Innovations for smoke management in passenger trains

Spanish manufacturer Construcciones y Auxiliar de Ferrocarriles developed an innovative alternative for compartmentation, based on a smoke extraction system, to guarantee safe conditions during evacuation processes in a passenger unit. To demonstrate its performance in a train unit, a real-scale experimental programme, supported by the application of fire computer modelling, was applied in a new Construcciones y Auxiliar de Ferrocarriles' rolling stock. The new smoke exhaust system aims to extract the smoke generated during a fire in the passenger area by exhaust fans of the heating, ventilation, and air conditioning system, allowing the ingress of fresh exterior air in the lower part of the rear ends of the car. These key elements create an air flow that evacuates the smoke to prevent people from being exposed to it. Full-scale fire tests were developed in the train unit following the Australian standard AS 4391-1999. A fire of 140kW was used, and the smoke was generated by a clean smoke machine. Measurement points included six thermocouple trees, 10 gas flow velocity probes and two GoPro HD video cameras (for the estimation of the visibility). The system performance was successful with the tenability criteria, since the value of visibility at the non-fire car was greater than 30 m and the temperature was lower than 30°C during all the tests at a height of 1.7m above the floor. Experimental results were used to validate the computational model. The computational model results show a good accuracy compared with the tests

Influence of the STA boundary conditions on thermal decomposition of thermoplastic polymers

The analysis of polymer chemical decomposition is often highly dependent on the test conditions. In fact, thermal analysis tends to be far more sensitive to instrumental parameters than other branches of chemical analysis. Some of the boundary conditions in thermal analysis have been widely studied in the literature, such as the heating rate or the atmosphere. However, the influence of the sample mass, the gas flow or the use of lid has not been studied enough for thermoplastic polymers. The aim of this paper is to analyse how the experimental boundary conditions of the simultaneous thermal analysis apparatus affect the thermal decomposition of thermoplastic polymers. To do so, a set of 35 experimental tests have been performed including variation of the sample mass, gas flow rate, heating rate, atmosphere and the use of lid in the crucible. Results enable us to analyse the influence in the mass loss and in the energy release or absorbed in the thermal decomposition of thermoplastic polymers, showing the impact of each boundary condition over the thermal decomposition. A comprehensive analysis of the thermal decomposition behaviour of the PVC and LLDPE by considering the influence of all the boundary conditions of the STA is covered. It is especially remarkable the influence of gas flow in the oxidative reactions, and of heating rate in the chemical reactions that thermoplastic polymers undergo in their decomposition. Additionally, sample mass comparison shows only deviation in the oxidative reactions and does not show deviation for the non-oxidative reactions. That seems to show a higher effect on the results because of the energy release in the decomposition reactions than because of the thermal lag due to heat transfer on the sample, as it is usually thought.Authors would like to thank the Consejo de Seguridad Nuclear for the cooperation and co-financing the project ‘‘Simulation of fires in nuclear power plants’’ and CAFESTO Project funded by the Spanish Ministry of Science, Innovation and Universities and the Spanish State Research Agency through Public–Private Partnerships (Retos Colaboración 2017 call, ref RTC-2017-6066-8) co-funded by ERDF under the objective ‘‘Strengthening research, technological development and innovation’’

LLDPE kinetic properties estimation combining thermogravimetry and differential scanning calorimetry as optimization targets

Thermal analysis techniques play a crucial role to characterize solid-phase thermal decomposition, since it provides information about how mass is lost (thermal gravimetric analysis) and energy released [differential scanning calorimetry (DSC)]. However, most of the input thermal parameters and kinetic properties to be used in fire computer modelling cannot be obtained directly from those tests. Early works looked forward achieving those parameters employing indirect fitting methods, which enable the user to obtain a set of parameters capable of simulating accurately the mass loss curve (TG) or its derivative (DTG). This work aims to study the possibility of adding the energy released as a new target in the process, applying the analysis to linear low-density polyethylene. Results obtained in the present work reveal the major challenge of getting a set of parameters that can also fit DSC curve. The level of accuracy of the fitting to TG curve is higher than to DSC curve. This fact increases the value of the errors when both curves are used as targets to approach. As a result, this paper includes an alternative to consider the effects of the DSC curve.The authors would like to thank to the Consejo de Seguridad Nuclear for the cooperation and co-financing the project ‘‘Simulation of fires in nuclear power plants’’ and to CAFESTO Project funded by the Spanish Ministry of Science, Innovation and Universities and the Spanish State Research Agency through public–private partnerships (Retos Colaboración 2017 call, ref RTC-2017-6066-8) co-funded by ERDF under the objective ‘‘Strengthening research, technological development and innovation’’

Assessing input variables in FDS to model numerically solid-phase pyrolysis of cardboard

Understanding a material's fire behaviour implies to know the thermal decomposition processes. Thermal analysis techniques are widely employed to study thermal decomposition processes, especially to calculate the kinetic and thermal properties. Cardboard boxes are widely employed as rack-storage commodities in industrial buildings. Hence, the characterization of the cardboard is considered a key factor for fire safety engineering, because it enables the determination of its thermal behaviour at high temperatures. The employment of mathematical or computational models for modelling the thermal decomposition processes is commonly used in fire safety engineering (FSE). The fire dynamics simulator (FDS) software is one of the most commonly used computational fluid dynamics softwares in FSE to address thermal analysis. To properly set up FDS and obtain accurate results, the numerical values of the thermal and kinetic properties are needed as input data. Owing to the large number of variables to be determined, a preliminary study is bound to be helpful, which can well assess the influence of each variable over the pyrolysis model, discarding or restricting their influence. This study, based on the Monte Carlo method, presents a sensitivity analysis for the variables utilized as input data by the FDS software. The results show the conversion factor α, i.e. the mass involved in each reaction, and the triplet kinetics have a major impact on the reproduction of the thermal decomposition process in fire computer modelling.Authors would like to thank to the Consejo de Seguridad Nuclear for the cooperation and co-financing the project ‘‘Simulation of fires in nuclear power plants’’ and to CAFESTO Project funded by FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación/Proyecto RTC2017-6066-8

A simple direct method to obtain kinetic parameters for polymer thermal decomposition

In a fire, the polymer combustion occurs when gaseous fuels react with oxygen. The heating of a material could force the release of gaseous fuels during thermal decomposition and pyrolysis. The rate of pyrolysis to define the gaseous fuels is usually interpreted by means of the Arrhenius expression and a reaction model expression, which are characterized by an activation energy, a pre-exponential factor, and a reaction order value. Many methods are available for determining kinetic parameters from thermogravimetric experimental data. However, the most challenging issue is achieving an adequate balance between accuracy and simplicity. This work proposes a direct method for determining the kinetic parameters with only a thermogravimetric experiment at a single heating rate. The method was validated with six polymers, and the results were compared with those from similar procedures, such as the Lyon method and generalized direct method. The results achieved using the simpler approach of the proposed method show a high level of accuracy.Authors would like to thank to the Consejo de Seguridad Nuclear for the cooperation and co-financing the project “Metodologías avanzadas de análisis y simulación de escenarios de incendios en centrales nucleares” and to CAFESTO Project funded by the Spanish Ministry of Science, Innovation and Universities and the Spanish State Research Agency through public–private partnerships (Retos Colaboración 2017 call, ref RTC-2017-6066-8) co-funded by ERDF under the objective “Strengthening research, technological development and innovation

Thermal oxidative decomposition estimation combining TGA and DSC as optimization targets for PMMA

Thermal analysis techniques play a key role to determine and characterize solid phase thermal decomposition. In this sense, Simultaneous Thermal Analysis (STA, i.e. TGA and DSC tests carried out simultaneously) are widely employed, since it provides information about how mass is lost and energy released while the temperature of the sample increases. Fire computer models combined with methods numerical methods are widely used to represent the results from tests and to achieve the values of the kinetic and thermal parameters. Previous works looked forward achieving those parameters using, as unique optimization target, the mass loss curve (TGA) or its derivative (DTGA). As the study of heat release rate is a decisive element to characterize the material properly, most recent works were adding additional measures. These extra measurements concern the heat transfer and the energy required or released during temperature programmed heating, such as heat rate release, heat of gasification, or the surface temperatures of the samples. The information about the energy is provided by the Differential Scanning Calorimetry curve (DSC). Despite of the employment of the information provided by the DSC, this information usually is not used as a target to approach the DSC simulated curve to the experimental one as TGA does. Based on the lack of use of the DSC curve as numerical approaching process to set the kinetic properties, we decide to explore the possibility of adding this as a new target in the process. Therefore, kinetic and thermal properties might be achieved fitting experimental and simulated curves simultaneously, which should allow us to take into account the decomposition process and their energy released. Results obtained in the present work reveal the major challenge of getting a set of parameters, which can fit DSC curve. The level of accuracy reached when only TGA is utilized as target to approach is higher than the level of accuracy of DSC curve. This fact makes increase the value of the errors when both curves are used as targets to approach. In other words, an approach to both curves simultaneously cannot be directly made. With this consideration in mind, this paper proposes an alternative methodology in order to fit TGA curve considering the optimization of the DSC curve. The methodology proposed in the present work is applied to the analysis of poly(methyl methacrylate) (PMMA).The authors would like to express their thanks to the Nuclear Safety Council for the cooperation and cofinancing of the project "Simulation of fires in nuclear power plants" and the Spanish Ministry of Economy and Competitiveness for the PYRODESIGN Project grant, Ref.: BIA2012-37890, financed jointly by ERDF

Las políticas del mercado de trabajo. Incentivos para el fomento del empleo en España

Análisis del desarrollo de las distintas políticas del mercado de trabajo en España, las normas jurídicas estatales que han regulado y regulan el ámbito de las mismas, con la exposición sintetizada de las singularidades que han pretendido aportar en su texto. En este análisis se han excluido las disposiciones sobre la materia de las Comunidades Autónomas, dado que el trabajo hubiera alcanzado fácilmente el doble de su extensión. También se realiza una referencia a la evolución de las medidas que organizaciones como la Oficina Internacional de Trabajo y la Organización para la Cooperación y Desarrollo Económico, han propuesto en las últimas décadas al respecto, sin olvidarnos, como no podía ser de otra manera, de la referencia al recorrido de las políticas sobre mercado de trabajo de la Unión Europea.Grado en Relaciones Laborales y Recursos Humano

Educação e liberdade na África lusófona

Cette oeuvre est indispensable pour tous ceux qui sont interesses à connaitre le continent africain en ce qui concerne spécialement les anciennes colonies portugaises. Dans ce but, ce livre écrit par un des plus grands éducateurs brésiliens en partenariat avec Sérgio Guimarães : Paulo Freire - présente les différents obstacles et les possibles débouchées pour ceux qui prétendent collaborer dans le contexte de l'alphabétisation dans langue portugaise.This work is very important for all interested in knowing the African continent in respect, especially, to the old Portuguese colonies. In this direction, the related book - written for one of the biggest Brazilian educators in partnership with Sergio Guimarães: Paulo Freire - presents the different obstacles and possible ways for those who intend to collaborate in the scope of the literacy in Portuguese language.Esta obra é indispensável para todos aqueles que são interessados em conhecer o continente africano no que diz respeito, especialmente, às antigas colónias portuguesas. Nesta direção, a referida obra - escrita por um dos maiores educadores brasileiros em parceria com Sérgio Guimarães: Paulo Freire- nos apresenta os diferentes obstáculos e possíveis saídas para aqueles que pretendem colaborar no âmbito da alfabetização em língua portuguesa

Reflexão – Ações afirmativas: o que pensava o judiciário antes do julgamento da Arguição de Descumprimento de Preceito Fundamental n. 186

Muito se tem discutido acerca das ações afirmativas, em específico, das cotas raciais nas universidades. Nessas discussões, as cotas perpassam por um viés, ora discriminatório, ora como uma benevolência do governo. O presente texto tem como objetivo fazer uma análise em nove decisões dos estados de Santa Catarina e Espírito Santo, no intuito de saber que fundamento norteia essas decisões. Para tanto, será feita primeiramente uma reflexão sobre a política de cotas nas universidades públicas brasileiras à luz dos princípios da igualdade e da não discriminação, mostrando o embasamento jurídico que perpassa por essa política. O texto aborda a implantação da política de cotas nas universidades brasileiras e alguns conceitos, como ações afirmativas, discriminação, igualdade e não discriminação..

An evaluation of a simple dynamical model for impacts between rigid objects

The main purpose of this work is to propose a dynamical model for simulating the response of different metallic objects when impacted by another rigid body. In addition, a methodology for estimating the model parameters is presented and discussed. Results from real experiments shows that by assuming certain characteristics on impacting objects, the dynamic model can reproduce the transient dynamics during contact time.Peer ReviewedPostprint (published version