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.

The age and composition of the pre-Cenozoic basement of the Jalisco Block: implications for and relation to the Guerrero composite terrane

Abstract: The Jalisco Block is thought to be part of the Guerrero terrane, but the nature and age of the underlying crystalline basement are largely unknown. We have collected a suite of schists, granitoids, and weakly metamorphosed marine sediments from various parts of the Jalisco Block including Atenguillo and Ameca, Mascota and San Sebastian, Cuale, Puerto Vallarta, Punta Mita, Yelapa, and Tomatlan. The schists range in age from 135 to 161 Ma, with many exhibiting Proterozoic and Phanerozoic zircon ages. The granitoids range in age from 65 to 90 Ma, and are calc-alkaline compositionally—similar to granitoids from the Puerto Vallarta and Los Cabos batholiths. The Jalisco granitoids also experienced similar uplift rates to granitoids from the regions to the north and south of the Jalisco Block. The marine sediments yield a maximum depositional age of 131 Ma, and also contain a significant zircon population with ages extending back to the Archean. Granitoids from this study define two age groups, even after the effects of thermal resetting and different closure temperatures are considered. The 66.8-Ma silicic ash flow tuff near Union de Tula significantly expands the extent of this Cretaceous–Paleocene age ash flow tuff unit within the Jalisco Block, and we propose calling the unit “Carmichael silicic ash flow tuff volcanic succession” in honor of Ian Carmichael. The ages of the basement schists in the Jalisco Block fully overlap with the ages of terranes of continental Mexico, and other parts of the Guerrero terrane in the south, confirming the autochthonous origin of the Jalisco Block rather than exotic arc or allochthonous origin. Geologic data, in combination with geochronologic and oxygen isotopic data, suggest the evolution of SW Mexico with an early 200–1,200-Ma passive margin, followed by steep subduction in a continental arc setting at 160–165 Ma, then shallower subduction by 135 Ma, and finally, emplacement of granitoids at 65–90 Ma.

Distribution pattern of picoplankton carbon biomass linked to mesoscale dynamics in the southern gulf of Mexico during winter conditions

Abstract: In order to characterize the carbon biomass spatial distribution of autotrophic and heterotrophic picoplankton populations linked to mesoscale dynamics, an investigation over an extensive open-ocean region of the southern Gulf of Mexico (GM) was conducted. Seawater samples from the mixed layer were collected during wintertime (February–March 2013). Picoplankton populations were counted and sorted using flow cytometry analyses. Carbon biomass was assessed based on in situ cell abundances and conversion factors from the literature. Approximately 46% of the total picoplankton biomass was composed of three autotrophic populations ( Prochlorococcus , Synechococcus , and pico-eukaryotes), while 54% consisted of heterotrophic bacteria populations. Prochlorococcus spp. was the most abundant pico-primary producer (>80%), and accounted for more than 60% of the total pico-autotrophic biomass. The distribution patterns of picoplankton biomass were strongly associated with the mesoscale dynamics that modulated the hydrographic conditions of the surface mixed layer. The main features of the carbon distribution pattern were: (1) the deepening of picoplankton biomass to layers closer to the nitracline base in anticyclonic eddies; (2) the shoaling of picoplankton biomass in cyclonic eddies, constraining the autoprokaryote biomasses to the upper layers, as well as accumulating the pico-eukaryote biomass in the cold core of the eddies; and (3) the increase of heterotrophic bacteria biomass in frontal regions between counter-paired anticyclonic and cyclonic eddies. Factors related to nutrient preferences and light conditions may as well have contributed to the distribution pattern of the microbial populations. The findings reveal the great influence of the mesoscale dynamics on the distribution of picoplankton populations within the mixed layer. Moreover, the significance of microbial components (especially Prochlorococcus ) in the southern GM during winter conditions was revealed, indicating that they may play an important role in the pelagic food web, and that they may have a substantial impact on the carbon cycle in oligotrophic regions.

Seasonal and Interannual Modulation of the Eddy Kinetic Energy in the Caribbean Sea

Abstract: Variability of the mesoscale eddy field in the Caribbean Sea is analyzed over the period 1993–2009 using geostrophic anomalies derived from altimeter data and a high-resolution regional model. The Colombia Basin presents the largest values of eddy kinetic energy (EKE) and its semiannual cycle, with a main peak in August–October and a secondary peak in February–March, is the dominant feature in the whole Caribbean EKE cycle. The analysis of energy conversion terms between low-frequency currents and eddies explains these peaks by enhanced baroclinic and barotropic instabilities, in response to seasonally varying currents in the region of the Guajira Peninsula. The semiannual acceleration of the atmospheric Caribbean low-level jet intensifies the southern Caribbean Current (sCC) twice a year in this region, together with its vertical and horizontal velocity shears. The asymmetry of the EKE seasonal cycle in the Colombia Basin is explained by a summer peak in the annual cycle of the whole sCC. Numeric...

Interconnection and damping assignment passivity-based control of a class of underactuated mechanical systems with dynamic friction

Abstract: This paper considers the extension of the interconnection and damping assignment passivity-based control methodology for a class of underactuated mechanical systems with dynamic friction. We present a new damping assignment approach to compensate friction by means of a nonlinear observer. Friction at the actuated joints is assumed to be captured by a bristle deflection model: the Dahl model. Based on the Lyapunov direct method we show that, under some conditions, the overall closed-loop system is stable and, by invoking the theorem of Barbashin–Krasovskii, we arrive to asymptotic stability conditions. Experiments with an underactuated mechanical system, the Furuta pendulum, show the effectiveness of the proposed scheme when friction is compensated. Copyright © 2010 John Wiley & Sons, Ltd.

Global regulation for robot manipulators under SP-SD feedback

Abstract: In this paper, we propose a simple controller: the saturated P-saturated D controller with gravity compensation to solve the global regulation problem under actuator torque constraints. The performance of the proposed controller is illustrated via simulations on a two degree-of-freedom robot.