Tecnura

27-41

Authors: Diego Alejandro Díaz Tamayo, Alejandro Garcés Ruiz , Diego González Ocampo

Context: Economic dispatch is classic methodology in power systems which is studied in stationary state despite being a dynamical problem. Method: This paper presents a methodology that considers this problem by including transient stability constraints. The mathematical model includes a set of ordinary differential equations which describes the dynamics of the systems after a failure. Due to the high complexity of the problem, we used an algorithm of Particle Swarm Optimization (PSO) to consider all the elements of the proposed model. Results: The algorithm has proved to be fast and generated good quality solutions. The proposed methodology was evaluated in the IEEE 39 node system of New England. Conclusions: The results demonstrated a reduction in the operative costs with a guaranteed stability index. Additionally, the computational time is low enough for the method to be implemented in real power systems

57-66

Authors: José Luis Suarez Castañeda, José William Restrepo Montoya, Adriana Quinchía Figueroa, Fredy Andrés Mercado Navarro

Context: This research focuses on determining the surface composition of different plant fibers in order to evaluate their possible use as reinforcement in polymer matrix composites. For this, a search was made for several types of fibers, as well as an analysis of their morphology before and after alkaline treatment. Method: The search was carried out within the metropolitan area of the Aburrá Valley, Colombia. For the treatment of the fibers, we performed, in first place, an immersion in dissolved NaOH at 6% w/v for 48 hours; secondly, a neutralization in 1% v/v acetic acid for one hour; and thirdly, they were dried at 60°C for 24 hours. Additionally, the techniques used for the analyzes were Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Results: Fique, Jute, Coconut husk, Flax and Cotton fiber fabrics were selected. FTIR analyzes show a trend towards the decrease of fatty acids, hemicellulose, lignins and β-bonds on the surface of the fibers, whereas SEM images show the removal of impurities, the exposure of roughness, and the creation of interfibral spaces. Conclusions: Alkaline treatment could favor both the anchoring mechanism of the thermosetting polymer to the surface of the fibers and the creation of bonds between the polar molecules of the fibers and the thermosetting polymer. This could reduce the relative slip between matrix and reinforcement during the application of loads

96-104

Authors: Fredy Hernán Martínez Sarmiento, Diego Armando Giral Ramírez

Context: The control and navigation systems of autonomous robots constitute a dynamic field of research in robotics. The possible solutions to problems are often evaluated with laboratory prototypes in order to determine their real performance. We propose in this paper an architecture for the design and development of robotic systems (particularly autonomous multi-robot Systems) that facilitate the work in laboratory due to an open robust and reliable architecture. Method: The architecture is supported in open source hardware and software. The operation and communication strategy is characterized by a low consumption of resources, both in processing and communication, and real-time operation. As developement platform and Operating System, we used Linux: the communication scheme and the embedded systems run on a 32-bit processor, with a 16-bit instruction set (not ARM, but with Harvard architecture), at 80 MHz (Tensilica Xtensa LX106) for the implementation of the agents. The tools used allow the solution to be bothe efficient and inexpensive. Results: The architecture has been successfully applied in the implementation of a strategy of navigation for a set of small autonomous robots. A set of robots were provided with wireless communication capability, minimum capacity of environmental sensing (obstacle detection) and a navigation algorithm based on population sizes (mimicking the bacterial Quorum Sensing). The system is implemented with great ease, demonstrating both the viability of the navigation strategy and the versatility, robustness and scalability of the OpenRRArch architecture. Conclusions: The proposed architecture constitutes a solution for the construction of distributed control systems, in particular multi-agent robotic systems. It enables the rapid, low-cost and high-performance implementation of systems with real-time cooperation and communication capabilities. The architecture allows the integration of agents with different processing capabilities, which allows adaptation to the needs of the task. The functions of each agent can be reduced or increased from their code, and/or by selecting other embedded hardware.

118-131

Authors: Gustavo Guerrero Gómez, Edwin Espinel Blanco, Heller Guillermo Sánchez Acevedo

Context: Since the estructural behavior of the walls in a building directly depends on the properties of the blocks used, these properties are very important. In particular, the final properties of a ceramic block (often used in masonry) depend on the cooking temperature of the pulp. Objective: The purpose of this research is to determine the relationship between the final properties of a ceramic block and the temperature at which it was cooked. Additionally, it is wroth considering how quickly these temperatures vary in the kiln. Method: In first place, a system based on Labview was used to record the temperatures in the oven. In second place, it was considered the temperature increasing rate according to the ideal curve for baking blocks, which was classified inside the oven. In third place, samples of the product were taken according to the technical norms NTC 4017 and NTC 4205 in order to determine the properties of the block. Results: According to the samples, we determined: the Initial absorption of water (TIA), the absorption rate at 24 hours of immersion, the compressive strength, and the Modulus of Rupture (MR). Additionally, applying a multiple linear regression analysis, it was found a relationship between the TIA, the temperature increase rate, and the MR. Conclusions: From the results in the research, it is possible to conclude that: blocks baked at more than 1000 °C have the highest modulus of rupture (1.54 MPa); however, it was found that blocks baked at lower temperature presented the highest initial absorption rate (0.37 gr/cm2/min) and the best compressive strength (7.28 MPa). Finally, since the temperature and time are not controlled during the baking process, it is difficult for properties to be the most suitable.