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Medina-Melendrez M.,Technological Institute of Culiacan | Castro A.,National Institute of Astrophysics, Optics and Electronics | Castro A.,Aix - Marseille University | Arias-Estrada M.,National Institute of Astrophysics, Optics and Electronics
Optics Express | Year: 2012

In Digital Holography there are applications where computing a few samples of a wavefield is sufficient to retrieve an image of the region of interest. In such cases, the sampling rate achieved by the direct and the spectral methods of the discrete Fresnel transform could be excessive. A few algorithmic methods have been proposed to numerically compute samples of propagated wavefields while allowing down-sampling control. Nevertheless, all of them require the computation of at least two 2D discrete Fourier transforms which increases the computational load. Here, we propose the use of an aliasing operator and a single discrete Fourier transform to achieve an efficient method to down-sample the wavefields obtained by the Fresnel transform. © 2012 Optical Society of America. Source

Santiesteban-Cos R.,Technological Institute of Culiacan
2015 European Control Conference, ECC 2015 | Year: 2015

In this work, a dynamic feedback control law based on the well known 'Twisting' algorithm is under study. Dynamic compensation is added to the Twisting algorithm, in order to use position feedback only, and keep properties such as finite time stability. Moreover, linear terms are considered to improve the robustness of the algorithm. In some mechanical applications, an observer or a differentiator design is required for control purposes when the whole state space is not available for measurement. An alternative solution for this problem is proposed: a finite time stable algorithm that uses dynamic position feedback. Indeed, this new proposal does not require to measure or estimate another signal but the position of the mechanical system. In the stability analysis, strict nonsmooth Lyapunov functions and homogeneity properties are used in order to show finite time stability and robustness. Based on the proposed algorithm, a control law for a one-link pendulum affected by Coulomb friction and bounded external perturbations is designed. © 2015 EUCA. Source

Rangel-Peraza J.G.,Technological Institute of Culiacan | Obregon O.,Brigham Young University | Nelson J.,Brigham Young University | Williams G.P.,Brigham Young University | And 3 more authors.
Lakes and Reservoirs: Research and Management | Year: 2012

The dynamics of water temperature, dissolved oxygen and total dissolved solids concentrations in Aguamilpa Reservoir was analysed by considering horizontal and water column variations. The reservoir model, CE-QUAL-W2, was used to simulate the temporal variations calibrated with data gathered every 2months from June 2008 to June 2009. Temperature depth profiles indicated a typical asymmetry of reservoirs exhibiting a large stratification in the lower part near the dam. Dissolved oxygen concentration profiles exhibited some degree of anoxia in the bottom water during the rainy season (May through October). This is most likely due to decomposition vegetation and organic matter via soil erosion and run-off from the basin accumulating at the bottom of the reservoir. The reservoir stratification is clearly seasonal, occurring during the rainy season, especially in the lowest reservoir zones. The CE-QUAL-W2 model results provided a comprehensive understanding of the temporal behaviour of the study variables during the modelling study period. Application of this water quality model is directed to water resource managers to help them better understand the dynamics of physico-chemical processes, and how they vary temporally and spatially in the reservoir, and to propose the best management practices for preserving or improving the water quality of the system. © 2012 The Authors. Journal compilation © 2012 Blackwell Publishing Asia Pty Ltd. Source

Diaz-Rodriguez M.,University of Los Andes, Venezuela | Bautista-Quintero R.,Technological Institute of Culiacan | Carretero J.A.,University of New Brunswick
Mechanisms and Machine Science | Year: 2015

This paper presents and compares three approaches for solving the inverse dynamic model of a general 3-PRS parallel manipulator. The first method obtains the inverse dynamic model by describing the manipulator as three open kinematic chains. Then, the vector-loop closure constraints introduce the relationship between the dynamics of the open kinematic chains and the original closed loop chains. The second method exploits the characteristic of parallel manipulators such that the platform and the links are considered as subsystems. The third method is similar to the second method but uses a different formulation of the Jacobian matrix. This work provides some insight on some advantages and/or disadvantages on how to formulate the dynamic model of a lower mobility parallel manipulator, which can be considered in topic such as the optimal design, parameter identification, and model-based control. © Springer International Publishing Switzerland 2015. Source

Estrada A.,National Autonomous University of Mexico | Loria A.,Supelec | Santiesteban R.,Technological Institute of Culiacan | Fridman L.,CINVESTAV
IMA Journal of Mathematical Control and Information | Year: 2013

We present a result on stabilization of strict feedback systems with unknown disturbances based on the so-called twisting algorithm, a second-order sliding mode controller for the double integrator. The novelty of the note relies in the stability analysis of the closed-loop system and the relaxation of stability conditions (we do not assume boundedness of trajectories). The proof of the main result is constructed along similar lines as for well-established theorems for nonlinear time-varying systems in cascade, with continuous right-hand sides. Although we restrict our analysis to second-order systems, the purpose of this note is to settle the basis for a methodological stability analysis approach for higher-order systems in strict feedback form, under the influence of uncertain perturbations. An illustrative example is provided. © 2012 The authors. Source

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