade” coffee market. The estimation method used in this paper will be OLS. The results suggest that limiting the duration of exclusivity contracts to 60 months can be harmful to the coffee suppliers and it can even seriously affect the market functioning. Ke

Schoolbag Weight Carriage in Children: The Analysis of Ground Reaction Forces during Walking, Running and Jumping

Public society and international scientific community have shown concern about the heavy scholar backpacks carried by children. The possible adverse effects on children’s health of carrying those heavy loads have been in the base of that concern. Thus, the purpose of this thesis was to improve the understanding of school backpacks problem and to contribute to a solution. Specifically, it was our aims: (i) review the existing evidence concerning the characterization of backpack carrying, the known impacts and the solutions; (ii) characterize the loads that students in Portugal carry on their backpacks; (iii) understand how those loads influences the GRF acting on subjects and; (iv) propose modifications on backpack design that do not significantly modifies the main design but can attenuate the GRF magnitude increments. The main conclusions were: (i) scientific community still couldn’t clearly and consistently identified the effects of carrying backpack loads on children health. There are several body structures been studied as they could be affected. Also, there are not a consensus around the load limit that children should carry, however, the limit that seems to be more often recommend is the 10% of the body weight; (ii) the population analysed, students in Portugal, often carried more load than the recommended 10% of body weight. 5th grade students carry more absolute load than the 9th grade students; (iii) the load carried influenced the ground reaction forces. That influence was different in function of the mean of locomotion and the age/school grade, and (iv) with the backpack modification, the introduction of elastic material on the backpack straps, were verified changes on the influence of the backpack carrying in GRF, mainly the decrease of force peaks and loading rate. The main findings of this study confirmed the idea that children in Portugal may be carrying heavier loads on their backpacks than they should, especially the younger ones, and that it influences the ground reaction forces acting on them. However, we saw that is possible to introduce discrete modifications on typical backpacks than can attenuate that effect. It is needed to study, in the future, the way that benefits can be maximized and should not be forgiven the organization/pedagogical measures that may reduce the backpack load.A comunidade científica internacional e a sociedade em geral, têm manifestado preocupação relativamente às elevadas cargas transportadas pelos alunos diariamente para a escola. Os possíveis efeitos adversos do transporte dessas cargas na saúde das crianças têm estado na base da preocupação. Assim, o intuito deste trabalho foi melhorar o conhecimento acerca do problema das mochilas escolares e contribuir para uma solução. Especificamente, foram nossos objetivos: (i) rever as evidências existentes concernentes à caracterização do transporte das mochilas, os impactos conhecidos e as soluções propostas; (ii) caracterizar as cargas que os alunos em Portugal transportam; (iii) perceber como essas cargas influenciam as forças reativas do solo que atuam sobre as crianças, e (iv) propor e estudar modificações no design das mochilas que não o alterem significativamente mas que consigam atenuar o incremento da magnitude das forças reativas do solo. As principais conclusões foram: (i) a comunidade científica ainda não identificou de forma clara e consistente os efeitos do transporte das mochilas na saúde das crianças. São várias as estruturas do corpo que estão a ser estudadas como pudendo ser afetadas, mas os resultados não são consistentes. Também não existe consenso acerca do limite de carga que as crianças devem transportar, porém, o limite que mais é recomendado na literatura é 10% do peso corporal; (ii) a população analisada, alunos em Portugal, transportam frequentemente cargas superiores aos 10% recomendados. Os alunos mais novos, do 5º ano de escolaridade, transportam cargas absolutas superiores aos alunos do 9º ano; (iii) a carga transportada influenciou as forças reativas do solo. Essa influência variou em função do tipo de locomoção e do ano de escolaridade, e (iv) com a modificação proposta para a mochila, a introdução de material elástico nas alças, verificaram-se alterações na influência sobre as forças reativas do solo, principalmente a diminuição da magnitude dos valores de pico e da taxa de carga. Estas conclusões confirmaram a noção de que as crianças podem estar a transportar cargas demasiado elevadas para a escola, especialmente os mais novos, e que isso influencia as forças reativas do solo que atuam sobre eles. Contudo, vimos que é possível realizar alterações discretas nas mochilas escolares típicas, que podem atenuar esse efeito. Será necessário estudar a forma como essa vantagem poderá ser maximizada, sem esquecer as medidas organizacionais e pedagógicas que podem reduzir a carga a ser transportada

EC2 model applied to the prediction of mechanical properties of soil cement based on test results at early ages

O modelo analítico proposto pelo Eurocódigo 2 (EC2) para a previsão das propriedades mecânicas do betão ao longo do tempo tem mostrado resultados bastante satisfatórios quando adaptado a formulações laboratoriais de Jet Grouting (JG) e de Cutter Soil Mixing (CSM). No entanto, apresenta com principal limitação o facto de estar dependente da realização de ensaios experimentais aos 28 dias de cura para a quantificação das respetivas propriedades, o que limita a sua aplicabilidade em fases mais avançadas do projeto, nomeadamente para fins de controlo de qualidade. No presente artigo o modelo analítico proposto pelo EC2 para a previsão da resistência e rigidez do betão é adaptado a formulações laboratoriais de JG e CSM. Em particular, a abordagem do EC2 é adaptada no sentido de considerar resultados laboratoriais a idades jovens, nomeadamente aos 3, 7 e 14 dias de cura, em substituição dos convencionais 28 dias. Os resultados obtidos mostram que o desempenho do modelo do EC2 aumenta proporcionalmente à idade dos resultados experimentais considerados. Contudo, observou-se também apenas uma ligeira diferença entre o desempenho do modelo do EC2 considerando resultados experimentais aos 14 e aos 28 dias, o que permite fazer um balanceamento entre a precisão do modelo e o tempo/custos totais do projeto.The Eurocode 2 (EC2) approach for strength and stiffness prediction of concrete has been successful adapted to soil-cement laboratory formulations for Jet Grouting (JG) and Cutter Soil Mixing (CSM) technologies. However, its dependence of 28 days test result represents an important limitation. Accordingly, in the present work EC2 approach is modified in order to use laboratory reference data at early ages (e.g. 3, 7 or 14 days) and the achieved results are compared with the conventional 28 days time of cure. As expected, the achieved results show a decrease in EC2 approach performance when reference data at early ages are used. However, it is also observed just a slightly difference in EC2 approach performance when test data at 14 days or 28 days are used. This observation allows us to balance the model prediction accuracy and time consuming in the final project and construction work costs

The minimum cost network upgrade problem with maximum robustness to multiple node failures

The design of networks which are robust to multiple failures is gaining increasing attention in areas such as telecommunications. In this paper, we consider the problem of upgrading an existent network in order to enhance its robustness to events involving multiple node failures. This problem is modeled as a bi-objective mixed linear integer formulation considering both the minimization of the cost of the added edges and the maximization of the robustness of the resulting upgraded network. As the robustness metric of the network, we consider the value of the Critical Node Detection (CND) problem variant which provides the minimum pairwise connectivity between all node pairs when a set of c critical nodes are removed from the network. We present a general iterative framework to obtain the complete Pareto frontier that alternates between the minimum cost edge selection problem and the CND problem. Two different approaches based on a cover model are introduced for the edge selection problem. Computational results conducted on different network topologies show that the proposed methodology based on the cover model is effective in computing Pareto solutions for graphs with up to 100 nodes, which includes four commonly used telecommunication networks.publishe

Intelligent decision support in beds management and hospital planning

Worldwide, due to the constant overcrowding experienced in hospitals, hospital beds are one of the most needed resources, proving to be an extremely important feature in hospitalization planning and management, since the main purpose is to optimize their occupancy rate. This study aims to predict the future flow of patients after admission to a particular inpatient specialty to allow a more assertive planning based on demographic data. All data sources were made available by the Centro Hospitalar do Tâmega e Sousa (CHTS) and are relative to a 5-year period, 2017 to 2021. From the results achieved with the Machine Learning (ML) models developed was possible to conclude that these can prove to be an asset for the hospital, since being known the flow of patients allows a more informed and careful management of the management of beds.The work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Application of data mining techniques in the estimation of the uniaxial compressive strength of jet grouting columns over time

Jet grouting (JG) is a soil treatment technique which is the best solution for several soil improvement problems. However, JG lacks design rules and quality controls. As a result, the main JG works are planned from empirical rules that are too conservative. The development of rational models to simulate the effects of the different parameters involved in the JG process is of primary importance in order to satisfy the binomial safety-economy that is required in any engineering project. In this paper, we present a new approach to predict the uniaxial compressive strength (UCS) of JG materials based on data mining techniques. This model was developed and verified using data from a JG laboratory formulation that involves the measurement of UCS. The results of the proposed approach are compared with the EC2 analytical model adapted to the JG material, and the advantages of the new approach are highlighted. We show that the novel data-driven model is able to learn (with high accuracy) the complex relationships between the UCS of JG material and its contributing factors.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/ 45781/2008Tecnasol-FG

Support vector machines in mechanical properties prediction of jet grouting columns

Strength and stiffness are the mechanical properties currently used in geotechnical works design, namely in jet grouting (JG) treatments. However, when working with this soil improvement technology, due to its inherent geological complexity and high number of variables involved, such design is a hard, perhaps very hard task. To help in such task, support vector machine (SVM), which is a data mining algorithm especially adequate to explore high number of complex data, can be used to learn the complex relationship between mechanical properties of JG samples extracted from real JG columns (JGS) and its contributing factors. In the present paper, the high capabilities of SVM in Uniaxial Compressive Strength (UCS) and Elastic Young Modulus estimation of JG laboratory formulations are summarized. After that, the performance reached by the same algorithm in the study of JGS are presented and discussed. It is shown, by performing a detailed sensitivity analysis, that the relation between mixture porosity and the volumetric content of cement, as well as the JG system are the key variables in UCS prediction of JGS. Furthermore, it is underlined the exponential effect of the age of the mixture in UCS estimation as well as the high iteration between these two key variables.Fundação para a Ciência e a Tecnologia (FCT

Application of a sensitivity analysis procedure to interpret uniaxial compressive strength prediction of jet grouting laboratory formulations performed by SVM model

Jet Grouting (JG) technology, one of the most efficient soft soils improvement methods, has been widely applied in important geotechnical works due to its versatility. However, there is still an important limitation to overcome related with the absence of rational approaches for its design. In the present work, three different Data Mining (DM) techniques, i.e., Artificial Neuronal Networks (ANN), Support Vector Machines (SVM) and multiple regression are trained in order to predict elastic young modulus (E0) of JG mixtures. It is shown that the complex relationships between E0 and its contribut- ing factors can be learned using DM tools, particularly by SVM and ANN algorithms. By performing a detailed sensitivity analysis, understandable knowledge is extracted from the trained models, in terms of the relative importance of the attributes, as well as its effect in E0 prediction. In addition, the mathemati- cal expression proposed by Eurocode 2 to estimate concrete stiffness, is adapted to JG material. Its low performance is assessed and compared with those achieved by DM models.The authors wish to thank to “Fundação para a Ciência e a Tecnologia” (FCT) for the finan- cial support under the strategic project PEst-OE/ ECI/UI4047/2011 and the doctoral Grant SFRH/ BD/45781/2008Tecnasol-FG

Uniaxial compressive strength prediction of jet grouting columns using support vector machines

Uniaxial compressive strength (UCS) is the mechanical properties currently used in geotechnical works design, namely in jet grouting (JG) treatments. However, when working with this soil improvement technology, due to its inherent geological complexity and high number of variables involved, such design is a hard, perhaps very hard task. To help in such task, a support vector machine (SVM), which is a data mining algorithm particularly adequate to explore high number of complex data, was trained to estimate UCS of JG samples extracted from real JG columns. In the present paper, the performance reached by SVM algorithm in UCS estimation is shown and discussed. Furthermore, the relation between mixture porosity and volumetric content of cement and the JG system were identified as key parameters by performing a 1-D sensitivity analysis. In addition, the effect and the interaction between the key variables in UCS estimation was measured and analyzed.Tecnasol-FGEFundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/45781/200

Support vector machines on mechanical behaviour prediction of soil-cement laboratory formulations to jet grouting columns

Fundação Para a Ciência e a Tecnologia (FCT) pelo apoio financeiro no âmbito do projeto PEst-OE/ECI/UI4047/2011 e pela bolsa de doutoramento SFRH/BD/45781/200