Tecnura

29-40

Authors: César Hernández, Ingrid Páez, Diego Giral

This paper proposed a hybrid algorithm for spectrum allocation in cognitive radio networks based on two algorithms, analytical hierarchical process (AHP) and multi-criteria optimization and compromise solution (VIKOR), for improving the performance of mobility spectrum of secondary users in cognitive radio networks. To evaluate the level of performance of the proposed algorithm, a comparative analysis between the proposed AHP-VIKOR, Grey Relational Analysis (GRA) and a random allocation of spectrum (Random) algorithm, is performed. The first two algorithms work with the same decision criteria: probability of channel availability, estimated time availability, signal-to-interference-plus-noise ratio and bandwidth. Unlike related work, benchmarking was validated through a trace of real spectral occupation data, captured in the GSM frequency band, which models the actual behavior of licensed users. For performance evaluation five metric were used, handoff failed average cumulative number, handoff average cumulative number, average bandwidth, delay and average cumulative throughput. The results of the comparative analysis with the other two algorithms show that the AHP-VIKOR algorithm proposed provides the best performance in spectral mobility

53-64

Authors: Ricardo Andrés García León, María Angélica Acosta Pérez, Eder Flórez Solano

The braking system of a car must meet a complex set of requirements, among which safety is paramount. The brakes must work safely and predictably under all circumstances, which means having a stable level of friction, under all conditions of temperature, as well as environmental factors. For proper design and operation of the brake discs it is necessary to consider different aspects such as geometry, material type, mechanical strength, maximum temperature, thermal deformation, resistance to cracking, among others. All these aspects make the corrosion process be accelerated, generating component wear thus, and of course uncertainty in the braking process.

75-88

Authors: Gloria Estefany Amarís Castro, Thomas Edison Guerrero Barbosa, Edgar Antonio Sánchez Ortiz

The importance of the behavior of the Saint Venant equations and its implications for flow analysis applied to models of hydraulic transit is the main theme of this research, where the basis of the applications and uses of these mathematical models is determined and the performance is evaluated these equations in 1D and its possible approaches for different conditions of a real situation using computational numerical experimentation for a section of a prismatic channel with a hydraulic section, in cases where the channel slope presents three types of conditions: supercritical, subcritical and horizontal slope for a design rate. The main objective of this research is to find a demonstration of the applicability of the Saint Venant equations for different conditions of approaching this problem from the point of view of the solution of the Saint Venant equations in one dimension. Scheme simple solution that produces useful solutions to the needs of engineering, finding that within the sewer network analysis there are many factors that can affect the solution of the Saint Venant equations

101-114

Authors: Alveiro Alonso Rosado Gómez, Alejandra Verjel Ibáñez

This paper shows data mining techniques to predict air tickets demand in Ocaña, North Santander, regarding to origin-destination: Ocaña-Bogota, Ocaña–Bucaramanga, Ocaña–Medellín, Ocaña – Cúcuta and Ocaña-Barranquilla. Some data studies were used to estimate new means of transportation demand in Ocaña. This research follows the process of knowledge extraction in databases. In the data mining process stage, it was selected decision trees technique and as algorithm J48. With this algorithm application, we found that people who travel monthly and weekly choose the plane, alike if they travel by health issues; otherwise, but if they travel to Barranquilla, Bogotá and/or Medellin for work, they choose bus

127-140

Authors: Germán Andrés Vargas Torres, Ricardo Andrés Castillo Estepa

This article presents an algorithm which commands a group of Bioloid humanoid robots in order to organize them around an object of interest, previously detected by an external vision system. The robots form a Multi-Agent System (MAS) oriented towards cooperative gathering tasks. Development of the MAS, as well as each of the organization algorithm’s components and simulation inside a virtual environment, are all detailed. The algorithm is subdivided in two dedicated threads: one of which handles machine vision (filtering, contour detection and classification achieved through EmguCV libraries) and operational space calculations; while the other operates ZigBee wireless communication with the robots. Furthermore, the robots possess their own embedded code which enables them to translate a sequence of received instructions into gait patterns which allow them to move towards the object of interest. Total execution time for the gathering task is chosen as the global performance measure to evaluate.

159-174

Authors: Ernesto Cadena Muñoz, Hermes Javier Eslava Blanco, José Alejandro Franco Calderón

This paper shows a review of the state of art of radio spectrum management,  some  basic concepts are defined  allowing to recognizing its  scope and importance for the sector and an analysis of different spectrum management  models is done highlighting features,  strengths and  weaknesses  of each  one for its application.  It  analyzes the context of the country, where it is observed that the traditional management model  used is not  efficient, generating economic losses for the country in one of the most important resources on Telecommunications, which leads us to reconsider the current model of  radio spectrum management  in  Colombia. Finally, we present the trends in  spectrum management and we highlight  the need for analysis  of the  model based on the  telecommunications  market, the requirements for its implementation in the country and the difficulties that may arise.

33-46

Authors: Juan Jairo Vaca González, Cristhian Andrés Peña Caro, Harold Vacca González

Serial robotic manipulators are efficient tools to carry out repetitive and precision tasks in industry, as long as there is understanding of the involved kinematics in the positioning and orientation of the final effector. This article presents a methodology to the solution of an inverse kinematic serial robot (Melfa RV-2A) problem through genetic algorithm (GA) implementation using the Screws direct kinematic model (SDKM). In order to do this, the Screws parameters that model the main four robot joints are obtained, the related workspace is calculated and the GA is designed considering a multi objective function of position and orientation located in the final effector, with respect to a coordinate and orientation of an established target point. The GA validation is carried out according to aptitude, convergence time and number of generations used in order to reach the main objective. Therefore, the implementation of a SDKM-based AG is a tool that could be used to calculate the inverse kinematic of serial robots. This implementation allows to establishing for the first time the matrix exhibition of a direct kinematic system to obtain the inverse kinematic solution of a serial robot. In consequence, it is demonstrated that this methodology is feasible and efficient to solve the inverse kinematic of any manipulator robot.

59-70

Authors: Silvio Delvasto Arjona, Álvaro Guzmán Aponte, John Alexander Torres León, Martha Lorena Cedeño Venté, David Felipe Acosta Guarín

This article presents the results of a research on the use of glass powder as substitute of feldspar for manufacturing stoneware tiles. Mixtures were prepared in which glass powder substituted feldspar in two different percentages (25 wt% and 50 wt%). Specimens of the obtained mixtures were molded, dried and sintered. Physical (apparent density, porousness, absorption, among others) and mechanical properties (flexion resistance) of standard sintered bodies (V0) were compared to the sintered bodies in which the melting material was substituted in the formulation by glass powder in percentages of 25% and 50% (V25 and V50). It was found that the glass powder addition in the formulations caused decrease in flexion resistance and increase in water absorption values. However, the melting action of glass powder reduced the sintering temperature in regards with the standard mixture in 150 °C for substitutions of 50% and 25%, respectively. By using Scanning Electron Microscopy (SEM) needles of primary mullite and secondary mullite (elongated needles) in a vitreous phase were identified

83-92

Authors: Alejandro Rivera Roldán, Miguel Alberto Becerra Botero, Jaime Alberto Guzmán Luna

This paper presents a vibration analysis on induction motors using Hidden Markov Models (HMM) applied to features obtained from the Empirical Mode Decomposition (EMD) and Hilbert-Huang transform to vibration signals obtained in the coordinates x and y, in order to detect malfunctions in bearings and bars. Additionally, a comparative analysis of the ability of the vibration signals in the x and y directions to provide information for failures detection is presented. Thus, an ergodic HMM initialized and trained by expectation maximization algorithm with convergence at 10e-7 and maximum iterations of 100 was applied to the feature space and its performance was determined by cross-validation with 80-20 with 30 fold for obtaining high performance fault detection in terms of accuracy

109-120

Authors: Carlos Javier Carvajal Montealegre

This paper describes the data mining process to obtain classification rules over an information security incident data collection, explaining in detail the use of genetic programming as a mean to model the incidents behavior and representing such rules as decision trees. The described mining process includes several tasks, such as the GP (Genetic Programming) approach evaluation, the individual's representation and the algorithm parameters tuning to upgrade the performance. The paper concludes with the result analysis and the description of the rules obtained, suggesting measures to avoid the occurrence of new informatics attacks. This paper is a part of the thesis work degree: Information Security Incident Analytics by Data Mining for Behavioral Modeling and Pattern Recognition (Carvajal, 2012)

133-144

Authors: María Elena Bernal Loaiza, German Cock Sarmiento, Jorge Hernán Restrepo Correa

This research focuses on the design of a simulation of the process in a flexible manufacturing cell at the Faculty of Engineering of the Universidad Tecnológica de Pereira, aiming at measuring and choosing the one alternative of solution that improves to a greater degree the productivity of the current system using the results provided by the software Promodel. In order to do this, the stages of the simulation as definition of the system, model formulation, identification of variables, data collection, implementation and interpretation were used. As a result, the productivity was calculated taking into account the variables of the model and simulation time, at the same time the information from each of the locations was interpreted, finding the percentage of use and total number of entities for locations with unit capacity, and for locations with greater capacity there is information concerning to the percentage of empty time, partially occupied, full and unavailable regarding available time. In contrast to other simulations, in this design, on the networks the type of network Crane was used, associated to the resources of model. Which facilitates the movement of robot arms with the parts circulating through the system.

157-170

Authors: Rafael Andres Robayo Salazar, Pedro Enrique Mattey Centeno, Yimmy Fernando Silva Urrego, Diana Marcela Burgos Galindo, Silvio Delvasto Arjona

The amount of construction, remodeling and demolition activities in the Colombian cities increases constantly due to growth and economic development of the urban population. However, these practices create big quantities of debris that have currently become an environmental problem in cities such as Cali (Colombia). The search for integral solutions that allow for an adequate management and reuse of the different materials that form construction and demolition debris was unthinkable some decades ago. Nonetheless, nowadays it is an urgent challenge for different sectors in the society that must join efforts to find solutions. Regarding this, the present article shows an analysis about the currently situation of the construction debris management in the aforementioned city and proposes different actions according to the necessary opportunities and challenges to achieve an integral management and reuse of these materials. The analysis of this topic could be a guide for future research, as well as promote its priority in the public agenda, creating the necessary conditions for the recycling process of the construction and demolition wastes to become a viable possibility in the Colombian cities through the obtained experience.

191-200

Authors: Wilson Rodríguez Calderón, Myriam Rocío Pallares-Muñoz

When we need to determine the solution of a nonlinear equation there are two options: closed-methods which use intervals that contain the root and during the iterative process reduce the size of natural way, and, open-methods that represent an attractive option as they do not require an initial interval enclosure. In general, we know open-methods are more efficient computationally though they do not always converge. In this paper we are presenting a divergence case analysis when we use the method of fixed point iteration to find the normal height in a rectangular channel using the Manning equation. To solve this problem, we propose applying two strategies (developed by authors) that allow to modifying the iteration function making additional formulations of the traditional method and its convergence theorem. Although Manning equation is solved with other methods like Newton when we use the iteration method of fixed-point an interesting divergence situation is presented which can be solved with a convergence higher than quadratic over the initial iterations. The proposed strategies have been tested in two cases; a study of divergence of square root of real numbers was made previously by authors for testing. Results in both cases have been successful. We present comparisons because are important for seeing the advantage of proposed strategies versus the most representative open-methods.

37-51

Authors: Ricardo Alfredo Cruz Hernández, Carlos Mauricio Pico Cortés, Ludwing Pérez Bustos

In this paper, it was evaluated the performance of concrete with crushed slag of cupola furnace (SCF) as sand replacement in percentages of 0 %, 10 %, 15 % and 20 %, subjected to accelerated chemical attacks of carbonation, sulfation and alkali-aggregate reaction (AAR). The sound absorption characteristics of the material were determined through the sound absorption coefficient (α), and the noise reduction coefficient (NRC). Carbonation was evaluated through a closed camera with the 70 % concentration of carbon dioxide and conditions of relative humidity between 50 % and 70 %. The results indicated that the penetration depth of CO2 is lower when greater the percentage of substitution is. To accelerate the attack by sulfates, specimens were immersed in aqueous solution of sodium sulfate anhydrous (Na2 SO4 ) 1N with cycles of wetting and drying. It determined that the impairment presented in concrete paste is directly proportional to the percentage of sand replacement. The acceleration of the AAR in the concrete was carried out by immersing specimens in an aqueous solution of sodium hydroxide (NaOH) for 16 days. The test concluded that the inclusion of SCF is not favorable for AAR. The measurement of sound absorption coefficient was taken by the method of impedance tube, relating minimum and maximum values of stationary wave amplitude. The results showed that SCF with higher sand replacement are favorable for the noise absorption in buildings.

63-73

Authors: Alfonso Mariano Ramos Cañón

Failure of slopes under monotonic undrained conditions of loading is an instability process which occurs in loose sands. It is well known that the behavior of sands is greatly influenced by their initial conditions, such as the initial density and confining pressure (Hyodo, Tanimizu, Yasufuku, & Murata, 1994). A common approach used to tackle issues associated with liquefaction is based on phenomenology. Moreover, the most used methodologies for evaluating the potential of liquefaction are based on field test such as SPT and CPT (Youd et al., 2001). These methodologies disregard important aspects like the anisotropy of stresses in the evaluation of susceptibility of liquefaction. An alternative and more rational way to understand the static liquefaction is based on sets of laboratory tests, and based on these results it’s proposed a generalization of the behaviour. For exampleWanatowski and Chu (2007) depict a relation between the stress ratio hL = qL /pL and void ratio for undrained triaxial tests isotropically and anisotropically compressed (qL and pL are the main pressure and the deviatoric stress in the onset of static liquefaction, respectively). On other hand, Chu and Wanatowski (2008) propose a mathematical equation between hL and the Been-Jefferies critical state parameter (ψ = e − ec ). This equation is obtained by assuming that the increase of plastic volumetrics train is equal to the increase of total volumetric strain and both of them are equal to zero in the peak of deviatoric stress. It means that the dilatancy is zero in the peak of undrained effective stress path. However, Lade (1994) demonstrates that sands subjected to undrained loading show a behavior that must be modelled by a flow rule highly non associative. A similar approximation for detecting the onset of static liquefaction is to characterize the instability line for a specific type of sand. The instability line can be defined as the boundary in which large strains are rapidly generated due to the inability of a soil element to sustain a given stress or load (Chu, Leroueil, & Leong, 2003). The instability line was firstly proposed by Vaid and Chern (1985) defining it as the locus of points at which flow liquefaction is initiated for the same initial void ratio under monotonic undrained triaxial tests. Many researchers have analysed the instability line (Lade, 1994; Chu & Wanatowski, 2008; Chu, Leroueil, & Leong, 2003; Wanatowski & Chu, 2007; Hyodo, Tanimizu, Yasufuku, & Murata, 1994; Andrade, 2009; Andrade, Ramos, & Lizcano, 2013). Andrade (2009) and Ramos, Andradeand Lizcano (2011) using two different elastoplastic constitutive models concluded that the slope of the instability line is not a constant of the material but it is a state parameter In this work, a criterion for detecting the onset of static liquefaction derived by Andrade, Ramosand Lizcano (2013) and Ramos, Andradeand Lizcano (2011) was extended to an isotropic elastoplastic constitutive model with kinematic hardening and bounding surface theory (Manzari-Dafalias model). The application of this criterion matches very well with experiments reported in the literature, allowing to generate numerical simulation for different conditions with a high level of confidence. By making use of numerical simulations previously validated with experiments, it is possible to supply the deficiency of the experimental approximation and to have a greater spectrum of the behavior of the sandy slopes subjected to static liquefaction. As result, the influence of void ratio, mean pressure and initial anisotropy on the onset of static liquefaction is investigated. Finally, despite of the multiple variables involved in the process of generation of static liquefaction, the behavior of the sand can be condensed in a linear relation between Δq/p0 and h0 . This kind of relation can be used in the practice of geotechnical engineering to quantify the degree of security of a slope given the initial conditions of stress and void ratio. The paper is organized as follow. The first section of this paper shows the instability criterion for detecting the onset of static liquefaction using the Manzari-Dafalias elastoplastic constitutive model. The ‘Validation’ section presents numerical simulations for prediction of static liquefaction and compares them with laboratory experiments. Finally, the influence of the void ratio, mean pressure and the initial stress anisotropy on the onset of static liquefaction is presented based on several simulations conducted with the constitutive model and the instability criterion. Findings from the application of the criterion are highlighted in the ‘Conclusions’ section.

84-92

Authors: William Mauricio Sanabria Becerra, Oscar Hernando Pardo Cuervo, Robinson de Jesús Torres Gómez

This paper shows the results of the research in terms of the evaluation of corrosion fatigue resistance of SAE 1020 steel in acidic conditions, using as corrosive substance: acetate buffer with pH 2, 4 and 6. The fatigue tests were performed according to the model of cantilever rotating bending. The results were compared with the limit of fatigue resistance of the material tested in air. It was observed a significantly reduced limit with increasing acidity of the substance. Likewise, localized corrosion type filiform corrosion was observed on the surface material, caused by the effect of the specimen aerated to be partially submerged in rotation. Limits fatigue strength determined using staircase method recommended by standard ISO 1143 and ISO 12107, with confidence level of 50 % and a probability of failure of 10 %. Finally, the surfaces were analyzed to find multiple origins of fracture and crack propagation lengths related to the acidity of the medium.

106-118

Authors: Ana María Mejía Solanilla, Ricardo Alberto Hincapié Isaza, Ramón Alfonso Gallego Rendón

In this article, a method to solve the multi-objective planning problem of electric power distribution systems is proposed by means of using a nondominated sorting elitist algorithm (NSGA-II). This method considers four mathematical models, where fixed costs, variable costs, fixed and variable costs, and network reliability are considered as objective functions. The set of constraints is comprised of technical and operational criteria. When all mathematical models are solved common elements to the solutions with each model are found. This process is repeated until a final configuration of the system is found. In this manner, in each step of the algorithm, sorts of cuts are generated, which reduce the solution space of the problem. The method is verified with a distribution system from the specialized literature, obtaining results that show the effectiveness of the method when an equilibrium point is found among all the objectives considered.

139-162

Authors: Sergey González Mejía, José Miguel Ramírez Scarpetta, Edna Joydeth Avella Rodríguez

This paper shows the design of two convolution image filter architectures, which use Hardware co-simulation through Xilinx System Generator Matlab toolbox to be implemented in a Xilinx Spartan 3AN FPGA. The purpose of the project is to evaluate the performance of parallel image processing versus the serial one. Initially the design and hardware implementation of the two architectures are performed, after, from the measurement of specific variables the best architecture is selected as an alternative for parallelization, using the tools provided by the toolbox evaluates the relationship between the degree of parallelism, execution times and hardware resources used , and finally among the most important conclusions are obtained that the processing time of the image is significantly reduced with increasing the degree of parallelization of the image

24-37

Authors: Helbert Eduardo Espitia Cüchango, Jorge Iván Sofrony Esmeral

In this document, it will be introduced the proposal for optimization algorithm based on particle swarms vorticity features, where a search group is considered through the association to the mid point of the swarm and an individual search is given for the best position of each individual. The search group seeks to achieve the convergence of the whole swarm, whereas the individual search allows better exploration in pursuant of space. The algorithm has convergence and exploration behavior given by the selected model which is based on the behavior of a swarm of individuals. For establishing the algorithm performance, a set of test functions in two dimensions is used.

53-64

Authors: Alejandro Garcés Ruiz, Carlos Adrián Correa Flórez, Alejandro Sánchez Salcedo

This paper presents an algorithm for the optimal operation of distributed energy storage units from perspective of active potential lost. An exact model based on Lagrange relaxation is proposed. Simulation results on the IEEE 37-bus test feeder demonstrate that energy storage system can be used for minimizing transmission losses in a distribution system by reshaping the load curve. The main contribution of this approach is the objective function and the optimization algorithm, Lagrange multipliers are used for determining optimal placement and sizing of the energy storage units. A discussion about the impact of energy storage units on the distribution planning is also presented.

78-89

Authors: Sergio Andrés Vanegas Herrera, Gustavo Chio Cho

The reliability index β is a parameter used to estimate the safety of a structure or an element during the design stage or service. This parameter defined in other codes in the world (European Committee for Standardisation (Eurocode), EN 1990:2002; American Association of State Highway and Transportation Officials (AASHTO), 2012), is not specified in the Colombian Code of Bridges Seismic Design (CCDSP-95) (1995). In this paper, it will be presented a study on the estimation of the reliability index β of the interior and exterior girders of a beam and slab bridge with reinforced concrete, 30 m in length, simply supported and designed according to the CCDSP-95. In the evaluation of the resistant moments, there were considered properties of materials using a normal distribution, and moreover, a Monte Carlo simulation was used to estimate load effect of moment at mid-span of the live load

103-113

Authors: Luz Amparo Quintero Ortiz, Ricardo Alfredo Cruz Hernández, Deyci Yamile Peña Santos

The purpose of this study is to determine correlations among content of concrete water, compressive resistance and Ultrasonic Pulse Velocity (UPV). Cylindrical concrete specimens, 200 mm long and 100 mm in diameter made from a mixture of Portland cement type I, and a water/cement ratio (w/c) 0.5, have been studied. The curing of the specimens was performed under standardized conditions and indoor environmental conditions. It determines the water content in each specimen by difference in weight and subjecting them to UPV tests and to compressive resistance test during the first 28 days after the setting. The results show a model of logarithmic type that describes the relationship between the compressive strength with the water content of concrete and the UPV during the curing stages proposed.

126-138

Authors: Carlos Alberto Ardila Albarracín, Francisco José Pino Correa, César Jesús Pardo Calvache, Luis Merchán Paredes

The small software development companies have difficulties in adopting practices about quantitative process management offered by reference models such as CMMI-DEV or ISO/IEC 15504 because it generates expensive investments in long-term periods of time. However, if they do not incorporate at least the essential practices, they won’t be able to obtain processes with less variability in its performance and that can be statistically under control which directly impacts the projects results because they would allow making better estimates. In this article, it is presented a general proposal of a framework for quantitative process management in very small entities (MaTGeC) that offers a guide to monitor and assess specific processes selected by the organization. Moreover, it is indicated the components that conform it, along with the practices, activities, roles and essential work products for that this kind of organizations to incorporate the quantitative management fundamentals in their more critical tasks.

27-37

Authors: Nelson Enrique Vera Parra, Danilo Alfonso López, Héctor Cristyan Manta Caro

Currently, mobile networks and next generation wireless networks such as, IPv6 low-power Wireless Personal Area networks 6LoWPAN, wireless sensor networks and hierarchical mobile networks in IPv6, are under rigorous research and development, thereforethose networks represent the next step in the evolution of the Machine-to-Machine M2M networks, while supporting broadband access for the next generation of intelligent systems, technologies and future Internet. These next generation networks impose restrictions on the processing power, bandwidth and energy resources, which represents a major constraint in the implementation of security mechanisms. In this regard, in recent years there have been various proposals for key management, digital signature procedures and data encryption based on elliptic and hyper-elliptic curves, to achieve levels of safety equivalent to convenWLRQDO DOJRULWKPV EDVHG RQ 'LI¿H+HOOPDQ DQG Rivest-Shamir-Adleman RSA, but reducing the key length and thus the computational and network resources. This paper reviews algorithms based on Elliptic Curves Cryptography ECC and their application to IPv6-enabled new generation wireless networks. This paper also describes a simulation test-bed for the evaluation of ECC, where we compare computational resources required and limitations for lightweight security mechanisms in se

53-63

Authors: Jesús D. González Llorente, Gustavo A. Puerto Leguizamón

CubeSats are small satellites that due to their size restriction have photovoltaic cells placed on theirs surface as the only energy source. The purpose of this work is to estimate the maximum amount of power that can be obtained from these solar cells, so that an energy balance can be made during the design of space mission with this kind of satellites. In the analyzed scenario, a CubeSat of 10cm x 10cm x 10cm (1U) has always a face oriented toward the Earth. Cosine loss and the temperature variation due to satellite orbit are considered. For the estimation we use a mathematical model of the solar cells, which is also used to estimate the maximum power point according to the incidence angle of the solar radiation and the temperature on a low orbit around the Earth. The results show the variation of the maximum electric power supplied by the panels on the illuminated portion of the orbit, without considering the Earth’s albedo. Apart from the power, the current -voltage curves are estimated for different locations over the CubeSat’s orbit.

76-90

Authors: Andrés Jaramillo Ortiz, Robinson Jiménez M, Olga Lucía Ramos

This paper details implementation of an artificial vision system through digital image processing, which allows automation of the quality control process. The prototype was implemented in a conveyor belt segment and was designed to discern the quality of two different industrial shapes, with a sensibility of +/- 0,1 mm and a speed rate of 1400 shapes per hour, identifying which pieces are within manufacture quality requirements. This work is divided in three main sections: hardware, electronic control and software.

103-119

Authors: Luis Alberto Paredes Chérrez, Óscar Javier Reyes Ortiz, Javier Fernando Camacho Tauta

Mechanic characterization of asphalt mixtures uses to be expensive and time consuming. How- ever, some researches try to correlate such prop- erties by simple, fast and less expensive tests. The main goal of this investigation consisted into establish the viability of use the simply sup- ported semicircular beam (SCB) to characterize dense asphalt mixtures designed under speci- fications of the Instituto de Desarrollo Urbano (IDU) and the Instituto Nacional de Vías (In- vias). The study started with the production of SCB specimens using different materials (soil aggregate, asphalt, asphaltite, reclaimed asphalt pavement and lime) and compaction techniques (vibration and gyratory compaction). The SCB tests were carried at a velocity of 1mm/min and 15ºC of temperature. From these tests, different parameters were obtained based on the definition in the Fénix test (maximum load, displacement at maximum loading, energy released during the cracking process, traction stiffness index and te- nacity index). From the results, it was found that the SCB tests were useful as a tool to character- ize the mechanical properties of the asphalt mix- tures. This conclusion is applicable for all kind of mixtures tested, ageing periods, compaction level and filler content.

134-153

Authors: Hernán Porras Díaz, Jhon Jairo Cáceres Jiménez, Elver Omar Gallo Lancheros

The state of the art of the processing methods for TLS (terrestrial laser scanner) digital point clouds is shown in this paper. The TLS is an instrument able to capture topographic and geometric information of any structure at millimeter accuracy. Also, in some cases, they capture radiometric information of the scanned objects. The collected information is represented by point clouds that are used on a wide range of applications such as planning of urban development, structural analysis, erosion and deforestation modeling, cultural heritage preservation and virtual navigation. The purpose of this work is to offer a review of the state of the art on the methods used through the several steps of the point cloud processing workflow: relative and absolute registration, segmentation, classification and three dimensional modeling.