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.

Adaptive identification of two unstable PDEs with boundary sensing and actuation

Abstract: In this paper we consider a problem of on-line parameter identification of parabolic partial differential equations (PDEs). In the previous study, on the actuation side, both distributed (SIAM J. Optim. Control 1997; 35:678–713; IEEE Trans. Autom. Control 2000; 45:203–216) and boundary (IEEE Trans. Autom. Control 2000; 45:203–216) actuations were considered in the open loop, whereas for the closed loop (unstable plants) only distributed one was addressed. On the sensing side, only distributed sensing was considered. The present study goes beyond the identification framework of (SIAM J. Optim. Control 1997; 35:678–713; IEEE Trans. Autom. Control 2000; 45:203–216) by considering boundary actuation for the unstable plants, resulting in the closed-loop identification, and also introducing boundary sensing. This makes the proposed technique applicable to a much broader range of practical problems. As a first step towards the identification of general reaction–advection–diffusion systems, we consider two benchmark plants: one with an uncertain parameter in the domain and the other with an uncertain parameter on the boundary. We design the adaptive identifier that consists of standard gradient/least-squares estimators and backstepping adaptive controllers. The parameter estimates are shown to converge to the true parameters when the closed-loop system is excited by an additional constant input at the boundary. The results are illustrated with simulations. Copyright © 2008 John Wiley & Sons, Ltd.

Provenance, age constraints and metamorphism of Ediacaran metasedimentary rocks from the El Triunfo Complex (SE Chiapas, México): evidence for Rodinia breakup and Iapetus active margin

Abstract: Metasedimentary rocks from the El Triunfo Complex (Jocote Unit) in the southern Chiapas Massif (SE Mexico) are constituted mainly by sillimanite-rich micaschist, locally intercalated with marble and calc-silicate rocks. Mafic rocks (now amphibolite) intruded the sequence prior to deformation and folding. Peak metamorphic conditions are estimated by geothermobaromerty at ~6.0 kbar and ~650oC. The timing of the metamorphic event is dated by LA-MC-ICPMS analysis on zircon rims at 438+23/–12 Ma. Furthermore, detrital zircon grains yield mainly Stenian–Tonian and minor early Mesoproterozoic ages, indicating provenance from Grenville-type orogens (such as Oaxaquia) and some older cratonic sources. The 87Sr/86Sr values of 0.70775–0.70777 and the δ13C values from +1.9‰ to +2.7‰ in associated calcite marble define the time of deposition between 600 and 580 Ma. Geochemical markers from metapelite samples (such as La/Th > 3.94, La/Sc > 3.72, Th/U > 8.19, Th/Co > 0.42 and CIA = 74 to 83), as well as Sm–Nd iso...

Reduction of wind stress due to swell at high wind conditions

Abstract: [1] Wind stress over the ocean depends on the sea surface roughness which is determined by the sea state. On one hand, underdeveloped wind seas, rougher than their fully developed counterpart, increase the drag. On the other hand, the presence of swell can modify wind stress by modifying the wind sea roughness. This latter mechanism is believed to have a great impact at high winds whenever underdeveloped local waves coexist with swell. Detailed measurements of wind stress and wavefield in fetch-limited growth conditions were made in an area subjected to strong and persistent winds. Through the analysis of wavefield observations, it is found that the presence of swell dampens the short wind waves. The observed attenuation is greater for younger wind seas and decreases as the wind waves become older. Results obtained from modeling the interaction of wind waves and the air flow above point out that the attenuation of short wind waves causes a reduction of the wave-supported stress, which in turn decreases the total wind stress.

Temperature modulates spatio-temporal variability of the functional reproductive maturation of Octopus maya (Cephalopoda) on the shelf of the Yucatan Peninsula, Mexico

Abstract: Laboratory studies have demonstrated that high temperatures inhibit spawning of Octopus maya; therefore, in oceanic warming scenarios the population dynamics may be affected. The aim of the present study was to go beyond laboratory studies under controlled temperatures to examine the possible relationship between large-scale thermal patterns and reproductive season (represented by functional maturation) of O. maya in the wild on the continental shelf of the Yucatan Peninsula, where it is endemic. The macroscopic maturity index (MaMI) was obtained in females, and reproductive complex index (RCI) and number of spermatophores in males. Associations between these indices and environmental temperature regime were inferred by sampling octopuses in an upwelling zone (Z-I), a transition zone (Z-II) and a nonupwelling zone (Z-III). The reproductive condition of O. maya differed between Z-I and Z-III. In all zones, the proportion of adults showing functional maturity was highest in both females (MaMI: 36–71% of values ≤0.2) and males (RCI: 12–40% of values ≥0.9; 41–49 spermatophores per octopus) during the season of winter storms (‘nortes’ season, November–February), when the sea-surface temperature oscillates around 25 °C. In Z-I, some individuals were functionally mature throughout the year, likely due to low temperatures maintained by summer upwelling. Zone-I had the greatest proportion of functionally mature males (up to 40% of adults in ‘nortes’ season) and the greatest number of spermatophores (mean 43–49 spermatophores per octopus in all seasons). Females in Z-III (without upwelling) were functionally mature mainly in the ‘nortes’ season when water temperature decreased, with only a small proportion mature in the rest of the year when water temperatures reached 31 °C. As predicted by laboratory studies, water temperature below 27 °C appears to be favourable for the functional reproductive maturation of wild O. maya.

Rupture length of the October 9, 1995 Colima-Jalisco Earthquake (Mw8) estimated from tsunami data

Abstract: We analyze tsunami data of the great 1995 Colima-Jalisco, Mexico earthquake, recorded in Cabo San Lucas, Baja California Sur, to estimate its rupture length, L. To model the tsunami arrival time, we assume a rectangular source area, oriented parallel to the trench, whose SE limit is fixed at the point of rupture initiation. The NW limit of the source area, i.e., L, is varied between 120 and 200 km. The comparison between synthetic and observed data strongly suggests that L of the earthquake was 160±20 km. This length agrees with those reported in various other studies of the earthquake. It, however, disagrees with a previous study, based on the same tsunami data, which suggested that the rupture may have extended 250 km NW from the epicenter [Tanioka and Ruff, 1996]. The cause of this discrepancy is most likely an error in the timing of the records used by Tanioka and Ruff [1996]. We conclude that the earthquake only partially ruptured the Rivera-North America plate interface. A 120 km-long segment in the NW extreme of this interface, which apparently ruptured in 1932, remains presently unbroken.