Variational Stereo Imaging of Oceanic Waves with Statistical Constraints

An image processing observational technique for the stereoscopic reconstruction of the wave form of oceanic sea states is developed. The technique incorporates the enforcement of any given statistical wave law modeling the quasi Gaussianity of oceanic waves observed in nature. The problem is posed in a variational optimization framework, where the desired wave form is obtained as the minimizer of a cost functional that combines image observations, smoothness priors and a weak statistical constraint. The minimizer is obtained combining gradient descent and multigrid methods on the necessary optimality equations of the cost functional. Robust photometric error criteria and a spatial intensity compensation model are also developed to improve the performance of the presented image matching strategy. The weak statistical constraint is thoroughly evaluated in combination with other elements presented to reconstruct and enforce constraints on experimental stereo data, demonstrating the improvement in the estimation of the observed ocean surface.

Optimal Multiresolution 3D Level-Set Method for Liver Segmentation incorporating Local Curvature Constraints

Advanced liver surgery requires a precise pre-operative planning, where liver segmentation and remnant liver volume are key elements to avoid post-operative liver failure. In that context, level-set algorithms have achieved better results than others, especially with altered liver parenchyma or in cases with previous surgery. In order to improve functional liver parenchyma volume measurements, in this work we propose two strategies to enhance previous level-set algorithms: an optimal multi-resolution strategy with fine details correction and adaptive curvature, as well as an additional semiautomatic step imposing local curvature constraints. Results show more accurate segmentations, especially in elongated structures, detecting internal lesions and avoiding leakages to close structures

Criterios de optimización de los incentivos en contratos de concesión ligados a indicadores de calidad de servicio para firmes bituminosos

Actualmente se está empezando a consolidar una nueva forma de gestionar la conservación y mantenimiento de la red viaria de las Administraciones Públicas, basándose en contratos de colaboración público-privadas (PPP). Las motivaciones que están provocando este movimiento son de diversa índole. Por un lado, en el seno de la Unión Europea, existen serias restricciones presupuestarias debido al alto endeudamiento del sector público, lo que está llevando a buscar la forma óptima de disminuir el endeudamiento público, sin dejar de prestar servicios a la sociedad como la conservación y mantenimiento de las redes viarias. Por esta vertiente, se trata de convertir contratos convencionales de conservación viaria a esquemas de colaboración público-privada, donde se transferiría al sector privado el riesgo de disponibilidad de la vía mediante el uso de indicadores de calidad y servicio. Con esta transferencia de riesgo, junto con la transferencia del riesgo de demanda/construcción, no consolidaría la deuda de la sociedad de propósito específico constituida para la gestión del contrato de colaboración público-privada dentro de las cuentas públicas, con lo que se conseguiría no aumentar el déficit público, permitiendo continuar ofreciendo el servicio demandado por la sociedad. Por otro lado, la segunda motivación del desarrollo de este tipo de contratos, no tan economicista como la anterior y más enfocada a la gestión, se trata de utilizar los contratos de gestión basados en el uso de indicadores de calidad de servicio para mejorar las prestaciones de la red viaria competencia de una Administración. Con el uso de estos indicadores, el gestor tiene una herramienta muy útil para controlar la actividad del sector privado y asegurar que se ofrece un buen servicio. En la presente tesis, la investigación se ha centrado más en la vertiente de los indicadores de calidad relacionados con la gestión eficiente de las vías objeto de conservación y mantenimiento mediante el empleo de contratos de gestión privada que utilicen este tipo de herramientas de control, monitorización y gestión. En una primera parte, la presente tesis estudia el estado de la red de carreteras, referido principalmente a España, comparando su estado con el resto de redes de carreteras de Europa, detectando las principales carencias de la misma, sobre todo en cuanto a la gestión y conservación de firmes. En un segundo bloque, la tesis analiza el estado del arte de los nuevos procedimientos de gestión de la conservación y mantenimiento basados en indicadores de calidad del servicio en el mundo, destacándose que se trata de un tema relativamente reciente, con gran interés para el sector de la gestión y financiación de infraestructuras viarias. Al ser tan novedoso, por la falta de experiencias previas, las distintas Administración, tanto propias como foráneas, han pecado de un exceso de celo a la hora de establecer los umbrales sobre los que giran los distintos indicadores de calidad de servicio que permiten controlar la gestión de la conservación y mantenimiento de la vía. Partiendo de la labor de análisis descrita, la tesis realiza una investigación más detallada de los indicadores de calidad de servicio correspondientes a firmes bituminosos, debido a que estos indicadores son los más delicados y decisivos a la hora de realizar una correcta gestión de la vía a largo plazo. Dentro de los indicadores de firmes bituminosos, se ha realizado un modelo específico de evolución de comportamiento a lo largo del tiempo de la regularidad superficial, parámetro básico para numerosas Administraciones y organismos investigadores para poder conocer la evolución de un firme a lo largo del tiempo. A esta metodología se le ha dado el nombre de Modelo JRB para evaluar la racionalidad económica de indicadores de calidad asociados a parámetros de firmes. El modelo propuesto básicamente evalúa el valor óptimo desde la perspectiva económica que ha de tener el parámetro técnico que defina alguna propiedad del firme, aplicado a la definición de los indicadores de calidad de servicio. Esta visión del valor umbral del indicador deja a un lado consideraciones de equidad o de cualquier otra índole, basándose más en una visión económica. La metodología del Modelo JRB se puede aplicar a cualquier indicador de calidad relacionado con firmes, ya que lo que se obtiene es el valor óptimo económico que debería tener el umbral del indicador de calidad. El Modelo JRB consta de varias fases. En las primeras etapas el Modelo realiza el cálculo de los costes totales de transporte utilizando como herramienta el software HDM-IV desarrollado por el Banco Mundial. En etapas posteriores, el Modelo realiza análisis de sensibilidad para distintas propuestas de sección de firme, intensidades de tráfico y restricciones al parámetro técnico que define el indicador de calidad de servicio. Como ejercicio práctico de cara a contrastar la metodología del Modelo JRB se ha realizado un Caso de Estudio. Se ha tomado un tramo teórico, con características similares a la red de carreteras española, y con una flota vehicular similar a la española, donde se ha elegido como indicador de calidad la regularidad superficial (IRI). Con las sensibilidades realizadas con el Modelo JRB, se ha determinado el rango de valores que debería tener un indicador de calidad basado en el IRI para que dichos valores fueran óptimos desde la perspectiva económica Nowadays is becoming a new way to manage O&M (operation and maintenance) in public road networks, based on PPP contracts (public-private partnership). There are several issues which are driving this trend. On the one hand, EU (European Union) has serious budgetary constraints due to the high public sector borrowing. EU politicians are looking for the best way to reduce public debt, keeping services to society such as O&M of road networks. For this aspect, conventional O&M contracts are switching to PPP scenarios, where availability risk would be transfer to private sector using PI (performance indicators), along with demand risk transfer With this risk transference, along with the transfer of demand/construction risk, SPV (specific purpose vehicle) debt doesn’t consolidate in public accounts, so deficit wouldn’t increase, allowing the continuation of services demanded by society. On the other hand, the second motivation for developing this kind of contracts, not so economist as above and more focused to management, it is about using O&M contracts based on the use of PI to improve road network maintenance. Using these indicators, manager has a very useful tool to monitor private sector activity and ensure that it is provided a good service. In this thesis, the research has been focused on PI quality aspect, related with efficient management of PPP contracts for roads, which use these tools for control, monitoring and management. In the first part, this thesis examines the state of road network, based mainly in Spain, comparing with other road networks in Europe, identifying the main gaps in it, especially with regard to the management and maintenance of pavements. In a second block, the thesis analyzes the state of art of new O&M contracts based on PI in the world, emphasizing that they are relatively recent. These kinds of contracts have a great interest in road management and financing sector. Administrations all around the world have launch tenders with very exigent PI thresholds due to several factors: this knowledge is a new area, the lack of previous experiences and the variety of Administrations which have bid these contracts. Building on the described analysis, thesis develops a more detailed research about PI for bituminous pavements, because these PI are the most delicate and decisive in making a proper long term road management. Among bituminous pavements PI, IRI (International Roughness Index) has been analyzed with more detail and has been developed a specific model of behaviour evolution over time for evenness (IRI), basic parameter for many administrations and research departments in order to know the evolution of a pavement over time. This methodology has been given the name of JRB Model to evaluate the economic rationality of performance indicators associated with pavements parameters. The proposed model basically evaluates the optimal value from an economic perspective it must have the technical parameter which defines some pavement characteristic applied to the definition of performance indicators. This point of view of indicator value threshold sets aside justice considerations or otherwise, based more on an economic perspective. JRB Model methodology can be applied to any performance indicator associated to pavements, because what you get is the economic optimum threshold should have the performance indicator. JRB Model consists of several phases. In the early stages, the Model calculates transport total cost using HDM-IV software, developed by the World Bank, as a tool. In later stages, the Model performs sensitivity analyzes for different pavement section, AADT and restrictions to the technical parameter which defines the performance indicator. As a practical exercise to test JRB Model methodology, it has done a Case Study. It has taken a theoretical section, with similar characteristics to Spanish road network, and a vehicles fleet similar to Spanish. Evenness (IRI) was chosen as a performance indicator. JRB Model calculated some sensitivities, which were useful to determined thresholds range for pavement performance indicators based on IRI to be optimal from an economic perspective.

Automatic granularity-aware parallelization of programs with predicates, functions, and constraints

Abstract is not available

Electrodynamic Tether at Jupiter I: Capture operation and constraints

Tethered spacecraft missions to the Jovian system suit the use of electrodynamic tethers because: 1) magnetic stresses are 100 times greater than at the Earth; 2) the stationary orbit is one-third the relative distance for Earth; and 3) moon Io is a nearby giant plasma source. The (bare) tether is a reinforced aluminum foil with tens of kilometer length L and a fraction of millimeter thickness h, which collects electrons as an efficient Langmuir probe and can tap Jupiter’s rotational energy for both propulsion and power. In this paper, the critical capture operation is explicitly formulated in terms of orbit geometry and established magnetic and thermal plasma models. The design parameters L and h and capture perijove radius rp face opposite criteria independent of tape width. Efficient capture requires a low rp and a high L 3/2/h ratio. However, combined bounds on tether bowing and tether tensile stress, arising from a spin made necessary by the low Jovian gravity gradient, require a high rp and a low L 5/2/h ratio. Bounds on tether temperature again require a high rp and a low L 3/8/(tether emissivity)1/4 ratio. Optimal design values are discussed.

A Cost-Benefit analysis model for technical debt management considering uncertainty and time

In the last few years, technical debt has been used as a useful means for making the intrinsic cost of the internal software quality weaknesses visible. This visibility is made possible by quantifying this cost. Specifically, technical debt is expressed in terms of two main concepts: principal and interest. The principal is the cost of eliminating or reducing the impact of a, so called, technical debt item in a software system; whereas the interest is the recurring cost, over a time period, of not eliminating a technical debt item. Previous works about technical debt are mainly focused on estimating principal and interest, and on performing a cost-benefit analysis. This cost-benefit analysis allows one to determine if to remove technical debt is profitable and to prioritize which items incurring in technical debt should be fixed first. Nevertheless, for these previous works technical debt is flat along the time. However the introduction of new factors to estimate technical debt may produce non flat models that allow us to produce more accurate predictions. These factors should be used to estimate principal and interest, and to perform cost-benefit analysis related to technical debt. In this paper, we take a step forward introducing the uncertainty about the interest, and the time frame factors so that it becomes possible to depict a number of possible future scenarios. Estimations obtained without considering the possible evolution of the interest over time may be less accurate as they consider simplistic scenarios without changes.

Electrodynamic tether applications and constraints

Propulsion and power generation by bare electrodynamic tethers are revisited in a unified way and issues and constraints are addressed. In comparing electrodynamic tethers, which do not use propellant, with other propellantconsuming systems, mission duration is a discriminator that defines crossover points for systems with equal initial masses. Bare tethers operating in low Earth orbit can be more competitive than optimum ion thrusters in missions exceeding two-three days for orbital deboost and three weeks for boosting operations. If the tether produces useful onboard power during deboost, the crossover point reaches to about 10 days. Power generation by means of a bare electrodynamic tether in combination with chemical propulsion to maintain orbital altitude of the system is more efficient than use of the same chemicals (liquid hydrogen and liquid oxygen) in a fuel cell to produce power for missions longer than one week. Issues associated with tether temperature, bowing, deployment, and arcing are also discussed. Heating/cooling rates reach about 4 K/s for a 0.05-mm-thick tape and a fraction of Kelvin/second for the ProSEDS (0.6-mm-radius) wire; under dominant ohmic effects, temperatures areover200K (night) and 380 K (day) for the tape and 320 and 415 K for that wire. Tether applications other than propulsion and power are briefly discussed.

kyrie2: query rewriting under extensional constraints in ELHIO

In this paper we study query answering and rewriting in ontologybased data access. Specifically, we present an algorithm for computing a perfect rewriting of unions of conjunctive queries posed over ontologies expressed in the description logic ELHIO, which covers the OWL 2 QL and OWL 2 EL profiles. The novelty of our algorithm is the use of a set of ABox dependencies, which are compiled into a so-called EBox, to limit the expansion of the rewriting. So far, EBoxes have only been used in query rewriting in the case of DL-Lite, which is less expressive than ELHIO. We have extensively evaluated our new query rewriting technique, and in this paper we discuss the tradeoff between the reduction of the size of the rewriting and the computational cost of our approach.

Effects of different swimming race constraints on turning movements

The aim of this study was to investigate the effects of different swimming race constraints on the evolution of turn parameters. One hundred and fifty-eight national and regional level 200-m (meters) male swimming performances were video-analyzed using the individualized-distance model in the Open Comunidad de Madrid tournament. Turn (p < .001, ES = 0.36) and underwater distances (p < .001, ES = 0.38) as well as turn velocity (p < .001, ES = 0.69) significantly dropped throughout the race, although stroke velocity and underwater velocity were maintained in the last lap of the race (p > .05). Higher expertise swimmers obtained faster average velocities and longer distances in all the turn phases (p < .001, ES = 0.59), except the approach distance. In addition, national level swimmers showed the ability to maintain most of the turn parameters throughout the race, which assisted them in improving average velocity at the end of races. Therefore, the variations in the turning movements of a swimming race were expertise-related and focused on optimizing average velocity. Turning skills should be included in the swimming race action plan.

Design and Simulation of Deep Nanometer SRAM Cells under Energy, Mismatch, and Radiation Constraints

La fiabilidad está pasando a ser el principal problema de los circuitos integrados según la tecnología desciende por debajo de los 22nm. Pequeñas imperfecciones en la fabricación de los dispositivos dan lugar ahora a importantes diferencias aleatorias en sus características eléctricas, que han de ser tenidas en cuenta durante la fase de diseño. Los nuevos procesos y materiales requeridos para la fabricación de dispositivos de dimensiones tan reducidas están dando lugar a diferentes efectos que resultan finalmente en un incremento del consumo estático, o una mayor vulnerabilidad frente a radiación. Las memorias SRAM son ya la parte más vulnerable de un sistema electrónico, no solo por representar más de la mitad del área de los SoCs y microprocesadores actuales, sino también porque las variaciones de proceso les afectan de forma crítica, donde el fallo de una única célula afecta a la memoria entera. Esta tesis aborda los diferentes retos que presenta el diseño de memorias SRAM en las tecnologías más pequeñas. En un escenario de aumento de la variabilidad, se consideran problemas como el consumo de energía, el diseño teniendo en cuenta efectos de la tecnología a bajo nivel o el endurecimiento frente a radiación. En primer lugar, dado el aumento de la variabilidad de los dispositivos pertenecientes a los nodos tecnológicos más pequeños, así como a la aparición de nuevas fuentes de variabilidad por la inclusión de nuevos dispositivos y la reducción de sus dimensiones, la precisión del modelado de dicha variabilidad es crucial. Se propone en la tesis extender el método de inyectores, que modela la variabilidad a nivel de circuito, abstrayendo sus causas físicas, añadiendo dos nuevas fuentes para modelar la pendiente sub-umbral y el DIBL, de creciente importancia en la tecnología FinFET. Los dos nuevos inyectores propuestos incrementan la exactitud de figuras de mérito a diferentes niveles de abstracción del diseño electrónico: a nivel de transistor, de puerta y de circuito. El error cuadrático medio al simular métricas de estabilidad y prestaciones de células SRAM se reduce un mínimo de 1,5 veces y hasta un máximo de 7,5 a la vez que la estimación de la probabilidad de fallo se mejora en varios ordenes de magnitud. El diseño para bajo consumo es una de las principales aplicaciones actuales dada la creciente importancia de los dispositivos móviles dependientes de baterías. Es igualmente necesario debido a las importantes densidades de potencia en los sistemas actuales, con el fin de reducir su disipación térmica y sus consecuencias en cuanto al envejecimiento. El método tradicional de reducir la tensión de alimentación para reducir el consumo es problemático en el caso de las memorias SRAM dado el creciente impacto de la variabilidad a bajas tensiones. Se propone el diseño de una célula que usa valores negativos en la bit-line para reducir los fallos de escritura según se reduce la tensión de alimentación principal. A pesar de usar una segunda fuente de alimentación para la tensión negativa en la bit-line, el diseño propuesto consigue reducir el consumo hasta en un 20 % comparado con una célula convencional. Una nueva métrica, el hold trip point se ha propuesto para prevenir nuevos tipos de fallo debidos al uso de tensiones negativas, así como un método alternativo para estimar la velocidad de lectura, reduciendo el número de simulaciones necesarias. Según continúa la reducción del tamaño de los dispositivos electrónicos, se incluyen nuevos mecanismos que permiten facilitar el proceso de fabricación, o alcanzar las prestaciones requeridas para cada nueva generación tecnológica. Se puede citar como ejemplo el estrés compresivo o extensivo aplicado a los fins en tecnologías FinFET, que altera la movilidad de los transistores fabricados a partir de dichos fins. Los efectos de estos mecanismos dependen mucho del layout, la posición de unos transistores afecta a los transistores colindantes y pudiendo ser el efecto diferente en diferentes tipos de transistores. Se propone el uso de una célula SRAM complementaria que utiliza dispositivos pMOS en los transistores de paso, así reduciendo la longitud de los fins de los transistores nMOS y alargando los de los pMOS, extendiéndolos a las células vecinas y hasta los límites de la matriz de células. Considerando los efectos del STI y estresores de SiGe, el diseño propuesto mejora los dos tipos de transistores, mejorando las prestaciones de la célula SRAM complementaria en más de un 10% para una misma probabilidad de fallo y un mismo consumo estático, sin que se requiera aumentar el área. Finalmente, la radiación ha sido un problema recurrente en la electrónica para aplicaciones espaciales, pero la reducción de las corrientes y tensiones de los dispositivos actuales los está volviendo vulnerables al ruido generado por radiación, incluso a nivel de suelo. Pese a que tecnologías como SOI o FinFET reducen la cantidad de energía colectada por el circuito durante el impacto de una partícula, las importantes variaciones de proceso en los nodos más pequeños va a afectar su inmunidad frente a la radiación. Se demuestra que los errores inducidos por radiación pueden aumentar hasta en un 40 % en el nodo de 7nm cuando se consideran las variaciones de proceso, comparado con el caso nominal. Este incremento es de una magnitud mayor que la mejora obtenida mediante el diseño de células de memoria específicamente endurecidas frente a radiación, sugiriendo que la reducción de la variabilidad representaría una mayor mejora. ABSTRACT Reliability is becoming the main concern on integrated circuit as the technology goes beyond 22nm. Small imperfections in the device manufacturing result now in important random differences of the devices at electrical level which must be dealt with during the design. New processes and materials, required to allow the fabrication of the extremely short devices, are making new effects appear resulting ultimately on increased static power consumption, or higher vulnerability to radiation SRAMs have become the most vulnerable part of electronic systems, not only they account for more than half of the chip area of nowadays SoCs and microprocessors, but they are critical as soon as different variation sources are regarded, with failures in a single cell making the whole memory fail. This thesis addresses the different challenges that SRAM design has in the smallest technologies. In a common scenario of increasing variability, issues like energy consumption, design aware of the technology and radiation hardening are considered. First, given the increasing magnitude of device variability in the smallest nodes, as well as new sources of variability appearing as a consequence of new devices and shortened lengths, an accurate modeling of the variability is crucial. We propose to extend the injectors method that models variability at circuit level, abstracting its physical sources, to better model sub-threshold slope and drain induced barrier lowering that are gaining importance in FinFET technology. The two new proposed injectors bring an increased accuracy of figures of merit at different abstraction levels of electronic design, at transistor, gate and circuit levels. The mean square error estimating performance and stability metrics of SRAM cells is reduced by at least 1.5 and up to 7.5 while the yield estimation is improved by orders of magnitude. Low power design is a major constraint given the high-growing market of mobile devices that run on battery. It is also relevant because of the increased power densities of nowadays systems, in order to reduce the thermal dissipation and its impact on aging. The traditional approach of reducing the voltage to lower the energy consumption if challenging in the case of SRAMs given the increased impact of process variations at low voltage supplies. We propose a cell design that makes use of negative bit-line write-assist to overcome write failures as the main supply voltage is lowered. Despite using a second power source for the negative bit-line, the design achieves an energy reduction up to 20% compared to a conventional cell. A new metric, the hold trip point has been introduced to deal with new sources of failures to cells using a negative bit-line voltage, as well as an alternative method to estimate cell speed, requiring less simulations. With the continuous reduction of device sizes, new mechanisms need to be included to ease the fabrication process and to meet the performance targets of the successive nodes. As example we can consider the compressive or tensile strains included in FinFET technology, that alter the mobility of the transistors made out of the concerned fins. The effects of these mechanisms are very dependent on the layout, with transistor being affected by their neighbors, and different types of transistors being affected in a different way. We propose to use complementary SRAM cells with pMOS pass-gates in order to reduce the fin length of nMOS devices and achieve long uncut fins for the pMOS devices when the cell is included in its corresponding array. Once Shallow Trench isolation and SiGe stressors are considered the proposed design improves both kinds of transistor, boosting the performance of complementary SRAM cells by more than 10% for a same failure probability and static power consumption, with no area overhead. While radiation has been a traditional concern in space electronics, the small currents and voltages used in the latest nodes are making them more vulnerable to radiation-induced transient noise, even at ground level. Even if SOI or FinFET technologies reduce the amount of energy transferred from the striking particle to the circuit, the important process variation that the smallest nodes will present will affect their radiation hardening capabilities. We demonstrate that process variations can increase the radiation-induced error rate by up to 40% in the 7nm node compared to the nominal case. This increase is higher than the improvement achieved by radiation-hardened cells suggesting that the reduction of process variations would bring a higher improvement.

Distributed cognitive radio systems with temperature-interference constraints and overlay scheme

Cognitive radio represents a promising paradigm to further increase transmission rates in wireless networks, as well as to facilitate the deployment of self-organized networks such as femtocells. Within this framework, secondary users (SU) may exploit the channel under the premise to maintain the quality of service (QoS) on primary users (PU) above a certain level. To achieve this goal, we present a noncooperative game where SU maximize their transmission rates, and may act as well as relays of the PU in order to hold their perceived QoS above the given threshold. In the paper, we analyze the properties of the game within the theory of variational inequalities, and provide an algorithm that converges to one Nash Equilibrium of the game. Finally, we present some simulations and compare the algorithm with another method that does not consider SU acting as relays.