Now showing items 289-308 of 358

    • Representaciones matemáticas de niños y niñas de 5-6 años cuando resuelven un problema abierto 

      Vanegas, Yuly Marsela; Prat, Montserrat; Edo, Mequè (Universidad Politécnica Salesiana, 2022)
      La resolución de problemas y la representación son dos procesos fundamentales de la actividad matemática. Ya que, su desarrollo proporciona una base clave para el aprendizaje de las matemáticas en todos los niveles escolares. ...
    • Reversible nilpotent centers with cubic homogeneous nonlinearities 

      Dukaric, Masa; Giné, Jaume; Llibre, Jaume (Elsevier, 2016)
      We provide 13 non--topological equivalent classes of global phase portraits in the Poincaré disk of reversible cubic homogeneous systems with a nilpotent center at origin, which complete the classification of the phase ...
    • Review of mathematical models for sow herd management 

      Pla Aragonés, Lluís Miquel (Elsevier, 2007)
      This paper is a survey of the different sow models described in literature, which made use of different mathematical methodologies, and were intended for sow herd management. Models were discussed under a wide classification, ...
    • Searching for large multi-loop networks 

      Feria Purón, Ramiro; Pérez Rosés, Hebert; Ryan, Joe (Elsevier, 2014)
      We describe and implement a computer-based method to find large multi-loop graphs with given degree and diameter. For some values of degree and diame- ter, our algorithm produces the largest known circulant graphs. We ...
    • Second-generation anticoagulant rodenticides in the blood of obligate and facultative European avian scavengers 

      Oliva-Vidal, Pilar; Martínez, José María; Sánchez-Barbudo, Inés S.; Camarero, Pablo R.; Colomer, M. Àngels (Maria Àngels); Margalida, Antoni; Mateo, Rafael (Elsevier, 2022)
      The widespread use of second-generation anticoagulant rodenticides (SGARs) and their high persistence in animal tissues has led to these compounds becoming ubiquitous in rodent-predator-scavenger food webs. Exposure to ...
    • Secure many-to-one communications in wireless sensor networks 

      Viejo Galicia, Alexandre; Domingo i Ferrer, Josep; Sebé Feixas, Francesc; Castellà Roca, Jordi (Molecular Diversity Preservation International (MDPI), 2009)
      Wireless Sensor Networks (WSN) are formed by nodes with limited computational and power resources. WSNs are finding an increasing number of applications, both civilian and military, most of which require security for the ...
    • Securing Databases by using Diagonal-based Order Preserving Symmetric Encryption 

      Martínez Rodríguez, Santi; Miret, Josep M. (Josep Maria); Valls Marsal, Magda; Tomàs, Rosana (Natural Sciences Publishing, 2014)
      The amount of information stored in databases is constantly increasing. Databases contain multiple records, each of them divided in several data fields. And some of these fields may contain sensitive information, so there ...
    • Sequence Mixed Graphs 

      Dalfó, Cristina; Fiol, Miguel Angel; López Lorenzo, Ignacio (Elsevier, 2017)
      A mixed graph can be seen as a type of digraph containing some edges (or two opposite arcs). Here we introduce the concept of sequence mixed graphs, which is a generalization of both sequence graphs and iterated line ...
    • Sex-related differences in body condition and serum biochemical parameters in red deer (Cervus elaphus) naturally infected with Mycobacterium bovis 

      López Olvera, Jorge R.; Fernández de Mera, I. G.; Vidal, D.; Vicente, J.; Fierro, Y.; Gortázar, C.; Serrano Ferrón, Emmanuel (Elsevier, 2013)
      Although Mycobacterium bovis infection is commonly reported in red deer (Cervus elaphus), potential differences in the effects of infection on male and female animals in terms of body condition and clinical biochemistry ...
    • Simulation Analysis and Comparison of New Hybrid TLI-µTESLA and Variant TESLA Protocols Using SHA-2 and SHA-3 Hash Functions 

      Eledlebi, Khouloud; Alzubaidi, Ahmed Adel; Yeun, Chan Yeob; Damiani, Ernesto; Mateu Meseguer, Víctor; Al-Hammadi, Yousof (MDPI, 2022)
      The evolution of 5G and 6G networks has enhanced the ability of massive IoT devices to provide real-time monitoring and interaction with the surrounding environment. Despite recent advances, the necessary security services, ...
    • Small Amplitude Periodic Orbits in Three-Dimensional Quadratic Vector Fields with a Zero-Hopf Singularity 

      García, I. A. (Isaac A.) (Springer, 2022)
      We consider some families of three-dimensional quadratic vector fields having a fixed zeroHopf equilibrium.We are interested in the bifurcation of periodic ν-orbits from the singularity, that is, those small amplitude ...
    • Small cutsets in arc-transitive digraphs of prime degree 

      López Masip, Susana-Clara (Elsevier, 2013)
      We give an upper bound for the size of non-trivial sets that have small boundary in a family of arc-transitive digraphs. We state the exact size for these sets in case of prime degree. We also give a lower bound for the ...
    • Some remarks on global analytic planar vector fields possessing an invariant analytic set 

      García, I. A. (Isaac A.) (Taylor and Francis, 2021-02-01)
      We study the problem of determining the canonical form that a planar analytic vector field in all the real plane can have in order to possess a given invariant analytic set. We determine some conditions that guarantee that ...
    • Space–time trends in Spanish bird electrocution rates from alternative information sources 

      Guil, Francisco; Colomer, M. Àngels (Maria Àngels); Moreno-Opo, Rubén; Margalida, Antoni (Elsevier, 2015)
      Interaction with man-made infrastructures is one of the main sources of non-natural bird mortality. Here, we use a long-term study (1980–2010) to analyse spatial and temporal patterns in avian electrocution in Spain, using ...
    • Spatio-temporal configurations of human-caused fires in Spain through point patterns 

      Costafreda Aumedes, Sergi; Comas Rodríguez, Carles; Vega García, Cristina (MDPI, 2016)
      Human-caused wildfires are often regarded as unpredictable, but usually occur in patterns aggregated over space and time. We analysed the spatio-temporal configuration of 7790 anthropogenic wildfires (2007–2013) in nine ...
    • Spectra and eigenspaces from regular partitions of Cayley (di)graphs of permutation groups 

      Dalfó, Cristina; Fiol, Miguel Angel (Elsevier, 2020)
      In this paper, we present a method to obtain regular (or equitable) partitions of Cayley (di)graphs (that is, graphs, digraphs, or mixed graphs) of permutation groups on n letters. We prove that every partition of the ...
    • Spectra and eigenspaces of arbitrary lifts of graphs 

      Dalfó, Cristina; Fiol, Miguel Angel; Pavlíiková, Sona; Sirán, Jozef (Springer, 2021-09-23)
      We describe, in a very explicit way, a method for determining the spectra and bases of all the corresponding eigenspaces of arbitrary lifts of graphs (regular or not).
    • Spectra and eigenspaces of arbitrary lifts of graphs 

      Dalfó, Cristina; Fiol, Miguel Angel; Pavlíková, Sona; Sirán, Jozef (Faculty of Mathematics, Physics and Informatics, Comenius University, 2019)
      We describe, in a very explicit way, a method for determining the spec-tra and bases of all the corresponding eigenspaces of arbitrary lifts of graphs (regularor not).
    • Stochastic smoothing of point processes for wildlife-vehicle collisions on road networks 

      Borrajo, M.I.; Comas Rodríguez, Carles; Costafreda Aumedes, Sergi; Mateu, Jorge (Springer, 2021)
      Wildlife-vehicle collisions on road networks represent a natural problem between human populations and the environment, that affects wildlife management and raise a risk to the life and safety of car drivers. We propose ...
    • Strongly formal Weierstrass non-integrability for polynomial differential systems in C2 

      Giné, Jaume; Llibre, Jaume (Bolyai Institute, University of Szeged; Hungarian Academy of Sciences, 2020)
      Recently a criterion has been given for determining the weakly formal Weierstrass non-integrability of polynomial differential systems in C2 . Here we extend this criterion for determining the strongly formal Weierstrass ...