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The effect of non-pharmacological interventions to contain the spread of SARS-CoV-2 have caused negative impacts, especially in education. Re-opening schools and universities is regarded as a high risk scenario. This paper seeks to understand, with the help of mathematical modeling, possible mechanisms through which the virus could spread in an academic environment and to quantify contagions attributable to participating in academic activities. To simulate the dynamics of contagion at the University, an agent-based mathematical model that incorporated stochastic differential equations was built using academic data for the University's 2020-2 semester. The model suggests that hybrid-attendance combined with epidemiological surveillance can produce very safe operating conditions without significantly contributing towards more COVID infections in the city of Bogotá. [ABSTRACT FROM AUTHOR]

For almost a year, humanity has been threatened by the new coronavirus known as SARS-CoV-2, which originated in China, and from there has spread to almost all regions around the globe. The incidence and mortality of this dangerous virus, which have recently increased in countries like Colombia, has overwhelmed public health systems and has created enormous difficulties and challenges at the economic, social, and political levels. With the aim of quickly finding treatment alternatives, running parallel to prevention initiatives spurred by the arrival of an effective vaccine, computational biology and computer-aided technologies have now been playing a booming role and have rapidly positioned themselves as key players in the pharmaceutical industry. This paper presents the main findings of a study focused on designing and discovering new agents with inhibitory capacity against the new coronavirus, describing the methodological strategy employed and presenting the implications, challenges, and future perspectives associated with finding a molecule with promising therapeutic potential. [ABSTRACT FROM AUTHOR]

This paper presents the results of four electromagnetic compatibility (EMC) tests carried out in the anechoic chamber of Universidad de los Andes (Bogotá, Colombia) on mechanical ventilators manufactured by different Colombian initiatives responding to the COVID-19 emergency. The four tests were carried out in accordance with the IEC 60601-1-2 product standard. The tests were the following: radiated immunity in the 80 MHz to 1000 MHz frequency, according to generic standard IEC 61000-4-3; radiated immunity at specific frequencies of 385 MHz, 450 MHz, 710 MHz, 745 MHz, 780 MHz, 810 MHz, 870 MHz and 930 MHz, in accordance with generic standard IEC 61000-4-3; conducted emissions, in accordance with the CISPR 11 standard; and radiated emissions, in accordance with the CISPR 11 standard. It describes the standards used to carry out the tests, the experimental setup used in each test, the observed results and the mitigation measures required to pass the tests. The results are discussed and necessary measures are suggested to promote the development of electromagnetic compatibility in Colombia. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of an isolated microgrid developed in La Guajira, north of Colombia. It was designed through the collaboration and capacity building of the community itself. Several activities were developed by the research group in order to improve the technical design. With the objective of reaching a consensus in terms of the final desgin, several visits were made to the community. During the implementation, some new ideas on how to improve the design appeared. In any case, if the microgrid (that uses both solar and wind energy) would be replicated in any other location, we strongly recommend to include, from the beginning, the community needs and the ideas of its inhabitants. [ABSTRACT FROM AUTHOR]

The execution of the programs directed to the improvement of the tertiary road network depends to a large extent on four entities: the ANI, the INVIAS and the Ministries of Transportation and Postconflict. In this article, which is an adaptation of his paper in the Forum Tertiary Paths for Peace, Luis Fernando Andrade, President of the ANI, says that innovation is necessary in paving methods, in the efficient use of materials that once Have been ignored and the role that academia has in this goal. And, on the other hand, the importance of linking communities in the construction and maintenance of the roads they use daily for the development of their family economies and access to basic services. [ABSTRACT FROM AUTHOR]

The National Federation of Coffee Growers (FNC) is the largest coffee growing organization in the country, and it assembles coffee growers from departments including Caldas, Antioquia, Quindío, and Risaralda. It has spent the past ninety years ensuring improvement in the quality of life for the people living in these areas. One of the FNC's many undertakings that should be emphasized is the construction of road infrastructure that allows for coffee to transported and therefore sold and the social development of the communities in its areas of influence. This paper is written by Mauricio Medina, the leader of the FNC's Social Development Unit, who emphasizes that if the projects are to be successful, it is necessary to turn to these types of experiences for post-conflict investments. [ABSTRACT FROM AUTHOR]

This paper presents UnaGrid/UnaCloud: an opportunistic computing infrastructure solution, which provides fundamental computing resources (processing, storage and networking) on demand and at lower cost, to support academic and e-Science projects. The proposed computing infrastructure is provided through the opportunistic use of idle computing resources available in a university campus. This paper describes the architectures defined, implementations deployed and test cases. The results obtained evidence high efficiency in result generation, improving limitations of projects depending on the agile provision of large computational capabilities, including scientific and academic initiatives. [ABSTRACT FROM AUTHOR]

This paper studies a series of practices and experiences taken from massive regional infrastructure projects sponsored by the IDB (Inter-American Development Bank). In an effort to contextualize the idea of a megaproject, it describes what one is, demonstrates its importance to the community where one is built, and investigates the relationship between the community and the megaproject itself. In addition, the paper takes a deep look at regional experiences, the training required to execute large projects, and other associated needs. Furthermore, insight is given on key elements of project preparation, types of organic changes that take place in project execution, and how these changes can be anticipated. Lastly, a few brief case studies of regional experiences are given to emphasize various lessons learned. [ABSTRACT FROM AUTHOR]

The Electrified Mass Rapid Transit Systems (EMRTS) are one of the possible alternatives in solving mobility problems in urban and interurban areas. In this paper, we present the theory which allows modeling and determination of the EMRTS electric load, which serves as a base for the development of a computing model. The paper presents two examples of application: a tramway line and a subway line, from which we can observe the energy supply requirements of these EMRTS to the electric distribution system. [ABSTRACT FROM AUTHOR]

Water Distribution System operation involves two issues that have large economic repercussions: pipe renewal and rehabilitation and reduction of Non-Revenue Water (NRW). This paper presents an algorithm that, based on the unitary power concept, selects the most important pipes to be replaced in order to reduce the dissipated power and the NRW, while keeping the pressure surface levelled. Additionally, the proposed methodology finds an ideal renewal scheme in terms of economic benefits and profitability. This paper includes two case studies in which the proposed methodology proved to be successful, achieving renewal schemes both profitable and hydraulically optimum. [ABSTRACT FROM AUTHOR]

UML, SysML, and WebML are graphical modeling languages (GML). Despite their similarities, these languages cannot be jointly interpreted, since they exhibit different kinds of models and diagrams. Some studies for examining the features of some GML are proposed in the state of the art, but applied to individual languages, avoiding the common features among such languages. In this paper, we propose an ontology design and implementation for summarizing GML concepts and relations. We use a methodology created in the Stanford University. The developed ontology can successfully answer 35 competence questions, some of them exemplified in this paper. [ABSTRACT FROM AUTHOR]

This paper describes the development of a computer application for production planning and scheduling in a Colombian auto part company. Such an application integrates sales forecasts and firm orders, to calculate a Master Production Schedule which is validated with a detailed shop floor scheduling plan. A case study illustrates the functionality of the proposed application and compares the computer-calculated production plans with the current practices. The results show that the implementation of the application can improve service levels and customer satisfaction, given some prerequisites described in the paper are met. [ABSTRACT FROM AUTHOR]

In the dynamic systems a fail can occur in any moment, the fail can be present for variations in one or more parameter of the dynamic system. This paper present a fail detection in a non linear system compose by two tanks in parallel one with constant transversal area and the other one with variable area, the work is develop with adaptive observers and LAMDA classification. The application on this paper is in a non linear system, the level control in the two tank system. [ABSTRACT FROM AUTHOR]

This paper shows the evaluation and design of traditional traverse flute through experimental and computational engineering analysis. This work required the study of the dynamic and acoustic parameters that govern the behavior of this type of instrument. A flute, as a musical instrument, must have certain sonorous and anatomical qualities for a pleasant performance by the player, as well as to the listener. The study of vortex generation caused by air entrainment in the tube is found to be of great importance, as it is shown in this paper. Basic engineering design criteria are presented for the improvement and construction of wind musical instruments, such as pipe-organs, quenas, ocarinas, to quote just a few. [ABSTRACT FROM AUTHOR]

Performance evaluation of communications systems is usually done by analytical techniques or simulation. The analytical approach is normally based on a probabilistic description of the system operations in terms of Markovian processes or queuing systems, but only is directly applicable for simple systems, or simplistic models of complex systems. Simulation is a powerful tool but requires enormous computations to yield accurate performance estimators. In this paper we present an alternative technique: Petri Nets, a graphical and mathematical modeling tool applicable to many systems. We used Stochastic Petri Nets to model and evaluate queuing systems and some protocols. Simple and accurate models were developed. The main definitions relating Petri nets in general, and to the particular classes of Petri nets are summarized in Section 1. The following sections contains queuing models (Section 2), Stop and Wait and Aloha protocols (Section 3), DSP protocol (Section 4). Section 5 concludes the paper. [ABSTRACT FROM AUTHOR]

This paper presents the results of the study that evaluates the incorporation of FACTS technologies in the expansion planning process of the Colombian National Transmission System (NTS). The application methodology uses as starting point the optimization of the exploitation of the existing system by increasing its transmission capacity and it is based on steady-state analysis. This paper presents the results of the feasibility study for a wide application of FACTS systems in the Colombian Transmission System for improving transmission capabilities and reliability and security levels after year 2005. [ABSTRACT FROM AUTHOR]

This paper describes some approaches for the water balance modeling of fluvial and coastal wetland systems, where one or more water bodies are interconnected, interacting with a river and/or the sea. The modeling methodology is based on the continuity equation and the hydraulic behavior of the connection channels. In this paper, the models for four wetland systems located in the Lower Magdalena River floodplain are presented. Typical results are included to illustrate the type of information these models can give to contribute to the knowledge of the dynamics of these fragile ecosystems, their recuperation, preservation, exploitation and sustainable management. [ABSTRACT FROM AUTHOR]

The long-standing conflict in Colombia has inflicted substantial costs on the population and the economic development of the country. Since conflict occurs mainly in the country's rural areas, the economic impacts of violence are higher for these territories. The purpose of this paper is to describe the impact of armed conflict on Colombia's rural population and the current conditions of rural areas as well as discuss whether the peace agreements with FARC may contribute to improve these conditions. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the role of engineering and research in the environmental licensing process in the light of institutional changes made in Chile since 2010: the creation of the Ministry of Environment and the Environmental Assessment Service. To do this, we will show the challenges posed by these new institutions, the opportunities identified and the work undertaken to address those changes. Finally, the results will be presented taking the Punta Alcalde project as a model. [ABSTRACT FROM AUTHOR]

Satisfaction is a dimension of usability for which quantitative metrics cannot be calculated during user interactions. Measurement is subjective and depends on the ability to interpret questionnaires and on the memory of the user. This paper represents an attempt to develop an automatic quantitative metric of satisfaction, developed using a Brain Computer Interface to monitor the mental states (Attention/Meditation) of users. Based on these results, we are able to establish a correlation between the state of Attention and the users' level of satisfaction. [ABSTRACT FROM AUTHOR]

Colombian amazon has a wide biologic diversity, with silvester and cultured species which use potential and abundance identified them as an important bioactive compounds source. That represents a wide opportunity to innovate and develop processes and technologies in different engineering fields (chemical, mechanical and food engineering). This paper presents experiences when the problem of sustainable use of biodiversity is tackled from engineering in the Colombian amazonic region. [ABSTRACT FROM AUTHOR]

The aim of this paper is to generate photogrammetrie products and to automatically map buildings in the area of interest in vector format. The research was conducted Bogotá using high resolution digital vertical aerial photographs and point clouds obtained using LIDAR technology. Image segmentation was also used, alongside radiometric and geometric digital processes. The process took into account aspects including building height, segmentation algorithms, and spectral band combination. The results had an effectiveness of 97.2% validated through ground-truthing. [ABSTRACT FROM AUTHOR]

The last stage of classical transport modelling, known as the sequential model of the four steps, estimates the flow pattern of the system. Then, in a post-processing phase all measures of system performance such as the level of service and externalities are estimated. This paper compares the estimated BPR and conical volume-delay with data taken in six multilane roads in Bogota, finding ranges of recommended function parameters values. We concluded that the values traditionally used for these functions are not the best for explaining the congestion that occurs in the environment studied. [ABSTRACT FROM AUTHOR]

The planning and management of port terminals traditio-nally done using management and operating ratios drawn from international experiences ratios not specifically for certain specific port systems, so it is difficult to plan and manage the exploitation of the Spanish containers termi-nals as very heterogeneous. The purpose of this paper is to show the application of a new methodology, in this case, artificial intelligence, through the use of probabilistic gra-phical models to determine optimal operating parameters and port planning, through the classification of the termi-nals by adding the inference virtual scenarios. [ABSTRACT FROM AUTHOR]

This paper provides an analysis of two cases of new infrastructure consolidation in industrial areas. The first involves the restructuring of industrial infrastructure in intraurban areas of Montreal in Quebec, Canada, carried out as a part of the technological upgrading process characteristic of transitions from industrial to knowledge-based societies. Local planning processes were identified that took into account the contribution of all social actors to a sustainable production model. The second case focuses on the consolidation of industrial infrastructure in Yumbo, Valle Department, Colombia, and suggests local strategies to ensure future territorial sustainability. [ABSTRACT FROM AUTHOR]

This paper proposes a methodology to enhance the estimation of parameter matrices in multivariate autoregressive models. It uses the Kalman filter and state space representation to improve the precision of parameter estimation, while maintaining a reduced computational burden. Two methods of covariance matrix adaptation are considered within the Kalman filter framework to improve the estimator convergence rate while preserving precision. The methodology is tested on simulated data, electroencephalographic recordings and performance. As a result, a reduction of the computational burden of up to 40% is achieved, but reconstruction error reaches as much as 3%. [ABSTRACT FROM AUTHOR]

This paper describes the behavior of GMAW welding process with metal cored wire, in welding unions of ASTM A131 grade AH 32 steel using two shielding gas compositions and methods of transfer in short circuit and pulsed arc. The mechanical properties and microstructure were evaluated and the results indicate that is obtained greater tensile strength and a more uniform hardness profile using the pulsed arc transfer mode. Likewise, the porosity in the foot of welding of joint in T with deposit in fillet are related by arc length. [ABSTRACT FROM AUTHOR]

The paper shows the experimental procedure used to record the vibrations generated by the passage of a train in a fixed point of the rail. Moreover, it also shows how to identify and characterize a defect on the surface of a wheel, by analyzing the joined time-frequency domain of these vibrations, using the short time Fourier transform -STFT. The results demonstrate the advantages of the STFT in this application, and that the use of a monitorizazing system of the vibration generated on the railway line is efficient and practical to implement a predictive maintenance of the train wheels. [ABSTRACT FROM AUTHOR]

This paper presents a vibration based fuzzy classifier used to detect fault conditions in bearings. The fuzzy knowledge foundation is obtained from the behavior of the vibration signal in presence of a fault condition in out-er race, inner race, cage and rolling element. The fuzzy system is implemented in Matlab® and it is validated in a vibration dedicate test bench used for research proposes. The system performance exhibits reliability and robustness in the fault detection in each experimental fault scenario. [ABSTRACT FROM AUTHOR]

The aim of this paper is the development of an accessibility estimation method as a transport policy assessment tool based on the state of the art of the accessibility concept and measurement techniques, and available information directly related to socioeconomic data, transport demand and supply characteristics for specific areas of Bogotá. Study areas and indicators are defined in order to determine relevant relationships between transport and access to opportunities for individuals with specific socioeconomic characteristics and present mobility conditions. In addition, evaluation of restricted travel budgets scenarios defined both by the standard transport theory and individuals is performed. [ABSTRACT FROM AUTHOR]

This paper presents a summary of the Project on Clusters in the Mining and Energy Industry that the Universidad de los Andes developed for the National Planning Department. The document starts with a description of the methodology that combines macro analysis with detailed analysis. Next, we present the main findings regarding the characterization and location of the mining and energy industries, as well as of the related industries. We end with a detailed presentation of the four cluster proposals designed to create value. The first proposal relates to the structuring of the marketing function to achieve improvements in the productivity of small and medium coal mining. The second one refers to the creation of a National Program to develop Goods and Services Suppliers for the oil and large coal mining industries. The last two proposals focus on the development of business clusters, the first one for petrochemicals and plastics in the Bolivar-Atlantico region and the other one for new plastic materials in Bogota, with a leading role of the academia. The whole analysis and the detailed proposals can be found in the project reports. [ABSTRACT FROM AUTHOR]

This paper presents a study, which estimates sugarcane bagasse potential as feedstock for the production of fuel gases that can be used for power generation. Chemical equilibrium was used to estimate the species (gases) produced by gasification, under adiabatic conditions, using different amounts of air-steam mixtures for partial oxidation. The software CEA (Chemical Equilibrium with Applications) was used to estimate the composition of about 150 species; only significant species are reported here. The parameters investigated were equivalence ratio defined as the stoichiometric air/air supplied to the reactor (1-4.5) and the steam to fuel ratio (0.1-0.7 kmol of steam/kmol of fuel). For the studied conditions, the composition of the gases were: CO(8% - 29,3%), N2 (26,5% - 57.9%), H2(3,6% - 29,3%), CH4(0-0,012), H2O(0,038-0,235). Heating value and energy conversion efficiency were calculated together with the composition of the gases. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to present a proposal aimed at improving the distribution and picking processes in a warehouse of an industrial company. Initially, it outlines the theory and problem to be solved, and concludes with a description of a case study. Warehousing activities affect the total logistics costs of a company or supply chain most; thus, optimizing the required spaces for warehousing is one of the most important activities when attempting to reduce operative costs in a company. The purpose of this study is to reduce the time required for picking activities and, therefore, obtain an improvement in the service and a reduction of the area used in the warehouse, which leads to cost reductions. [ABSTRACT FROM AUTHOR]

This paper presents a review of the discrete wave number method (DWN), and its application in layered media subjected to a lineal source in the case of Sh waves. The method allows for the numerical calculation of the Green function; it decomposes the displacement field as a superposition of plane waves. The solution is expressed as an integral equation over the horizontal wavenumber domain. The evaluation of the integral equation implies infinite sources distributed along the horizontal x-axis at equal intervals. The method is used to calculate the green function in a layered media; the enforcement of boundary conditions at the interface of each layer allows us to find the appropriate coefficients for the plane wave expansion. Finally, seismographs are calculated for a linear array of surface receivers. [ABSTRACT FROM AUTHOR]

The use of more refined models and computational techniques for seismic hazard evaluation and the availability of more data related to seismic events have allowed the updating of national seismic hazard studies. This paper summarizes the new methodology used to estimate the expected seismic intensities for design and construction of earthquake resistant structures in the country. Seismic intensities are obtained for different return periods and spectral ordinates, for the different heights of buildings. This data is useful in establishing design values in the new national building code NSR-10 and for the development of seismic microzonation studies. [ABSTRACT FROM AUTHOR]

Knowing the amount and type of Domestic Solid Waste (DSW) that is deposited in the landfill gives us the possibility to consider options in how to make sustainable use of it. Waste from any location, if properly handled, can be turned into the raw material for other processes. The aim of this study was to quantify the components of the DSW likely to be recycled, deposited in the landfill in the city of Ensenada, Baja California, Mexico, so that they could be valued on the market as recyclables. The average weekly market could be 643.67 tons of food waste for composting, 389.45 tons of paper and cardboard, 217.55 tons of plastic, 78.81 tons of glass, 32.20 tons of metal and 8.11 tons of aluminum. This should result in a total of approximately MXP $ 911,224.18 (USD $ 71693.48) for the marketing of major recyclables. [ABSTRACT FROM AUTHOR]

Due to the inadequate conjunction between water wealth and urban development, we are constantly having to deal with tragedy, spending huge resources on ongoing repair work on constructions and on helping the lood victims. However, no country is exempt from urban loods, its consequences may be vary according to the characteristics of the cities and their relationships with their bodies of water. After reviewing disaster statistics and the basic concepts of risk, and evaluating typical engineering proposals, this paper introduces some background to the problems in Colombia, and proposes a new form of river management as a solution. [ABSTRACT FROM AUTHOR]

Urban infrastructure is essential for the development of modern societies: its assessment and risk-management must be undertaken within the framework of decisions of public-interest. The fact that infrastructure is made up of networks imposes the need for a systemic approach rather than one that emphasizes individual elements. This paper proposes a hierarchical description of infrastructure systems at different levels of resolution, allowing for effective risk-assessment through the use of simpliied representations of the network for the assessment of failure probability and consequences. Finally, the approach to risk-management is undertaken by means of theory of incentives. [ABSTRACT FROM AUTHOR]

The organizations are more interested in the impact that can generate risk and in particular associated to IT. Every day it is possible to see that different business of sectors like: finance, governance, health, production, among others, they are reporting economical lost due to fails or attacks over theirs IT services, which can affect the reputation, relationships with the clients and their self financial and operational robustness. There are two fundamental pillars for the risk analysis: standards and norms and the other side the methodologies; with these pillars along is impossible to assure the results without the governability of this risk analysis. In this paper, we show what kind of standards and legal documents must be considered in a risk assessment process and after we are going to explain how is possible to use a methodology and how to connect this methodology with the IT governance process in a successful way. [ABSTRACT FROM AUTHOR]

In this paper the results of electromagnetic field characterization produced by wireless communication systems, such radio, TV antennas and mobile telephone base stations in urban environments are presented. The characterization was carried out in 110 sites in the city of Cali - Colombia during three measurement campaigns. In general, the values found were lower than 5% of the reference level established by the International Commission for the Protection of Non-Ionizing Radiation, ICNIRP (0,2 mW/cm²) and adopted by the Colombian government. However, in three sites the measured values were close to this level and in other two sites the level was exceeded. [ABSTRACT FROM AUTHOR]

Activated carbons (AC) are microporous materials that have high adsorptive capacity. The heterogeneity of any adsorbent, in particular of the AC, can be separated into two large families: energetic and structural. Structural heterogeneity is caused by the presence of pores of different sizes, shapes and how they are interconnected, while the energy heterogeneity is caused by surface irregularities, as well as by the presence of functional groups and / or impurities. In this paper we discuss different models of surface heterogeneity in materials with slit pores and its effect on adsorption isotherms and the pore size distributions (PSD). [ABSTRACT FROM AUTHOR]

This paper shows an assessment exercise of the air pollutant emissions measurement methods required by the IDEAM and environmental authorities, particularly the stack particulate matter isokinetic sampling and the diesel exhaust opacity measurement. The assessment methodology included the identification and assessment of critical factors, a review of currently applied controls and a practical performance assessment exercise. Serious training of the personnel in charge of isokinetic sampling resulted in misinterpretation of sampling methods, which means that a training and certification scheme is needed. On the other hand, the individual characteristics of the opacity meters and the appropriate design of the software to comply with the technical standards are not well known by suppliers. Therefore, better accreditation procedures for the technologies being imported are needed. [ABSTRACT FROM AUTHOR]

This paper presents the results of stated-preference in a discrete choice experiments designed to examine the potential demand for a new type of passenger train between Tunja and Bogotá. The study investigates choice behaviour between three modes of transportation: bus, train and car. Each mode is represented in terms of cost, travel time and headway with a mixed logit model, which includes regularly for individuals. The model was used to experiment with different scenarios, finding the modal split for each. [ABSTRACT FROM AUTHOR]

This paper proposes an Ant Colony Optimization method to solve the investment problem for the Transmission Expansion Planning Problem for Electrical Power Systems. Operative problem of Linear Programming is solved trough a High Order Interior Point Method. Moreover, the solution of a Non Linear Interior Point Method is used as a sensitivity index to initialize pheromone matrix used in the Ant Colony Algorithm, where is proposed a method with two stages to obtain a solution. The methodology is tested on the 24 and 6 Bus IEEE systems. [ABSTRACT FROM AUTHOR]

Phasor measurement units are a technological resource that allows observing with great accuracy the dynamic state of the electric power system. Its application allows, among many things, the implementation of indexes for the on line assessment of voltage security. This paper presents a brief review on the development of these indexes and the results of a study on the establishment semantic - graphic scales for three of them which express to the control center operator in a qualitative way the state of system voltage security [ABSTRACT FROM AUTHOR]

The heat treatments used to improve abrasion resistance of High-Chromium white casted irons (WCI) tend to ease the retained austenite/martensite transformation temperature and favor carbide precipitation within the metallic matrix. In this paper, the effect of four different destabilization heat treatment temperatures was examined for a 26Cr2.5C2Mo WCI under means of optical microscopy. The specimens were obtained under two different casting process, regular sand-casting and permanent molding. The abrasion resistance was measured as mass loss in a dry sand/rubber wheel abrasion test according to ASTM G65. The results show that the solidification speed has a direct effect on the abrasion resistance; manly due to both the eutectic carbide size and its distribution. As predicted, the abrasion resistance of both samples was maximized under certain destabilization temperature, for which carbide size and hardness was optimized. [ABSTRACT FROM AUTHOR]

Economic growth in Bogota and its region will produce important changes in urban development and mobility. Increases in private vehicle ownership in the next decades will contribute to urban sprawl and car dependency in a development pattern similar to the one lived by North American cities. This paper underlines the policy and strategy to be adopted by Bogota District in order to prevent a path of non-sustainable development, promote a more inclusive city and an efficient integration with the Region. [ABSTRACT FROM AUTHOR]

How sustainable is a transport scheme is not easy to define. There are certain aspects in which schemes as the London congestion charge can or can't contribute to the improvement of the quality of life and the rational use of resources. Through 3 criteria: economic, social and environmental, the following paper reviews the characteristics of this transport scheme based on the concept of sustainable mobility to conclude that socially speaking it has been successful while economically it can be improved while its environmental effects are still to be established. [ABSTRACT FROM AUTHOR]

The GALIL rifle developed by the Israel Military Industries (IMI) is manufactured in Colombia, by the military industry (INDUMIL). This rifle is the standard for Colombian forces. The rifles have night sights that use Gaseous Tritium Light Sources (GTLS) that are imported. An important step for INDUMIL to obtain the required authorizations to handle this radioactive material is to determine the health risk, associated with the use of Tritium in GTLS. The study carried out follows the recommendations of the Nuclear Regulatory Commission (USA). The study concludes that the risk associated with storing and transporting sights between INDUMIL factories, fitting sights on rifles, using these rifles and discarding sights is very low. A future paper will deal with the risk in case of accidents. [ABSTRACT FROM AUTHOR]

Biofuels constitute an important alternative for the current national and worldwide energy demand. The main goal of this paper is to summarize the recent contributions of Universidad de los Andes for the development of technologies related to its production. Such efforts have been conveyed to the use of sub products like oil palm empty-fruit-bunch or domestic solid waste for ethanol production, hydrogen production and liquid fuels through anaerobic digestion and waste pyrolysis respectively, and biodiesel by fatty acids esterification. Generally, the limitations of these technologies stand on discovering adequate catalysts either from biological or chemical origin, finding optimum reaction conditions (temperature, pressure and reactive systems) accounting yield and selectivity and, finally, feedstock selection from an economical perspective. [ABSTRACT FROM AUTHOR]