bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymmetric hollow-fiber filtration membranes based on insoluble polyimide (R-BAPB): Influence of coagulation bath on porous structure
Authors: Borisov I L , Bazhenov S D , Vasilevsky V P , Bakhtin D S , Balynin A V , Yushkin A A , Vaganov G V , Didenko A L , Yudin V E , Volkov A V 
Published: December 2020

Abstract
The insoluble polyimides are the most promising group of polymer materials for fabrication of solvent stable filtration membranes suitable for operation at elevated temperatures. In order to synthesize asymmetric membranes from insoluble polyimide, it is proposed to fabricate the membranes from a pre-polymer solution (polyamide acid – PAA) by non-solvent induced phase separation method followed by imidization to form non-soluble porous polyimide membrane. The thermoplastic crystallizable polyimide R-BAPB, which is resistant to a number of known organic solvents, was chosen as a membrane material. For the first time, hollow fiber membranes based on imidized PAA (R-BAPB) with a controlled distribution of pores on the inner side of the hollow fiber were formed. It has been established that the use of “hard” non-solvents, such as water or aqueous-organic solutions, is preferable for the formation of a porous structure in the membranes based on PAA (R-BAPB). Synthesized PAA membranes were used to prepare porous membranes based on the thermoplastic polyimide R-BAPB by thermal imidization. Imidization process was confirmed by an increase in the glass transition temperature of the material to 220 °C (corresponds to the glass transition temperature of polyimide (R-BAPB)) and is accompanied by a significant increase in its elastic modulus. The results of the measurements of the transport properties of polyimide membranes for gases and liquids indicate that microfiltration transport pores are present in the membranes.
Mechanism of isotope exchange of hydrogen with water in membrane contact devices
Authors: Rastunova I L , Chebotov A U , Vorakso I A , Rozenkevich M B 
Published: December 2020

Abstract
The article presents the results of an experimental study of the isotope exchange process between hydrogen and water in membrane contact devices with a Nafion-type membrane and a platinized heterogeneous RCTU-3SM catalyst. A mathematical description of the mechanism of mass transfer in a membrane contact device is proposed. The design of the presented membrane contact devices makes it possible to create countercurrent separation units that do not require a vertical arrangement.
Anti-corrosive characterization of silicon, titanium, and zirconium oxide coatings deposited on aeronautical aluminum substrates via sol-gel
Authors: Bautista-Ruiz J , Bautista-Ruiz WA , Aperador W 
Published: December 2020

AbstractCurrently, aircraft wings made of AA2024 T3 aluminum are primed between the aluminum substrate and the outer layer of paint to improve the material’s adhesion and corrosion resistance. This type of primer contains chromates whose treatment generates highly toxic hexavalent chromium. This work studied the effect of applying dip-coating coatings of combined silicon, titanium, and zirconium oxides on AA2024 T3 aluminum substrates synthesized via sol-gel. The influence of the number of layers on the substrates anti-corrosive behavior in a 3% NaCl solution was studied using electrochemical impedance spectroscopy techniques and potentiodynamic polarization curves. The substrates corrosion resistance was found to improve substantially concerning the number of layers deposited.
Effect of the application technique on the colorimetric coordinates for a ceramic enamel
Authors: Bautista-Ruiz J , Torres N , Aperador W 
Published: December 2020

Abstract
In ceramic tiles production processes for ornamental purposes, the industry uses enamel as raw materials that support the pigments that give coloration and tonal constancy in a glassy matrix. These parameters are of great interest in the acceptance of the final product by the consumer. Due to the increasing number of complaints related to variations in tone in ceramic enamel of the tiles produced by a ceramic company in northeastern Colombia, this work studied the enamel approval methodology’s effect on the final tone of the ceramic pieces. A ceramic enamel was prepared and applied by the enameling pad technique on tiles manufactured by dry pressing. By applying the spectrophotocolorimetric technique, the colorimetric parameters were determined. The Tukey test’s statistical results did not show statistical significance in the tile samples’ tonal variation.
Study of the silica–magnesia relationship in silicate slags on electrical conductivity at high temperature
Authors: Pérez Villamil F R , Patiño López W E , López Beltrán S Y 
Published: December 2020

Abstract
Slags are metallurgical aggregates with beneficial minerals and in some processes, they constitute the most abundant mass of the operation and for this reason their control is necessary. These materials have physicochemical behaviors that serve to model the process variables. A particular condition of silicate slags in processes for obtaining some ferroalloys is that there are relationships between compounds that allow predicting the behavior of other variables, these relationships are maintained during production. This study aims to know the electrical behavior of a slag so that the data will contribute to have an additional control in the operation of an electric arc furnace. An alumina content of up to 50% was gradually added to one sample and the other was remelted on three occasions, for all cases the electrical conductivity was determined at a temperature between 1400 °C and 1600 °C. For the electrical resistance value, a Miller 400 type resistivity measurement advice was used, and the temperature was achieved by melting the samples in a high-frequency induction furnace with a collapsible silicon carbide crucible, lined with high-grade refractory alumina. Analysis of the electrical conductivity data for silicate slags made it possible to demonstrate that they are proportional to the values of the major oxides of the slag in their silica-magnesia ratio.
Simultaneous sulfidation/oxidation of a ferritic steel under a simulated mixture of flue gas from an oil refinery
Authors: Alviz-Meza A , Kafarov V , Cardenas Y , Peña-Ballesteros D Y 
Published: December 2020

Abstract
Ferritic steels are exposed to simultaneous oxidizing/sulfiding environments during their service in industrial furnaces, which intensify their degradation and reduce their expected lifetime. This research supplies different corrosion details from those highly reported for the studied alloy under single oxidation or sulfidation atmospheres, as well as from those works developed on oxyfuel gas mixtures. The experimental data obtained by us were compared with an oxidation paper previously published by the same authors but without the additional effect of sulfur oxides. The simulated conditions used included temperatures from 450 to 750 °C, exposure times up to 200 h, and a flue gas molar composition without the carbon dioxide influence. As a result, the oxidation mechanism was markedly affected by bulk and surface sulfur compounds, due to their strong adsorption, pathways blocking, and induced layer spallation. This study aimed to identify sulfur compounds onto the oxide layers by means of X-ray photoelectron spectroscopy, which were later validated through a ferritic-steel sample extracted from a refinery furnace. Finally, the present work contributes to the field of physics-physical chemistry- by providing the thermodynamic equilibrium of sulfur oxides at tested conditions and the kinetic behavior of the scale.
Temperature acquisition and heat loss on the wall of an intermittent kiln
Authors: Guerrero-Goméz G , Moreno-Gamboa F , Vera-Duarte L E 
Published: December 2020

Abstract
In the research the temperature acquisition was carried out inside and outside the wall an intermittent furnace and the evaluation of the energy loss on the wall during baking process, the first phase begins with the design, programming and implementation of an virtual instrument for data temperature acquisition and generation of temperatures profiles then, heat loss due to conduction on the furnace wall was determined considering one-dimensional heat flow, in radial direction and in a transitory state. The virtual instrument was programmed every 5 minutes and 1596 data were recorded, the input heat supplied to the furnace was 49.2x106 KJ and the energy losses due to the furnace wall were 5.2x106 KJ indicating the 10.57 percent of the supplied energy. Results of research have made it possible to establish trends in the temperature distribution, as well as identify thermal energy entering and leaving the furnace to propose improvements in performance of the furnace that increase its energy efficiency, reduce fuel consumption and gas emissions to the environment avoiding acute respiratory diseases.
Combustion of a hydrogen/carbon monoxide/carbon dioxide mixture in hot and diluted streams
Authors: Cardona-Vargas A , Valencia D , Arrieta C E , Amell A 
Published: December 2020

Abstract
This work presents an experimental investigation on the combustion behavior of a mixture of hydrogen, carbon monoxide and carbon dioxide in hot and diluted streams, like those obtain under flameless combustion regimes. A jet in a hot coflow burner was used to carry out the experiments. This burner consists of a central fuel jet surrounded by a combustion products stream, which comes from a premixed flame under lean conditions. In this way, it is possible to obtain high temperature and low oxygen concentration in the jet flame. Here, a mixture of 40% H2, 40% CO and 20% CO was issued through the jet nozzle. This composition corresponds to a renewable fuel known as syngas. Three oxygen composition in the oxidant stream were evaluated: 2.0%, 4.7% and 6.9%. Temperature and species concentration values were measured along axial and radial lines under a fix Reynolds’s number. The results suggest that when oxygen concentration increases, CO and NO emissions of the total process decreases.
Fly ash as to solidify liquid radioactive waste
Authors: Bautista-Ruiz J , Bautista-Ruiz W A , Diaz-Lagos M , Martinez-Ovalle S A 
Published: December 2020

Abstract
The “Termopaipa” power plant located in Boyaca, Colombia, generates electricity based on coal and whose residue is fly ash. In this study we consider it important to understand its physical, chemical and morphological characteristics to be used for purposes beneficial to the environment and to use them as a solidifier of liquid radioactive waste. The treatment of radioactive waste involves the set of physical and chemical processes that entail the change of some characteristic of the initially generated waste in order to optimize the safety and / or economy of its management. This treatment requires the transformation of the radioactive waste into an acceptable final product for its transport and / or temporary storage and / or definitive storage. This transformation can be carried out through the incorporation of residues in phases such as Mullite and quartz identified by X-ray diffraction, or encapsulation within porous structures present in the ashes observed by scanning electron microscopy and fixation based on an electrostatic interaction mechanism. originated on its surface due to the presence of aluminate and silicate groups identified by X-ray photoelectron spectroscopy.
Development of the manufacturing technique of crucibles to melt aluminum and improve its physical and mechanical properties by microwave oven
Authors: Perez-Rangel N Y , Florez-Solano E , Espinel-Blanco E 
Published: December 2020

Abstract
There are several techniques that are used to melt metal materials, among which we have conventional casting, by agitation, by compression and by molding. It is currently being studied in a technique based on electromagnetic radiation with the implementation of conventional microwave oven, thus improving the results in terms of time in the casting process; to carry out this electromagnetic casting process, a high-frequency wave-receiving medium is required to reach the melting temperature of the material on which it is being worked. In the case of aluminum, a working temperature of approximately 700 °C is required to achieve phase change of the material. This project produces a fine-grained silicon carbide-based crucible, taking into account that it is a semiconductor and refractory material capable of capturing electromagnetic waves, for the purpose of allowing the use of a microwave oven in the aluminum smelting process; presenting in this way a new casting technique that promises a significant saving in the execution time and saving the implementation process in recycling and reuse of aluminum and improving its physical and mechanical properties by means of irradiation casting electromagnetic.
Physical analysis of building materials with soil
Authors: Jaramillo H Y , Gómez J A , Martinez C A 
Published: December 2020

AbstractIndustrialization in construction has allowed the use of materials such as concrete and steel, these being essential for the construction of large buildings and structures, however, in some vulnerable areas, using this type of techniques and materials represents a high cost, due to which the traditional or vernacular architecture is a sustainable alternative. This research carries out a physical analysis of the materials used in the constructions on land that are developed in the municipality of Ocana, Norte de Santander, Colombia. The results obtained indicate that the soil used in the analyzed structures has a maximum density of 1.41 g/cm3 with a humidity percentage of 32.55%; likewise, in natural condition these soils have a liquid limit of 67.85 a limit plastic of 45.72 and a plasticity index of 22.13. In other words, the soil has characteristic plastic characteristics of a fine soil. This corresponds to the granulometric classification of the soil, which corresponds to a high plasticity Silt, which has sands with diameters between 395 μm and 76.1 μm. It also has a specific gravity of 2.65 g/cm3.
Design of an integrated cooling system by means of thermal variation flows
Authors: Zambrano-Becerra S F , Galvis-Sanchez P M , Perez-Rangel N Y 
Published: December 2020

Abstract
This project focuses on climate and to be more specific in high temperatures evidenced in some departments of Colombia. At present, the most widely used means of transport are motorcycles which must be supervised under a legal rule, taking into account their safety; therefore, it is necessary to use a certified helmet that fulfils the function of protecting this individual; these helmets in addition to having a definite shape and structure where it surrounds the skull completely in the part of the head also allows the option of having the chin protected or discovered depending on the speed at which the motorcycle is already established factory. Helmets normally have a system that aims not to allow internal heating of this for the convenience of the user, it consists of holes that allow the air flow that occurs when the driver is in motion to be transported throughout the hull and thereby cool it down gradually when driving, however, it does not fully serve its purpose as the distribution is not uniform and there are locations in the hull where this heat is concentrated, thus presenting a high temperature within the hull that makes the driver uncomfortable, taking into account the place and climate in which it is located. This study proposes a portable cooling system for motorcycle helmet that allows whoever is the carrier a state of comfort when driving your vehicle making your helmet stay cool despite the weather and temperatures that have naturally on the site of circulation, All this with the implementation of peltier cells and the use of air flow at the time of driving.
Scheduling optimization for smart microgrids considering twolevels transactions of electric vehicles and energy markets
Authors: Garcia-Guarin J , Infante W , Alvarez D , Rivera S 
Published: December 2020

Abstract
Smart microgrid planning poses some challenges, including bi-directional energy flow both inside and outside the smart microgrid. This research studies at the internal flow level energy transactions with the internal resources of the microgrid, and at the external flow level the energy transactions with external stakeholders to the microgrid. Electric vehicles can operate bidirectionally and participate at the internal and external level of smart microgrids. In this context, this study analyzes electric vehicles both levels. (1) At the level of internal participation, electric vehicles operate in a residential area of a microgrid that is also connected to energy storage systems and elements with uncertainty, such as photovoltaic generation systems and residential loads. Prices are set by considering operating costs within the smart microgrid. (2) The level of external participation refers to an electric vehicle station that offers three services: charging, discharging and swapping battery. Prices are stochastic and come from the spot market prices of electric vehicles. Consequently, it is proposed that the aggregator must plan the optimal scheduling for the visit scenarios of two-level stochastic electric vehicles. The system can also trade energy that come from a local and wholesale energy market. Results demonstrate that two-level operation can help to evaluate the economic impact of electric vehicles.
Compensation of frequency mismatch between transmitter and receiver local oscillators to enhance 5G-based radio-over-fiber transmissions
Authors: Hidalgo-Monsalve D , Medina-Delgado B , Guevara-Ibarra D , Amaya-Fernández F , Álvarez-Guerrero J 
Published: December 2020

Abstract
Radio-over-fiber is a cost-effective support for the forthcoming 5G developments aimed to fulfill the ever-increasing demand for information. However, such systems are limited by transmission impairments that reduce the quality of communication. To enhance the system performance, an adaptive decision-feedback equalizer based on the least mean square algorithm is proposed in this work to compensate for frequency mismatch in the transmitter and receiver local oscillators in a radio-over-fiber transmission scenario when considering the latest 5G New radio standard. Simulation results in MATLAB exhibit a major impact from the equalization technique in improving the system performance in the presence of such a frequency offset, allowing the optical link to be extended from ∼100 km with no equalizer up to ∼690 km after equalization. Thus, it was demonstrated that the proposed adaptive equalization technique is a promising contender to enhance 5G-based Radio-over-Fiber data transmissions.
Thermal and mechanical properties laboratory evaluation of hollow brick made of fired clay and rice husk additive
Authors: Díaz-Fuentes C X , Sánchez-Molina J , Zamora Mestre J L 
Published: December 2020

Abstract
Hollow bricks in fired clay for masonry are important in design and construction of buildings. Their thermal and mechanical properties must be considered because of the impact they have on energy consumption. The objective of this research is to evaluate thermal and mechanical properties of a new hollow brick, called Eco Design, made of fired clay and rice husk additive, in order to identify the benefits of its use in the construction of masonry walls in regions with a tropical climate. The methodology develops simulation of thermal properties of brick, manufacturing at the laboratory level and characterization of mechanical properties of finished product. Thermal validation simulates the behavior of heat transfer and fluxes of Eco Design in mixtures of 100% fired clay, 95% -5%, 85% -15% and 70% -30% fired clay with rice husk, respectively. Eco Design samples are manufactured by extrusion and fired at 1000 °C. The characterization of mechanical properties of samples manufactured consists of determining dimensions, water absorptive capacity, linear shrinkage, mass losses and mechanical resistance to compression according to Colombian normative. The results indicate that Eco Design brick has a thermal benefit of 6.9 °C in 95% -5% mixture, as the percentage of rice husk increases, benefit increases 0.75 °C additional. Furthermore, the implementation of rice husk additive improves 7.15% mechanical resistance to compression and increases 18.3% water absorption capacity. Finally, the assessment of thermal and mechanical properties of Eco Design is a reference to promote innovation in ceramic industry in Norte de Santander and Colombia.
Determination of the structural efficiency of quadric and cylindrical surfaces when used as reinforced concrete roof structures
Authors: Márquez J F , Jácome J L , Palacios J D 
Published: December 2020

Abstract
Modern architecture of civil engineering structures made of reinforced concrete is demanding solutions to problems related to design and construction of roofs shaped as creative forms which require an adequate combination of arts and physical-mathematical models. In that sense, the quadric and cylindrical surfaces offer an attractive based on their volumetric expression, historicity, and mathematical feasibility. In this work, seven cylindrical and quadric surfaces named elliptic cylinder, parabolic cylinder, elliptic cone, elliptic paraboloid, hyperbolic paraboloid, ellipsoid and hyperboloid of two sheets have been analysed to find out which of them show to be more efficient when used as reinforced concrete roof structures. To do so, the configuration of each structure hase been adjusted in terms of similar stiffness, strength parameters and enclosed volume. The structural efficiency was computed using the results of weight/load ratio, available strength, material consumption and relative stiffness. The solution of the model has been achieved using a combination of exact solutions and numerical methods. To compute the model results a Matlab® code was written and validated using the structural software SAP2000®. The best structural efficiency in terms of stiffness, strength, and materials consumption was obtained for roofs configurated using surfaces built from parabolas, i.e., elliptic paraboloid, hyperbolic paraboloid, and parabolic cylinder. The results of this work can be used in future studies and applications related to arhitectural comfort, structural behaviour and material consumption in construction of roofs.
Mathematical analysis of the dynamic behavior three motorcycle disc brakes
Authors: García-León R A , Quintero-Quintero W , Gomez-Camperos J A 
Published: December 2020

Abstract
The disc brake system is currently used in the motorcycles due to the efficiency in the braking process. In this way, the main objective of this work was to determine mathematically dynamic calculations of the braking system of three different brake discs of different cylinder capacity and, thus, analyze the behavior for optimal operation under different conditions. The geometries of these disc brakes were drawn with the aid of SolidWorks design software. The results obtained show that it was possible to validate the correct functioning of the braking system at different operating conditions using mathematical calculations; also, when the systems that have higher cylinder capacity guarantee better braking distance for a given time and speed. These systems work in optimal conditions of real operation, always guaranteeing high levels of safety and operation compared to other types of geometries.