Colombia is beginning in bioenergy and requires policies and infrastructure for the production of biofuels. In recent years, biofuels come forward supported by the adoption of law decrees that allow the introduction of biofuels, at first mixed with fossil fuels such as gasoline and diésel instance. This article “Topic Review” presents the beginning and development of biofuels in Colombia, as well as the current production situation, companies and organizations leading this project, in order to adopt a renewable and sustainable energy. In analyzing this issue on biofuels in Colombia a clear beginning to the independence of fossil fuels, with the premise of a sustainable energy matrix to ensure industry growth, social development and environmental protection is noted. On the other hand the trend is observed worldwide to adopting biofuels mainly oil-dependent countries, with South American countries like Brazil, Colombia and Argentina the champions in these proposals. Colombia in turn presented in this field of biofuels available land resources, labor, internal consumption and production policies; but with the existence of difficulties in social inequality, internal conflicts, monopolies and political barriers that could prevent private and foreign investment.

The praccis teaching’s strategy looks for, to translate dialogically, something strange, something from the world of science, into an approaching or perhaps something of his self, in the world of life. The scientist facts in this case, the strange thing, are the results of research on productivity in Ayapel´s swamp, Colombia, which is mediated by the praccis teaching strategy, in order to come closer to the people, who live in the same location, to facilitate the movement of knowledge. This research is made up of four parts: a first rigorously exposition of how productivity in Ayapel´s swamp is; a second which describes the praccis strategy; third which explains how to build the teaching strategy with knowledge from the marsh productivity and fourth, showing how the strategy was implemented and the results were that the semantic fields and their relationship with the links of the strategy praccis were attractive to residents of Ayapel.

En este artículo de reflexión, se analiza el diseño actual de las políticas ambientales en Colombia, las cuales se han centrado principalmente en el aprovechamiento de los recursos naturales como fuentes de materiales y energía para generar crecimiento económico. En este sentido, es evidente que la preocupación colectiva por el manejo de la oferta ambiental, como base para el desarrollo sostenible establecido en la Constitución, no ha logrado implementarse de forma efectiva, principalmente por el enfoque reactivo y coercitivo de las políticas y normativas vigentes, aunadas a un escaso fomento para la transformación del estilo de vida consumista nacional, situación que ha generado un efecto rebote incrementando los niveles de uso y consumo de los recursos naturales (especialmente de los denominados no renovables) y limitado la eficiencia energética; por ejemplo, esto puede observarse en el sector minero-energético nacional. Considerando que existe una preocupación global por la sostenibilidad, es necesario que el diseño de las políticas ambientales nacionales se aleje del optimismo económico y tecnológico del modelo económico vigente e incorpore, de forma cierta en sus políticas, estrategias que permitan equilibrar las relaciones de oferta y demanda de los servicios ambientales que sustentan el desarrollo nacional, alentando, al tiempo, el consumo responsable de la población colombiana, además de atender las iniciativas comunitarias de regulación e inclusión social en el manejo de los bienes y servicios ambientales para generar procesos de sostenibilidad fuerte.

Sewage sludge was added as part of ceramic slurry for making bricks. Raw materials (clay and sludge) were characterized in terms of chemical composition, mineralogical phases, thermal behavior and physical characteristics. Test tiles with up to 15% inclusion of sludge in the dry state of standard dimensions according Norma Técnica Colombiana (NTC) 296 and calcined at temperatures of 950 °C, 1000 °C and 1050 °C. In accord of the NTC 4017, compression resistance test, were performed in order to evaluate the effect on this property has the percentage amount of addition of the sludge. From environmental point of view, the safety of metals in sludge was evaluated by developing the Toxicity Characteristic Leaching Procedure (TCLP) test bricks made with the addition of the residue.

In this article evaluates the mechanical properties of composite materials based on fly ash and Coal-fired power plants Termozipa combined with the stretch film (stretch film), linear low density polyethylene post-consumer and partially thermoplastic polymer, crystalline Industrial post. Mixtures were obtained by varying the content of fly ash, 0 to 50 % by weight in each of the three polymeric materials, within a machine type Brabender mixer. The mechanical properties evaluated were: tensile strength, Shore D hardness, and energy absorption, the results obtained indicate that in all cases, as fly ash is added, the mechanical properties increase.

This article of scientific and technological research studies safety perception

on pedestrian bridges, through an approach based on two main areas: the microeconomic and psychological. This paper estimates simultaneously a hybrid model of choice and latent variables, with data from a stated preference survey, finding that this model fits better than a mixed logit reference model, which indicates that safety perception determines the behaviour of pedestrians when faced with the decision to use or not a pedestrian bridge. It was found that gender, age and educational level are attributes that affect safety perception. The calibrated model suggests several strategies to increase the use of pedestrian bridges, which are discussed, finding that the use of pedestrian barriers causes a loss of utility that should be studied as an extension of this work.

The electricity market has been developed in Colombia since 1995, has strengthened institutionally, its development has been dynamic, and also has solved different difficulties. Management systems, that support the market administration, have evolved following this development, however some of these are isolated from each other, or have been developed on different platforms making it difficult to ensure sustainability, maintenance and to incorporate changes. As referenced with other markets in the world, great dynamics is observed in incorporating information and communication technologies, regulatory developments or customer requirements. A technological renovation that preserves the acquired knowledge is required, and that allows easily incorporate the development trends of the market. This article presents the results of the proposed methodology for technological renovation framed in Colciencias CNBT 833559938649 technological research project, in management system for electric power market in Colombia, Phase I.

This paper present the result obtained in the research related the Eastern municipalities of Antioquia with special focus in the municipality of San Carlos about the transfer of the power sector delivered to them during the years between 2000-20012, for concept to the intensive use of natural resources of the region (water and earth) that the power company make in the regions with hydropower settlements. In conclusions, we observed a compensatory inequality in the municipalities studied due the criterion for delivering predominates transfers is the installed capacity and the watershed criterion above the reservoir criterion which is more closely related to the consumption of land, and is the most visible contribution of natural capital of the municipalities in hydroelectric settlements element

In this study a proposal to improve the inventory system for a distributor of food in the city of Santa Marta is made, in order to achieve a reduction in inventory costs and increased economic benefit of the organization, through planning and control of purchases and sales of products. The process used is the classification of the products handled by the Company with the ABC method according to importance of each product in the total sales of the distributor; then the model of Economic Order Quantity applies - CEP the right time, in order to systematize the newspapers counts on products stored in the warehouse, establishing records of sales, determine the optimum amount of orders, in which to order merchandise suppliers and minimum reorder quantities.

Air transport has been characterized for being one of the fastest growing sectors. This significant growth is a challenge for airport infrastructures in terms of capacity and management. The shift to commercialization and privatization of airports has followed the same path of the deregulation and privatization of airlines, but with certain delayed. One of the common reasons for these new processes is the improvement in efficiency levels in order to face a highly competitive industry. This reflection paper focuses on a generalized idea that considers the form of a firm ownership and its management model is positively associated to high levels of productivity. Studies addressed in the present paper are limited to those papers considering DEA as the technique of efficiency analysis for being one of the most accepted in the academic literature.

This paper presents the application of the Kanban methodology and analysis of the effect that this can generate in a manufacturing of distribution transformers. By applying the proposed methodology can be improved production scheduling, with the aim of reducing the amount of product in process is not used, so that inventory is reduced. To analyze the effect of applying the Kanban methodology in the company, the simulation technique was used, for which the current process and proposed to the rules of the Kanban methodology is modeled. From these results that yield modeling, it shows that there is an improvement in production lines where kanban methodology is used.

This article presents a case report about faults presented in power transformer cores and shows some technical and methodological experiences in partial and total repair to several units, carried out in Industrias Explorer Ingeniería S.A.S, a company dedicated to the maintenance and repair of power transformers. The methodology for the selection of foil type, court system, assemble, adjustment and pressing of the core are also presented, since these activities are crucial to get an equipment with fewer no-load losses, as well as lower levels of noise. The stages for the magnetic flux density calculation, test circuit for core saturation, considerations to thermographic inspection and no-load losses measurement, type foil selection and assembling technique employed are described. Some experiences are presented: partial core reposition, replacement core isolation of affected areas using Nomex fibers between sheets, total core replacement due to failure caused by poor cutting during manufacturing process, replacement of total core due to failure caused by double grounding that produced heating of it affecting the interlamination isolation between their sheets placing them in shortcut. In all cases there is a reduction on no-load losses. Finally the performance of power Transformers after been in service is presented and described.

This paper presents a result of research financed with own resources; It presents a state-space model of a three-phase controlled Active Front End rectifier. Using this model, we design a control law oriented voltage (VOC), directed to behavior as resistive load, unity power factor, which is tested by simulation using SimPowerSystem Toolbox in Matlab - Simulink ®.