Simón Bolívar University

About: Simón Bolívar University is a education organization based out in Caracas, Venezuela. It is known for research contribution in the topics: Population & Crystallization. The organization has 5912 authors who have published 8294 publications receiving 126152 citations.

Artificial Neural Networks for Surface Roughness Prediction when Face Milling Al 7075-T7351

Abstract: In this work, different artificial neural networks (ANN) are developed for the prediction of surface roughness (R a ) values in Al alloy 7075-T7351 after face milling machining process. The radial base (RBNN), feed forward (FFNN), and generalized regression (GRNN) networks were selected, and the data used for training these networks were derived from experiments conducted using a high-speed milling machine. The Taguchi design of experiment was applied to reduce the time and cost of the experiments. From this study, the performance of each ANN used in this research was measured with the mean square error percentage and it was observed that FFNN achieved the best results. Also the Pearson correlation coefficient was calculated to analyze the correlation between the five inputs (cutting speed, feed per tooth, axial depth of cut, chip’s width, and chip’s thickness) selected for the network with the selected output (surface roughness). Results showed a strong correlation between the chip thickness and the surface roughness followed by the cutting speed.

A review of diode and solar cell equivalent circuit model lumped parameter extraction procedures

Abstract: This article presents an up-to-date review of several methods used for extraction of diode and solar cell model parameters. In order to facilitate the choice of the most appropriate method for the given particular application, the methods are classified according to their lumped parameter equivalent circuit model: single-exponential, double-exponential, multiple-exponential, with and without series and parallel resistances. In general, methods based on numerical integration or optimization are recommended to reduce the possible uncertainties arising from measurement noise .

Etnobotánica médica de una comunidad campesina del estado Trujillo, Venezuela: un estudio preliminar usando técnicas cuantitativas.

Abstract: In order to document the relative importance of medicinally used taxa, the use of medicinal plants in a rural community in Trujillo State, Venezuela, was quantitatively evaluated. The diagnostic of the most common health problems was made with the help of information provided by the state’s Direction of Epidemiology. Ethnopharmacological information was gathered through interviews at the homes of the participants, using the TRAMIL structured interview. Ethnopharmacological data was analyzed using the quantitative indexes of use value for each species (UVIs) and significative level of use (TRAMIL). 32 species of medicinal plants from 25 botanical families were recorded as well as their traditional uses and modes of administration. Among them 10 species are wild and 22 species are cultivated plants. PALABRAS CLAVE

Endophytic microorganisms for biocontrol of the phytopathogenic fungus Botrytis cinerea

Abstract: Botrytis cinerea is the most widely studied necrotrophic phytopathogenic fungus. It causes economic losses that are difficult to calculate due to the large number of hosts. While there are a wide array of fungicides on the market to control this phytopathogen, they are not considered sustainable in terms of the environment and human health. The search for new alternatives to control this phytopathogen has led to the use of endophytic microorganisms as biological control agents. Endophytic bacteria and endophytic fungi have been isolated from different plant species and some have proven effective in inhibiting B. cinerea. Furthermore, a significant number of fungistatic or fungicidal metabolites which could be used as alternative complementary chemical controls have been isolated from these fungi and bacteria. In this review, in addition to the metabolites which have shown fungicide activity against this phytopathogen, the different genera and species of endophytic bacteria and fungi are also considered. These have been isolated from various plant species and have displayed antagonistic activity against B. cinerea.