963 resultados para Automobiles, Racing -- Aerodynamics
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El presente trabajo ahonda en el conocimiento del viento urbano. La investigacin pasa revista a la historia de la relacin del viento y la ciudad y revisa tres pares de disciplinas implicadas en comprender mejor dicha relacin: la arquitectura y el urbanismo, la meteorologa y la climatologa y, por ltimo, la ingeniera aeroespacial y la aerodinmica civil. Se estudian el comportamiento y la fluidez del viento al desplazarse por cuerpos romos no fuselados (los edificios y la trama urbana), as como sus efectos dentro de la ciudad. Asimismo, se examinan las metodologas existentes para comprenderlo, medirlo y analizarlo, desde los estudios de proporcin y modelamiento en tneles de viento hasta las simulaciones virtuales y las dinmicas de fluidos CFD. Posteriormente se reconoce un caso de estudio que permite analizar el viento como un factor aislado, pero desde los parmetros morfolgicos de una ciudad en la que se generan patrones aerodinmicos muy caractersticos: Punta Arenas, la ciudad ms austral del mundo, donde los vientos corren casi siempre desde la misma direccin, el oeste, a ms de 33,3 m/s, lo que equivale a 120 Km/h. La hiptesis de la investigacin es que la morfologa del casco histrico de Punta Arenas genera patrones aerodinmicos que condicionan el bienestar en los espacios pblicos. El objetivo general de la investigacin es estudiar los efectos aerodinmicos presentes en la morfologa urbana para mejorar la permanencia en los espacios pblicos, proponiendo estrategias para el desarrollo morfolgico y volumtrico de los cuerpos edificados. En el desarrollo del caso de estudio se reconocen, al interior del can urbano, las temperaturas, los ndices de asoleamiento y sus conos de sombra, la direccin del viento y la visualizacin del vrtice al interior del can urbano, para determinar cmo estos factores impactan en el espacio pblico. Las conclusiones indican que los patrones aerodinmicos presentes en la morfologa urbana conducen el viento hacia los espacios pblicos que se encuentran o desprotegidos del viento o con excesiva turbulencias, por tanto, los patrones aerodinmicos inciden en el uso estancial de los espacios pblicos, generando problemas mecnicos al peatn e incidiendo en la sensacin trmica en dichos espacios. Ello permite confirmar que es posible modificar y mejorar el uso de los espacios pblicos si somos capaces de modelar la morfologa urbana con el fin de reorientar los patrones aerodinmicos que afectan significativamente a dichos espacios. ABSTRACT This work deepens into the knowledge of urban wind. The study reviews the history of the relationship between the wind and the city and reviews three pairs of disciplines involved in understanding better these relationship: Architecture and Urbanism, Meteorology and Climatology and, finally, Aerospace and Civil Aerodynamics. The behavior and flow of wind through blunt bodies not fairings (the buildings and the urban fabric) and its effects within the city are studied. Also, existing methodologies to understand, measure and analyze the wind are examined, from the studios of proportion and modeling in wind tunnels to virtual simulations and fluid dynamics CFD. Subsequently, a case study to analyze the wind as an isolated factor is recognized, but from the morphological parameters of a city where very characteristic aerodynamic patterns are generated: Punta Arenas, the southernmost city in the world, where the winds run almost always from the same direction, the "West", at more than 33.3 m/s, which is equivalent to 120 km/h. The research hypothesis is that the morphology of the historic center of Punta Arenas generates aerodynamic patterns that determine the well-being in public spaces. The overall objective of the research is to study the aerodynamic effects present in the urban morphology to improve retention in public spaces, proposing strategies for morphological and volumetric development of the built bodies. In developing the case study are recognized, within the urban canyon, temperatures, rates of sunlight and shadow cones, wind direction and visualization of the vortex into the urban canyon, to determine how these factors impact in public space. The findings indicate that the aerodynamic patterns in urban morphology lead wind to public spaces that are unprotected or find themselves in a condition of excessive wind or turbulence; therefore, aerodynamic patterns affect the use of public spaces, generating mechanical problems for pedestrians and affecting the thermal sensation in such spaces. This confirms that it is possible to modify and improve the use of public spaces if we are able to model the urban morphology in order to reorient the aerodynamic patterns that significantly affect those spaces.
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To combat unsustainable transportation systems characterized by reliance on petroleum, polluting emissions, traffic congestion and suburban sprawl, planners encourage mixed use, densely populated areas that provide individuals with opportunities to live, work, eat and shop without necessarily having to drive private automobiles to accommodate their needs. Despite these attempts, the frequency and duration of automobile trips has consistently increased in the United States throughout past decades. While many studies have focused on how residential proximity to transit influences travel behavior, the effect of workplace location has largely been ignored. This paper asks, does working near a TOD influence the travel behaviors of workers differently than workers living near a TOD? We examine the non-work travel behaviors of workers based upon their commuting mode and proximity to TODs. The data came from a 2009 travel behavior survey by the Denver Regional Council of Governments, which contains 8,000 households, 16,000 individuals, and nearly 80,000 trips. We measure sustainable travel behaviors as reduced mileage, reduced number of trips, and increased use of non-automobile transportation. The results of this study indicate that closer proximity of both households and workplaces to TODs decrease levels of car commuting and that non-car commuting leads to more sustainable personal travel behaviors characterized by more trips made with alternative modes.
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Um dos grandes desafios enfrentados pelos fabricantes de turbinas hidrulicas prevenir o aparecimento de vibraes induzidas pelo escoamento nas travessas do pr-distribuidor e ps do rotor. Considerando apenas as travessas, e atribudos a tais vibraes, foram relatados 28 casos de trincas ou rudos anormais nas ltimas dcadas, que acarretaram enormes prejuzos associados a reparos, atrasos e perda de gerao. O estado da arte na preveno destes problemas baseia-se na utilizao de sofisticados, e caros, programas comerciais de dinmica dos fluidos computacional para o clculo transiente do fenmeno. Este trabalho faz uma ampla reviso bibliogrfica e levantamento de eventos de trincas ou rudos ocorridos em travessas nos ltimos 50 anos. Prope, ento, um enfoque alternativo, baseado exclusivamente em ferramentas de cdigo aberto. A partir de hipteses simplificadoras devidamente justificadas, o problema formulado matematicamente de forma bidimensional, no plano da seo transversal da travessa, levando em conta a interao fluido-estrutura. Nesta estratgia, as equaes de Navier-Stokes so resolvidas pelo mtodo dos elementos finitos por meio da biblioteca gratuita oomph-lib. Um cdigo especial em C++ desenvolvido para o problema de interao fluido-estrutura, no qual o fenmeno de turbulncia levado em considerao por meio de um algoritmo baseado no modelo de Baldwin-Lomax. O mtodo proposto validado por meio da comparao dos resultados obtidos com referncias e medies disponveis na literatura, que tratam de problemas de barras retangulares suportadas elasticamente. O trabalho finaliza com a aplicao do mtodo a um estudo de caso envolvendo uma travessa particular.
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Background: The importance that birds of the Columbidae family have had throughout history is visible on the Mediterranean coast. Pigeon fancying is the art of breeding and training carrier pigeons and currently, several breeds exist. The sport of racing pigeons consists in covering a distance at maximum possible speed. However, pigeon breeding has another modality called sport pigeon, where several males follow a female. This study focusses on ethnobotanical knowledge of native and exotic plant species that are used for diet, breeding, stimulation, healing illnesses and staining the plumage of pigeons bred in captivity. Methods: Using semi-structured interviews, we gathered information about the different plant species traditionally used for pigeon-breeding in the region of Valencia. Background material on remedies for bird illnesses was gathered from folk botanical references, local books and journals. The plant species were collected in the study area, then identified in the laboratory using dichotomous keys and vouchered in the ABH (Herbarium of Alicante University). We used Excel 2003 to perform a simple statistical analysis of the data collected. Results: We collected 56 species of plants (and one variety) that included 29 botanical families. The total number of species was made up of 35 cultivated and 21 wild plants. The most common were Gramineae (14 species), Leguminosae (6 species), and Compositae (4 species). Conclusions: Pigeon breeding is an immensely popular activity in Eastern Spain, and ethnobiological knowledge about breeding pigeons and caring for them is considerable. The names and traditional uses of plants depend on their geographical location, vernacular names serve as an intangible heritage. Feeding, environmental features, and genetic makeup of individuals are relevant aspects in the maintenance of avian health.
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Tese de doutoramento, Educao (Psicologia da Educao), Universidade de Lisboa, Instituto de Educao, 2016
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Like other regions of the world, the EU is developing biofuels in the transport sector to reduce oil consumption and mitigate climate change. To promote them, it has adopted favourable legislation since the 2000s. In 2009 it even decided to oblige each Member State to ensure that by 2020 the share of energy coming from renewable sources reached at least 10% of their final consumption of energy in the transport sector. Biofuels are considered the main instrument to reach that percentage since the development of other alternatives (such as hydrogen and electricity) will take much longer than expected. Meanwhile, these various legislative initiatives have driven the production and consumption of biofuels in the EU. Biofuels accounted for 4.7% of EU transport fuel consumption in 2011. They have also led to trade and investment in biofuels on a global scale. This large-scale expansion of biofuels has, however, revealed numerous negative impacts. These stem from the fact that first-generation biofuels (i.e., those produced from food crops), of which the most important types are biodiesel and bioethanol, are used almost exclusively to meet the EUs renewable 10% target in transport. Their negative impacts are: socioeconomic (food price rises), legal (land-grabbing), environmental (for instance, water stress and water pollution; soil erosion; reduction of biodiversity), climatic (direct and indirect land-use effects resulting in more greenhouse gas emissions) and public finance issues (subsidies and tax relief). The extent of such negative impacts depends on how biofuel feedstocks are produced and processed, the scale of production, and in particular, how they influence direct land use change (DLUC) and indirect land use change (ILUC) and the international trade. These negative impacts have thus provoked mounting debates in recent years, with a particular focus on ILUC. They have forced the EU to re-examine how it deals with biofuels and submit amendments to update its legislation. So far, the EU legislation foresees that only sustainable biofuels (produced in the EU or imported) can be used to meet the 10% target and receive public support; and to that end, mandatory sustainability criteria have been defined. Yet they have a huge flaw. Their measurement of greenhouse gas savings from biofuels does not take into account greenhouse gas emissions resulting from ILUC, which represent a major problem. The Energy Council of June 2014 agreed to set a limit on the extent to which firstgeneration biofuels can count towards the 10% target. But this limit appears to be less stringent than the ones made previously by the European Commission and the European Parliament. It also agreed to introduce incentives for the use of advanced (second- and third-generation) biofuels which would be allowed to count double towards the 10% target. But this again appears extremely modest by comparison with what was previously proposed. Finally, the approach chosen to take into account the greenhouse gas emissions due to ILUC appears more than cautious. The Energy Council agreed that the European Commission will carry out a reporting of ILUC emissions by using provisional estimated factors. A review clause will permit the later adjustment of these ILUC factors. With such legislative orientations made by the Energy Council, one cannot consider yet that there is a major shift in the EU biofuels policy. Bolder changes would have probably meant risking the collapse of the high-emission conventional biodiesel industry which currently makes up the majority of Europes biofuel production. The interests of EU farmers would have also been affected. There is nevertheless a tension between these legislative orientations and the new Commissions proposals beyond 2020. In any case, many uncertainties remain on this issue. As long as solutions have not been found to minimize the important collateral damages provoked by the first generation biofuels, more scientific studies and caution are needed. Meanwhile, it would be wise to improve alternative paths towards a sustainable transport sector, i.e., stringent emission and energy standards for all vehicles, better public transport systems, automobiles that run on renewable energy other than biofuels, or other alternatives beyond the present imagination.
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To date, the negotiations over chemicals in the Translatlantic Trade and Investment Partnership (TTIP) have not shown sufficient ambition. The talks have focused too much on the differences in the two systems, rather than on the actual levels of health and environmental protection for substances regulated by both the US and the EU. Given the accomplishments within the OECD and the UN Globally Harmonised System of Classification and Labelling of Chemicals (GHS), the question is whether TTIP can be any more ambitious in the area of chemicals? We find that there is no detailed or systematic knowledge about how the two levels of protection in chemicals compare, although caricatures and stereotypes abound. This is partly due to an obsessive focus on a single US federal law, the Toxic Subtances Control Act (TSCA), whereas in practice US protection depends on many statutes and regulations, as well as on voluntary withdrawals (under pressure from the Environmental Protection Agency) and severe common law liability. This paper makes the economic case for firmly addressing the regulatory barriers, discusses the EUs proposals, finds that the European Parliaments Resolution on TTIP of July 2015 lacks a rationale (for chemicals), argues that both TSCA and REACH ought to be improved (based on better regulation), discusses the link with a global regime, advocates significant improvement of market access where equivalence of health and environmental objectives is agreed and, finally, proposes to lower the costs for companies selling in both markets by allowing them to opt into the other partys more stringent rules, thereby avoiding duplication while racing-to-the-top. The living agreement on chemicals ought to be led by a new TTIP institution authorised to establish the level of health and environmental protection on both sides of the Atlantic for substances regulated on both sides. These findings will lay the foundation for a highly beneficial lowering of trading costs without in any way affecting the level of protection. Indeed, this is exactly what TTIP is, or should be, all about.This paper is the 10th in a series produced in the context of the TTIP in the Balance project, jointly organised by CEPS and the Center for Transatlantic Relations (CTR) in Washington, D.C. It is published simultaneously on the CEPS (www.ceps.eu) and CTR websites (http://transatlantic.sais-jhu.edu).
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Michelle Egan and Jacques Pelkmans provide an overview of the TBT chapter in TTIP and the various issues between the US and the EU in this area, which in turn requires extensive expositions of domestic regulation in the US and the EU. TBTs, outside heavily regulated sectors such as chemicals, automobiles or medicines (which have separate chapters in TTIP), can be caused by divergent (voluntary) standards, technical regulations and conformity assessment. Indeed, in all three the US and the EU have long experienced frictions with considerable trading costs. The 1998 Mutual Recognition Agreement about conformity assessment only succeeded in two out of six sectors. The US and European standardisation traditions differ and this paper explains why it is so hard, also economically, to realise convergence. However, the authors reject the unproductive stand-off between US and EU negotiators on standardisation and suggest to clarify the enormous economic installed base of prominent US standards in the world economy and build a solution from there. As to technical regulation, the prospect of converging regulation (via harmonisation) is often dim, but equivalence (given similar levels of regulatory protection) can be an option.
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This paper provides an overview of methods employed to quantify non-tariff measures (NTMs) and then analyses their differences and looks at what these mean for the Transatlantic Trade and Investment Partnership (TTIP) negotiations. The authors find several similarities in the approaches taken. Because all studies conclude that NTMs matter, they argue that policy-makers are right to focus on regulatory cooperation in TTIP. Given the significant differences in NTMs across sectors, policy-makers are urged to dive deep into sector-specific elements of NTMs and focus on those sectors where the largest potential gains can be made (i.e. where NTMs are highest, such as in agriculture, automobiles, steel, textiles and insurance services). An area identified for further research is the fact that unlike trade taxes (i.e. tariffs), regulatory barriers to trade are not generally targeted as the primary policy objective, but rather stem from other strategic policy concerns such as consumer safety and/or social and environmental protection. This element should be further investigated.
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Daybook, image #28
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Albert Kahn, architect. Built 1936
