Ensenada Center for Scientific Research and Higher Education

About: Ensenada Center for Scientific Research and Higher Education is a facility organization based out in Ensenada, Mexico. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 1934 authors who have published 3733 publications receiving 63115 citations.

Consensus-based control for a network of diffusion PDEs with boundary local interaction

Abstract: In this paper the problem of driving the state of a network of identical agents, modeled by boundary-controlled heat equations, towards a common steady-state profile is addressed. Decentralized consensus protocols are proposed to address two distinct problems. The first problem is that of steering the states of all agents towards the same constant steady-state profile which corresponds to the spatial average of the agents initial condition. A linear local interaction rule addressing this requirement is given. The second problem deals with the case where the controlled boundaries of the agents dynamics are corrupted by additive persistent disturbances. To achieve synchronization between agents, while completely rejecting the effect of the boundary disturbances, a nonlinear sliding-mode based consensus protocol is proposed. Performance of the proposed local interaction rules are analyzed by applying a Lyapunov-based approach. Simulation results are presented to support the effectiveness of the proposed algorithms.

Fixed-camera visual servo control for planar robots

Abstract: We present a new controller to solve the visual servo control problem for planar robots in the fixed-camera configuration. For a static target we characterize the global closed loop attractor using the full robot dynamics, and prove local asymptotic stability of the end-effector tracking error. Neither the inverse kinematics nor the inverse Jacobian are used in the controller. Experimental results on a 2-DOF direct drive manipulator are presented.

An attenuation study using earthquakes from the 1997 Umbria-Marche sequence

Abstract: We studied spatial and temporal characteristics of seismic attenuation inCentral Italy using S- and coda- waves recorded by the MarchesanSeismograph Network from earthquakes located in the epicentral area ofthe 1997 Umbria-Marche sequence The amplitude decay of the S waveswith distance was defined calculating empirical attenuation functions at 15frequencies between 1 and 25 Hz We analyzed separately foreshocks andaftershocks and we found the same attenuation functions, suggesting thatthe possible temporal variations could be confined in a small area Thefrequency dependence of QS was approximated by the equation QS=18 · f20between 1 and 10 Hz At higher frequencies (10–25 Hz), the frequencydependence of Qs weakens, having an average value of QS=990 We also estimated Q from coda waves (QC) using the single-scattering models of Aki andChouet (1975) and Sato (1977) We found that QC=77 · f06, (between 2 and 20Hz) at the western side of the mountain chain, using either foreshocks oraftershocks This relation is consistent with previous estimates of QCreported for the Central Apennines For a volume sampling the Colfioritobasin, the Apennines and the Marche region we found that QC=55 · f08,indicating highattenuation below the mountain belt To detect small temporal changes ofQ, we calculated spectral ratios of 5 temporal doublets located in theepicentral area and recorded at the closest station We found temporalchanges of Q that vary from 27% to 56%, depending on the locationof the doublets This variability suggests that the temporal change ofattenuation may depend on the spatial variation of Q and perhaps on thespatial distribution of tectonic stress in the epicentral area