Effects of Composite Rheology on Plate-Like Behavior in Global-Scale Mantle Convection

Earth's upper mantle rheology controls lithosphere-asthenosphere coupling and thus surface tectonics. Rock deformation experiments and seismic anisotropy measurements indicate that composite rheology (co-existing diffusion and dislocation creep) occurs in the Earth's uppermost mantle, potentially affecting convection and surface tectonics. Here, we investigate how the spatio-temporal distribution of dislocation creep in an otherwise diffusion-creep-controlled mantle impacts the planform of convection and the planetary tectonic regime as a function of the lithospheric yield strength in numerical models of mantle convection self-generating plate-like tectonics. The low upper-mantle viscosities caused by zones of substantial dislocation creep produce contrasting effects on surface dynamics. For strong lithosphere (yield strength > 35 MPa), the large lithosphere-asthenosphere viscosity contrasts promote stagnant-lid convection. In contrast, the increase of upper mantle convective vigor enhances plate mobility for lithospheric strength <35 MPa. For the here-used model assumptions, composite rheology does not facilitate the onset of plate-like behavior at large lithospheric strength

CrossDetect : detección de pasos de peatones usando algoritmos de visión por computador para la mejora del posicionamiento de vehículos

El objetivo de este proyecto es utilizar pasos de peatones, de los denominados pasos de cebra, como puntos de referencia dentro del entorno, de tal forma que estos sirvan para corregir el error de posicionamiento que cometen sistemas como la Odometría Visual o el GPS, a la hora de localizar un vehículo en el plano. El trabajo desarrollado en este proyecto se podría dividir en dos partes. La primera de ellas, es el desarrollo de un algoritmo de visión por computador que permite reconocer los pasos de peatones mediante un sistema de cámaras estereoscópicas instalado en un coche. Para lograr este objetivo, en primer lugar, las imágenes obtenidas por una de las cámaras son procesadas con la combinación de un ltro de percentil 43 aplicado a nivel local más una umbralización (Sebsadji et al., 2010). Este proceso se realiza con el n de extraer aquellos píxeles de la imagen original que pertenecen potencialmente a marcas pintadas en la carretera. Si un píxel de la captura inicial tiene un nivel de gris mayor que el de su correspondiente de la imagen ltrada más el umbral seleccionado, ese píxel es considerado perteneciente a una marca vial, lo que en de nitiva, quiere decir que éste tiene un nivel de gris mucho más alto que el de aquellos píxeles próximos a él. El resultado de este proceso, por tanto, es una imagen binaria que representa en blanco todos aquellos píxeles que pueden pertenecer a una marca vial. Aparte de las marcas viales, fuera de la calzada hay muchos píxeles que cumplen esta condición. Para eliminar de la imagen binaria obtenida todos aquellos que no están sobre la carretera, se utiliza un algoritmo, perteneciente a otro proyecto de la universidad, que realiza este proceso utilizando el mapa de disparidad y el u-disparity de la escena. Es posible obtener estas estructuras gracias al sistema estereoscópico de cámaras. Tras estos dos procesos se obtiene una imagen binaria que representa únicamente las marcas viales. Si además la parte inferior de la imagen es muy oscura, previamente a estas operaciones se le realiza una mejora de contraste, que realza la zona de la misma correspondiente a la calzada. También serealiza una erosión para eliminar errores de segmentación. Una vez extraídas las marcas viales de la imagen original, se distinguen las que son pasos de peatones del resto mediante un análisis de las frecuencias de la transformada rápida de Fourier (Fast Fourier Transform, FFT). Para obtener ésta se usa la proyección horizontal, la cual se obtiene como resultado de la suma de los píxeles de cada columna de la imagen binaria obtenida. Cuando se detecte un paso de peatones, se calculará su posición en la imagen y su distancia con respecto al vehículo. Para determinar la posición, se utiliza la losofía anterior de la proyección horizontal, aplicada en esta ocasión a las las de la imagen binaria (proyección vertical). Una vez calculada ésta, se hace uso del per l de la calzada y los parámetros ópticos del sistema para calcular su distancia. Para aproximar el per l de la calzada se utilizará el v-disparity y la Transformada de Hough para rectas. En la segunda parte del trabajo, una vez detectado un paso de peatones y conocida su posición relativa respecto al vehículo, se pretende usar esta información para corregir el error de posicionamiento que introducen otros sistemas de localización. Usando como dato la cartografía de OpenStreetMap (OSM), si un sistema de localización como el GPS, o la Odometría Visual, predice que el coche se aproxima a un paso de peatones, el algoritmo de visión entraría en funcionamiento. Si el paso de peatones fuera detectado por el algoritmo de visión antes o después de lo previsto por el sistema de posicionamiento tradicional, el error que éste cómete podría ser estimado y corregido, reposicionando el vehículo en su localización correcta dentro del mapa. Esta parte sólo es desarrollada de manera teórica en el presente proyecto, de tal manera que se propone su implementación para futuros trabajos.The objective of this project is to use zebra crossings as reference points within the environment, in order to correct the positioning error of systems like visual odometry or GPS, when locatinh a vehicle in a map. The work developed in this project can be divided into two parts. The rst one, consists in the development of a computer vision algorithm that can recognize zebra crossings using a stereoscopic camera system installed in a car. To achieve this goal, images obtained by the cameras are processed by a mix of a local 43rd percentile lter plus a thresholding (Sebsadji et al., 2010). The nal purpose of this is to extract from an image taken by one of the cameras those pixels which potentially belong to markings painted on the road. If the pixel in the original image had a gray level higher than its corresponding in the ltered image plus the threshold, that pixel would be considered to belong-to a road marking and therefore that pixel contains a gray level much higher than the pixels next to it. The result of this process is a binary image which represents in white colour those pixels that belong to a road marking. In addition to the road markings, outside the road there are many pixels that meet this condition. An algorithm belonging to another college project is used to remove all those pixels that are not on the road from the binary image. This algorithm performs this process using the disparity map and the u disparity. This is possible thanks of the stereoscopic camera system. After these two processes take place, a binary image which represents only road markings is obtained. A contrast enhancement of this part of the image is done if the bottom part of the picture is too dark. An erode operation is also performed to remove segmentation errors. When road markings in the image have been extracted from it, zebra crossings are distinguished of the rest of road markings using a frequency analysis of the Fast Fourier Transform (FFT); this transform is obtained from the histogram that results of the adding of the pixels of each of the colums from the ltered image (horizontal projection). When the zebra crossing is detected its position is computed using the vertical projection and its distance is obtained by using the v disparity and the Hough Transform. In the second part of this paper, once a zebra crossing has been detected and its position relative to the vehicle is known, this information will be used to correct the positioning error that another location systems, like GPS or Visual Odometry, have. Using the OpenStreetMap mapping as an input, if a system like GPS predicted the car is close to a zebra crossing, the algorithm would be activated. If the zebra crossing was detected by our algorithm before or later than the traditional positioning system expects, the error could be inferred and corrected, repositioning the vehicle in its correct location on the map. This part is only theoretically developed, however its implementation is intended in future researches.Ingeniería Industria

Dynamics of pastoral traditional ecological knowledge : a global state-of-the-art review

Traditional ecological knowledge enables pastoralists to cope with social-ecological changes, thereby increasing thesustainability of their practices and fostering social-ecological resilience. Yet, there is a significant knowledge gap concerning the extentto which pastoral traditional ecological knowledge has changed over time at the global level. We aim to fill this gap through a systematicliterature review of 288 scientific studies on pastoral traditional ecological knowledge. We reviewed 152 papers in detail (selectedrandomly from the 288) for their content, and focused specifically on 61 papers that explicitly mentioned one of the four types ofknowledge transition (i.e., retention, erosion, adaptation, or hybridization). Studies on pastoral traditional knowledge represent lessthan 3% of all the scholarly literature on traditional ecological knowledge. Geographical distribution of the 288 case studies was largelybiased. Knowledge domains of pastoral knowledge such as herd and livestock management, forage and medicinal plants, and landscapeand wildlife were relatively equally covered; however, climate-related knowledge was less often studied. Of the 63 papers that explicitlymentioned transition of pastoral traditional ecological knowledge, 52 reported erosion, and only 11 studies documented explicitlyknowledge retention, adaptation, or hybridization of traditional knowledge. Thus, adaptation and hybridization was understudied,although some case studies showed that adaptation and hybridization of knowledge can efficiently help pastoralists navigate amongsocial-ecological changes. Based on the review, we found 13 drivers which were mentioned as the main reasons for knowledge transitionamong which social-cultural changes, formal schooling, abandonment of pastoral activities, and transition to a market economy weremost often reported. We conclude that future research should focus more on the diverse dynamics of pastoral traditional knowledge,be more careful in distinguishing the four knowledge transition types, and analyze how changes in knowledge impact change in pastoralpractices and lifestyles. Understanding these phenomena could help pastoralists' adaptations and support their stewardship of theirrangeland ecosystems and biocultural diversity.Peer reviewe

Soc-based in-cycle load identification of induction heating appliances

The equivalent load of an induction hob is strongly dependent on many parameters such as the switching frequency, the excitation level and the size, type, and material of the vessel. However, real-time methods with the ability to capture the variation of the load with the excitation level have not been proposed in the literature. This is an essential issue as most of the commercial induction hobs are based on an ac-bus voltage arrangement. This article proposes a method based on a phase-sensitive detector that offers an online tracking of the equivalent impedance for this type of arrangements. This algorithm enables advanced control functionalities such as clustering of vessels, material recognition, and premature detection of ferromagnetic saturation, among others. After simulation and experimental validation, the method is implemented into a prototype with a system-on-chip to verify its real-time behavior. The proposed approach is applied to different real-life situations that prove its great performance and applicability

Environmental control on the structure of echinoid assemblages in the Bellingshausen Sea (Antarctica)

The Bellingshausen Sea is one of the most remote and least surveyed seas of the Southern Ocean, so that little was known about benthic communities and those factors that determine community structuring until recently. The present work aims at characterizing the structure and spatial distribution of echinoid assemblages in the Bellingshausen Sea, as well as identifying the environmental factors that determine assemblage structuring. Echinoids were collected at 32 stations using an Agassiz trawl, at depths of 86–3,304 m, during BENTART oceanographic expeditions led in 2003 and 2006. Sediment and bottom water properties were analysed using an USNEL-type box corer and a Neil Brown Instrument System Mark III CTD, respectively. Echinoids were found at all stations, except Peter I Island. Seventeen species were identified, representing 22 % of the echinoid species present in the Southern Ocean and increasing twofold the number of species recorded in the Bellingshausen Sea so far. The echinoid fauna is dominated by the very abundant species Sterechinus antarcticus. Depth is the key factor that determines the nature of echinoid assemblages, which are mainly divided into the continental shelf, the slope and the deep-sea basin. In addition, sediment properties, namely redox values, organic matter and mud content, best match species dispersion on the shelf. Sediment properties affect echinoid distribution depending on species food range and feeding strategy. As it might be expected, sediment properties more strongly influence specialist feeders (Schizasteridae and Cidaridae) than generalists (Echinidae).Versión del edito

Gothic stonework in the region of maestrazgo. Virtual models of vaulted systems for three octogonal chapels

Entre los siglos XIII y XV, la comarca histórica del Maestrazgo, vivió un momento de gran expansión económica que se vió reflejado en el auge de la arquitectura gótica, y de forma destacada en las poblaciones de Morella y Sant Mateu por su situación estratégica entre los reinos de Valencia y Aragón. Estas dos poblaciones albergan algunas de las más relevantes construcciones de esta época de las que, sin embargo, no existe información suficiente sobre su historia y procesos constructivos. Para cubrir este vacío se propone el estudio de tres casos concretos de un mismo tipo de capilla ochavada (1) que, según las fuentes bibliográficas consultadas, podrían haber sido realizadas por el mismo maestro cantero, Domènech Prunyonosa. El objetivo consiste en determinar las propuestas de los modelos teóricos utilizados a partir de un levantamiento topográfico y fotogramétrico de cada uno delos casos seleccionados lo suficientemente preciso para poder definir el despiece exacto de los nervios y plementerías que configuran sus correspondientes sistemas abovedados

Exploiting Term Hiding to Reduce Run-time Checking Overhead

One of the most attractive features of untyped languages is the flexibility in term creation and manipulation. However, with such power comes the responsibility of ensuring the correctness of these operations. A solution is adding run-time checks to the program via assertions, but this can introduce overheads that are in many cases impractical. While static analysis can greatly reduce such overheads, the gains depend strongly on the quality of the information inferred. Reusable libraries, i.e., library modules that are pre-compiled independently of the client, pose special challenges in this context. We propose a technique which takes advantage of module systems which can hide a selected set of functor symbols to significantly enrich the shape information that can be inferred for reusable libraries, as well as an improved run-time checking approach that leverages the proposed mechanisms to achieve large reductions in overhead, closer to those of static languages, even in the reusable-library context. While the approach is general and system-independent, we present it for concreteness in the context of the Ciao assertion language and combined static/dynamic checking framework. Our method maintains the full expressiveness of the assertion language in this context. In contrast to other approaches it does not introduce the need to switch the language to a (static) type system, which is known to change the semantics in languages like Prolog. We also study the approach experimentally and evaluate the overhead reduction achieved in the run-time checks.Comment: 26 pages, 10 figures, 2 tables; an extension of the paper version accepted to PADL'18 (includes proofs, extra figures and examples omitted due to space reasons

Hyperbolic subdiffusive impedance

We use the hyperbolic subdiffusion equation with fractional time derivatives (the generalized Cattaneo equation) to study the transport process of electrolytes in media where subdiffusion occurs. In this model the flux is delayed in a non-zero time with respect to the concentration gradient. In particular, we obtain the formula of electrochemical subdiffusive impedance of a spatially limited sample in the limit of large and of small pulsation of the electric field. The boundary condition at the external wall of the sample are taken in the general form as a linear combination of subdiffusive flux and concentration of the transported particles. We also discuss the influence of the equation parameters (the subdiffusion parameter and the delay time) on the Nyquist impedance plots.Comment: 10 pages, 5 figure