Sequential non-rigid structure from motion using physical priors

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.We propose a new approach to simultaneously recover camera pose and 3D shape of non-rigid and potentially extensible surfaces from a monocular image sequence. For this purpose, we make use of the Extended Kalman Filter based Simultaneous Localization And Mapping (EKF-SLAM) formulation, a Bayesian optimization framework traditionally used in mobile robotics for estimating camera pose and reconstructing rigid scenarios. In order to extend the problem to a deformable domain we represent the object's surface mechanics by means of Navier's equations, which are solved using a Finite Element Method (FEM). With these main ingredients, we can further model the material's stretching, allowing us to go a step further than most of current techniques, typically constrained to surfaces undergoing isometric deformations. We extensively validate our approach in both real and synthetic experiments, and demonstrate its advantages with respect to competing methods. More specifically, we show that besides simultaneously retrieving camera pose and non-rigid shape, our approach is adequate for both isometric and extensible surfaces, does not require neither batch processing all the frames nor tracking points over the whole sequence and runs at several frames per second.Peer ReviewedPostprint (author's final draft

Real-time 3D reconstruction of non-rigid shapes with a single moving camera

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper describes a real-time sequential method to simultaneously recover the camera motion and the 3D shape of deformable objects from a calibrated monocular video. For this purpose, we consider the Navier-Cauchy equations used in 3D linear elasticity and solved by finite elements, to model the time-varying shape per frame. These equations are embedded in an extended Kalman filter, resulting in sequential Bayesian estimation approach. We represent the shape, with unknown material properties, as a combination of elastic elements whose nodal points correspond to salient points in the image. The global rigidity of the shape is encoded by a stiffness matrix, computed after assembling each of these elements. With this piecewise model, we can linearly relate the 3D displacements with the 3D acting forces that cause the object deformation, assumed to be normally distributed. While standard finite-element-method techniques require imposing boundary conditions to solve the resulting linear system, in this work we eliminate this requirement by modeling the compliance matrix with a generalized pseudoinverse that enforces a pre-fixed rank. Our framework also ensures surface continuity without the need for a post-processing step to stitch all the piecewise reconstructions into a global smooth shape. We present experimental results using both synthetic and real videos for different scenarios ranging from isometric to elastic deformations. We also show the consistency of the estimation with respect to 3D ground truth data, include several experiments assessing robustness against artifacts and finally, provide an experimental validation of our performance in real time at frame rate for small mapsPeer ReviewedPostprint (author's final draft

Simulacion de Redes VSAT

Entre las tecnologías disponibles para redes de telecomunicación cada vez es más popular el sistema VSAT o satélite, augurando un éxito para redes WAN comparable al conseguido por las ethernet en redes locales LAN. En esta comunicación se presenta el resultado de simulación de varias redes VSAT. Se utilizó el entorno de simulación BONeS donde se trabaja de forma gráfica, construyendo la red como una interconexión de bloques. En España, una empresa de la importancia de CAMPSA usa una red VSAT para el telemando de los oleoductos de todo el territorio nacional. En la comunicación se incluirán resultados para este caso concreto

Cellular Sensing Governs the Stability of Chemotactic Fronts

In contexts ranging from embryonic development to bacterial ecology, cell populations migrate chemotactically along self-generated chemical gradients, often forming a propagating front. Here, we theoretically show that the stability of such chemotactic fronts to morphological perturbations is determined by limitations in the ability of individual cells to sense and thereby respond to the chemical gradient. Specifically, cells at bulging parts of a front are exposed to a smaller gradient, which slows them down and promotes stability, but they also respond more strongly to the gradient, which speeds them up and promotes instability. We predict that this competition leads to chemotactic fingering when sensing is limited at too low chemical concentrations. Guided by this finding and by experimental data on E. coli chemotaxis, we suggest that the cells' sensory machinery might have evolved to avoid these limitations and ensure stable front propagation. Finally, as sensing of any stimuli is necessarily limited in living and active matter in general, the principle of sensing-induced stability may operate in other types of directed migration such as durotaxis, electrotaxis, and phototaxis

Fractional Powers of Non-Negative Operators in Fréchet Spaces

[EN] In the present paper the theory of fractional powers, which has been restricted to date to certain operators on Banach spaces, is generalized to certain particular operators in Frchet spaces. The main difficulty consists in the fact that neither the holomorphlc functional calculus nor the results on Banach algebras are available for bounded operators on Frchet spaces. All the basic properties which a good theory of fractional powers must fulfill are proved, except for the spectral relation,Martinez, C.; Sanz, M.; Calvo Roselló, V. (1989). Fractional Powers of Non-Negative Operators in Fréchet Spaces. International Journal of Mathematics and Mathematical Sciences. 12(2):309-320. http://hdl.handle.net/10251/19145630932012

Fractional Powers of Non-Negative Operators in Fréchet Spaces

[EN] In the present paper the theory of fractional powers, which has been restricted to date to certain operators on Banach spaces, is generalized to certain particular operators in Frchet spaces. The main difficulty consists in the fact that neither the holomorphlc functional calculus nor the results on Banach algebras are available for bounded operators on Frchet spaces. All the basic properties which a good theory of fractional powers must fulfill are proved, except for the spectral relation,Martinez, C.; Sanz, M.; Calvo Roselló, V. (1989). Fractional Powers of Non-Negative Operators in Fréchet Spaces. International Journal of Mathematics and Mathematical Sciences. 12(2):309-320. http://hdl.handle.net/10251/19145630932012

Development and experimental validation of an overlay mortar with biocide activity

Biodeterioration of concrete by microorganism colonisation may be a problem in several structures, especially in irrigation and hydroelectric canals. The main problem in such structures is the proliferation of algae and cyanobacteria that affect the performance of the structure, increase the maintenance costs and affects its durability. A research was conducted to develop a novel cement-based material with biocide activity that can be used as an overlay mortar in existing structures, such as canals and pipes. With this aim, ten commercial biocides were evaluated in a laboratory campaign to assess the effectiveness of the compounds against the microbial colonisation of concrete. Both mono- and multicomponent formulations were designed from the commercial products, to increase their antimicrobial effect obtaining a set of biocide formulations. The formulations were submitted to a flowchart process to determine their influence on the physical properties of the concrete, evaluate the release of the actives, and their antimicrobial efficiency both before and after accelerated aging processes. During the campaign, some formulations were observed to diminish the strength of the concrete. Such behaviour was normally due to the interaction of the active with the cement hydration process. Other formulations showed a high release of active from the concrete in water, compromising the durability of the treatment. In general, monocomponent formulations did not succeed to fulfill all the requirements, thus multicomponent formulations were analysed. One studied multicomponent formulation presented particularly good results in all properties analysed. This product did not significantly change the properties of concrete and the release of active in water from the concrete was low, while the antimicrobial effects were long lasting.Peer ReviewedPostprint (author's final draft

Bed capacity and surgical waiting lists: a simulation analysis

Waiting time for elective surgery is a key problem in the current medical world. This paper aims to reproduce, by a Monte Carlo simulation model, the relationship between hospital capacity, inpatient activity, and surgery waiting list size in teaching hospitals. Inpatient activity is simulated by fitting a Normal distribution to real inpatient activity data, and the effect of the number of beds on inpatient activity is modelled with a linear regression model. Analysis is performed with data of the University Multi-Hospital Complex of Santiago de Compostela (Santiago de Compostela, Spain), by considering two scenarios regarding the elastiticity of demand with bed increase. If demand does not grow with an increase on bed capacity, small changes lead to drastic reductions in the waiting lists. However, if demand grows as bed capacity does, adding additional capacity merely makes waiting lists worse

Implicaciones para las pequeñas y medianas empresas por la aplicación del IVA

En este trabajo se pretende analizar los efectos de la actuación del Sector Público en la economía, especialmente a través del sistema tributario, en una etapa de crisis económica como la que estamos sufriendo desde el año 2008. La Administración ha aprobado una serie de medidas con el objeto de producir unos efectos relevantes para nuestra economía, concretamente para las pequeñas y medianas empresas. Nos centramos en el estudio de una de esas medidas aprobadas por la Administración, el Régimen Especial del Criterio de Caja.Departamento de Economía AplicadaGrado en Administración y Dirección de Empresa