bluuebunny/crossref_metadata_2025 huggingface dataset:
A thermodynamic approach to choosing pervaporatives membranes
Authors: Amrani Mahacine
Published: August 2022

This work describes separating a mixture of several components obtained as a product of methyl polymethyl methacrylate (PMMA) thermo-degradation. It was aimed at purifying methyl methacrylate monomer (MMA) obtained by 95% mass thermal degradation to reach 99.5% maximum pervaporation concentration. This work studied the theory of pervaporation and applying the main thermodynamic criteria for choosing suitable polymer membranes for separating the MMA/PRP/ISB mixture. Such thermodynamic criteria were based on monomer interaction with and solubility on the membrane. The advantage of using this separation technique lies mainly in the fact that this method has low energy consumption compared to other processes, such as distillation or crystallisation.
Proposing and evaluating applications for products obtained during chromium chip alkaline hydrolysis produced during leather tanning
Authors: Díaz Andrea , Jiménez Juliana , Pérez Monica , Narváez Rincón Paulo César
Published: August 2022

Some applications for products obtained by chromium chip alkaline hydrolysis produced during leather tanning were evaluated in this work, considering the concept of maximising tanneries’ solid residue reuse for different industrial applications and minimising the environmental impact so produced. When Cr(OH)3 is transformed into Cr2(OH)(SO4) it can be used in tanning leather (i.e. as tanning salt). When compared to commercial salts, it was determined that it could be applied to mixtures containing this salt, replacing it by up to 40%. Chromium content reduction was evaluated for collagen hydrolyzate by pH control after alkaline hydrolysis of the chips and by applying adsorbent materials such as bentonite, alfalfa and sorghum biomass and activated charcoal, a maximum 55% Cr removal being obtained when the first two adsorbent materials were used.
A virtual art museum
Authors: Ortíz Triviño Jorge Eduardo , Cipagauta Rodolfo
Published: August 2022

This paper presents some indispensable technical aspects for designing an art museum based on virtual reality (VR) technology. A VR setting can be produced which is able to submerge users having a basic immersion level in a didactic, entertaining, cultural and artistic experience. Specialised tools, object-orientated programming language and low-cost peripheral equipment are suggested so that the VR experience can be developed and executed on reasonably-priced computers. The VR concept, characteristics, components, application and systems are analysed, as is the design for implementing it.
Designing an application for managing distribution transformer load
Authors: Sánchez Olga Liliana , Velasco Medina Jaime , Lozano Carlos Arturo
Published: August 2022

This paper presents a software application for distribution transformer load management and calculating the electricity distribution network service quality index (i.e. EDS and EFS indexes). Transformer operation state, calculating core and coil losses and selecting distribution transformers based on technical-economic criteria using daily-load curves are the load management strategies presented here. The application consists of a programme allowing to data acquisition input, an Excel-based spread-sheet having the equations for calculating load management data and a user-interface presenting the load management application’s results. The application was validated by technical-economic evaluation of three distribution transformers when supplying demand.
Comparing the MOLAP the ROLAP storage models
Authors: Tamayo Marysol , Moreno Arboleda Francisco Javier
Published: August 2022

Data Warehouses (DWs), supported by OLAP. have played a key role in helping company decision-making during the last few years. DWs can be stored in ROLAP and/or MOLAP data storage systems. Data is stored in a relational database in ROLAP and in multidimensional matrices in MOLAP. This paper presents a comparative example, analysing the performance and advantages and disadvantages of ROLAP and MOLAP in a specific database management system (DBMS). An overview of DBMS is also given to see how these technologies are being incorporated.
Developing an artificial neural network model for predicting concrete’s compression strength and electrical resistivity
Authors: Lizarazo Marriaga Juan Manuel , Gómez Cortés José Gabriel
Published: August 2022

The present study was conducted for predicting the compressive strength of concrete based on unit weight ultrasonic and pulse velocity (UPV) for 41 different concrete mixtures. This research emerged from the need for a rapid test for predicting concrete’s compressive strength. The research was also conducted for predicting concrete’s electrical resistivity based on unit weight ultrasonic, pulse velocity (UPV) and compressive strength with the same mixes. The prediction was made using simple regression analysis and artificial neural networks. The results revealed that artificial neural networks can be used for effectively predicting compressive strength and electrical resistivity.
Extracting oil from coffee
Authors: López Fontal Elkin Mauricio
Published: August 2022

The present work describes oil being extracted from toasted coffee by the extrusion method; two products are obtained from this process: coffee oil and pulp. Toasted coffee was used which has a high amount of sensorial compounds. It should be noted that a significant criterion in evaluating the quality of coffee lies in its aroma.
When extracting oil from coffee, a significant part of toasted coffee’s aromatic content leaves with it, varying according to the extraction method. A fixed oil having a high volatile load is thus obtained, presenting favorable sensory characteristics. The pulp was physically and chemically analysed to show its benefit and particular properties and, according to the results so obtained, it is a product having potential usefulness.
Current data warehousing and OLAP technologies’ status applied to spatial databases
Authors: Abril Fradel Diego Orlando , Pérez Castillo José Nelson
Published: August 2022

Organisations require their information on a timely, dynamic, friendly, centralised and easy-to-access basis for analysing it and taking correct decisions at the right time. Centralisation can be achieved with data warehouse technology. On-line analytical processing (OLAP) is used for analysis. Technologies using graphics and maps in data presentation can be exploited for an overall view of a company and helping to take better decisions. Geographic information systems (GIS) are useful for spatially locating information and representing it using maps. Data warehouses are generally implemented with a multidimensional data model to make OLAP analysis easier. A fundamental point in this model is the definition of measurements and dimensions; geography lies within such dimensions. Many researchers have concluded that the geographic dimension is another attribute for describing data in current analysis systems but without having an in-depth study of its spatial feature and without locating them on a map, like GIS does. Seen this way, interoperability is necessary between GIS and OLAP (called spatial OLAP or SOLAP) and several entities are currently researching this. This document summarises the current status of such research.
Multidisciplinary design optimisation techniques
Authors: Tovar Andres , Arzola de la Peña Nelson , Gómez Cassab Alexander
Published: August 2022

Design optimisation of a multidisciplinary project in engineering involves the decomposition of a system into disciplines and the subsequent association of their contributions. This work was aimed at presenting the most common decomposition and association techniques currently used in multidisciplinary design optimisation (MDO). Amongst the decomposition techniques this work includes hierarchical and non-hierarchical approaches as well as the most popular numerical procedures. The association techniques include: one-level methods (e.g. all-at-once optimisation and simultaneous analysis and design), multilevel methods (e.g. concurrent subspace optimisation and collaborative optimisation) and robust design. This work also incorporates an illustrative numerical example.
Stability analysis of a PFTR reactor for a first order kinetic reaction using the Lyapunov functionals
Authors: Durán Peralta Héctor Armando , Córdoba C. Luis Fernando
Published: August 2022

The stability of reactors having encompassing concentration and temperature parameters, such as continuous flow stirred tank reactors (CSTR), has been widely explored in the literature; however, there are few papers about the stability of tubular reactor having distributed spatial concentration and temperature parameters such as the plow flow tubular reactor (PFTR). This paper analyses the stability of isothermal and non-isothermal PFTR reactors using the Lyapunov functional method. The first order kinetic reaction was selected because one of this paper’s objectives was to apply Lyapunov functionals to stability analysis of distributed parameter reactors (technique used in electrical engineering systems’ stability analysis). The stability analysis revealed asymptotically stable temperature and concentration profiles for isothermal PFTR, non-isothermal PFTR with kinetic constant independent of temperature and adiabatic non-isothermal PFTR. Analysis revealed an asymptotically stability region for the heat exchange reactor and an uncertain region where it may have oscillations.
Characterising requirement engineering process and methodological tools for geographical information system (GIS) applications
Authors: Medina Cardona Luis Fernando
Published: August 2022

This article describes the requirements engineering process and the methodological tools used in geographical information system (GIS) applications as a way to face the absence of a consistent and complete specific alternative for this domain. Requirements engineering for GIS applications are thus introduced; requirements types, actors involved and communication aspects important for the process are exhibited and current methodologies are classified in modelling and specification languages. Additionally, geomatic standards as a transversal element for GIS applications are presented.
Evaluating Colombian SMEs’ technological innovation: Part 1: conceptual basis, evaluation methodology and characterisation of innovative companies
Authors: Torres Luz Marina , Castellanos Domínguez Óscar Fernando , Fúquene Montañez Aida Mayerly
Published: August 2022

Innovative processes currently constitute one of the most important alternatives for increasing organisations’ levels of competitiveness and productivity. The Colombian state (being conscious of this) has generated mechanisms aimed at encouraging technological and innovative development activities in SMEs, as was the case with the Colombian Prize for Entrepreneurial Technological Innovation for SME (Innova) 2006. The experience acquired through the technical evaluation of such prize was a valuable element for identifying Colombian MSMSC innovative characteristics and trends. The present article seeks to establish the current state of innovation in SMEs from experience gained when evaluating and awarding the Innova prize; a frame of reference concerning innovation and design, the methodology used for evaluating the prize and some general statistics regarding the results obtained in 2006 are thus presented. A future publication will give the factors influencing innovation taking geographical regions, sectors and impact as reference. Such results revealed innovative initiatives in strategic sectors such as computer science and services, the leadership of cities such as Bogotá and Medellin and the need for producing clear guidelines for incorporating process and product design into being part of the innovative process.
Grade-two resistance screw shear connector behavior for a 28 MPa concrete section
Authors: Larrañaga Rubio Sherley , Molina Herrera Maritzabel
Published: August 2022

Screw shear connectors are being more commonly used in compound concrete sections in Colombia; however, they have been designed in line with Colombian Seismic-Resistant Standards (NSR-98) rather than those established for stud shear connectors. This work represents a starting point for analysing screw shear connector behavior. 54 specimens were made for the experiment, consisting of a metallic profile and two concretes slabs where the connectors were embedded. 1/2” (12.7mm), 5/8” (15.9mm) and 3/4” (19.1mm) diameter screws were used and placed at different distances. The push-out test was used with these specimens and results were provided by using some equations for determining this type of connector’s strength in steel-concrete sections.
Studying a new technique and implementing a pilot-line process for obtaining dextrins from cassava starch
Authors: Aristizábal Galvis Johanna , Leonardo Moreno Fabián , Basto Ospina Gustavo
Published: August 2022

This study proposes and develops a new technique for dry-route dextrin production consisting of converting cassava starch pellets on a fixed-bed dryer; this technique is more applicable to rural Colombian agro-business in technical, economic, social and environmental terms, particularly to so-called “rallanderías” compared to currently available dextrin production technology. The proposed process is practically clean, requires low investment, allows humid starch-cake to be directly used without the need for expensive pre-drying equipment, eliminates large quantities of dust being produced thereby leading to an easily-handled and packaged product being obtained. Different dextrinisation technologies were compared; a pilot-line was implemented which included blending, granulation and drying units. The variables evaluated were cassava-starch variety, catalyst concentration and agglutinant type and concentration; pellet-size, bed-thickness and air-speed were also evaluated during blending, granulation and drying stages, respectively. It was determined that using 0.1-0.3% HCl on cassava starch, 1.5-3% cassava starch paste, L/D=1.25 pellets, a 55°C pre-drying phase and 150°C final conversion on 2 cm thickness fixed-bed dryer at 2-3 m/s air speed led to obtaining low friability (13%), high rupture force (1.3 kg-f), high solubility (9O-100%) and low fluidity (50-70 s) dextrin pellets. An adhesive was then obtained from the dextrin resulting from the process described above for sealing cardboard-boxes and cartons having greater stickiness, tensile strength and stability compared to corn dextrin adhesive, suggesting that the proposed new cassava dextrin production technique constitutes a good technological option for adding value to Colombian cassava production at small “rallandería” level.
Collaborative evaluation as a mechanism for improving evaluation of classroom learning
Authors: Collazos Ordóñez César Alberto , Ochoa Sergio F. , Mendoza Jair
Published: August 2022

Evaluating learning is a very important aspect of the teaching-learning process. Using collaborative techniques can lead to developing such important feelings as belonging to a group, acceptance and autonomy amongst students in formal education. The model being proposed here involved a combination of collaborative techniques for approaching how knowledge may be effectively evaluated.
Determining adjustment variables for rationalising a design for fleet operation in public passenger transport
Authors: Flórez Valero Carlos Fabián , Jiménez Póveda Pedro Luís
Published: August 2022

This investigation was aimed at establishing aspects leading to adjusting the operational design of public transport fleet operation to make it more profitable for private investors. Data obtained from more than a year’s operation by the Alianza Sat S.A. was used (this being a bus-company alliance grouping about 100 buses from some of Bogota’s collective transport companies) for carrying out the present investigation regarding fleet administration and operation.
Simply implementing conventionally-designed routing plans is not enough for rationalising fleet operation, as most public collective transport is not directly operated by companies The Alianza Sat S.A. bus fleet was used for testing hypotheses demonstrating that current operational design for the company’s routes (in Bogota’s current public transport market conditions) leads to reducing the company’s income. The investigation revealed that public passenger transport bus fleet revenue can be increased if aspects different to those considered in standard route design methodology are controlled. The investigation has determined alternative rationalisation for operational collective public passenger transport company design regarding adjusting aspects such as the demand pattern, operating scheme, route variability, etc. This will provide an innovative and useful tool for rationalising the operational design of bus routes operating in cities having weak public transport control and excess bus supply.
A study of poly(vinyl alcohol) thermal degradation by thermogravimetry and differential thermogravimetry
Authors: Esteban Barrera Julián , Alexander Rodríguez John , Ernesto Perilla Jairo , Algecira Enciso Néstor Ariel
Published: August 2022

The thermal degradation of poly(vinyl alcohol) (PVA) having different degrees of hydrolysis and molecular weights was studied by thermogravimetry (TGA) and differential thermogravimetry (DTGA). Four degradation events were identified whose intensity was related to the degree of hydrolysis. It was verified that the solid-state degradation mechanism for high hydrolysis degrees corresponded to eliminating water-forming side groups in stoichiometric amounts. The presence of acetate groups and lower melting points delayed the polymer’s thermal decomposition at lower hydrolysis degrees. There was no direct correlation in these samples between weight-loss during the first degradation event and the stoichiometric quantities which would be produced by eliminating the side groups. Reaction order and energy activation value qualitative coincidence was found by evaluating experimental data by using Freeman-Carroll and Friedman kinetic models.
A fully integral, differential, high-speed, low-power consumption CMOS recovery clock circuit
Authors: Pacheco Bautista Daniel , Castillo Soria Francisco Rubén , Linares Aranda Mónico , Salim Maza Manuel
Published: August 2022

The clock recovery circuit (CRC) plays a fundamental role in electronic information recovery systems (hard disks, DVD and CD read/writeable units) and baseband digital communication systems in recovering the clock signal contained in the received data. This signal is necessary for synchronising subsequent information processing. Nowadays, this task is difficult to achieve because of the data’s random nature and its high transfer rate. This paper presents the design of a high-performance integral CMOS technology clock recovery circuit (CRC) working at 1.2 Gbps and only consuming 17.4 mW using a 3.3V power supply. The circuit was fully differentially designed to obtain high performance. Circuit architecture was based on a conventional phase lock loop (PLL), current mode logic (MCML) and a novel two stage ring-based voltage controlled oscillator (VCO). The design used 0.35 µm CMOS AMS process parameters. Hspice simulation results proved the circuit’s high performance, achieving tracking in less than 300 ns.
Proposal of bimodal solution for urban vehicular contamination problem
Authors: Osorio Gómez Gilberto , Viganò Roberto
Published: August 2022

In research field of alternative solutions to internal combustion engine vehicles, the Politecnico di Milano has developed a design and manufacturing project for an adaptable electro-mechanical kit intended to transform a city car with endothermic propulsion into a bimodal one, using existent technologies and innovative solutions. This project involves mechanical and electrical competences in order to develop a new transmission parallel to the current endothermic propulsion and its control system. This paper describes, in general, the developed procedure to obtain the final prototype. At first, the requirements and constraints to fulfil a standard transport urban cycle has been established and the vehicle to modify was selected, in this case the Fiat Grande Punto. Next, new components and the required space to their installation have been identified and specified, whilst mechanical components were designed and manufactured. Instruments of reverse engineering and virtual prototyping have been employed to carry out the geometrical models, simulations and layouts and to identify useful spaces in the vehicle. Finally, general modifications, installation of new components, implementation of control and data acquisition system, fine-tuning and check of specifications fulfilment have been carried out. A 30 km range working in electrical mode, with a top speed of 70 km/h, is assured with the developed kit. These results demonstrate the feasibility to implement a forward bimodal propulsion system into a commercial city car with a little invasive commercial kit, and now, the Politecnico is working at its industrialization and implementation to different models of city cars. Regione Lombardia (Regional government in Italy) has funded this project as an investigation oriented to find new solutions to sustainable transport and reduction of environmental pollution.
Natural elements’ methods applied to structural problems
Authors: González Torres Libardo Andrés , Garzón Alvarado Diego Alexander , Roa Garzón Máximo Alejandro
Published: August 2022

This paper was aimed at reviewing the theory and numerical implementations of the natural elements method (NEM, meshless method) used for resolving structural problems. An exact analytical solution and the finite element method were used for comparing the results obtained for two lineal-elastic structural problems in two spatial dimensions. The interpolation procedure used by the method for obtaining the trial functions and the most important features of the standard NEM are described. The results of two simulations concerning structural problems are presented using a code written in Matlab 6.5 for resolving differential lineal elasticity equations in two dimensional domains it was found that NEM is similar to the finite element method in terms of stability and convergence, having the advantage of mesh being automatically produced and the approximated solution not depending on the distribution of the node cloud, thereby defining the geometric domain.
Using commercial simulators for determining flash distillation curves for petroleum fractions
Authors: Eduardo Tarifa Enrique , Erdmann Eleonora , Humana Demetrio , Franco Domínguez Samuel , Mercado Fuentes Lorgio
Published: August 2022

This work describes a new method for estimating the equilibrium flash vaporisation (EFV) distillation curve for petroleum fractions by using commercial simulators. A commercial simulator was used for implementing a stationary model for flash distillation; this model was adjusted by using a distillation curve obtained from standard laboratory analytical assays. Such curve can be one of many types (eg ASTM D86, D1160 or D2887) and involves an experimental procedure simpler than that required for obtaining an EFV curve. Any commercial simulator able to model petroleum can be used for the simulation (HYSYS and CHEMCAD simulators were used here). Several types of petroleum and fractions were experimentally analysed for evaluating the proposed method; this data was then put into a process simulator (according to the proposed method) to estimate the corresponding EFV curves. HYSYS- and CHEMCAD estimated curves were compared to those produced by two traditional estimation methods (Edmister’s and Maswell’s methods). Simulation-estimated curves were close to average Edmister and Maxwell curves in all cases. The proposed method has several advantages; it avoids the need for experimentally obtaining an EFV curve, it does not depend on the type of experimental curve used to fit the model and it enables estimating several pressures by using just one experimental curve as data.
Plataforma autónoma inteligente para fútbol robot
Authors: Rodríguez Garavito Cesar Hernán , Delgado Rivera Jesús Alberto
Published: August 2022

Este artículo presenta el diseño, la implementación y los resultados obtenidos, confrontados con simulación, de una plataforma hardware-software para fútbol robot en un entorno artificial que consta de un campo o arena de juego, un agente móvil controlado por la aplicación (AMC), un agente móvil controlado por usuario (MCU), una bola de golf, un sensor para capturar el estado del entorno y un controlador de trayectoria. El problema que enfrenta el agente AMC en su entorno es la búsqueda de una posición con línea de vista libre para golpear la bola hacia la portería del equipo contrario, mientras esquiva adversarios en su camino. El campo de juego es un área confinada de 1,5 m x 2 m, en la cual el agente móvil se desplaza según la cinemática de un robot diferencial a una velocidad máxima de 25,7cm/s, el móvil posee la capacidad de pateo de una bola de golf, la cual se puede impulsar a una velocidad máxima de 1,43 m/s. Por otro lado, se implementa y optimiza un sensor de posición. El proceso parte con la captura de imágenes de la arena de juego, continúa con la conversión al formato HSI y la aplicación de filtros digitales sobre las imágenes, y termina con el cálculo de las componentes cartesianas a partir de los patrones en color, que identifican a los móviles y bola de juego, la velocidad que alcanza el sensor es de 30 cuadros por segundo. Finalmente, se realiza el control de navegación inteligente a través de una estrategia híbrida, en la cual se combina linealmente el efecto de dos controladores basados en lógica difusa, uno para llevar el agente a la posición de tiro al arco y el otro para esquivar obstáculos mientras navega a la posición de tiro.
Post-harvest physiological study and evaluation of the quality of Cv. Horvin plums (prunus domestica l.) in three cold-storage conditions
Authors: Parra Coronado Alfonso , Hernández Hernández José Eugenio , Camacho-Tamayo Jesús Hernán
Published: August 2022

The plum cv. Horvin is a highly perishable fruit; this hampers post-harvest handling and there is currently no cold storage chamber or suitable post-harvest handling infrastructure in Colombia. The present work was aimed at evaluating the quality of the plum cv. Horvin in three storage conditions. The plum cv. Horvin is a climacterical fruit, its respiratory rate being influenced by storage conditions showing a direct relationship with temperature. It was found that 4°C was the best storage temperature for maintaining cv. Horvin plum quality, having a 13.23% accumulated weight loss, greater than 20 N firmness and more than 11°Brix total soluble solids (SST) at the end of a 31-day storage period. Weight loss, respiratory rate, firmness, titratable acidity (AT) and SST/AT ratio were the parameters best representing cv. Horvin plum maturity during storage. Total soluble solids did not reveal high variability in the storage conditions analysed here; this parameter should not be taken as being a post-harvest maturity index.
Separating a water-propanol mixture using PDMS pervaporation membranes
Authors: Amrani Mahacine
Published: August 2022

Recovering and purifying organic solvents during chemical and pharmaceutical synthesis has great economic and environmental importance. Water-alcohol mixture pervaporation was investigated using a pervaporation cell and hydrophobic membranes. This work studied polydimethylsiloxane (PDMS) membrane performance and hydrophobic membranes for removing propanol from aqueous mixtures. PDMS is recognised as being alcohol permselective during pervaporation. It was also observed that water was transferred through a hydrophobic membrane as water’s molecular size is smaller than that of propanol. A laboratory-scale pervaporation unit was used for studying this membrane’s separation characteristic in terms of pervaporation flux and selectivity for feeds containing up to water mass and 30°C-50°C. Total propanol/water flux was observed to vary as operating temperature increased. Although PDMS membranes presented good characteristics for separating water/propanol mixtures, the separation factor and pervaporation flow decreased as water content in the feed increased. The tested membrane was found to be very efficient for water concentrations of less than 0.3, corresponding to total flux transfer maximum.
Multiple robot systems’ communication using MAD-Smart methodology
Authors: Jiménez Builes Jovani Alberto , Ovalle Carranza Demetrio Arturo , Branch Bedoya John William
Published: August 2022

This paper was aimed at exhibiting the real need for having good communication within multiple robots systems using MAD-Smart methodology. Such methodology consists of conceptualising, analysing and designing multiple robot teams by defining a set of activities. MAD-Smart assists developers in further understanding not only the problem to be solved but the final characteristics which a particular system must accomplish and the role played by each agent in resolving problems. This methodology has already been validated by implementing the SMART (robotic multi agent system) project, educational robotics: intelligent machines in education and sensory and perception models in robotic agents for material identification. MAD-Smart has been shown to be more relevant in handling agent roles than the agents themselves for a given communication model. This issue reflects this methodology’s degree of abstraction since a role defining as an abstract representation of high level behavioural allows generalising the best possible scenarios which can be found in a given multi-robot system.
Optimum control criteria for an electric driver for dynamic systems
Authors: Sandoval Ruiz Cecilia E. , Velazco S. Katerine C. , Díaz P. José Gregorio
Published: August 2022

This work was aimed at optimizing control parameters for variable speed control and post-tensioning torque by controlling the current of DC motors forming part of a dynamic system (in a paper-making production line) by designing controllers based on absolute value and optimal symmetry criteria. A mathematical model representing an electric drive system for controlling DC motor speed and torque in a paper-rolling system was defined, a control algorithm adjusting the parameters was designed and an electric drive system simulated. The methodology consisted of a literature search and a field study for defining the model and establishing the parameters to be simulated, thereby presenting an analytical and descriptive project. The results led to observing the efficiency of the controllers so designed and the overall drive system for which speed and current (power) continue being the reference signal, leading to the conclusion that the criteria selected for control design were suitable and representing an input in developing applications for monitoring dynamic electric drive systems.
Designing robust control-based HIV-treatment
Authors: Olarte Dussán Fredy Andrés , Clavijo Ramírez Carlos Arturo , Díaz Morales Hernando
Published: August 2022

Designing a robust control-based treatment for human immunodeficiency virus (HIV)-infected patients was studied. The dynamics of the immune system’s response to infection was modelled using a 5th order nonlinear model with separate efficacy coefficients for protease inhibitor (PIs) and reverse transcriptase inhibitors (RTIs). The immune res-ponse has been represented as an uncertain system due to errors in parameter estimation and the existence of un-modelled dynamics. A polytopic system was constructed incorporating all possible system parameter values. A con-trol system was designed using robust pole location techniques stabilising the polytopic system around an equilibrium point having a low viral load. Numerical simulation results (including the organism’s pharmacokinetical response to anti-retroviral drugs) showed that the control law could lead to long-term stable conditions, even in extreme cases.
A study of coal-solid waste blend reactivity
Authors: Guerrero Nayibe , Guzmán Anyela , Montoya Diana Milena , Londoño Carlos , Chejne Janna Farid
Published: August 2022

The Flynn-Wall-Ozawa method was used for analysing coal-solid waste blend reactivity in an oxidising atmosphere.  The presence of biomass strongly affected coal combustion kinetics when the blend contained more than 30% of it.  Activation energy values (evaluated by different blends) were 28.7495 kJ/mol for 0% biomass, 31.3915 kJ/mol for 30% biomass, 39.0365 kJ/mol for 50% biomass, 102.431 kJ/mol for 70% biomass and 107.8075 kJ/mol for 100% biomass; these values were close to those reported in the literature. First-order kinetics correlated the data very well for the 100% coal sample and the blend having 30% biomass and 70% coal. Eighth-order kinetics were more suitable for correlating the experimental data for the 70% biomass-30% coal blend and the 100% biomass sample.  Combustion was done without previous pyrolysis of the blends; however segregation of phenomena could be appreciated. This seems to indicate that combustion and devolatilisation are independent processes which should be taken into account when building equipment using these kinds of blend.
Cement plant gaseous pollutant emission reduction technologies
Authors: Hoyos Barreto Andrés Emilio , Jiménez Correa Mónica María , Ortíz Muñoz Alejandro , Montes de Correa Consuelo
Published: August 2022

A brief description of SOX, NOX and CO2 formation is presented, these being the main pollutants emitted in the
cement industry gas stream Several technologies for reducing NOX, SOX and CO2 emissions in long wet kilns are introduced: primary measures preventing contaminant formation and secondary/tube end emission reduction measures. Strategies for preventing CO2 (greenhouse effect gas) formation are also addressed, such as fuel and raw material substitution and CO2 capture technologies which are still being developed.
A tool for enabling multimodal access to WWW resources from several devices
Authors: Caicedo Castro Isaac Bernardo , Rueda Fajardo Francisco
Published: August 2022

Most World Wide Web (WWW) resources are currently accessible from PCs and through HTTP; however, multimodal application research is being carried out and tools and proposals are being developed allowing access to WWW resources from several devices and mechanisms. The motivation for developing multimodal and multi-device applications has arisen from organisations’ need to avoid duplicating information and services available in applications and Web pages. This article describes the structure of a tool allowing multimodal and multi-device access to WWW resources through HTTP, SMS, WAP, MMS and S@T. This work’s main contribution lies in its proposing a possible and simple architecture for accomplishing this and validating it through implementing a prototype.
Generating the body of the methods from class diagram operation semantics
Authors: Zapata Jaramillo Carlos Mario , Muñetón Andrés Felipe
Published: August 2022

Well-known CASE tools only generate the heading of the methods to automatically generate source code from UML diagrams.  Some proposals partially generate the body of the methods; however, they use non-standard modeling elements or hand-made source code elements. This paper proposes a process for generating the body of the methods from class diagram operations in an attempt to overcome such constraints. “Semantics of class operations” was thus defined as a way of linking class diagram operations to development platform implemented methods. These kinds of semantics use pre- and post-conditions belonging to the operations and the development platform library meta-model. This process is also exemplified by giving a case study. An UML instance of the java.sql package meta-model was created for developing the case study.
Studying and comparing spectrum efficiency and error probability in GMSK and DBPSK modulation schemes
Authors: Torres Nova Juan Mario , Paz Penagos Hernán
Published: August 2022

Gaussian minimum shift keying (GMSK) and differential binary phase shift keying (DBPSK) are two digital modulation schemes which are -frequently used in radio communication systems; however, there is interdependence in the use of its benefits (spectral efficiency, low bit error rate, low inter symbol interference, etc). Optimising one parameter creates problems for another; for example, the GMSK scheme succeeds in reducing bandwidth when introducing a Gaussian filter into an MSK (minimum shift ke-ying) modulator in exchange for increasing inter-symbol interference in the system. The DBPSK scheme leads to lower error pro-bability, occupying more bandwidth; it likewise facilitates synchronous data transmission due to the receiver’s bit delay when re-covering a signal.
Evaluating a k-nearest neighbours-based classifier for locating faulty areas in power systems
Authors: Mora Flórez Juan José , Morales España Gérman , Barrera Cárdenas Rene
Published: August 2022

This paper reports a strategy for identifying and locating faults in a power distribution system. The strategy was based on the K nearest neighbours technique. This technique simply helps to estimate a distance from the features used for describing a particular fault being classified to the faults presented during the training stage. If new data is presented to the proposed fault locator, it is classified according to the nearest example recovered. A characterisation of the voltage and current measurements obtained at one single line end is also presented in this document for assigning the area in the case of a fault in a power system. The proposed strategy was tested in a real power distribution system, average 93% confidence indexes being obtained which gives a good indicator of the proposal’s high performance. The results showed how a fault could be located by using features obtained from voltage and current, improving utility response and thereby improving system continuity indexes in power distribution systems.
Pesticide sorption and desorption from soils having different land use
Authors: Madrigal Monárrez Ismael , Benoit Pierre , Barriuso Enrique , Réal Benoît , Dutertre Alain , Moquet Michel , Trejo Hernández Maria , Ortíz Hernández Laura
Published: August 2022

This study was carried out within the framework of a multidisciplinary project for evaluating buffer zones for combating pesticide contamination of surface water. Such areas are effective in removing pesticides transported by run-off; however, little information is available about the fate of the pesticides so intercepted. Two herbicides having contrasting properties (isoproturon, moderately hydrophobic (log Kow = 2.5), diflufenican, strongly hydrophobic (log Kow = 4.9)) and isopropylaniline (an isoproturon metabolite) were used for characterising sorption and desorption from soil having three different land uses: grass buffer strip, woodland and cultivated plot. The experiments were carried out in controlled laboratory conditions using isoproturon labelled with 14C in the benzene ring. The results demonstrated that diflufenican and isopropilaniline retention was more significant than isoproturon in three soils. The three molecules’ Kd values revealed that isoproturon and diflufenicanil retention was more important in woodland soil where carbon content was more significant (ZB 0-2: Kd IPU = 15.1 Ls kg-1; Kd DFF = 169.2 Ls kg-1). Isopropilanilina Kd was higher in grass buffer strip soil (BE 0-2: Kd IPA = 53.1 L kg-1). These differences were related to different organic matter content and nature according to the type of land use.
Avances más recientes sobre la aplicación de la altimetría radar por satélite en hidrología. Caso de la cuenca amazónica
Authors: León Hernández Juan Gabriel , Domínguez Calle Efraín Antonio , Duque Nivia Guillermo
Published: August 2022

El presente artículo sintetiza los principios de la altimetría radar por satélite y presenta las aplicaciones más relevantes que dicha tecnología ha aportado al estudio de aguas superficiales continentales bajo un dominio que se comienza a conocer como hidrología espacial. Dentro de estos, uno de los más importantes tiene que ver con la generación de estaciones virtuales (intersección entre el barrido del satélite y un cuerpo de agua: río, lago, mar interior). Dichas estaciones están siendo actualmente utilizadas como mecanismo de apoyo para el monitoreo hidrológico, especialmente, en lo referente a la densificación de las redes hidrométricas instaladas in situ. Adicionalmente, estas pueden ser caracterizadas con datos provenientes del espacio de la misma manera en que son caracterizadas las estaciones in situ procurando información de carácter hidráulico (pendiente del fondo del cauce, profundidad del flujo cero, coeficiente de Manning, entre otros) que hasta el momento sólo podía ser deducida a partir de mediciones directas en campo.
Synthesising Fe-Mo catalysts supported on silica for the selective oxidation of methane to formaldehyde
Authors: Guerrero Fajardo Carlos Alberto , Sánchez Castellanos Francisco José
Published: August 2022

The selective oxidation of methane to formaldehyde was analysed using iron-molybdenum catalysts supported on silica prepared by the sol-gel method which leads to obtaining a greater surface area and high iron and molybdenum metal dispersion on the silica’s amorphous surface. Seven catalysts were prepared, one of them as silica support, another as 0.5% wt iron load without molybdenum and the remaining five having 0.1%-1.0% weight molybdenum and 0.5% wt iron loads. The highest BET areas were 830 and 879 m2.g-1 for catalysts 2 (0.5% Fe - 0% Mo) and 4 (0.5% Fe - 0.3% Mo) respectively, having 28% average microporosity and 47% average mesoporosity. X-ray diffraction confirmed the catalysts’ amorphous structure. The TPR spectrum showed low hydrogen consumption attributed to the absence of isolated Fe and Mo species. ESCA analysis revealed the same Fe/Mo atomic ratio on the catalyst surface as in the bulk preparation. Catalytic activity was carried out at atmospheric pressure, CH4/ O2/N2 = 7.5/1/4 reaction mixture, 400-800°C temperature interval. Catalysts 4 (0.5% Fe - 0.3% Mo), 5 (0.5% Fe - 0.5% Mo) and 7 (0.5% Fe - 1.0% Mo) displayed greater methane conversion, whereas catalysts 5 (0.5% Fe - 0.5% Mo), 4 (0.5% Fe - 0.3% Mo), 2 (0.5% Fe - 0% Mo) and 7 (0.5% Fe - 1.0% Mo) gave better formaldehyde product results. The highest conversion per-centage (4.07% mol) was presented at 700°C for catalyst 4 (0.5% Fe-0.3% Mo). Formaldehyde yield was 202,0 gHCHO.kg-1cata.h-1 at this temperature.
A novel hybrid PWM algorithm having superior harmonic performance
Authors: López Mesa Diana Jimena , Camacho Muñoz Guillermo Alberto , Díaz Chávez Jaime Oscar , Gaviria López Carlos Alberto , Bolaños Pantoja Gilberto
Published: August 2022

This paper presents a novel hybrid modulation algorithm which improves the harmonic performance of eight of the most common pulse width modulation (PWM) algorithms for voltage source inverters (VSI) in the electric drive field. From harmonic analysis of these eight algorithms, a methodology was established for designing a hybrid modulation scheme offering superior harmonic performance. The algorithm so designed was validated theoretically by calculating the total harmonic distortion factor FDIST and experimentally by measuring the weighted total harmonic distortion factor VWTHD.
A state-of-the-art review of interoperability amongst heterogeneous software systems
Authors: Zapata Jaramillo Carlos Mario , González Calderón Guillermo
Published: August 2022

Information systems are sets of interacting elements aimed at supporting entrepreneurial or business activities; they cannot thus coexist in an isolated way but require their data to be shared so as to increase their productivity. Such systems’ interoperability is normally accomplished through markup standards, query languages and web services. The literature contains work related to software system interoperability; however, it presents some difficulties, such as the need for using the same platforms and different programming languages, the use of read only languages and the deficiencies in the formalism used for achieving it. This paper presents a critical review of the advances made regarding heterogeneous software systems’ interoperability.
Numerical models for the phenomenological study of flameless combustion
Authors: Herrera Múnera Bernardo Argemiro , Amell  Arrieta Andrés Adolfo , Cadavid Sierra Francisco Javier
Published: August 2022

Flameless combustion is a technique which offers environmental advantages such as lower than 100 ppm NOx and CO emissions due to below 200 K temperature gradients. Flameless combustion also supplies higher than 70% energy efficiency. Knowledge of the phenomena in this combustion regime has been facilitated by using numerical simulation. This paper reviewed the specialised literature about the most commonly used turbulence, combustion, heat transfer and NOx formation models in modelling flameless combustion with CFD codes. The review concluded that the k-ε standard model is the most used for turbulence. Finite rate/eddy dissipation with modified constants and eddy dissipation concept models are suitable for combustion reactions, discrete ordinates and weighted sum gray gas (WSGG) models are used for radiation and thermal, prompt and N2O intermediate models are used for NOx.
Flotation kinetic constants of two Colombian coals' vitrinite maceral
Authors: Piñeres Mendoza Jorge Luís , Barraza Burgos Juan Manuel , Blandón Montes Astrid del  Socorro
Published: August 2022

Vitrinite maceral flotation kinetic constants are important in designing flotation columns to be used in separating this maceral group. This work shows the effect of pH, air speed and froth concentration on vitrinite maceral flotation kinetic constants by using two Colombian bituminous coals: El Cerrejón (Guajira) and La Jagua (Cesar). A 5 m high pilotscale flotation column was used in all runs. The samples were processed using 4-10 pH, 0.7-2.1 cm/s air speed and 2-6 ml/kg of coal froth concentration ranges. Both La Jagua and El Cerrejón coals showed high kinetic constants figures in acid conditions (0.692 min-1 at pH 4 and 0.559 min-1 at pH 5, respectively). The results showed that, generally, the best operating conditions for obtaining high vitrinite maceral kinetic constant values were having an acid medium and low air flow and froth concentration.
A review of electricity market modelling tools
Authors: Londoño Hernández Sandra Milena , Lozano Moncada Carlos Arturo
Published: August 2022

Deregulating electricity markets around the world in the search for efficiency has introduced competition into the electricity marketing and generation business. Studying interactions amongst the participants has thus acquired great importance for regulators and market participants for analysing market evolution and suitably defining their bidding strategies. Different tools have therefore been used for modelling competitive electricity markets during the last few years. This paper presents an analytical review of the bibliography found regarding this subject; it also presents the most used tools along with their advantages and disadvantages. Such analysis was done by comparing the models used, identifying the main market characteristics such as market structure, bid structure and kind of bidding. This analysis concluded that the kind of tool to be used mainly depends on a particular study’s goal and scope.