Guillermo Fernández-Anaya

Adaptive synchronization of high-order chaotic systems: a feedback with low-order parametrization

Abstract In this work, an adaptive strategy for chaos synchronization is developed. The proposed scheme allows the synchronization of high-order chaotic systems. Only one tuning parameter is required to perform the chaos synchronization. The nonidentical chaotic synchronization can be attained. Computer simulations are provided to verify the operation of the designed synchronization scheme. The proposed controller is implemented to secure communication and synchronization of inhomogeneous oscillators chain. Nevertheless, other practical applications can be physically carried out.

DNA fragment assembly using optimization

The DNA fragment assembly is an important phase required to obtain complete genomes. Optimization using nature inspired algorithms has been proposed by several authors. We present another nature inspired algorithm based on Particle Swarm Optimization and Differential Evolution. These algorithms are compared using a set of common benchmarks and showing some advantages in our proposed algorithm. We also applied the Traveling Salesman Problem (TSP) with better results than the nature inspired algorithms as we could obtain the true optima for 16 commonly used benchmarks for the first time to the best of our knowledge. The benchmarks are much smaller than the real organism assembly problems and scaling up from the benchmarks to real organisms presents important challenges. We propose a way to solve the scale up problems and test them using the Staphylococcus aureus COL Main Chromosome with the TSP approach.

Benchmark datasets for the DNA fragment assembly problem

Many computational intelligence approaches have been used for the fragment assembly problem. However, the comparison and analysis of these approaches is difficult due to the lack of availability of standard benchmarks. Although similar datasets may be used as a starting point, there is not enough information to reproduce the exact overlaps matrix for the fragments used by the various approaches, creating a problem for consistency. This paper presents a collection of benchmark datasets for a wide range of fragment lengths, number of fragments, and sequence lengths, along with a description of the method used to produce them. A website has been created to maintain the datasets and the tables of results at http://chac.sis.uia.mx/fragbench/. Researchers are invited to add to the datasets by following the method described, as well as to submit results obtained by their algorithms on the benchmarks.

MIMO systems properties preservation under SPR substitutions

The preservation of some control-oriented positive real properties (passivity, positivity, bounded realness, as well as input-output behavior) in multi-input multi-output transfer functions is studied, when performing substitutions (of the complex Laplace variable s) by a particular class of rational strictly positive real (SPR) functions, the so-called SPR functions of zero relative degree (SPR0 functions). We also consider here the preservation of stability properties of a class of unforced linear time-invariant systems with memoryless (possibly time-varying nonlinear) input depending on the system output.

Synchronization of nonlinear fractional order systems

This paper deals with the master–slave synchronization scheme for partially known nonlinear fractional order systems, where the unknown dynamics is considered as the master system and we propose the slave system structure which estimates the unknown state variables. For solving this problem we introduce a Fractional Algebraic Observability (FAO) property which is used as a main tool in the design of the master system. As numerical examples we consider a fractional order Rossler hyperchaotic system and a fractional order Lorenz chaotic system and by means of some simulations we show the effectiveness of the suggested approach.

A new observer for nonlinear fractional order systems

In this work an observer structure for a certain class of nonlinear fractional order systems is proposed. For solving this task we introduce a Fractional Algebraic Observability (FAO) property which is used as a main tool in the design of the observer system. We apply our proposals in the master-slave synchronization problem, where the coupling signal is viewed as output and the slave system is regarded as observer (the slave is requested to recover the unknown state trajectories of the master). Finally, as numerical example we consider a fractional order Rössler hyperchaotic system and by means of some simulations we show the effectiveness of the suggested approach.

Can the Lorenz-Gauge Potentials Be Considered Physical Quantities?.

Two results support the idea that the scalar and vector potentials in the Lorenz gauge can be considered to be physical quantities: (i) they separately satisfy the properties of causality and propagation at the speed of light and do not imply spurious terms and (ii) they can naturally be written in a manifestly covariant form. In this paper we introduce expressions for the Lorenz-gauge potentials: at the present time in terms of electric and magnetic fields at the retarded time. These expressions provide a third result in favour of a physical interpretation of the Lorenz-gauge potentials: (iii) they can be regarded as causal effects of the observed electric and magnetic fields.

Modified Classical Graph Algorithms for the DNA Fragment Assembly Problem

DNA fragment assembly represents an important challenge to the development of efficient and practical algorithms due to the large number of elements to be assembled. In this study, we present some graph theoretical linear time algorithms to solve the problem. To achieve linear time complexity, a heap with constant time operations was developed, for the special case where the edge weights are integers and do not depend on the problem size. The experiments presented show that modified classical graph theoretical algorithms can solve the DNA fragment assembly problem efficiently.

Distance-based Formation Control Using Angular Information Between Robots

Distance-based formation of groups of mobile robots provides an alternative focus for motion coordination strategies respect to the standard consensus-based formation strategies. However, the setup formulation introduces non rigidity problems, multiple formation patterns that verify the distance constraints or local minima appeared when collision avoidance strategies are added to the control laws. This paper proposes a novel combined distance-based potential functions with attractive-repulsive behavior in order to simplify the navigation problem as well as the use of angular information between robots to reduce the likelihood of unwanted formation patterns. Moreover, this approach eliminates the local minima generated by the control laws to reach the desired formation configuration in the case of three robots. The analysis addresses the case of omnidirectional robots and is extended to the case of unicycle-type robots with numerical simulations and real-time experiments.

Formation Tracking Based on Approximate Velocities

This paper analyses the formation tracking of groups of mobile robots moving on the plane. A leader robot is chosen to follow a prescribed trajectory whilst the rest, considered as followers, are f...