Aircraft turning ground maneuvers

In this project a fully parameterized mathematical model of an aircraft turning on the ground in order to get the maximum aircraft speed and minimum infrastructure taxiway radius for three different types of aircrafts (A320, A380 and B737) is developed. The mathematical model takes the form of a system of coupled ordinary differential equations (ODEs). The airframe is considered as a rigid body with six DOF and the equations of motion are derived by balancing the respective forces and moments. Other formulas as Newton’s second law, centripetal equations, friction formulas and other equations will be used to calculate the safest velocity depending on the radius of the taxiway curvature. The software Matlab will be used so as to make all the calculations and will enable us to change the parameters such as mass, friction or radius to find new velocities according to the aircraft. Moreover, the use of Microsoft Excel software to insert those results already found in Matlab and create new tables depending on the radius and ground weather conditions (dry or wet). The results show that each aircraft has a different safety velocity although they turn with the same taxiway radius. There is also a bibliographic and modelling work explaining how to get all the equations and the different types of taxiway entries

Tracking environmental change in seagrass meadows: understanding indicator behaviour across space and time

[eng] Nearshore marine ecosystems like seagrass meadows face a wide range of anthropogenic influences, impacting the system at different spatial and temporal scales. Managing these systems in the face of these pressures requires detailed knowledge of how seagrass habitats respond to these various threats. A plethora of useful indicators have been developed to help managers and policy makers track seagrass meadow health and status, detect environmental impacts or measure the effectiveness of management interventions. However, choosing between these indicators can often be a daunting task since they vary considerably in their overall behaviour in relation to ecosystem and environmental changes. This thesis assesses the most commonly employed seagrass indicators to determine if they are adequate and appropriate to the specific needs of coastal ecosystem management. This assessment is based on evaluating three fundamental characteristics of each indicator – the robustness of its response, the specificity or generality of its response, and the time of response. We use a variety of complementary approaches to explore indicator behaviour. In Chapter 3, we use field-based studies to assess how seagrass indicators respond to the construction of a breakwater in the vicinity of a Posidonia oceanica seagrass meadow. Chapters 4 and 5 examine long-term trends in seagrass indicators to improving water quality conditions after significant regional management interventions. In addition, in Chapter 6, we comprehensively review seagrass indicator responses to multiple stressors. Chapters 3, 4 and 5 focus largely on the Catalan Coast in the Mediterranean with Posidonia oceanica as a target species. Chapter 6 in contrast is a broad review of a wide range of indicators used across several seagrass species worldwide. A central learning across these studies was that the level of biological organisation of the indicator (i.e. Physiological, biochemical, growth, morphological, structural or demographic) is critical in determining the specificity or generality of response: the lower the level (e.g. biochemical), the most specific the response, while the higher the level (e.g. population, community), the wider the response. Thus, biochemical indicators are ideal to determine the identity or even the origin of a pressure while structural indicators, in contrast, are useful as generic indicators of declining conditions. Response times are also heavily determined by the level of organisation, particularly in the detection of improving environmental quality along the Catalan coast. Biochemical indicators responded unequivocally to water quality improvements observed both in the experimental field study (Chapter 3) as well as in the analysis of the long-term data series (Chapters 4 and 5). The meta-analysis confirmed that these trends in specificity and response time were not unique to Posidonia oceanica or the Catalan coast and highlighted the critical role of plant size in determining indicator time responses. Large species take considerably longer to register a response to environmental degradation as well as improvement – a critical factor that needs to be accounted for in designing monitoring programmes and interpreting ecosystem trends. Taken together, these results suggest that differences in the behaviour of seagrass indicators require that they should be carefully selected to match the objectives of management. Based on the results reported in this thesis, where different sets of indicators have been proven successful for given management objectives, we finally develop a simple decision tree to help managers chose the most reliable sets of indicators matching their objectives. Understanding the diversity of responses that seagrass indicators display can make them a powerful set of tools in the ecosystem manager’s toolkit. Carefully employed, they can serve as bespoke solutions to a wide range of management objectives as we seek to monitor and protect these vital ecosystems and coastal water quality in the face of increasing coastal pressures.[cat] Entendre com responen les fanerògames marines a les pressions, és clau per a poder gestionar tant els herbeis com les aigües costaneres. Actualment, disposem d’un gran nombre d’indicadors basats en fanerògames marines. Però, la manca d’informació sobre com responen als canvis ambientals, fa que no sigui fàcil escollir quins indicadors són els més adients per a cada tipus i objectiu de gestió. Aquesta tesi avalua les tres característiques bàsiques de la resposta dels indicadors més utilitzats als canvis ambientals: la robustesa de la resposta, la especificitat dels indicadors a diferents pressions i el temps de resposta. Per analitzar aquestes tres característiques, fem servir diferents aproximacions complementàries. Al capítol 3, analitzem la resposta de diferents indicadors a les obres d’ampliació del port de Blanes, situat just al costat d’un herbei de Posidonia oceanica. Als capítols 4 i 5, estudiem com responen els indicadors a la millora de la qualitat de l’aigua a la costa catalana. Finalment, al capítol 6, presentem una metaanàlisi que estudia com responen els indicadors a diferents factors d’estrès. De totes tres aproximacions, hem pogut comprovar que el nivell d’organització dels indicadors (i.e. bioquímic, estructural) és clau a l’hora de determinar el grau d’especificitat de la resposta dels indicadors a les pressions: generalment, a més baix nivell d’organització (e.g. bioquímic), més específica és la resposta i com més alt (e.g. demogràfic), més ampli és el rang de pressions que un indicador pot detectar. El temps de resposta dels indicadors varia també en funció del nivell d’organització dels indicadors, especialment, quan es tracta de la detecció de millores ambientals. A més a més, la metaanàlisi destaca la importància de la mida de les plantes per determinar el temps de resposta. Les espècies grans triguen més a detectar la degradació de les condicions ambientals i, molt més, a detectar la millora, especialment, si s’utilitzen indicadors estructurals o demogràfics. Basant-nos en els resultats d’aquesta tesi, hem elaborat un esquema per ajudar els gestors a escollir el conjunt d’indicadors que més s’ajusti a cada objectiu de gestió. Utilitzats correctament, aquests indicadors són molt útils per fer el seguiment, tant de l’estat de salut dels herbeis, com de la qualitat del medi

Medidas municipales contra la peste en la Lleida del siglo XIV e inicios del XV

La recurrencia de los ciclos pestíferos durante la segunda mitad del siglo XIV generó una respuesta por parte de las autoridades municipales que intentaron prevenir la llegada de la enfermedad. Al mismo tiempo y compartiendo el objetivo, los médicos de la comunidad universitaria escribieron tratados destinados tanto a profesionales como a la población en general. Es el caso del Regiment de preservació de pestilència (1348) del profesor de medicina del Estudio General de Lleida, Jaume d’Agramont. El propósito de este artículo es identificar las acciones desplegadas por el municipio ilerdense durante las epidemias posteriores a lapeste negra y analizarlas a la luz de las recomendaciones contenidas en la obra de Agramont.This article does not intend to delve into the typology of the bacteria or viruses that caused the diseases and is also far from a positivist compilation of symptoms that may fit our respective disease labels. Our objective is to understand a disease as social construct in a specific historical-cultural framework, which helps us to interpret the medical mentality of trecentist society. It is ultimately an attempt to understand the instruments of a society medically very distinct from ours, which constructed the idea of late medieval pestilence based on its knowledge. We should therefore see the disease through the eyes of contemporary individuals, adopting their understanding of the social construct. This is the only way to understand their struggle against suddendeath.La recurrencia de los ciclos pestíferos durante la segunda mitad del siglo XIV generó una respuesta por parte de las autoridades municipales que intentaron prevenir la llegada de la enfermedad. Al mismo tiempo y compartiendo el objetivo, los médicos de la comunidad universitaria escribieron tratados destinados tanto a profesionales como a la población en general. Es el caso del Regiment de preservació de pestilència (1348) del profesor de medicina del Estudio General de Lleida, Jaume d’Agramont. El propósito de este artículo es identificar las acciones desplegadas por el municipio ilerdense durante las epidemias posteriores a lapeste negra y analizarlas a la luz de las recomendaciones contenidas en la obra de Agramont

Local bisection for conformal refinement of unstructured 4D simplicial meshes

We present a conformal bisection procedure for local refinement of 4D unstructured simplicial meshes with bounded minimum shape quality. Specifically, we propose a recursive refine-to-conformity procedure in two stages, based on marking bisection edges on different priority levels and defining specific refinement templates. Two successive applications of the first stage ensure that any 4D unstructured mesh can be conformingly refined. In the second stage, the successive refinements lead to a cycle in the number of generated similarity classes and thus, we can ensure a bound over the minimum shape quality. In the examples, we check that after successive refinement the mesh quality does not degenerate. Moreover, we refine a 4D unstructured mesh and a space-time mesh (3D + 1D) representation of a moving object

Medidas municipales contra la peste en la Lleida del siglo XIV e inicios del XV

La recurrencia de los ciclos pestíferos durante la segunda mitad del siglo XIV generó una respuesta por parte de las autoridades municipales que intentaron prevenir la llegada de la enfermedad. Al mismo tiempo y compartiendo el objetivo, los médicos de la comunidaduniversitaria escribieron tratados destinados tanto a profesionales como a la población en general. Es el caso del Regiment de preservació de pestilència (1348) del profesor de medicina del Estudio General de Lleida, Jaume d'Agramont. El propósito de este artículo es identificar las acciones desplegadas por el municipio ilerdense durante las epidemias posteriores a la peste negra y analizarlas a la luz de las recomendaciones contenidas en la obra de Agramont.This article does not intend to delve into the typology of the bacteria or viruses that caused the diseases and is also far from a positivist compilation of symptoms that may fit our respective disease labels. Our objective is to understand a disease as social construct in a specific historical-cultural framework, which helps us to interpret the medical mentality of trecentist society. It is ultimately an attempt to understand the instruments of a society medically very distinct from ours, which constructed the idea of late medieval pestilence based on its knowledge. We should therefore see the disease through the eyes of contemporary individuals, adopting their understanding of the social construct. This is the only way to understand their struggle against suddendeath

Medidas municipales contra la peste en la Lleida del siglo XIV e inicios del XV

La recurrencia de los ciclos pestíferos durante la segunda mitad del siglo XIV generó una respuesta por parte de las autoridades municipales que intentaron prevenir la llegada de la enfermedad. Al mismo tiempo y compartiendo el objetivo, los médicos de la comunidad universitaria escribieron tratados destinados tanto a profesionales como a la población en general. Es el caso del Regiment de preservació de pestilència (1348) del profesor de medicina del Estudio General de Lleida, Jaume d’Agramont. El propósito de este artículo es identificar las acciones desplegadas por el municipio ilerdense durante las epidemias posteriores a la peste negra y analizarlas a la luz de las recomendaciones contenidas en la obra de Agramont