Tecnura

15-31

Authors: Amaury Pérez Sánchez, Eddy Javier Pérez Sánchez, Rutdali María Segura Silva

Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried out by using the process simulator CHEMCAD® version 5.2.0, in order to determine the composition and mass flow-rate of each process involved in the production, as well as the main operating parameters of the equipment used. Two sensitivity studies were carried out: firstly, the influence of the temperature and pressure values applied at the LLV Separator on the amounts of ethyl-benzene and styrene to be obtained by the intermediate and top currents of this equipment; secondly, the influence of the operating pressure of the Distillation Column No. 1 (benzene-toluene column) on the quantity of ethyl-benzene and styrene obtained at the bottom stream. The simulating software MATLAB® version 7.8.0 was used to process the results obtained. Results: Around 9234.436 kg/h of styrene is obtained in the last distillation column with 99.6% purity. Additionally, it was found that the water is the main impurity found on this stream, which represents 0.35% of the weight. Conclusions: The LLV Separator must operate at a low temperature (5 – 10 ºC) and at a relatively high pressure (10 bar), whereas the Distillation Column No. 1 must work at a pressure near atmospheric (1.0 bar), or preferably under vacuum conditions in order to obtain the highest yields of styrene and ethyl-benzene.

47-60

Authors: Alfonso James Alzate Gomez, Andrea Bedoya Londoño, Jesser James Marulanda Durango

Context: Reducing the oscillations of the electrical power systems is an important task in order to maintain their stability. This paper presents a methodology for adjusting the parameters of a fuzzy oscillations controller with a Static Var Compensator (SVC) and a Static Synchronous Compensator (STATCOM). Methodology: The methodology consists of tuning a fuzzy controller to dampen oscillations in an electrical power system, with different optimization techniques such as: Genetic Algorithms (GA), Particle Swarm Optimization (PSO), and Chaotic Optimization Algorithm (COA). Results: The voltage and speed oscillations of a system composed of a synchronous machine connected to an infinite bus bar (SMIB) are obtained through simulations. There is data before and after connecting a SVC and a STATCOM, installed independently and in different operating conditions. The results obtained show that using a technique for adjusting parameters in the fuzzy controller is better than the adjustment of trial and error. Conclusion: With the obtained results, it is possible to verify the effectiveness of the fuzzy controller using Flexible AC Transmissions Systems (FACTS).

78-95

Authors: Mauricio Castro Franco, Dayra Yisel García Ramírez, Andrés Fernando Jiménez López

Context: Interpolating soil properties at field-scale in the Colombian piedmont eastern plains is challenging due to: the highly and complex variable nature of some processes; the effects of the soil; the land use; and the management. While interpolation techniques are being adapted to include auxiliary information of these effects, the soil data are often difficult to predict using conventional techniques of spatial interpolation. Method: In this paper, we evaluated and compared six spatial interpolation techniques: Inverse Distance Weighting (IDW), Spline, Ordinary Kriging (KO), Universal Kriging (UK), Cokriging (Ckg), and Residual Maximum Likelihood-Empirical Best Linear Unbiased Predictor (REML-EBLUP), from conditioned Latin Hypercube as a sampling strategy. The ancillary information used in Ckg and REML-EBLUP was indexes calculated from a digital elevation model (MDE). The “Random forest” algorithm was used for selecting the most important terrain index for each soil properties. Error metrics were used to validate interpolations against cross validation. Results: The results support the underlying assumption that HCLc captured adequately the full distribution of variables of ancillary information in the Colombian piedmont eastern plains conditions. They also suggest that Ckg and REML-EBLUP perform best in the prediction in most of the evaluated soil properties. Conclusions: Mixed interpolation techniques having auxiliary soil information and terrain indexes, provided a significant improvement in the prediction of soil properties, in comparison with other techniques.

107-118

Authors: Oscar Mauricio Salazar Ospina, Paula Andrea Rodríguez Marín, Demetrio Arturo Ovalle Carranza, Néstor Darío Duque Méndez

Context: There are many repositories that allow searching and retrieving learning objects, so a lot of learning resources can be accessed. However, it is required to improve the presentation and visualization of those learning resources considering the student’s preferences, needs, and cognitive features. Method: The aim of this paper is to incorporate a customized interface with an adaptive multi-agent system for learning objects recommendation from local and remote repositories based on the student’s cognitive profile. Results: The prototype validation was made through a case study in which the interface has adapted not only the presentation but the visualization of learning objects taking into account the student’s preferences, needs and cognitive features. Conclusions: We can conclude that personalized adaptive interfaces demonstrate their efficacy and represent a great contribution to e-learning environments since they modify in real time the visualization and presentation of educational resources using the student’s cognitive profile.

138-140

Authors: Fernando Quevedo García, Yefer Asprilla Lara, Mario Guadalupe González Pérez

Context: Empirical evidence shows that vehicle ownership has increased exponentially in the last fifteen years in the Metropolitan Area of Guadalajara, amounting more than two million vehicles. Moreover, a high percentage of these vehicles is very old and lack air-pollution control systems such as catalytic converters. The goal of this paper is to meditate about motorized transport in the second largest city in Mexico. Method: A descriptive analytical method was used to review data and information from governmental and non-governmental sources. Air contaminants are related to car ownership increment, county multi-modal transport distribution, registered vehicles, and the amount of vehicles that have been verified and certified by the government air quality program. From a systems theory point of view, current scenarios are analyzed and inferences are made. As a result, there are balancing and unbalancing forces that affect the homeostasis of this metropolitan area. Results: Air-quality regulations have failed to echo among their citizens that neglect to tune up and verify emissions from their vehicles. Therefore, government officials and the society itself must reconsider their efforts and renew air quality policies based on low emissions, safe, reliable, and sustainable transportation to avoid air quality contingencies. In addition, data clearly suggests that land and urbanistic planning has not followed a systemic approach. Conclusions: Guadalajara metropolitan area clearly shows a lack of a systemic methodology in planning its urbanistic and land development. Hence, a perverse synergy of hostile conditions have emerged within its territory and internal combustion vehicles are the most important destabilizing force in the homeostasis of the city increasing entropy. The presence of this entropy is forcing the inhabitants in Guadalajara to migrate to a multi-modal sustainable transportation system, and start a systematic car substitution program that ensures zero or very low vehicle emissions.