14 resultados para Diagnostic attitude

em Universidad Politécnica de Madrid


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This paper shows the role that some foresight tools, such as scenario design, may play in exploring the future impacts of global challenges in our contemporary Society. Additionally, it provides some clues about how to reinforce scenario design so that it displays more in-depth analysis without losing its qualitative nature and communication advantages. Since its inception in the early seventies, scenario design has become one of the most popular foresight tools used in several fields of knowledge. Nevertheless, its wide acceptance has not been seconded by the urban planning academic and professional realm. In some instances, scenario design is just perceived as a story telling technique that generates oversimplified future visions without the support of rigorous and sound analysis. As a matter of fact, the potential of scenario design for providing more in-depth analysis and for connecting with quantitative methods has been generally missed, giving arguments away to its critics. Based on these premises, this document tries to prove the capability of scenario design to anticipate the impacts of complex global challenges and to do it in a more analytical way. These assumptions are tested through a scenario design exercise which explores the future evolution of the sustainable development paradigm (SD) and its implications in the Spanish urban development model. In order to reinforce the perception of scenario design as a useful and added value instrument to urban planners, three sets of implications –functional, parametric and spatial— are displayed to provide substantial and in-depth information for policy makers. This study shows some major findings. First, it is feasible to set up a systematic approach that provides anticipatory intelligence about future disruptive events that may affect the natural environment and socioeconomic fabric of a given territory. Second, there are opportunities for innovating in the Spanish urban planning processes and city governance models. Third, as a foresight tool, scenario design can be substantially reinforced if proper efforts are made to display functional, parametric and spatial implications generated by the scenarios. Fourth, the study confirms that foresight offers interesting opportunities for urban planners, such as anticipating changes, formulating visions, fostering participation and building networks

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This paper presents some results of a R+D project entitled “e-Learning system for Practical Training of University students in Education Faculties (ForELearn)”, developed in Spain by the Universidad de Granada and the Universidad Politécnica de Madrid and funded by the Spanish Ministry of Education. In a first phase, through the use of AulaWeb Learning Management System, a set of adaptations and improvements of this software application have been done for the design and development of an experimental course of Practicum supervision. Next, the implementation of this course by means of a group of face to face and online seminars provides experimental data for the analysis and discussion about the point of view of users (preservice teachers) that have tracked their practice supervision with AulaWeb.

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Commitment and involvement from the different members of an organization are two key elements for an organization to achieve its environmental excellence. Firstly, businesses are aware of the close relationship between their activities and the environment, for they are not only polluting agents but also agents with the capacity to reduce adverse environmental impacts. Secondly, the fact that employees can play a relevant role in terms of the socially responsible measures to be taken by organizations has started to become an irrefutably important issue. This piece of research is intended to help gain knowledge concerning the attitude of the two main actors in productive activity toward the environmental, that is, employers and employees; as well, this research intends to identify factors determining behaviour towards the environmental. For this, we have gathered the ideas and assessments contained in the discourse of a group of small and medium-sized businesses, large company owners and officers, employees, and work related risk prevention representatives. Qualitative work consisted of in-depth interviews and the creation of discussion groups.

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Aims: To assess the clinical presentation and acute management of patients with transient loss of consciousness (T-LOC) in the emergency department (ED). Methods and results: A multi-centre prospective observational study was carried out in 19 Spanish hospitals over 1 month. The patients included were 14 years old and were admitted to the ED because of an episode of T-LOC. Questionnaires and corresponding electrocardiograms (ECGs) were reviewed by a Steering Committee (SC) to unify diagnostic criteria, evaluate adherence to guidelines, and diagnose correctly the ECGs. We included 1419 patients (prevalence, 1.14%).ECG was performed in 1335 patients (94%) in the ED: 498 (37.3%) ECGs were classified as abnormal. The positive diagnostic yield ranged from 0% for the chest X-ray to 12% for the orthostatic test. In the ED, 1217 (86%) patients received a final diagnosis of syncope, whereas the remaining 202 (14%) were diagnosed of non-syncopal transient lossof consciousness (NST-LOC). After final review by the SC, 1080 patients (76%) were diagnosed of syncope, whereas 339 (24%) were diagnosed of NST-LOC (P , 0.001). Syncope was diagnosed correctly in 84% of patients. Only 25% of patients with T-LOC were admitted to hospitals. Conclusion Adherence to clinical guidelines for syncope management was low; many diagnostic tests were performed with low diagnostic yield. Important differences were observed between syncope diagnoses at the ED and by SC decision.

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This paper describes a mobile-based system to interact with objects in smart spaces, where the offer of resources may be extensive. The underlying idea is to use the augmentation capabilities of the mobile device to enable it as user-object mediator. In particular, the paper details how to build an attitude-based reasoning strategy that facilitates user-object interaction and resource filtering. The strategy prioritizes the available resources depending on the spatial history of the user, his real-time location and orientation and, finally, his active touch and focus interactions with the virtual overlay. The proposed reasoning method has been partially validated through a prototype that handles 2D and 3D visualization interfaces. This framework makes possible to develop in practice the IoT paradigm, augmenting the objects without physically modifying them.

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Numerical explorations show how the known periodic solutions of the Hill problem are modified in the case of the attitude-orbit coupling that may occur for large satellite structures. We focus on the case in which the elongation is the dominant satellite’s characteristic and find that a rotating structure may remain with its largest dimension in a plane parallel to the plane of the primaries. In this case, the effect produced by the non-negligible physical length is dynamically equivalent to the perturbation produced by an oblate central body on a mass-point satellite. Based on this, it is demonstrated that the attitude-orbital coupling of a long enough body may change the dynamical characteristics of a periodic orbit about the collinear Lagrangian points.

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Numerical explorations show how the known periodic solutions of the Hill problem are modified in the case of the attitude-orbit coupling that may occur for large satellite structures. We focus on the case in which the elongation is the dominant satellite?s characteristic and find that a rotating structure may remain with its largest dimension in a plane parallel to the plane of the primaries. In this case, the effect produced by the non-negligible physical dimension is dynamically equivalent to the perturbation produced by an oblate central body on a masspoint satellite. Based on this, it is demonstrated that the attitude-orbital coupling of a long enough body may change the dynamical characteristics of a periodic orbit about the collinear Lagrangian points.

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The left ventricular (LV) summit is the most common site of idiopathic epicardial LV arrhythmias and frequently represents a diagnostic and a therapeutic challenge.1 We present a case of sustained monomorphic ventricular tachycardia (SMVT) originating at the LV summit that underwent failed cryosurgical epicardial ablation and was successfully treated with the aid of merged hemodynamic and contrast-enhanced MRI (CE-MRI).

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BETs is a three-year project financed by the Space Program of the European Commission, aimed at developing an efficient deorbit system that could be carried on board any future satellite launched into Low Earth Orbit (LEO). The operational system involves a conductive tape-tether left bare to establish anodic contact with the ambient plasma as a giant Langmuir probe. As a part of this project, we are carrying out both numerical and experimental approaches to estimate the collected current by the positive part of the tether. This paper deals with experimental measurements performed in the IONospheric Atmosphere Simulator (JONAS) plasma chamber of the Onera-Space Environment Department. The JONAS facility is a 9- m3 vacuum chamber equipped with a plasma source providing drifting plasma simulating LEO conditions in terms of density and temperature. A thin metallic cylinder, simulating the tether, is set inside the chamber and polarized up to 1000 V. The Earth's magnetic field is neutralized inside the chamber. In a first time, tether collected current versus tether polarization is measured for different plasma source energies and densities. In complement, several types of Langmuir probes are used at the same location to allow the extraction of both ion densities and electron parameters by computer modeling (classical Langmuir probe characteristics are not accurate enough in the present situation). These two measurements permit estimation of the discrepancies between the theoretical collection laws, orbital motion limited law in particular, and the experimental data in LEO-like conditions without magnetic fields. In a second time, the spatial variations and the time evolutions of the plasma properties around the tether are investigated. Spherical and emissive Langmuir probes are also used for a more extensive characterization of the plasma in space and time dependent analysis. Results show the ion depletion because of the wake effect and the accumulation of- ions upstream of the tether. In some regimes (at large positive potential), oscillations are observed on the tether collected current and on Langmuir probe collected current in specific sites.

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In the framework of the ITER Control Breakdown Structure (CBS), Plant System Instrumentation & Control (I&C) defines the hardware and software required to control one or more plant systems [1]. For diagnostics, most of the complex Plant System I&C are to be delivered by ITER Domestic Agencies (DAs). As an example for the DAs, ITER Organization (IO) has developed several use cases for diagnostics Plant System I&C that fully comply with guidelines presented in the Plant Control Design Handbook (PCDH) [2]. One such use case is for neutron diagnostics, specifically the Fission Chamber (FC), which is responsible for delivering time-resolved measurements of neutron source strength and fusion power to aid in assessing the functional performance of ITER [3]. ITER will deploy four Fission Chamber units, each consisting of three individual FC detectors. Two of these detectors contain Uranium 235 for Neutron detection, while a third "dummy" detector will provide gamma and noise detection. The neutron flux from each MFC is measured by the three methods: . Counting Mode: measures the number of individual pulses and their location in the record. Pulse parameters (threshold and width) are user configurable. . Campbelling Mode (Mean Square Voltage): measures the RMS deviation in signal amplitude from its average value. .Current Mode: integrates the signal amplitude over the measurement period

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El principal objetivo de la tesis es estudiar el acoplamiento entre los subsistemas de control de actitud y de control térmico de un pequeño satélite, con el fin de buscar la solución a los problemas relacionados con la determinación de los parámetros de diseño. Se considera la evolución de la actitud y de las temperaturas del satélite bajo la influencia de dos estrategias de orientación diferentes: 1) estabilización magnética pasiva de la orientación (PMAS, passive magnetic attitude stabilization), y 2) control de actitud magnético activo (AMAC, active magnetic attitude control). En primer lugar se presenta el modelo matemático del problema, que incluye la dinámica rotacional y el modelo térmico. En el problema térmico se considera un satélite cúbico modelizado por medio de siete nodos (seis externos y uno interno) aplicando la ecuación del balance térmico. Una vez establecido el modelo matemático del problema, se estudia la evolución que corresponde a las dos estrategias mencionadas. La estrategia PMAS se ha seleccionado por su simplicidad, fiabilidad, bajo coste, ahorrando consumo de potencia, masa coste y complejidad, comparado con otras estrategias. Se ha considerado otra estrategia de control que consigue que el satélite gire a una velocidad requerida alrededor de un eje deseado de giro, pudiendo controlar su dirección en un sistema inercial de referencia, ya que frecuentemente el subsistema térmico establece requisitos de giro alrededor de un eje del satélite orientado en una dirección perpendicular a la radiación solar incidente. En relación con el problema térmico, para estudiar la influencia de la velocidad de giro en la evolución de las temperaturas en diversos puntos del satélite, se ha empleado un modelo térmico linealizado, obtenido a partir de la formulación no lineal aplicando un método de perturbaciones. El resultado del estudio muestra que el tiempo de estabilización de la temperatura y la influencia de las cargas periódicas externas disminuye cuando aumenta la velocidad de giro. Los cambios de temperatura se reducen hasta ser muy pequeños para velocidades de rotación altas. En relación con la estrategia PMAC se ha observado que a pesar de su uso extendido entre los micro y nano satélites todavía presenta problemas que resolver. Estos problemas están relacionados con el dimensionamiento de los parámetros del sistema y la predicción del funcionamiento en órbita. Los problemas aparecen debido a la dificultad en la determinación de las características magnéticas de los cuerpos ferromagnéticos (varillas de histéresis) que se utilizan como amortiguadores de oscilaciones en los satélites. Para estudiar este problema se presenta un modelo analítico que permite estimar la eficiencia del amortiguamiento, y que se ha aplicado al estudio del comportamiento en vuelo de varios satélites, y que se ha empleado para comparar los resultados del modelo con los obtenidos en vuelo, observándose que el modelo permite explicar satisfactoriamente el comportamiento registrado. ABSTRACT The main objective of this thesis is to study the coupling between the attitude control and thermal control subsystems of a small satellite, and address the solution to some existing issues concerning the determination of their parameters. Through the thesis the attitude and temperature evolution of the satellite is studied under the influence of two independent attitude stabilization and control strategies: (1) passive magnetic attitude stabilization (PMAS), and (2) active magnetic attitude control (AMAC). In this regard the mathematical model of the problem is explained and presented. The mathematical model includes both the rotational dynamics and the thermal model. The thermal model is derived for a cubic satellite by solving the heat balance equation for 6 external and 1 internal nodes. Once established the mathematical model of the problem, the above mentioned attitude strategies were applied to the system and the temperature evolution of the 7 nodes of the satellite was studied. The PMAS technique has been selected to be studied due to its prevalent use, simplicity, reliability, and cost, as this strategy significantly saves the overall power, weight, cost, and reduces the complexity of the system compared to other attitude control strategies. In addition to that, another control law that provides the satellite with a desired spin rate along a desired axis of the satellite, whose direction can be controlled with respect to the inertial reference frame is considered, as the thermal subsystem of a satellite usually demands a spin requirement around an axis of the satellite which is positioned perpendicular to the direction of the coming solar radiation. Concerning the thermal problem, to study the influence of spin rate on temperature evolution of the satellite a linear approach of the thermal model is used, which is based on perturbation theory applied to the nonlinear differential equations of the thermal model of a spacecraft moving in a closed orbit. The results of this study showed that the temperature stabilization time and the periodic influence of the external thermal loads decreases by increasing the spin rate. However, the changes become insignificant for higher values of spin rate. Concerning the PMAS strategy, it was observed that in spite of its extended application to micro and nano satellites, still there are some issues to be solved regarding this strategy. These issues are related to the sizing of its system parameters and predicting the in-orbit performance. The problems were found to be rooted in the difficulties that exist in determining the magnetic characteristics of the ferromagnetic bodies (hysteresis rods) that are applied as damping devices on-board satellites. To address these issues an analytic model for estimating their damping efficiency is proposed and applied to several existing satellites in order to compare the results with their respective in-flight data. This model can explain the behavior showed by these satellites.

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In this work, a new law for magnetic control of satellites in near-polar orbits is presented. This law has been developed for the UMPSat-2 microsatellite, which has been designed and manufactured by Universidad Politécnica de Madrid, Madrid. The control law is a modification of the B-dot strategy that enables the satellite to control the rotation rate. Besides, the satellite?s equilibrium state is characterized by having the rotation axis perpendicular to the orbit?s plane. The control law described in the present work only needs magnetometers and magnetorquers, as sensors and actuators, respectively, to carry out a successful attitude control on the spacecraft. A description of the analysis is included. Performance and applicability of the proposed method have been demonstrated by control dynamics together with Monte Carlo techniques and by implementing the control law in the UPMSat-2 mission simulator. Results show good performance in terms of acquisition and stability of the satellite rotation rate and orientation with respect to its orbit?s plane.

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All around the ITER vacuum vessel, forty-four ports will provide access to the vacuum vessel for remotehandling operations, diagnostic systems, heating, and vacuum systems: 18 upper ports, 17 equatorialports, and 9 lower ports. Among the lower ports, three of them will be used for the remote handlinginstallation of the ITER divertor. Once the divertor is in place, these ports will host various diagnosticsystems mounted in the so-called diagnostic racks. The diagnostic racks must allow the support andcooling of the diagnostics, extraction of the required diagnostic signals, and providing access and main-tainability while minimizing the leakage of radiation toward the back of the port where the humans areallowed to enter. A fully integrated inner rack, carrying the near plasma diagnostic components, will bean stainless steel structure, 4.2 m long, with a maximum weight of 10 t. This structure brings water forcooling and baking at maximum temperature of 240?C and provides connection with gas, vacuum andelectric services. Additional racks (placed away from plasma and not requiring cooling) may be requiredfor the support of some particular diagnostic components. The diagnostics racks and its associated exvessel structures, which are in its conceptual design phase, are being designed to survive the lifetimeof ITER of 20 years. This paper presents the current state of development including interfaces, diagnos-tic integration, operation and maintenance, shielding requirements, remote handling, loads cases anddiscussion of the main challenges coming from the severe environment and engineering requirements.

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El trabajo realizado en la presente tesis doctoral se debe considerar parte del proyecto UPMSat-2, que se enmarca dentro del ámbito de la tecnología aeroespacial. El UPMSat-2 es un microsatélite (de bajo coste y pequeño tamaño) diseñado, construido, probado e integrado por la Universidad Politécnica de Madrid (España), para fines de demostración tecnológica y educación. El objetivo de la presente tesis doctoral es presentar nuevos modelos analíticos para estudiar la interdependencia energética entre los subsistemas de potencia y de control de actitud de un satélite. En primer lugar, se estudia la simulación del subsistema de potencia de un microsatélite, prestando especial atención a la simulación de la fuente de potencia, esto es, los paneles solares. En la tesis se presentan métodos sencillos pero precisos para simular la producción de energía de los paneles en condiciones ambientales variables a través de su circuito equivalente. Los métodos propuestos para el cálculo de los parámetros del circuito equivalente son explícitos (o al menos, con las variables desacopladas), no iterativos y directos; no se necesitan iteraciones o valores iniciales para calcular los parámetros. La precisión de este método se prueba y se compara con métodos similares de la literatura disponible, demostrando una precisión similar para mayor simplicidad. En segundo lugar, se presenta la simulación del subsistema de control de actitud de un microsatélite, prestando especial atención a la nueva ley de control propuesta. La tesis presenta un nuevo tipo de control magnético es aplicable a la órbita baja terrestre (LEO). La ley de control propuesta es capaz de ajustar la velocidad de rotación del satélite alrededor de su eje principal de inercia máximo o mínimo. Además, en el caso de órbitas de alta inclinación, la ley de control favorece la alineación del eje de rotación con la dirección normal al plano orbital. El algoritmo de control propuesto es simple, sólo se requieren magnetopares como actuadores; sólo se requieren magnetómetros como sensores; no hace falta estimar la velocidad angular; no incluye un modelo de campo magnético de la Tierra; no tiene por qué ser externamente activado con información sobre las características orbitales y permite el rearme automático después de un apagado total del subsistema de control de actitud. La viabilidad teórica de la citada ley de control se demuestra a través de análisis de Monte Carlo. Por último, en términos de producción de energía, se demuestra que la actitud propuesto (en eje principal perpendicular al plano de la órbita, y el satélite que gira alrededor de ella con una velocidad controlada) es muy adecuado para la misión UPMSat-2, ya que permite una área superior de los paneles apuntando hacia el sol cuando se compara con otras actitudes estudiadas. En comparación con el control de actitud anterior propuesto para el UPMSat-2 resulta en un incremento de 25% en la potencia disponible. Además, la actitud propuesto mostró mejoras significativas, en comparación con otros, en términos de control térmico, como la tasa de rotación angular por satélite puede seleccionarse para conseguir una homogeneización de la temperatura más alta que apunta satélite y la antena. ABSTRACT The work carried out in the present doctoral dissertation should be considered part of the UPMSat-2 project, falling within the scope of the aerospace technology. The UPMSat-2 is a microsatellite (low cost and small size) designed, constructed integrated and tested for educational and technology demonstration purposes at the Universidad Politécnica de Madrid (Spain). The aim of the present doctoral dissertation is to present new analytical models to study the energy interdependence between the power and the attitude control subsystems of a satellite. First, the simulation of the power subsystem of a microsatellite is studied, paying particular attention to the simulation of the power supply, i.e. the solar panels. Simple but accurate methods for simulate the power production under variable ambient conditions using its equivalent circuit are presented. The proposed methods for calculate the equivalent circuit parameters are explicit (or at least, with decoupled variables), non-iterative and straight forward; no iterations or initial values for the parameters are needed. The accuracy of this method is tested and compared with similar methods from the available literature demonstrating similar precision but higher simplicity. Second, the simulation of the control subsystem of a microsatellite is presented, paying particular attention to the new control law proposed. A new type of magnetic control applied to Low Earth Orbit (LEO) satellites has been presented. The proposed control law is able to set the satellite rotation speed around its maximum or minimum inertia principal axis. Besides, the proposed control law favors the alignment of this axis with the normal direction to the orbital plane for high inclination orbits. The proposed control algorithm is simples, only magnetorquers are required as actuators; only magnetometers are required as sensors; no estimation of the angular velocity is needed; it does not include an in-orbit Earth magnetic field model; it does not need to be externally activated with information about the orbital characteristics and it allows automatic reset after a total shutdown of attitude control subsystem. The theoretical viability of the control law is demonstrated through Monte Carlo analysis. Finally, in terms of power production, it is demonstrated that the proposed attitude (on principal axis perpendicular to the orbit plane, and the satellite rotating around it with a controlled rate) is quite suitable for the UPMSat-2 mission, as it allows a higher area of the panels pointing towards the sun when compared to other studied attitudes. Compared with the previous attitude control proposed for the UPMSat-2 it results in a 25% increment in available power. Besides, the proposed attitude showed significant improvements, when compared to others, in terms of thermal control, as the satellite angular rotation rate can be selected to achieve a higher temperature homogenization of the satellite and antenna pointing.