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Villarreal A.,Rafael Maria Baralt National Experimental University | Nozawa S.,Central University of Venezuela | Gil B.,University of Zulia | Hernandez M.,University of Zulia
Acta Botanica Venezuelica | Year: 2010

The composition and dominance of weeds in an urban area were determinated as a significant contribution to the regional flora and the study of weeds of ruderal areas, native or exotic. Collections were made from May 2006 until May 2007. It was identified 85 species, distributed in 66 genera and 30 families, of which Chamaecrista pilosa, Cleome viscosa and Evolvulus frankenoides were new weeds for Zulia State. Families with higher number of species were Poaceae with 17, Fabaceae s.s. 10, Euphorbiaceae seven and Cyperaceae with five. The five dominant species according to the IVI were Cenchrus ciliaris with 34.4%, Sida salviifolia (7.1%), Merremia quinquefolia (6.4%), Portulaca pilosa (5.2%) and Stylosanthes hamata (5.0%). Source

Castellanos M.I.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas | Castellanos M.I.,Rafael Maria Baralt National Experimental University | Duque Z.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas
Acta Microscopica | Year: 2013

In natural media the aluminum has high corrosion resistance. However, in saline environments, it has been shown that alloys like 3003 have a high susceptibility to pitting corrosion. Generally, these alloys are susceptible to this type of corrosion by formation of galvanic cells between the intermetallic particles present in the alloy and the aluminum metal matrix. Currently, we have no studies to indicate its behavior in lacustrine media as Maracaibo Lake, which has significant levels of chloride (1300 mg / L) and microbiota promoter of biofouling. Hence there is a concern to assess the potential of Al 3003, available on the domestic industry, and of interest for use in the construction of water transport units for operation in this lake. To this end, in a first phase, biofouling and aggressiveness were studied on the 3003 alloy in laboratory and field conditions, using isolated heterotrophic biomass culture isolated from probes exposed in the Lake. Analyses consisted of microbiological, electrochemical and microscopic techniques. The results indicated that under the studied conditions the Al 3003 showed a tendency to decrease and stabilize the speed and potential of corrosion. The SEM micrographs showed the development of a population in the materials without localized damage. From this an apparent resistance to the conditions evaluated is deduced. Source

Aboukheir H.,Rafael Maria Baralt National Experimental University
IEEE Latin America Transactions | Year: 2010

The continuous advances in systems theory have been based on precise process models, experimental models who includes the information of actuators, sensors, uncertainties and nonlinearities. The study presented as follows is focused on the development of a technique for closed loop identification using Youla Parametrization combined with Neuro Fuzzy nets. The proposed methodology have been evaluated over SISO and MIMO plants achieving great precision on the different cases where is tested, resulting on an excellent option for process models construction for development of new theories in control design. © 2005 IEEE. Source

Aboukheir H.,Rafael Maria Baralt National Experimental University
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2012

In recent years, fractional order systems have begun to attract the attention of the worldwide scientific community, the reason lies in the fact that many real systems can be characterized more accurately by using dynamic models of non-integer order, this work arise to describe the fundamentals of fractional order discrete system in a state space representation, later to design the predictive control law by building a new structure for the prediction, and the specification of a fractional cost function which is minimized to obtain the corresponding controller, the proposal is evaluated through simulations. © 2012 IFAC. Source

Rafael Maria Baralt National Experimental University | Entity website

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