232 research outputs found
Overall synthesis and conclusions
No full textThis chapter first systematically summarizes the most important findings and policy implications of each of the chapters included in this book volume. Next it synthesizes the overall findings and policy implications, and discusses future avenues for policy making and research. A first conclusion is that the chapters make clear that the ranges in policy relevant implications of AVs, within the scope of each chapter/topic, are still relatively broad. Secondly we conclude that research that is conceptually rich is more valuable for policy making. Thirdly we hypothesize that context matters for the uptake, impacts, and specific system design characteristics of real world AV implementation. Fourth we conclude that research on the global south has been limited so far. Fifth we argue that AVs, shared vehicles and electric vehicles (EVs) might stimulate each other in a positive way, in all directions. Finally we conclude that AVs will have wider societal implications, such as in the area of land use, accessibility, social exclusion, governmental expenditures, the labor market, and the environment. The more indirect the effects of AVs are, the more difficult they are to understand. For policy making a first conclusion is that the issues of ethics, cyber security and data protection deserve way more attention than they currently get. We also conclude that future motorway network extensions might not be no-regret anymore, because of possible congestion reductions due to AVs, but also because of decreasing marginal values of time. Finally we argue that countries that introduce AVs later than other countries can learn a lot from the real world experiences elsewhere.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and Logistic
Post hos nostra terra est: mapping the Late Roman ecumene with the Expositio totius mundi et gentium
No full textThis paper studies the landscape of the Late Roman ecumene as depicted by the Expositio totius mundi et gentium (Expos. mundi),1 written by an anonymous author in the middle of the 4th century CE. It will first contextualise the text and assess its structure, language and genre. The contribution will then focus on the distinction between Rome, the Sasanids and utopic societies in the east near Eden, the political and military organization of the Imperium Romanum as well as its economic framework and varying expressions of its culture. As
this paper will show, the anonymous author does not present detailed descriptions of Rome’s geographical landscape. Instead, the primary focus is on material resources of the Roman Empire, their potential for economic exploitation and the trading opportunities resulting from it. Rome’s cultivated landscapes are thereby regarded as important preconditions for its success on an economic, political and cultural level
Numerical simulation of a slow loss of flow accident in a nuclear research reactor
No full textAs simulações numéricas de acidentes em reatores nucleares de pesquisa necessitam de constante aprimoramento, originando metodologias validadas, o que permite aproximar os cálculos numéricos a um comportamento físico. O trabalho proposto consiste em elaborar uma metodologia numérica tridimensional para análise de um acidente tipo perda lenta de vazão, comumente nomeado de SLOFA, do inglês, slow loss of flow accident, para o reator nuclear IEA-R1. Utilizando códigos numéricos para escoamentos tridimensionais (ANSYS CFX®) foi possível observar a dinâmica do escoamento, prever a localização da temperatura máxima do revestimento e o instante da inversão do sentido de escoamento. Sete modelos de turbulência foram analisados individualmente para elaboração da metodologia, porém, inúmeras dificuldades foram observadas no processo de solução para os modelos ZE, EVTE, SSG, k - ε, k - ω, SST e DES. O modelo que atendeu aos requisitos estabelecidos, entre eles, tempo computacional e solução numérica compatível com solução física, foi o modelo de turbulência k - ω. Entre as justificativas para este resultado pode-se citar a ausência da lei logarítmica de parede e simplicidade na solução das equações de transporte para condição analisada. Os resultados apresentaram alinhamento quantitativo e qualitativo com as curvas de temperatura experimentais. Nas condições de regime permanente quanto para o regime transiente, o desvio máximo observado foi de 3,4°C para temperatura. As curvas de temperatura numérica capturam o mesmo comportamento físico observado nos testes experimentais, tanto no instante da inversão do escoamento, quanto no início da perda dos efeitos do empuxo. Portanto, esta metodologia tridimensional representa um avanço frente aos resultados apresentados pelos códigos unidimensionais reportados na literatura (RELAP, MERSAT, CATHARE) para a mesma base de dados experimental, visto que o desvio médio observado nestes códigos é de 7,2°C.Numerical analyses for nuclear accidents in research reactors need constant improvement, leading to validate methodologies, bringing numerical calculations closer to physical behaviour. The proposed work consists of the creation of a validated numerical methodology for the analysis of a slow flow loss accident for the IEA-R1 nuclear reactor. To model three-dimensional flows, the numerical code (ANSYS-CFX®), it was possible to observe the flow dynamics and predict the location of the maximum cladding temperature and flow inversion inside the flow channel. Seven turbulence models were individually analyzed to elaborate on the methodology. However, numerous difficulties were observed in the solution process for the ZE, EVTE, SSG, k - ε, k - ω, SST and DES turbulence models. The model that met the requirements, including computational time and numerical solution compatible with the physical solution, was the turbulence model k - ω. Among the justifications for this result is the absence of the logarithmic wall law and simplicity in the solution of the transport equations for the analyzed condition. The results presented a quantitative and qualitative alignment with the experimental temperature database. For both steady-state and transient-state, the maximum deviation observed was 3.4°C for temperature. The numerical temperature curves captured the same physical behaviour observed in the experimental tests, as much as in the moment of the flow inversion and at the beginning of the loss of the buoyancy effects. Therefore, the three-dimensional methodology presented in this work represents an advance over the results presented by the one-dimensional codes reported in the literature (RELAP, MERSAT, CATHARE), considering the same experimental database, since the average deviation observed in these codes is 7.2°C
Development of multi-physics capabilities in coupling computational fluid dynamics and thermodynamics for molten salt reactor applications
No full textExisting knowledge gaps in Molten Salt Reactors (MSR), such as understanding fuel salt chemistry and fission product retention, require rigorous investigations to support reactor safety. The objective of this work was to develop a novel computational toolset tailored for multi-physics simulations of MSR studies that could fill the aforementioned knowledge gaps. This toolset studied the intricate dependence between thermal-hydraulics and salt chemistry by coupling the computational fluid dynamics code OpenFOAM with the computational thermodynamics code Thermochimica . This coupling facilitates the simulation of scenarios relevant to MSR reactor safety, which is especially important given that MSRs have a low technical readiness level relative to other reactor technologies.
Two demonstration problems exemplify the applications and outcomes of this project, which was in support of the SAMOSAFER Co-ordinated Research Project of the European Commission. The initial problem revolves around the first step of the molten salt clean-up fluorination process, which vaporizes molten fuel components (i.e., UF4) into its volatile form (i.e., UF6). Simulations revealed that the fluorination time is strongly dependent on the molten salt system, salt viscosity, and temperature. Compared with experimental results, the simulations displayed a strong correlation in vaporization rates under steady-state conditions, giving credence to the validity of the local equilibrium hypothesis. The second demonstration problem centred on the molten salt fast reactor. Here, normal operating conditions were examined, focusing on fission product retention and release, such as Cs, La, Xe in promising molten fluoride systems (e.g., LiF – ThF4 – UF4 77.5-20-2.5 mol%). Simulations demonstrated that most fission products are retained by the salt and the evaporation rates of several compounds, such as, LiF, ThF4, UF4, CsF, Cs2, Cs2F2, LaF3, F, F2 posed to be almost insignificant when compared to other known volatile/gaseous fission products, such as xenon. This investigation provided an understanding of how fast the UF4/UF3 molar ratio reaches optimal design limits, which plays a pivotal role in controlling corrosion. In conclusion, the outcomes underscore advancements in computational capabilities, promising to elucidate further the intricacies of designing and testing multifaceted scenarios in the realm of MSRs.University of Ontario Institute of Technolog
Coupled computational fluid dynamics and computational thermodynamics simulations for fission product retention and release: A molten salt fast reactor application
No full textThis study presents a computational capability for fission product retention and release in two-phase, multi-species systems representing Molten Salt Reactors (MSR) with coupled thermal-hydraulics and fuel coolant chemical behaviours. This is demonstrated through four simulated cases centred on the proposed Molten Salt Fast Reactor (MSFR). This is achieved by two-way coupling the Computational Fluid Dynamics (CFD) code OpenFOAM and the Computational Thermodynamics (CT) code Thermochimica, using the Joint Research Centre Molten Salt Database (JRCMSD). Local chemical equilibrium is assumed, implying that chemical kinetics are predominantly governed by mass transport. Four simulations address normal operating conditions, exploring: (i) dilution of fission products injected within the molten salt coolant, (ii) molten salt coolant evaporation rate, (iii) release of radioactive gaseous species, (iv) shifts in the UF4/UF3 ratio, and (v) comparison of vapour pressures of gaseous species. The influence of temperature-dependent viscosity on retaining fission products, compared to consistent values, is also discussed. The feasibility of integrating CFD with Thermochimica showed promising results, broadening insights into multiphysics systems and setting the stage for its application in more intricate scenarios
Walking as Do-It-Yourself Urbansim
No full textThis article develops a series of theoretical notions arising in the context of an urban art project that took place in London in the summer of 2004 under the title “Where do you breathe?”1 As a participatory urban intervention, the project challenged the notion of authorship in public space by casting the act of walking as a transformation of urban space, and examined the potentials for a practice of photography based on interaction rather than passive representation
Spinal anaesthesia for brachytherapy for carcinoma of the cervix a comparison of two dose regimes of hypebaric bupivacaine
No full textIncludes abstract.Includes bibliographical references.The main purpose of the study was to help establish the best dose regimen of hyperbaric bupivacaine, when combined with intrathecal fentanyl, for spinal anaesthesia for brachytherapy for carcinoma of the cervix. This procedure is performed as a day case at Groote Schuur Hospital
Policy implications of the potential carbon dioxide (CO<sub>2</sub>) emission and energy impacts of highly automated vehicles
No full textThis chapter explores the extent to which the adoption of highly automated vehicles (AVs) will lead to carbon dioxide (CO2) emission reduction in the future. Additionally, policy implications are given. Based on existing literature, this chapter shows that the adoption of AVs will result in a modest improvement of CO2 emission per kilometer traveled compared to non-autonomous vehicles in the future. Combined with the expectations that AVs will lead to a modest to, even, high growth in vehicle kilometers traveled (VKT) compared to business as usual, the net energy and CO2 emission balance for AVs seems, at its best, to be neutral, but is probably negative. The potential accelerating role of AVs in relation to the uptake of electric vehicles might have the largest positive impacts on the CO2 emissions per kilometer driven, but this accelerating role of AV technology in relation to the uptake of electric vehicles is uncertain. For the time being the most useful policy implication to curb road transport CO2 emissions seems to be to continue with policies that promote the use of alternatives for fossil fuels, such as electricity.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and Logistic
Creativity in co-Design for Physical Education: Comparing Contributions of Children and Professionals
No full textThis study is carried out within the context of a research and innovationproject Co-design with Kids that aims to support teaching of broad so-called ‘21stcentury’ skills. In this project, design toolboxes for use within primary educationare developed and studied, with real life clients and assignments. In the casedescribed in this paper, the assignment was to create new concepts for physicaleducation (PE). To be able to assess the value of design outcomes created in aco-design trajectory by children, we compared their design outcomes to thosecreated in a similar design process by professionals. Six teams of children (n=21,11-12 years old) and three teams of professionals (n=10, with a background indesign, sports or physical education) developed concepts in separate co-creationsessions. We present a first assessment of the differences and similarities increativity of the design outcomes of the two groups. This assessment of textualsummaries shows no remarkable differences between design outcomes ofchildren and those of professionals in terms of elaboration, originality andrelevance. This indicates that children could be involved as design partners.Further research is needed to gain insight into the specific value of involvingchildren as design partners.Accepted author manuscriptDesign Conceptualization and CommunicationScience Education and Communicatio
A biopolítica como a política da vida e da vitalidade humana : aproximações, discrepâncias, comensurabilidades e avanços conceituais nas propostas de Michel Foucault e Nikolas Rose
No full textThis Master's Dissertation proposes to analyze the notion of biopolitics and its derived concepts as conceptualized, in the 1970s, by the French philosopher Michel Foucault. At the same time, it also intends to analyze the same notion, biopolitics, proposed in the first decade of the 21st century, by the English sociologist Nikolas Rose. Both approaches have their own characteristics. Biopolitics theorized by Michel Foucault refers to the entry of life into the political strategies of States, which occurred between the 17th and 18th centuries, when sovereign power assumed the role of managing the life and vitality of man-species, aiming to, above all, to increase the population’s level of health. The conception of biopolitics formulated by Nikolas Rose concerns the politics of life that has taken shape in the last three decades. It is not delimited by the poles of health and illness, it is concerned with optimizing human vitality and is put into practice by social actors themselves in conjunction with medical authorities. Furthermore, 21st century biopolitics is related to the formation of social relations based on shared somatic statuses. This research seeks, through Content Analysis, to identify the approximations, discrepancies and advances in relation to these concepts from one author and the other, enabling us to draw a parallel between the biopolitics defined by both authors. The results point to the coexistence and specific complementarities between the two notions of biopolitics.A presente Dissertação de Mestrado busca analisar a noção de biopolítica tal como conceituada, na década de 1970, pelo filósofo francês Michel Foucault e, na primeira década do século XXI, pelo sociólogo inglês Nikolas Rose. Ambas as abordagens guardam características próprias. A biopolítica teorizada por Michel Foucault refere-se a entrada da vida nas estratégias políticas dos Estados, o que se deu entre os séculos XVII e XVIII, quando o poder soberano assume o papel de gerenciar a vida e a vitalidade do homem-espécie, objetivando, sobretudo, aumentar o nível de saúde da população. A concepção de biopolítica formulada por Nikolas Rose diz respeito à política da vida que tomou forma nas últimas três décadas. Ela não está delimitada pelos polos da saúde e da doença, está preocupada com a otimização da vitalidade humana e é posta em prática pelos próprios atores sociais em conjunto com autoridades médicas. Além disso, a biopolítica do século XXI está relacionada à formação de relações sociais a partir de status somáticos partilhados. Essa pesquisa busca, através da Análise de Conteúdo, identificar as aproximações, discrepâncias e avanços com relação a esses conceitos de um e de outro autor, possibilitando-nos traçar um paralelo entre a biopolítica definida por ambos os autores. Os resultados apontam para a coexistência e a complementaridades específicas entre as duas noções de biopolítica
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