### Recent Submissions

• #### Integrable zero-Hopf singularities and 3-dimensional centers ﻿

(2018-01-25)
In this paper we show that the well-known Poincaré-Lyapunov nondegenerate analytic center problem in the plane and its higher dimensional version expressed as the 3-dimensional center problem at the zero-Hopf singularity ...
• #### On bipartite-mixed graphs ﻿

(Wiley, 2018-04-04)
Mixed graphs can be seen as digraphs that have both arcs and edges (or digons, that is, two opposite arcs). In this arti- cle, we consider the case where such graphs are bipartite. As main results, we show that in this ...
• #### On the multiple zeros of a real analytic function with applications to the averaging theory of differential equations ﻿

(IOP Publishing, 2018-11-21)
In this work we consider real analytic functions $d(z,\la,\e)$, where $d : \Omega \times \mathbb{R}^p \times I \to \Omega$, $\Omega$ is a bounded open subset of $\R$, $I \subset \mathbb{R}$ is an interval containing the ...
• #### Cyclicity of polynomial nondegenerate centers on center manifolds ﻿

(Elsevier, 2018-11-09)
We consider polynomial families of ordinary differential equations on $\R^3$, parametrized by the admissible coefficients, for which the origin is an isolated singularity at which the linear part of the system has one ...
• #### Endorsement deduction and ranking in social networks ﻿

(Elsevier, 2016)
Some social networks, such as LinkedIn and ResearchGate, allow user endorsements for specific skills. In this way, for each skill we get a directed graph where the nodes correspond to users’ profiles and the arcs represent ...
• #### A Privacy-Preserving Pay-by-Phone Parking System ﻿

(Institute of Electrical and Electronics Engineers (IEEE), 2017)
Most cities around the world require drivers to pay for the time they occupy a parking spot. In this way, drivers are encouraged to shorten parking time so that other drivers are given a reasonable chance of finding ...
• #### The 2-adic valuation of the cardinality of Jacobians of genus 2 curves over quadratic towers of finite fields ﻿

(World Scientific Publishing, 2018)
Given a genus 2 curve C defined over a finite field Fq of odd characteristic such that 2|#Jac(C)(Fq), we study the growth of the 2-adic valuation of the cardinality of the Jacobian over a tower of quadratic extensions of ...
• #### Improving a smart metering system using elliptic curves and removing the trusted dealer ﻿

(2018)
Fine-grained electricity consumption information has been proven to allow to infer people’s habits from their consumption patterns. Hence, smart metering systems need a secure way to regularly transmit the electricity ...
• #### An improved upper bound for the order of mixed graphs ﻿

(Elsevier B.V., 2018)
A mixed graph G can contain both (undirected) edges and arcs (directed edges). Here we derive an improved Moore-like bound for the maximum number of vertices of a mixed graph with diameter at least three. Moreover, a ...
• #### Carrion ecology modelling for vulture conservation : are vulture restaurants needed to sustain the densest breeding population of the African white-backed vulture? ﻿

(Wiley, 2015)
As obligate scavengers, vultures are entirely dependent on carrion resources. In this study we model the carrion ecology of an ecosystem in Swaziland which is home to the densest breeding population of the African White-backed ...
• #### Algebraic and computer-based methods in the undirected degree=diameter problem – a brief survey ﻿

(Indonesian Combinatorial Society (InaCombS)Graph Theory and Applications (GTA) Research CentreUniversity of Newcastle (Australia)Institut Teknologi Bandung (ITB) (Indonesia), 2014)
This paper discusses the most popular algebraic techniques and computational methods that have been used to construct large undirected graphs with given degree and diameter.
• #### Bi-Objective Optimization Model Based on Profit and CO2 Emissions for Pig Deliveries to the Abattoir ﻿

(MDPI, 2018)
This paper presents a bi-objective model for optimizing pig deliveries to the abattoir accounting for total revenue and CO2 emissions. Fattening farms house the most important stage in pig production, and operations on ...
• #### Effects of a mixture of ligands on metal accumulation in diffusive gradients in thin films (DGT) ﻿

(CSIRO Publishing, 2018)
Natural waters contain mixtures of ligands, which collectively affect the availability of trace metals. The individual contribution of each complex to the overall metal flux received by a sensor can be described in terms ...
• #### Harvester ant nest distribution depends on soil disturbance regime ﻿

(Elsevier, 2018-09-17)
Nest densities of harvester ants (Messor barbarus) are high in rain-fed cereal fields in north-eastern Spain where the ants remove large quantities of seeds, contributing to reductions in weed populations. The distribution ...
• #### Center problem for trigonometric Liénard systems ﻿

(Elsevier, 2017)
We give a complete algebraic characterization of the non-degenerated centers for planar trigonometric Liénard systems. The main tools used in our proof are the classical results of Cherkas on planar analytic Liénard systems ...
• #### Nondegenerate centers for Abel polynomial differential equations of second kind ﻿

(Elsevier, 2017)
In this paper we study the center problem for Abel polynomial differential equations of second kind. Computing the focal values and using modular arithmetics and Gröbner bases we find the center conditions for such systems ...
• #### Liénard equation and its generalizations ﻿

(World Scientific Publishing, 2017)
In this paper, we first present a survey of the known results on limit cycles and center conditions for Liénard differential systems. Next we propose a generalization of such systems and we study their center conditions ...
• #### Integrability conditions for complex kukles systems ﻿

(Taylor & Francis, 2017)
In this paper, we provide necessary and sufficient conditions for the existence of local analytic first integrals for a seventh-parameter family of complex cubic systems called the complex Kukles systems.
• #### Center conditions for polynomial Liénard systems ﻿

(Springer International Publishing, 2017)
In this paper we study the center problem for polynomial Liénard systems of degree n with damping of degree n. Computing the focal values we find the center conditions for such systems for n=5 and using modular arithmetics ...
• #### On the Integrability of Liénard systems with a strong saddle ﻿

(Elsevier, 2017)
We study the local analytic integrability for real Li\'{e}nard systems, $\dot x=y-F(x),$ $\dot y= x$, with $F(0)=0$ but $F'(0)\ne0,$ which implies that it has a strong saddle at the origin. First we prove that this problem ...