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In recent years, there has been great interest in sustainable construction, which has led to an increased interest in 3D printing or additive manufacturing. However, the use of this technique with conventional materials is not enough to reduce the large environmental impact generated by the construction sector. Although most of the research and advances are focused on the 3D printing of Portland concrete, this review has been oriented towards the 3D printing of building materials based on soils and clays, which can provide an affordable (as it is a locally available material in many regions of the planet), environmentally sustainable, and low-cost approach, which is highly beneficial for housing construction. This paper has been oriented towards the search of scientific literature and prototypes that have been elaborated using ancestral materials, such as soil-clay-sand-sand-fibers like straw and water, for the elaboration of constructive pieces such as 3D printed walls or adobes. The objective of this paper is to close the gap on the use of mixtures based on soils, which, although they seem to have been fully studied for several centuries, to date their application in 3D printing is reduced. Readjustments in properties of soil mixtures such as fluidity for pumping or extrusion, buildability and good working time are variables that are reported in this paper. In addition, this review describes the mixtures that have been developed for 3D printing from soils and clays, and the main characteristics that have been found. Finally, the challenges that still remain for the blends to be applied on a massive industrial scale are presented. [ABSTRACT FROM AUTHOR]

This paper proposes the geometry-based polylinal routing method as a solution for motion planning in object sorting exercises in manufacturing processes. This algorithm is based on geometric properties that arise from the interaction among objects within the configuration space. The method proposed in this paper, during its experimental phase, successfully generated smooth routes with a processing time ranging from 62.5-125 ms on a computer equipped with an AMD Ryzen 7 2700X Eight-Core 3.70 GHz processor and 16 GB of RAM. When compared to the RRT algorithm, it exhibits a higher efficiency of 38% to 48%, resulting in a reduction in iterative processes and a shorter response time. Therefore, the proposed method presents a viable solution for addressing motion planning scenarios in object sorting exercises. [ABSTRACT FROM AUTHOR]

The high penetration of distributed renewable resources requires integration strategies that ensure a balance between supply and demand. Transactive energy (TE) comprises a set of mechanisms capable of achieving this objective by using value as an operational parameter. This paper presents a review of the state of the art in TE, aiming to provide the reader with a general overview of concepts and applications. To accomplish this, the document offers a review of market and operational structures, with a particular focus on the role of TE in the composition of local energy markets. Furthermore, an analysis of the value concept in energy is proposed as a linking element between two current topics of academic interest: multi-energy systems and the water-energy-food nexus. Finally, some international and national pilot projects are showcased, allowing for the identification of the practical validity of the concepts described. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the mechanical behavior of buried pipes subjected to thermal load cycles. Firstly, stresses and deformations are measured experimentally on a buried pipe subjected to monotonic and cyclic thermal loads, hence reproducing the typical operating conditions of buried piping systems. Subsequently, a numerical model is developed using the finite element method, which is validated using the results obtained experimentally. Subsequently, this computational model was used to carry out a parametric study of the influence of the mechanical properties of the soil on the stress state of the system. Finally, from the results obtained experimentally and numerically, it is concluded that the most critical situation in terms of stresses takes place when the pipe is firstly placed into operation, i.e. in the first cycle of thermal load and the other variables studied have little impact. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the compressive strength of concrete cylinders reinforced with expanded metal meshes. The investigation aims at comparing the compressive strength of concrete specimens strengthened with expanded metal meshes with different orientations. A series of compression tests were performed to obtain the structural performance on jacketed specimens, and then compare these with the unreinforced concrete cylinders. Expanded metal tubes were fabricated using circular geometries with two cell orientations. The results showed that cell orientation enhance the compressive strength of the specimens. [ABSTRACT FROM AUTHOR]

The proliferation of renewable energy sources and their impact on power systems makes it necessary to conduct studies to ensure the proper operation of the power system. This paper investigates recent research on the impact of renewable energy sources on voltage stability and new methods used to assess this stability. The effects of solar and wind power generation both individually and collectively are studied, along with other inverter models through which renewable energy sources are connected to transmission systems or distribution networks. In addition, the results are highlighted by categorizing them into a deterministic and probabilistic approach. [ABSTRACT FROM AUTHOR]

In pavement engineering, non-petroleum based materials are strongly sought as substitutes/improvers for asphalt. Bioasphalt production with biomass is the most common technique with economic, social and environmental benefits. This paper aims to conduct a literature review of asphalt upgrading with biomass in biochar or bio-oil by-products. A review of 80 scientific articles was carried out, which studied the conventional and rheological properties of asphalt with optimal percentages of biomodifiers addition, considering them as new technologies in road constructions. The results show that the dose and type of the biomaterial has a great influence as a modifier, since the performance of biomass-based bioasphalt guarantees positive reactions with a minimum addition of 1% palm oil up to 100% wood ash as a maximum. In conclusion, the higher the dose of biomodifier at high temperatures, the greater the improvement in viscosity, stability, penetration degree, softening point, indirect tensile strength, modulus of resistance, deformation resistance, fatigue resistance, skid resistance and moisture resistance of asphalt, besides having better oxidative aging conditions, since the asphalt binder is generally compatible with most biomaterials, being viable as a source of renewable, sustainable and quality energy. [ABSTRACT FROM AUTHOR]

In this paper, new models for credit risk prediction in Colombia are proposed by using different artificial intelligence techniques. These models can be used to support the risk management area in banks, and they aim to identify clients that could be in default, generating a possible credit risk for financial institutions. Three techniques are used to obtain the models (neuronal networks, decision trees, and support vector machines) that predict the next payment of a client's fee based on basic data from the client and previous recorded installment payments. Decision trees turns out to be more accurate than the other techniques that have been used when predicting credit risk with a ROC area of 88.29%. The proposed models reach accuracies that are like some other papers in the state of the art and in some cases, they overcome models in other studies. [ABSTRACT FROM AUTHOR]

This paper presents a new control method for a Half-Bridge ac-dc Boost converter with power factor correction. The proposed controller includes a pre-compensation loop in order to remove the steady-state phase error in the current control loop. As a consequence, a better power factor is achieved even under soft load conditions or voltage variations in the power source. The paper explores all the stages in the design of the controller, from the derivation of the transfer function, based on an average model, the design of the controllers, a method for eliminating the voltage unbalance in the DC side, the conception and design of the pre-compensation loop, and evaluation of the effect of the precompensation loop in the stability of the system. Finally, the proposed controller is verified experimentally in a real Half-Bridge ac-dc Boost converter which is tested under different operational conditions. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of an online fault diagnostics, for the detection of operational faults present in the pilot water processing plant, within the framework of the REAGRITECH project of the UNESCO chair of sustainability, modeled as a system of discrete events (SED), making use of interpreted Petri nets (IPN). An analysis of the operation of the real system is carried out, from which some operating scenes are identified, which allow the construction of a controller in charge of representing, in a simulated way, the real behavior of the plant. From this, an input-output (I/O) information matrix is obtained, where the inputs correspond to the control command signals, and the outputs are the sensor signals. These data are entered as parameters to an identification algorithm, which delivers as a result the model of the IPN identified from the data, that is, information of an IPN: incidence matrix A, input function (Fe) with the labels associated with the transitions, the output function (Fs) and an output matrix φ that relates the sensors to each slot in the system. Based on the identified model, a detectability analysis is carried out to find out if the system is detectable or not by events, building a diagnostic from predefined faults. It is concluded that the diagnostic tool implemented is capable of detecting faults present in the pilot water processing plant, within the framework of the REAGRITECH project, making an analysis of the marking in the diagnostic places, and in the Post risk places of the system. [ABSTRACT FROM AUTHOR]

This paper presents the application of an artificial neural network (ANN) to develop a model able to predict the holdup of a two-phase flow composed of water and mineral oil in a horizontal pipe. The surface velocities of each fluid and the pressure differential in the pipe are used as input parameters of the multi-layer artificial neural network with backpropagation, while the volumetric fraction of the fluids is used as an output parameter in the training. The 56 experimental data were obtained in the laboratory LabPetro-CEPETRO-UNICAMP. The results of the predictive model with the best performance show a mean absolute error (AAPE) of 3.01 % and a coefficient of determination R² of 0.9964, using 15 neurons in the hidden layer of the network and the TanSig transfer function. [ABSTRACT FROM AUTHOR]

Currently, there are different options to increase the ultimate resistance of plate girders subjected to patch loading. Some of these alternatives include the use of closely spaced transverse stiffeners and the use of longitudinal stiffeners. Nevertheless, recent investigations have demonstrated that the resistance is also improved by using delta stiffeners, which are obtained by welding two plates between the web plate and the loaded flange. This paper aims at studying the elastic buckling behavior of slender plate girders designed following AASHTO norms with delta stiffeners subjected to patch loading. The research is carried out by means of eigenvalue analysis using the finite element method. A parametric study is performed to evaluate the influence of various geometrical parameters on the buckling coefficient of the girder. Finally, design recommendations are suggested based on the obtained results. [ABSTRACT FROM AUTHOR]

This paper presents the results of the performance diagnosis of a 6-cylinder engine-generator set, originally designed to run on diesel fuel or natural gas, operating in spark ignition mode and fueled with high butane content liquefied petroleum gas (LPG). In order to assess the steady-state and transient operation of the engine-generator, an original protocol for testing and recording of operating variables was designed, based on a stepped sequence of loads, comprising cold start, idling, operation at some mean load points and at a limited full load. During the tests, the variation of crankshaft rotational speed, warm-up time, engine temperatures, block vibrations, active/reactive power and engine-generator frequency, as well as exhaust emissions were continuously logged. The results show that, during the cold starting process, the engine is slow to reach nominal rated speed, its warm-up time is lengthy and its speed response during load transients is also sluggish, the latter being reflected in the voltage and frequency deviations of the output power; also, during transients, vibration levels are intensified, though the values are within the acceptable ranges according to the regulations. The torque performance of the engine-generator set is good when operating with LPG, satisfying the requirements for class G2 engine-generator units, but during transient processes it does not meet the specifications required for class G1, in terms of frequency and voltage deviations. In light of the emission limits suggested by the Environmental Protection Agency (EPA) for stationary units, it can be concluded that, without appropriate adjustments and regulations particular to LPG, the engine-generator set does not meet the carbon monoxide emission limits. [ABSTRACT FROM AUTHOR]

Inverters are the key actuator in the control of AC microgrids, since they manage the power flows of both the generators and energy storage devices. In general, there are three types of inverters depending on the control strategy: grid feeding inverters, grid forming inverters and grid supporting inverters. Those inverters can be implemented with different hardware topologies, each one of them with advantages and disadvantages. This paper presents a synthesis of the inverter topologies widely used in AC microgrids. Moreover, this paper also describes the inverters architectures and main control strategies. [ABSTRACT FROM AUTHOR]

The adoption of Information and Communication Technologies -ICT- has caused multiple transformations in both the public and private sectors. The use of ICT in the justice sector speeds up judicial processes. However, this use raises risks since justice is part of the critical infrastructure of nations. In addition to the judicial information’ characteristics, an interruption in the provision of these services would be catastrophic. For this reason, cybersecurity plays a role in each stage of digital judicial processes. This paper aims to propose cybersecurity recommendations to digital judicial processes in the Colombian case based on a literature analysis, which described the digital justice landscape with an emphasis on Latin America. It also analyzes which ICT is used in each stage of the digital judicial process, their cyber risks, and the recommendations to face them. Also, how the functions of the National Institute of Standards and Technology –NIST- cybersecurity framework are considered. [ABSTRACT FROM AUTHOR]

The Product Recall study is a relevant issue for both quality management and supply chain management. This paper identifies the main contributions, approaches, and methodologies proposed in the scientific literature to address product recall through a bibliometric analysis and a taxonomical classification regarding works made over the last 20 years. For this, a literature review was carried out in the Taylor and Francis, EBSCO, Science Direct, Scopus, Springer Link, IEEE, Google Scholar, and ProQuest databases. The bibliometric analysis allowed us to identify the main clusters related to product recalls. The taxonomical classification allowed the grouping of works into six categories: type of work, quality approach, problem approach, type of methodology, data characteristics, and product category. The sectors with the highest level of occurrence of product recalls are the toy industry, automotive sector, electrical supplies, and food industry. [ABSTRACT FROM AUTHOR]

In this study we considered the optimization problem that integrates the logistics operations of location, routing and multiperiod inventory in a two echelon distribution network, named 2eLIRP. In this paper we propose a new hybrid metaheuristic based on Tabu search, genetic algorithms and the nearest neighbor heuristic. The performances of our technique was compared with classics metaheuristics and the results of the experiments carried out in 96.67% were better. [ABSTRACT FROM AUTHOR]

This paper introduces the design, construction, and static testing of a solid rocket motor. The design was based on the solid rocket motor design methodology (SRM). The rocket motor included the igniter system, the combustion chamber, the solid propellant, and the nozzle. The internal diameter of the combustion chamber and the total length of the rocket motor were 27,67 mm and 230 mm, respectively. The rocket motor nozzle was of the convergent-divergent Laval type. The propellant was based on the mixture of potassium nitrate (KNO3) (oxidant) and high purity sugar (or sucrose: C12H22O11) (fuel), whose synthesis was achieved through a thermal fusion process (150-170 °C for 20-25 min). The performance of the rocket motor was evaluated using a static combustion test; resulting in a maximum thrust force (load) of 227 N, a total impulse of 98,69 Ns and a specific impulse of 65,8 s, thus allowing its classification as a class G rocket motor. The results obtained are considered of great importance in the development and characterization of solid rocket motors, necessary to promote the experimental rocketry in Colombia. [ABSTRACT FROM AUTHOR]

This paper proposes a desing of a boost-type DC-DC converter, based on a state space model and calculation of a controller with multiplicative unstructured uncertainty. Performance of the converter at low frequencies was analyzed; as well, weight of the weighting function was adjusted, to reduce noise at certain frequencies. Results of system simulation, in open loop and closed loop, demostrate that the designed controller allows modifying cutoff frequency, through the variation of weighting functions. It is concluded that this technique optimizes dynamics behavior of the system. [ABSTRACT FROM AUTHOR]

This paper addresses the design and implementation of a backhaul telecommunication network in the region of Sucre (Colombia) as a disruptive solution to extend connectivity from the core network located in the city of Chalán, to the rural communities of Chalán and Ovejas. Internet connectivity will be delivered through a self-manageable telecommunications wireless technology known as WiBACK, supporting future 5G communication. Results will layout the roadmap and benchmarking of upgrade scenarios of Colombian access network, envisioning broadband rural connectivity in the context of post-conflict. [ABSTRACT FROM AUTHOR]

This paper presents a proposal for a technological model that seeks to serve as a starting point for implementations of educational solutions that support training processes through ubiquitous education; This model was implemented on a technological platform based on Mobile Cloud Computing (MCC), which is supported on cloud computing technologies (Cloud Computing). To validate the application of the model, a case study was implemented, which is based on the topic of Mathematical Problems Resolution, an issue that is developed in subjects of first semesters at the university level. The implementation was carried out by developing an app (application for mobile devices) using the Microsoft Azure platform, as a Mobile Cloud Computing platform and the C # and ASP: NET development tools. The database manager used is MySQL. [ABSTRACT FROM AUTHOR]

This paper proposes a new equivalent circuit to model supercapacitors. The proposed circuit is an array of RC branches described by differential conformable fractional derivative equations. A parameter identification algorithm based on experimental data is implemented. Validation results using experimental data show that the proposed equivalent circuit can be used to model the real behavior of the supercapacitors. [ABSTRACT FROM AUTHOR]

Precision and accuracy, which are common requirements in manufacturing processes, are defined by the manufacturing context, both from the specifications of the process and from the manufacturing system itself. In this context, the kinematic calibration of electromechanical systems contributes to achieve manufacturing requirements. This paper presents a kinematic calibration method for a CNC router that operates in a context of ISO 2768-c linear dimensional tolerances. The calibration method is based on the estimation of the parameters of a kinematic model with a representation of dimensional variations (linear and angular) of the structure. The estimation of the parameters is based on machining errors measured by monocular photogrammetry of a geometric pattern that records a machining. The calibration was implemented on a CNC machine by adjusting the G code, thus meeting the manufacturing requirements demanded by the proposed context. [ABSTRACT FROM AUTHOR]

People and activities, they carry out in daily life are subject to constant decision-making, the consequences of which are largely uncertain. This decision-making involves a rational process that is based on the quantity and quality of the information, the processing capacity and the use of the rationality of people, which allows facing scenarios in the short, medium and long term. In the current context, the difficulties in the development of this process are greater, due to the abundance of data, the doubt of its veracity and the speed of exchange, so that scenarios of chaos and uncertainty are generated. Under this dynamic, forecasting and prediction can be less effective, offer less certainty about the result and, at the same time, produce biases in the information. These predictive problems are observable, for example, in the estimation of economic growth, human behavior, stock markets, natural phenomena, conflicts, migration, the spread of diseases, geopolitics, negotiations, among others. These difficulties are caused, in large part, by the techniques or tools used for data processing and by the processing capacity of the information systems, which have limitations for the combination of different types of information. In this sense, the scientific community has endeavored to propose new methods and develop better techniques that allow capturing and processing the greatest amount of useful information in the decision-making process. This is known as decision science; a broad and transversal term to a large number of areas and fields of study, ranging from the human and social sciences to the pure sciences. Thus, this paper will focus on those areas that are dedicated to proposing methods and techniques that allow improvements and applications to be made in the aggregation and treatment of data for decision-making. [ABSTRACT FROM AUTHOR]

The data collected in the air pollution monitoring such as PM10 is obtained at automated stations that generally contained missing values due to machine failures, routine maintenance, or human errors. Incomplete data sets may cause information bias. Therefore, it is important to find the best way to estimate these missing values to ensure the quality of the analyzed data. In this paper PM10 particulate data considered in time as a functional object were evaluated, for this case the database of the environmental monitoring network of the Environmental Corporation of La Guajira (Corpoguajira) was used. In this study we have implemented the methodology by Jeng-Min Chiou (2014) to impute functional data. The detection of outliers of pollutants is very important for monitoring and control of air quality. Additionally, we have implemented the method of imputation of missing data and detection of outliers for functional data. We considered PM10 particle concentrations in the environmental monitoring stations over the area of influence of the open pit mining during 2012. To impute functional missing data, it was based on applying tools such as functional principal component analysis (ACPF) and graphic procedures to detect outlier curves such as the bagplot and functional highest density region (HDR) boxplot. The results indicate that Barranca station is an atypical curve and it was observed that the imputed intervals capture the dynamics that are shared with the other trajectories of the different stations. [ABSTRACT FROM AUTHOR]

Mathematical Model of a Series-Parallel (SP) photovoltaic (PV) generator represents each module through an equivalent electrical circuit denominated single diode model, this model has associated a nonlinear equation system that describes the electrical behavior of SP generator. This paper presents a solution of this system using optimization methods widely using: Trust Region Dogleg and Particle swarm optimization (PSO) for solving the electrical model of PV generator operating under homogeneous or non-homogeneous conditions, changing the number of submodules and shading pattern. It has been made simulations about generators composed by 3 and 15 series submodules, operating under different partial shading conditions. Between the implemented methods, Trust Region Dogleg show a better performance than other methods, with 2 and 14 times less computation time than the reference method and PSO, respectively, and a RMSE equal or 50% lower than PSO. [ABSTRACT FROM AUTHOR]

To satisfy the regulations for water supply suitable for human consumption is one of the main objectives of the drinking water treatment plants. The above, given the pollution of the supply sources and the climatic changes that put at risk the components of the system in general. This paper analyzes the turbidity as an indicator parameter of the purification process in a municipal plant, by determining the level of correlation that the turbidity shows with other parameters and according to historical records between the years 2011 and 2015. Thus, by sampling and testing the influent and effluent that is periodically performed for the plant to measure the water quality supplied to the community it is possible to determine the levels of the water quality parameters, and the Pearson's linear correlation coefficients are also calculated between these. In conclusion, turbidity shows a significant positive linear correlation with fecal coliforms (r = 0.70), total coliforms (r = 0.40), and apparent color (r = 0.40). Additionally, turbidity and fecal coliforms show the best correlations, offering two linear regression models for the forecast of each variable. [ABSTRACT FROM AUTHOR]

This paper presents the results of a research project entitled "Simas Y FreeStyler: La Representacion Del Conocimiento Como Medio Para La Gestion Del Aprendizaje Autónomo "funded by the UNAD and UDI. It is assumed that the creation of learning communities among researchers, educators and students, supported by digital environments is an alternative for improving the quality of education and ensure the inclusion of IT. This paper presents the results of a descriptive research exercise which incorporates tools for the representation and evaluation in solving case studie by group of tenth grade students. The results show that there are effects of these tools on students' abilities to solve challenges commonly faced otherwise. It was noticed the Value that social networks can have when forming learning communities. [ABSTRACT FROM AUTHOR]

This paper presents a detection system which generate an alarm if exist an anomaly state in the stability control system of an aircraft. A servo type controller with integrator for the regulation of the Roll, Pitch and Yaw was designed starting from the lateral longitudinal and dimensional model. The models are excited with steps of random sizes and disturbed with different random signals to generate the database of suitable and non-suitable states. Radial base classifiers were trained and validated for its use in the detection of anomalous behaviors that may occur in the aircraft stability. The accuracy obtained with the classifiers was greater than the 93.33% for all the variables studied, indicating that classification techniques used, offer reliability in the determination of anomalous States in the simulation of the flight of the aircraft and that could be used in reall flights [ABSTRACT FROM AUTHOR]

This paper presents the sizing of the blades of a 1 kW hydrokinetic turbine with 3 blades with hydrodynamic multielement profiles using the Blade Element Momentum theory (BEM). The hydrodynamic profile used was the Eppler 420. The turbine was designed from a water flow velocity of 1.5 m/s with a tip speed ratio of the blade (λ) of 6.325, a pitch angle of the blade section (θ) of 0°, a power coefficient of 0.4382 and a mechanical efficiency of 70%. The Eppler 420 multi-element profile was selected for the design of the blade because it has a high ratio between the lift coefficient and the drag. A 2D computation study in the JavaFoil code of the Eppler 420 profile was carried out in order to determine the optimal lengths of the main element and the optimal flap for a deflection angle of 30° under conditions of a low Reynolds number. [ABSTRACT FROM AUTHOR]

With the technological advance in electricity generation techniques and the prevailing need for sustainable development of countries, the massive use of alternative energies has been in force for the last 15 years, with clear goals towards 2020 for sustainable development. At the regulatory level, Colombia cannot be left behind in the regulation, and progress has already been made on the subject with law 1715 of 2014 and several decrees of incentives in the promotion of renewable energies. The objective of this paper is to show the state of the art on the way in which the net balance and residential energy self-consumption by DER is handled by several tax regulations in different countries of Europe; moreover, it will also go into detail about the advantages offered by using a selected methodology to consider fair charges of support for the use of the electrical network by generators distributed from photovoltaic solar energy, all this as a contribution to advances already made in this field. This is provided from a network planning approach, in which a long-term methodology is selected that efficiently integrates the distributed generation into the interconnected system and allows transition periods in its implementation to avoid disruption of network operators (ORs). Likewise, this analysis is supported by the simulated operation of a system with DER together with the changes in load flows due to decongestion and surplus injection that the electric system has in the scenario of massive use of these resources. [ABSTRACT FROM AUTHOR]

In nature there are societies of living beings that coordinate their actions in a non-centralized way. For example, emergent processes that combine the actions of individuals in the achievement of a common goal occur in ant colonies. This paper describes a management layer that facilitates emerging coordination processes in multi-robot systems, which together with other two layers (one of individual management and another of knowledge management), manage the processes necessary for the operation of the multi-robot system. In particular, this layer allows the appearance of emergency and self-organization in the system. [ABSTRACT FROM AUTHOR]

Geolocation through a GNSS service (Global Navigation Satellite System) is only possible with the simultaneous reception of the signal from at least four satellites. The probability of loss of visibility of GNSS satellites in urban environments is especially critical due to the architectural elements typical of a city, making it impossible to locate a receiver. This will be crucial for certain applications, for example, an armored car carrying valuables requires continuous position monitoring. This paper describes a method for a mission planning in urban environments, according to the needs of positioning. integrating the calculation of satellites' position through orbital mechanics, with Google Street View images and semantic segmentation with Deep Learning techniques. In this way, establish the visibility relationship between an observer and the satellites of a GNSS service. [ABSTRACT FROM AUTHOR]

Natural stone has been an important element in Colombian construction since the hispanic period, especially in Bogotá city capital from Colombia. Sandstone and limestone rocks are ornamental and structural elements on heritage buildings and new constructions, and their use is important to revitalization of urban spaces for the enjoyment of the population. This paper shows the results of some technological characterization tests of two rock types widely used in construction, commonly known as Piedra Muñeca or Piedra Bogotana and Marmol Royal Bronce, used in historical buildings as well as modern ones. Petrophysical and mechanical properties of these rocks identified in a preliminary way were: Petrographic analysis, physical properties (bulk density, bulk porosity and water absorption), compressive strength, flexural strength, weathering resistance and impact resistance, as shown in the Brazilian technical standard ABNT NBR15845. The obtained results allows to determine, in an early way, that the two varieties (yellow and pink) of the Piedra bogotana stone can be used as a structural element (walls, columns, beams and foundations) and also as a dimension stone for buildings, floors and squares. It´s recommended the use of yellow variety specially on interior spaces. Marmol Royal Bronce can be used in finishes and also in any type of facing, floor and as a structural element in highly traffic streets. [ABSTRACT FROM AUTHOR]

The production of energy is directly related to the growing demand and excessive dependence on the production of fossil resources, that is, coal, oil and natural gas, which must be planned in a safe, clean, efficient and sustainable scenario. The objective of this paper is to analyze oil production in the Bolivarian Republic of Venezuela, during the period between 2002 and 2015. An econometric model was developed using the Cobb-Douglas production function and the results obtained allowed observing the existing gap between real production and the goals proposed by the Venezuelan State. [ABSTRACT FROM AUTHOR]

Internal combustion engines are complex machines that constitute an object of design, and in which diverse processes and variables encounter. In the industrial field, the design of a new engine begins with the conception of a wellestablished solution with consideration on the experience of the designers. To perform the structural design of an engine, it is needed to determine the forces and moments acting on its components, derived from the processes along the cycles of work, with observation of the variations of the pressures and the temperatures in the cylinder and of the forces and moments of inertia in the components of the mechanisms and the structure. It is the purpose of the present paper to introduce the development of a series of procedures to obtain the preliminary dimensions of the main components of an engine (power mechanism, engine block and cylinder head dimensions), applying the machine design fundamentals and the thermodynamic and dynamic characterization of a generic engine of combustion, using the minimum information (power, torque, engine speed, and conditions of exploitation). To systematize the engine preliminary design, a spreadsheet based on Microsoft Excel was developed. To use this spreadsheet, the user must specify composition of the fuel, the type of ignition, and the wished characteristics of the engine. The outputs of the spreadsheet are the global stoichiometric balance of fuel-air chemical reactions, the heat release rate, the indicator diagram, the forces and moments acting on the main components of the crank-train mechanism, such a valuable information required to conduct the dimensioning of the engine components making use of the fundamentals of strength of materials. [ABSTRACT FROM AUTHOR]

Expanded cycles, like the one developed by Atkinson for internal combustion engines (ICM), are used to make better use of fuel and increase thermal efficiency. In this paper, the Watt's and Stephenson's kinematic structures is presented from the point of view of the mechanics of machinery and graphs theory, which by means of multi-link arrangements, allow recreating the mechanism presented by James Atkinson. By applying a kinematical analysis to these kinematic structures, the problems related to the piston speeds and accelerations that prevent the massive introduction of the "classical Atkinson cycle" in automotive engines are revealed. Despite this fact, the Atkinson cycle is highlighted in this work as a real promising constructive technology, given the advances in electronic hardware and control technologies. [ABSTRACT FROM AUTHOR]

In this paper, we study the unbalance and misalignment effect on the acceleration vibration parameters commonly used in the diagnosis of early bearing failures. This research provides a diagnostic parameter called AFC. Measurements of the AFC parameter are sensitive to the existence of the defect; however, misalignment, unbalance and their interactions do not cause a statistically significant effect in their values. The purpose of finding this parameter is to avoid false alarms or cover up faults in bearings within mechanisms susceptible to unbalance and misalignment. Among the methods studied, there are the spectral analysis, the study of global values of the acceleration measurement with different processing like the high-frequency detection HFD, the acceleration envelope ENV, the kurtosis K, the crest factor FC and the asymmetry of the signal Ske, among other parameters proposed by the authors. In this regard, an experimental device was built, and a multilevel factorial experiment (23) was designed where the factors were bearing damage, unbalance and misalignment. Three replicates were performed (24 experimental units). [ABSTRACT FROM AUTHOR]

In this paper, the results of a numerical analysis to obtain the stress intensity factor in mixed mode, KI and KII, in a cracked concrete dam submitted to seismic loads are presented. The numerical model was implemented in the commercial finite element code Abaqus/Standard. Koyna dam geometry was used, including a crack parallel to the horizontal plane. In order to evaluate the importance of guaranteeing an adequate crack sealing using epoxy resin, a second parametric study was done considering partial crack sealing. The study results allow determining the cracks that endangered the dam structural integrity under seismic loads. [ABSTRACT FROM AUTHOR]

Obtaining precise solutions with the finite element method (FEM) for diffusive problems with multiple phases entails a high computational cost. For this reason, the extended finite element method (XFEM) has become the usual tool for the analysis of this type of problems. However, when XFEM is applied to two-phase problems with very different conductivities, inaccurate representations of the flows in the vicinity of the interface are obtained. To alleviate this deficiency of the XFEM. additional restrictions must be added to the method, originating a modification of it, known as XFEM+. Since XFEM+ is relatively recent and little known and implemented at the time of designing applications for real problems of engineering and science, this paper presents its theoretical development, as well as the numerical results obtained for 2D problems, compared to FEM and XFEM. A contribution of this work is given by the implementation of the methods for quadrilateral elements. The numerical results obtained for this type of elements, and different interfaces, show the remarkable improvement of the XFEM when increasing the order of interpolation. [ABSTRACT FROM AUTHOR]

An analysis of combined effect of temperature and load frequency on the fatigue crack growth rate and cracking velocity for Chlorinated Polyvinyl Chloride (CPVC) is presented in this paper. CPVC is a thermoplastic material used for piping systems where higher temperature and chemical resistance are important, becoming a good alternative to metals. The Dual Boundary Element Method (DBEM) is used to determine three dimensional states of stresses and strains at each increment of crack. Stress intensity factors at the crack tip are determined using the J-integral, and the crack growth direction is defined by the maximum principal stress criteria. A mathematical model proposed by Kim & Wang in 1994 based on experimental results is applied to predict cracking velocity. In this work, a specimen with lateral crack using temperature values between 23 and 70 °C and frequencies between 0.1 and 10 Hz is evaluated. The results show that cracking velocity increases with temperature increase and with frequency decrease. These results are compared to Paris & Erdogan model showing good agreement which reveals that DBEM could be an accurate tool to investigate the prediction of crack growth in polymers. [ABSTRACT FROM AUTHOR]

Colombia has a high potential for biomass. In rural areas its use is focused on firewood for water heating and food cooking; therefore, it is essential to adopt solutions derived from new technological advances and studies in the generation of energy from this resource so that it contributes to social, cultural and economic changes leading to quality of life improvement in these isolated areas. In the processes of agricultural modernization, the transport sector plays an important role, as in planting and harvesting its use optimizes times in the harvesting of fruits by means of their transport to collection centers, as well as it allows to minimize times in pruning work, irrigation and soil preparation. Besides, it generates good agricultural practices and contributes to consolidate a more productive and sustainable field. Nevertheless, the vehicles used are powered by internal combustion engines and, due to their technical characteristics, they do not adapt to the requirements of Colombian geography; thus, it is important to develop technologies that lead to a rational use of energy, taking advantage of the great biomass potential that many regions of the country have. Accordingly, this is proposed to develop an electric charging station; an initial part of a macro project that is being developed in SENA which looks for the incorporation of electric utility vehicles to be used in the planting and harvesting of cocoa. In this paper, a physical-chemical characterization of two types of organic substrates (manure of pigs and chickens) is carried out in order to acknowledge the methane energy potential for the design of an electric station that serves as a feeder for rechargeable batteries. As a relevant result, the sample obtained from the 1: 3 ratio of pig manure is highlighted since a better methane production is achieved in a retention time of approximately 30 days, achieving a daily charge of the batteries in an estimated time of 6 hours which contributes to a management of slow charge cycles according to its control algorithm and to a complete equalization of the 1.980 cells that make up the 6 modules of the batteries. [ABSTRACT FROM AUTHOR]

This paper presents the thermal analysis and mathematical modeling of a discontinuous agitation reactor. A data acquisition phase was implemented in terms of operation and utility of the agitation reactors. Subsequently, the concepts of thermodynamics, fluid mechanics, heat transfer and matter transport were applied to perform the respective thermal analysis and thus, determine the energy contained and transferred in the fluids used. In addition, a mathematical model was deduced in the EES software to examine its behavior, taking into account the operational variables subjected to various types of fluids. Finally, the physical-chemical environment of the reactor was simulated to validate the calculated data and compare them with the experimental values, relating the geometry of the equipment to the performance conditions and the specifications of the final product. [ABSTRACT FROM AUTHOR]

In this paper, the permeability and tortuosity of mesoporous ceramics of kaolin and diatomite are reported. The cylindrical samples with weight percentages of 60% diatomite, 30% kaolin and 10% CaCO3 were made by casting, with an average diameter of 5 cm and a thickness of 0.6 cm. The drying process was carried out through the forced circulation stove at 100 °C for 24 hours and the sintering at temperatures of 800 °C, 850 °C, 900 °C, 950 °C, 1000 °C and 1100 °C, using an electric muffle with a ramp of 5 °C/min. For the determination of water permeability, a variable load permeameter was used, while the tortuosity was found from the product of the form factor and its porosity. The results of tortuosity were found in the range of 3.32 to 7.16, whereas permeability varied between 3.09x10-6 and 22.2x10-6 cm/s, evidencing an inverse behavior between these parameters when increasing to temperature. [ABSTRACT FROM AUTHOR]

Previous scientific research has not focused on downdraught beehive kilns, which are the most used in the Colombian brick (ceramic) industry. Hence, in the present paper, an analytical mathematical model is developed in order to simulate the exhaust gas behavior. To do so, gas combustion and heat and mass transfer to the products and the walls are modelled within the kiln. The obtained model is validated by experimental data. Finally, with the experimental data acquired in the discharge duct and chimney, a heat recovery system is proposed to make use of the residual energy. [ABSTRACT FROM AUTHOR]

In this paper, several wavelet-based techniques for removal of gaussian noise in astronomical images are compared. Validation experiments were carried out with previously processed images from the SDSS, by adding noise artificially and comparing the effectiveness of each method in the reconstruction of original image by means of quantitative indicators like the mean square error and the signal to noise ratio. Results obtained with some of used methods are quite satisfactory. Also, their comparison with other papers shows contradictory conclusions about the best option among the considered methods. Authors of those papers made their validation experiments with another kind of images of non-astronomical origin, having therefore other characteristics. [ABSTRACT FROM AUTHOR]

This paper presents results in a research project based on the creation of a video game that uses social networking capabilities for the prevention of Pulmonary Tuberculosis. First, it presents a review that focuses on video games, online social networks and their uses health field. This paper shows "Planet TB", a videogame that incorporates all of the described contents, as solution perspective. [ABSTRACT FROM AUTHOR]

This paper presents a mechanism to cooperation in large scale resource social dilemmas. The mechanism was developed considering the Colombian electricity crisis (1992-1993). The paper offers a dynamic hypothesis as extension of the small scale resource social dilemmas theory to large scale situations that integrates the effects of delays, expectations, and perceptions about cooperation. This work also presents simulations that suposes the dynamic hypothesis as explanation of the variation of the electricity demand in the 1992 1993 Colombian electricity crisis. The results explain also the variation of demand after and before shortages in that crisis. As a conclusion, we suggest that perception, and expectations in dynamic complexity situations should be considered as a fundamental issue for explaining cooperation [ABSTRACT FROM AUTHOR]

This paper shows a description about UPV and TCQSM methods, developed to determinate quality and service level in urban collective public transit by bus, in order to provide a framework which permits to make a comparison of these two (2) methods to obtain the compatibility degree among formulated scales of service level. As a result of this research, this paper presents contributions of analyzed methods to measure service quality of urban collective public transit by bus. [ABSTRACT FROM AUTHOR]

Surgery equipment sterilization is an important part of many serious medical procedures due to it prevents infections and diseases transmission. The saturated steam autoclave may be used to carry out the sterilization process according to the required medical standards. For this, certain temperature and pressure conditions must be granted in the sterilization chamber of the autoclave to perform an accurate sterilization process. However, the dynamical behavior of an autoclave used to be complex, requiring the use of control strategies to perform a correct sterilization process. This paper presents the identification and temperature control of a saturated steam autoclave for the sterilization equipment utilizing the pole placement technique. Initially, temperature data of autoclave was acquired using a data acquisition system. Then, a linear model of the autoclave was obtained. Using the linear model, a PI and PID controllers were tuned to achieve the desired closed loop specifications. Controllers were validated in Simulink for the temperature conditions of the autoclave in presence of external disturbance and random noise in the feedback loop. Results show that the PID controller has a good performance on the autoclave temperature regulation in presence of external disturbances. [ABSTRACT FROM AUTHOR]