Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

In the present paper is exposed the study of hydric erosion at 31 de Diciembre channel micro basin from Managua. The objective of the study was to determinate the hydric erosion in the rural area of the micro basin, with the Revised Universal Loss Equation (RUSLE), using the erosivity rainfall, the soil slope, soil type, soil use, and practices of soil conservation. An estimation of the RUSLE equation factors was made in a raster format, and with the raster tools from the spatial analysis of ArcGIS, a erosion rate map for the rural area was made. The study suggests that the mean annual erosion rate rage from 25 to 100 Ton/ (ha-year) in the middle side of the micro catchment, representing a high level of erosion, and range from 6 to 25 Ton/ (ha-year) in the upper side, that represent a moderate level of erosion.

The Computerized Numerical Control (CNC) is a technology that allows, through the use of a computer, to control and monitor the movements of a machine tool. The Superior Technological Institute of San Andrés Tuxtla (ITSSAT) has a CNC milling machine tool with European technology acquired by the state government in 2003 for engineering student practices. The machine was obsolete and out of operation, a situation that obligates not to use the CNC in practice for a while since the industries that manufacture them use licensed software and electronic cards that have a high cost for repair. The purpose of this article is to present a methodology for the restoration and start-up of CNC machines without having to resort to the manufacturer. The results show the methodology whose main function is the communication of the CNC machine with the PC through the implementation of the alternate software Mach 3 and the electronic card LPT-Mach 3 achieving the operation of the machine and the milling of materials with academic and industrial purposes.

One of cases considered for diagnosing DNA damages is diagnosing DNA probable damages against oxidizing agents, including oxidizing chemicals and various incident rays which cause the bases in the DNA to be oxidized and especially bases G in the DNA sequence which is more easily oxidized than the other bases. Therefore, the main objective of this comprehensive survey is to provide relevant information on measure physical chemical properties of nucleic acids during DNA radicalization and incidence of cancer using theoretical methods. The aim of the present study is to examine the single-stranded NBO with sequences of GG, CG, AA AG AC: AT CT GT TT followed by the levels of energy and form of orbital LUMO and HOMO obtained from Gaussian computations for above double-stranded sequences. Our results showed that form B genetic material is the most stable structure against physical and chemical agents. Only the number of molecular population and the levels of molecular dynamic vibration and molecular thermochemistry such as enthalpie and entropie are temperature independent. In addition to this, the gap between the layers and the potential and energy needed to oxidize the components in the two strands of DNA and its optimum structure will not change with temperature. Optimum conditions on DNA and its bonds are the temperature of 37 ° C and pH is 7 to 8.7. DNA has form B and the rate of physical protection is the highest.

El Cacao Community, municipality of Mozonte, Nueva Segovia department is located to 234 km from the capital Managua. In winter they feed of the water of creeks and gullies, while in summer they feed of a water eye where there are some minimum installations for storage and distribution. Physicochemical studies, microbiological, pesticide and wave metals; determined the presence of diverse types of pollutants from chemically nature principally microbiological in these waters. It has shown that 123 persons use the source in study (54 % adults, 43% child and 3 % elders). The applied surveys to 24 family heads form El Cacao Community, show a relation between sanitary education and quality of the water, because the people lack of the knowledge of the hygienic sanitary procedure orientated to improvement of the living conditions. Demonstrating this way, the existing relation between educational level and the family´s income levels with the conditions of health observed and their relation with the water management form the source until the home. Concluding that the life expectancy of the persons in this community is low and this one below the national value (75.1 years).

This article will present the design and implementation of a plant in an industrial company that allows the reuse of solid waste from the tanning process during the process of making hides for use in a complementary process. The problems that arise when not having this type of process is incurring in extra costs to outsource services for the disposal of these wastes, contributing to the increase of pollution in the city. To implement this improvement, it will be necessary to carry out a preliminary analysis to be able to elaborate the most optimal plant design proposal that fits this process. The production line is made up of four Units, the first Raw Material Conditioning Unit; the second Mixing and Molding Unit; the third Pressing and Drying Unit, and finally the Finishing Unit.

This paper deals with the importance of research competence in university students studying some engineering and a proposal for their development. The methodology used was developed in three phases, the first phase consisted of identifying the problem of lack of research in the countries of Latin America, for this purpose, research rankings, rankings of research centers and ranking of universities were analyzed, because they are the spaces where research should be developed in each country. The second phase consisted of making the state of the art about the efforts made in each country to achieve research competence. The third phase was the description of the proposal of research seedbeds for the development of said competence. The main result was the proposal of research seedbeds for the development of the research competence in engineering, which is being applied at this moment. In conclusion we have that the binomial of the research nurseries and the combined learning will allow to develop the research competence in engineering students.

The helical coil heat exchangers are employed in several applications due to their compact structure and the high heat transfer coefficients usually obtained. In the present work, the design of a helical coil heat exchanger is accomplished in order to carry out the cooling of a liquid acetone stream. The equipment will has an overall heat transfer coefficient of 23.88 kcal/h.m2.ºC; a heat transfer area of 6.60 m2; an actual number of turns of coil equal to 53; and a height of 2.58 m. Both the acetone and the water stream do not exceed the maximum pressure drop established by the process.  The influence of increasing both the acetone feed flowrate and inlet temperature on four design parameters of the helical coil heat exchanger: global heat transfer coefficient, heat transfer area, actual number of turns of the coil, and height of the equipment, was also determined, obtaining as a result that the increase of the two initial variables increases the values ​​to be obtained of these four parameters. Excel spreadsheets were used to obtain the graphics and to solve the design methodology used in this study.

In the present study an evaluation of the effect of four additives on the ceramic body is made: fly ash, talc, kaolin and feldspar; with the objective of determining the best formulations that allow to develop, after the thermal cycle and without modifications to the current production process of a certain ceramic company, microstructures that increase the mechanical resistance of semigres ceramic tiles. The obtaining of the ceramic test pieces was carried out using the procedure and the formulation proposed by the production company. The properties studied were linear contraction percentage, water absorption and mechanical resistance to bending. The corresponding tests were carried out in accordance with the corresponding standards. The highest value of mechanical resistance to bending was 57.91 N / mm2 corresponding to ceramic specimens with the optimized formulation: standard body plus 2% talc and 2% kaolin.

In this paper the study of erosivity rainfall factor in the Xolotlán Lake sub catchment is exposed, that belong to the 9525 catchment from Nicaragua. The objective of the study was to determinate the Revised Universal Loss Equation (RUSLE) erosivity factor”, from daily pluviograph data of the station 69027 (Managua Airport) and monthly pluviometric data in 7 stations distributed in the sub catchment and nearby. A simple lineal regression was done with the monthly R and monthly precipitation, with a correlation coefficient of r2 = 0.86.  Since in the sub cathcment there is only one pluviograph station, the Modified Fournier Index was used to estimate de R values in the pluviometrics stations. The study suggests that the annual mean erosivity factor rage from 5,000 Mj mm / (ha-h-year) in the lower side of the sub catchment to 7,250 in the upper side, that represent a rain with a moderate erosivity power.

Industrial arms should be able to perform their duties in environments where unpredictable conditions and perturbations are present. In this paper, controlling a robotic manipulator is intended under significant external perturbations and parametric uncertainties. Type-2 fuzzy logic is an appropriate choice in the face of uncertain environments, for various reasons, including utilizing fuzzy membership functions. Also, using the neural network (NN) can increase robustness of the controller. Although neural network does not basically need to build its type-2 fuzzy rules, the initial rules based on sliding surface of higher order sliding mode controller (HOSMC) can improve the system's performance. In addition, self-regulation feature of the controller, which is based on the existence of the neural network in the central type-2 fuzzy controller block, increases the robustness of the method even more. Effective performance of the proposed controller (IT2FNN-HOSMC) is shown under various perturbations in numerical simulations.