1,210 research outputs found

    El tapial de las murallas de Granada

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    Español: En este trabajo se establecen las características del material empleado en las construcciones de los distintos recintos amurallados de la ciudad de Granada, que se conocen históricamente como "Alcazabas de Granada" y arrabales, distinguiendo entre material de interior de muro y revestimientos. Como objetivo final, este estudio nos ha permitido establecer conclusiones más precisas sobre la metodología constructiva utilizada en estos recintos amurallados, y la evolución de ésta a lo largo de las distintas épocas. Inglés: This paper deals with a general analysis of the materials used in the city walls, commonly known as Alcazabas, of Granada. The study concentrates in the material of the inner walls as well as the exterior. This has allowed for a deeper insight in the construction methods used for city walls during different ages

    Robust Pose Control of Robot Manipulators Using Conformal Geometric Algebra

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    A controller, based on sliding mode control, is proposed for the n-link robotic manipulator pose tracking problem. The point pair (a geometric entity expressed in geometric algebra) is used to represent position and orientation of the end-effector of a manipulator. This permits us to express the direct and differential kinematics of the endeffector of the manipulator in a simple and compact way. For the control, a sliding mode controller is designed with the following properties: robustness against perturbations and parameter variations, finite time convergence, and easy implementation. Finally, the application, of the proposed controller in a 6 DOF robotic manipulator is presented via simulation.Consejo Nacional de Ciencia y Tecnologí

    Visual Servoing and Robust Object Manipulation Using Symmetries and Conformal Geometric Algebra

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    Object tracking and manipulation is an important process for many applications in robotics and computer vision. A novel 3D pose estimation of objects using reflectionally symmetry formulated in Conformal Geometric Algebra (CGA) is proposed in this work. The synthesis of the kinematics model for robots and a sliding mode controller using the CGA approach is described. Real time implementation results are presented for the pose estimation of object using a stereo vision system.ITESO, A.C.CINVESTA

    Robust Tracking of Bio-Inspired References for a Biped Robot Using Geometric Algebra and Sliding Modes

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    Controlling walking biped robots is a challenging problem due to its complex and uncertain dynamics. In order to tackle this, we propose a sliding mode controller based on a dynamic model which was obtained using the conformal geometric algebra approach (CGA). The CGA framework permits us to use lines, points, and other geometric entities, to obtain the Lagrange equations of the system. The references for the joints of the robot were bio-inspired in the kinematics of a walking human body. The first and second derivatives of the reference signal were obtained through an exact robust differentiator based on high order sliding modes. The performance of the proposed control scheme is illustrated through simulation.CINVESTA

    Microgrid Power Sharing Framework for Software Defined Networking and Cybersecurity Analysis

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    Hierarchical control is a widely used strategy that can increase resilience and improve the reliability of the electrical network based on microgrid global variables. Large amounts of data required during transitions prompt the use of more reliable and flexible communications to achieve the control objectives. Such communications can involve potential cyber vulnerabilities and latency restrictions, which cannot be always addressed in real-time. To accurately capture the system’s overall operation, this paper proposes a co-simulation framework driven by flexible communications and a resilient control algorithm to regulate the frequency and voltage deviations in a networked microgrids. Model-based predictive control has been implemented, to avoid slow transient response associated with linear hierarchical control. Software-Defined Networking (SDN) is responsible for increasing the communication intelligence during the power-sharing process. The effects of critical communications and overall system performance are reviewed and compared for different co-simulation scenarios. Graphical Network Simulator (GNS3) is used in combination with model-based predictive control and SDN, to provide latency below 100 ms, as defined in IEC 61850. Testing of the proposed system under different cyber attack scenarios demonstrate its excellent performance. The novel control architecture presented in the paper provides a reference framework for future cloud computing-based microgrids

    Phylogeographic structure of Canthon cyanellus (Coleoptera: Scarabaeidae), a Neotropical dung beetle in the Mexican Transition Zone: Insights on its origin and the impacts of Pleistocene climatic fluctuations on population dynamics

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    Canthon cyanellus is a roller dung beetle with a wide distribution range in the tropical forests of the New World. In Mexico, it inhabits the Pacific and the Gulf coasts, the Yucatan Peninsula and the south mainly in the State of Chiapas. This species shows a wide geographical variation in cuticle color, which has been used as defining trait for subspecies. In this study we analyzed the phylogeographic and demographic history of the Mexican populations of C. cyanellus using DNA sequences of the nuclear ITS2, and the mitochondrial COI and 16S genes. We found that not all the current valid subspecies are supported by the molecular analysis. The populations are genetically and geographically structured in five lineages. The diversification events that gave origin to the main lineages within this species complex occurred during the Pleistocine in a time range of 1.63–0.91 Myr. The demographic history of these lineages suggests post-glacial expansions toward the middle and the end of the Pleistocene. The combined data of mitochondrial and nuclear DNA suggest that the phylogeographic structure and demographic history of the C. cyanellus populations are the result of: the geological and volcanic activity that occurred from the end of the Pliocene to the Pleistocene; and the contraction and expansion of tropical forests due to the glacial and inter-glacial cycles during the Pleistocene. Landscape changes derived from historical events have affected the demographic history of the populations of this species. The results presented here point to the need to review the taxonomic status and delimitation of the lineages encompassed in the Canthon cyanellus complex.This work was financial supported by the Consejo Nacional de Ciencia y Tecnología, México (CONACyT, grant number CB-168373, 257039). This paper constitutes a partial fulfilment of the Graduate Program in Biodiversidad: Conservación y Gestión de las Especies y sus Hábitat of the Centro Iberoamericano de la Biodiversidad (CIBIO), Universidad de Alicante, España

    Epidemiological implications of the genetic diversification of dengue virus (DENV) serotypes and genotypes in Mexico

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    Variation and clade shifts in dengue virus (DENV) genotypes are responsible for numerous dengue fever outbreaks throughout Latin America in the past decade. Molecular analyses of dengue serotypes have revealed extensive genetic diversification and the emergence of new genotypes in Brazil (DENV-4 genotype I) and elsewhere in tropical and subtropical America. The goal of the present study is to assess the extent to which the adventitious introduction of DENV genotypes and their increasing genetic diversity affects dengue epidemiology in Mexico. A nuanced sequence inspection and phylogenetic analysis of the C-prM nucleotide region of DENV was performed for specimens collecting in 2009 from the Veracruz State, Mexico. Findings were contrasted with specimens collected in adjacent years and analysed based on the epidemiological patterns reported between 1990 and 2019. Additionally, the identification process of various DENV genotypes was assessed, including: (1) DENV-1, genotype V, (2) the DENV-2 Asian/American and Asian II genotypes (3) DENV-3, genotype III, and (4) DENV-4, genotype I. This resulted in the discovery of a distinct genetic cladistic pattern for serotype DENV-2. Lastly, study findings suggest that a correlation exists between the emergence of novel genotypes and genetic diversification, with the increasing incidence of DENV infections in Mexico in 2009

    Dataset on the epidemiology and genetic diversification of dengue virus (DENV) serotypes and genotypes in Mexico

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    This work is licensed under a Creative Commons Attribution 4.0 International License.Dengue virus (DENV) evolution has had a significant impact on disease pathogenesis, virulence, and epidemiology in Mexico. Novel genotypic variation in DENV serotypes and genotypes may influence the magnitude and severity of dengue epidemics, as evidenced by 2009 data from Veracruz State. The data presented herein is related to the publication entitled “Epidemiological Implications of the Genetic Diversification of Dengue Virus (DENV) Serotypes and Genotypes in Mexico” [1]. Raw data and trees provide epidemiological data on DENV prevalence and a comprehensive phylogeny of both representative sequences collected from an NCBI repository, and 28 additional isolates from acute-phase plasma samples diagnosed with dengue fever or severe dengue (Raw sequencing data is hosted in the public repository Mendeley Data (http://dx.doi.org/10.17632/bf2kdhhf6x.2). Phylogenetic trees for each DENV serotype (DENV-1, -2, -3 and -4) were constructed using these sequences by a maximum likelihood methodology as well as a Bayesian Markov chain Monte Carlo (MCMC) integration approach. Phylogenetic trees exhibited: (1) DENV-1, genotype V, (2) the DENV-2 Asian/American and Asian II genotypes, (3) DENV-3, genotype III, and (4) DENV-4, genotype I. This data can be beneficial for future analyses on DENV serotype and genotype structure and the introduction of novel DENV genotype sequences in the Americas, for the further elucidation of dengue etiology.Consejo Nacional de Ciencia y Tecnología, Mexico EHG (Registration Number: 111110038; CVU: 49406)ED-de-la-C CONACYT Registration Number: 280838; CVU: 485179COMECYT Scholarship Number: 18BTD002
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