Mostrando ítems 261-280 de 1587

Gains in active learning of physics: a measurement applying the test of understanding graphs of kinematics

Hernández, C A; Prada Núñez, R; Gamboa, A A (Reino Unido, 2021-06-11)

To teach the subject of physics in the classroom it is required that the teacher has and plans to carry a didactic strategy with him. Within this context is the methodology called Active physics learning, which is a ...
Numerical simulation to analyze the physical behavior of centrifugal pumps as a turbine

Prada Botia, Gaudy Carolina; Pabón León, J A; Orjuela Abril, M S (Journal of Physics, 2021-05)

In this research, a methodology based on the development of numerical simulations is proposed to analyze the physical behavior of centrifugal pumps such as a turbine. Numerical simulations were carried out using OpenFOAM ...
Formation of critical thinking related to the energetic efficiency of applied physics processes of civil engineering works

Journal of Physics: Conference Series (Reino Unido, 2021-06-11)

Current problems associated to contamination and climate change claim for urgent solutions to make real a sustainable development of modern societies. To answer that call, the efficiency of applied physics processes must ...
Curricula framework for a digital transformation master’s in science and engineering

Vera Contreras, Milton Jesús; Vera-Rivera, F. H.; Puerto Cuadros, Eduard Gilberto (Journal of Physics: Conference SeriesReino Unido, 2021-06-09)

Digital transformation is an interdisciplinary work that has the objective to analyze data in real-time for better decision making, where it involves the modeling and the simulation of physical-mathematical and social ...
Effect of layer thickness on anticorrosive performance of 316L steel coated with bismuth-titanium films

GARZÓN AGUDELO, PEDRO; Bautista-Ruiz, Jorge (Journal of Physics: Conference Series, 2021-05)

. Bismuth and titanium are elements with remarkable properties and applications in technological developments and in the field of biomedical engineering. The sol-gel method was used to form a bismuth-titanium system, ...
Development of a gravimetric fuel measurement system for the evaluation of engine performance physical parameters

Prada Botia, Gaudy Carolina; Rojas Suárez, J P; Orjuela Abril, M S (Reino Unido, 2021)

This paper presents the implementation and design features of a gravimetric-based fuel consumption system. The proposed system comprises a gravimetric balance with serial output, a fuel pump, and a control valve that are ...
Effect of a regenerator on hybrid solar gas turbine performance in Barranquilla, Colombia

Moreno Gamboa, Faustino; Acevedo-Paéz, J C; Sanin-Villa, D (Journal of Physics: Conference Series, 2021)

A thermodynamic analysis of a hybrid gas turbine solar plant, represented in three basic subsystems related to the power cycle, the combustion chamber subsystem, and the solar concentrator subsystem, allows evaluating ...
Daily performance of a solar hybrid regenerative gas turbine in Colombia

Moreno Gamboa, Faustino; Vera Duarte, Luis Emilio; Guerrero Gómez, G (Reino Unido, 2021-06-11)

This work presents the evolution of the operation of a regenerative hybrid solar gas turbine in an average day of the year. The system is evaluated by means of a thermodynamic model that includes a solar concentrated ...
Diagnosis of physical conditions for the implementation of a reverse logistics management model in a supply chain

GARZÓN AGUDELO, PEDRO; palacios alvarado, wlamyr; Medina Delgado, Byron (Journal of Physics: Conference SeriesReino Unido, 2021-06-09)

The objective of this research was to structure a Reverse Logistics Management model applied to the furniture sector in the city of San José de Cúcuta, Colombia, based on the identification and analysis of the current ...
A Complete Prefeasibility Evaluation of On-Site Energy Generation System

Romero-Garcia, Gonzalo; Villada Castillo, Dora Clemencia; Rojas Suárez, Jhan Piero (International Journal of Energy Economics and PolicyTurquía, 2022-03-20)

The recent global concern to mitigate the ecological impact on energy production has promoted the search for alternatives that allow a better use of resources. In this panorama, the cogeneration process appears as a solution ...
Parametric Study of a Hybrid Renewable Energy Power Generation System in the Colombian Caribbean Region

Rojas Suárez, Jhan Piero; Romero-Garcia , Gonzalo; Villada Castillo, Dora Clemencia (International Journal of Energy Economics and PolicyTurquía, 2022-03-20)

The global environmental problems have increased the interest in renewable energies, in this article a wind-solar hybrid system is proposed as an alternative for energy production. To carry out this study, the research ...
Autoregressive modelling of chromatographic signals from urine samples for prostate cancer diagnosis

Soto Vergel, Angelo Joseph; Medina Delgado, Byron; palacios alvarado, wlamyr (Journal of Physics: Conference SeriesReino Unido, 2021-06-09)

This article evaluates autoregressive modeling as a feature extraction method in a database of chromatographic signals from urine samples for non-invasive diagnostic support of prostate cancer in response to the research ...
Investigation of Emission Characteristics and Lubrication Oil Properties in a Dual Diesel–Hydrogen Internal Combustion Engine

Pardo García, Carlos Eduardo; Orjuela Abril, Martha Sofia; Pabón León, Jhon (LubricantsSuiza, 2022-04-05)

: Hydrogen is considered one of the main gaseous fuels due to its ability to improve thermal performance in diesel engines. However, its influence on the characteristics of lubricating oil is generally ignored. Thus, in ...
Study of the Cylinder Deactivation on Tribological Parameters and Emissions in an Internal Combustion Engine

Orjuela Abril, Martha Sofia; FONSECA VIGOYA, MARLEN DEL SOCORRO; Pardo García, Carlos Eduardo (LubricantsSuiza, 2022-04-07)

In the present investigation, a study is carried out using numerical simulation on the effects of cylinder deactivation on tribological parameters and emissions in an internal combustion engine. For the development of ...
CFD Analysis of the Effect of Dimples and Cylinder Liner Honing Groove on the Tribological Characteristics of a Low Displacement Engine

Orjuela Abril, Martha Sofia ; FONSECA VIGOYA, MARLEN DEL SOCORRO; Pabón León, Jhon (LubricantsSuiza, 2022-04-07)

The contact between the piston rings and the cylinder liner is an interface with a strong influence on the tribological behavior and, therefore, directly affects the useful life of the engine components and fuel consumption. ...
Optimization of Phycobiliprotein Solubilization from a Thermotolerant Oscillatoria sp

Barajas Solano, andres F (ProcessesSuiza, 2022-04-24)

The present study evaluated the effect of multiple variables (drying time, drying temperature, biomass/solvent ratio, glass beads/biomass ratio, extraction time, and extraction speed) in the solubilization of three different ...
Bubble coalescence model effect on oxygen mass transfer using non-newtonian fluids

Niño, Lilibeth; Peñuela Vásquez, Mariana; Gelves, German (Journal of Engineering Science and TechnologyMalasia, 2021-08)

A modified bubble coalescence model including rheological conditions and shear forces in non-Newtonian fluids is evaluated using CFD (Computational Fluid Dynamics). Euler's model, along with population balance equations, ...
Enhancement of Metabolite Production in High-Altitude Microalgal Strains by Optimized C/N/P Ratio

Suárez Quintana, William H.; García Rico, Ramón O.; García Martínez, Janet B.; Urbina Suarez, Néstor A.; López-Barrera, Germán L.; Barajas Solano, Andrés F.; Zuorro, Antonio (Applied SciencesSuiza, 2022-07-04)

: This study evaluated the role of C/N/P in the increase in the synthesis of carbohydrates, proteins, and lipids in two high-mountain strains of algae (Chlorella sp. UFPS019 and Desmodesmus sp. UFPS021). Three carbon ...
Kinetic modeling of biosurfactant production from crude oil using Bacillus subtilis cells

Alvarado, Kelly; Niño, Lilibeth; German, Gelves (South African Journal of Chemical EngineeringPaíses Bajos, 2022-06-23)

Crude oil and its derivatives have high application in different industries, and unforeseen spills or overexploitation generate a significant threat in ecosystems, causing negative impacts on soil, water, and air. There ...
Analysis of the physicochemical process in the production of biogas from equine manure

Sanchez-Beltrán, J M; Acevedo-Páez, J C; Moreno Gamboa, F (Journal of Physics: Conference Series, 2021)

. The present research aims to evaluate the physicochemical variables involved in the anaerobic digestion process to produce methane from manure on an agricultural farm; the farm has 2 equines that generate 12 Kg of ...

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Gains in active learning of physics: a measurement applying the test of understanding graphs of kinematics
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Hernández, C A | 2021-06-11

To teach the subject of physics in the classroom it is required that the teacher has and plans to carry a didactic strategy with him. Within this context is the methodology called Active physics learning, which is a strategy within the classroom and in the laboratory, as it allows the student to learn physics without depending on a textbook or the teacher who guides the course. The test of understanding graphs of kinematics assesses students' comprehension of kinematics. We report the application of an active learning experience for the conceptual learning of kinematics of students taking the subject of physics in an elementary and middle school. The study is quasi-experimental with a single group of 29 students using a pretest-interventionposttest design. With the results of the pretest and posttest the Hake learning gain index was estimated and showed evidence of the implementation of active learning in the conceptual evolution of students in kinematic concepts and their representation by means of graphs. This becomes a precedent for the improvement of pedagogical practice in favor of quality education.

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Numerical simulation to analyze the physical behavior of centrifugal pumps as a turbine
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Prada Botia, Gaudy Carolina | 2021-05

In this research, a methodology based on the development of numerical simulations is proposed to analyze the physical behavior of centrifugal pumps such as a turbine. Numerical simulations were carried out using OpenFOAM software. For the validation of the numerical model, the construction of an experimental test bench was carried out. The analysis carried out involves the evaluation of performance parameters of the pump as a turbine, such as head, power, and efficiency. Additionally, the effect of the rotation speed on the previous parameters is evaluated. From the results obtained, it was shown that the maximum relative error was 4%, 3.4%, and 3.8% for the head, power, and efficiency parameters, respectively. In general, it was evidenced that the proposed numerical simulation has the ability to describe the real trends of the pump as a turbine for different flow conditions. In addition, an 11% increase in rotational speed was shown to cause a 12%, 1.9%, and 3% increase in head, power, and maximum efficiency. The proposed methodology is considered an adequate tool to analyze performance and identify the best efficiency point of pump systems such as a turbine. In this way, greater energy use is guaranteed.

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Formation of critical thinking related to the energetic efficiency of applied physics processes of civil engineering works
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| 2021-06-11

Current problems associated to contamination and climate change claim for urgent solutions to make real a sustainable development of modern societies. To answer that call, the efficiency of applied physics processes must be continuously evaluated. Particularly, engineering programs are called to strengthen the training offer related to basic and applied physics sciences considering energetic transformation and transferring processes. In the civil engineering field, design, construction, functioning, and final disposition of buildings can be understood as applied physics processes. This work proposes an approach for defining and studying possible variables related to energetic processes and their mutual relationship. Such variables must be able to describe the processes of energetic changes which can occur during construction of civil works. To do so, qualitative analysis of mathematic expressions is done to promote the formation of abstract mental connections made of sensitivity and logical thinking. The methodology is based on four moments: (a) students´ brainstorming related to a particular issue, (b) identification of main topics related to energy transformation, (c) variable operationalization, (d) proposal of mathematical expressions. This proposal is expected to facilitate the construction of concepts related to sustainable development and help students to trust themselves when taking well thought out risks.

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Curricula framework for a digital transformation master’s in science and engineering
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Vera Contreras, Milton Jesús | 2021-06-09

Digital transformation is an interdisciplinary work that has the objective to analyze data in real-time for better decision making, where it involves the modeling and the simulation of physical-mathematical and social processes and the monitoring of machinery that using information and communication technologies. Nowadays the fourth industrial revolution technologies are the driver for this transformation and soon will be quantum computing and other physics and mathematics advances. Therefore, in this academic-scientific work, a curricular framework is proposed for a master's program in digital transformation for science and engineering; the framework follows the literature review and analysis to formulate the denomination and justification for the master's degree. The results are (i) a general three-level model as a roadmap for the specific curricular design of a master’s in digital transformation for science and engineering; (ii) the recommendation that a master's program has a research focus in the two categories established by the Colombian standard (research and practitioner); (ii) finally, a political, economic, social, technological, environmental, and legal analysis justifies a master’s in digital transformation for science and engineering. The research model details the phases that were carried out to characterize and identify the curriculum framework that will be the basis for formalizing the master's degree document.

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Effect of layer thickness on anticorrosive performance of 316L steel coated with bismuth-titanium films
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GARZÓN AGUDELO, PEDRO | 2021-05

. Bismuth and titanium are elements with remarkable properties and applications in technological developments and in the field of biomedical engineering. The sol-gel method was used to form a bismuth-titanium system, which allowed to establish if it was possible to obtain films with anticorrosive properties on 316L stainless steel. The anticorrosive response was evaluated by means of Tafel curves, defining the parameters to obtain thin and functional films with good tribological properties. The coatings were obtained by the spin coating technique, varying the spin speeds from 3000 rpm to 5000 rpm with monolayer and bilayer systems. More positive values of corrosion potential were obtained when the steel is coated by the films, which implies a lower propensity to corrosion in saline medium, lower corrosion rates and higher potentials are reported for films with higher titanium content, likewise, better efficiency of the films with respect to the uncoated substrate is presented, the higher the titanium content and a strong influence between the calculated efficiencies and the centrifugation speeds is not observed

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Development of a gravimetric fuel measurement system for the evaluation of engine performance physical parameters
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Prada Botia, Gaudy Carolina | 2021

This paper presents the implementation and design features of a gravimetric-based fuel consumption system. The proposed system comprises a gravimetric balance with serial output, a fuel pump, and a control valve that are integrated into a complete engine test bench via Arduino UNO®. The study implements an instrumentation methodology to minimize measurement disturbance and error propagation, which represents a major concern in engine experimental testing. Moreover, an interactive virtual environment is developed to reinforce user interaction via LabView™. Results demonstrated that the proposed measurement system features robust and reliable operation while maintaining negligible disturbance and overall uncertainty ranging from 0.010-0.23 g/s. Additionally, it was evidenced that the measurement system allows the analysis of key parameters to evaluate engine performance. The study of the fuels blends shows that the ethanol content causes a 6.8% increase in brake specific fuel consumption and a 4% decrease in the brake thermal efficiency. Due to the low cost of the developed measurement system can be easily adapted to test bench laboratories to promote a better learning process and in industrial sectors for better energy management.

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Effect of a regenerator on hybrid solar gas turbine performance in Barranquilla, Colombia
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Moreno Gamboa, Faustino | 2021

A thermodynamic analysis of a hybrid gas turbine solar plant, represented in three basic subsystems related to the power cycle, the combustion chamber subsystem, and the solar concentrator subsystem, allows evaluating the performance of a hybrid cycle from a reduced number of parameters, which include energy losses in each of its components. The solar radiation values are estimated with an evaluated and validated theoretical model, the combustion chamber uses natural gas as fuel and the numerical values of the system are taken from the Solugas experimental plant in Spain. This work presents an integrated model that allows to estimate the operation of a hybrid solar Brayton power plant in any place and day of the year. The evaluation of the plant in Barranquilla, Colombia is shown from the influence of the regenerator has on the plant performance and solar concentrating system. The results show that the regenerator can increase the overall efficiency of the plant by 29% and allows reaching a maximum temperature of the central receiver of the concentrator of 1044 K at noon, when solar radiation is maximum.

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Daily performance of a solar hybrid regenerative gas turbine in Colombia
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Moreno Gamboa, Faustino | 2021-06-11

This work presents the evolution of the operation of a regenerative hybrid solar gas turbine in an average day of the year. The system is evaluated by means of a thermodynamic model that includes a solar concentrated heliostat field solar concentrator with central receiver, a combustion chamber, and the thermal engine. The model is applied in Barranquilla, Colombia using local temperature and the solar radiation estimated with a theoretical model. Power output, the global efficiency and thermal engine efficiency are estimated. Additionally, to estimate the temperatures in different states of the cycle with and without regenerator. Finally, the impact of the regenerator is evaluated, which can increase the temperature of the solar receiver by up to 13.6%, and the inlet temperature to the combustion chamber increases by 17.3% at noon, when solar radiation is maximum.

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Diagnosis of physical conditions for the implementation of a reverse logistics management model in a supply chain
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GARZÓN AGUDELO, PEDRO | 2021-06-09

The objective of this research was to structure a Reverse Logistics Management model applied to the furniture sector in the city of San José de Cúcuta, Colombia, based on the identification and analysis of the current business practices adopted by the companies that are part of this sector. For this purpose, engineering methods and techniques were used to propose alternatives that contribute to achieve a competitive growth, a better use of resources and environmental impact through strategies for the reuse of products or materials that, based on their physical properties, represent the best feasibility conditions. The type of research used was descriptive, with a qualitative approach. The methods used for data collection were mainly surveys, interviews and direct inspection of the companies studied, which made it possible to evaluate the physical variables of the object of study. It was possible to demonstrate that furniture manufacturing companies can adopt better reverse logistics practices in the manufacturing processes through referencing and articulation with strategic allies in the distribution channels. It was possible to establish the importance of implementing this model as a strategy to diagnose physical conditions and improve production systems to achieve a more efficient use of physical manufacturing resources.

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A Complete Prefeasibility Evaluation of On-Site Energy Generation System
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Romero-Garcia, Gonzalo | 2022-03-20

The recent global concern to mitigate the ecological impact on energy production has promoted the search for alternatives that allow a better use of resources. In this panorama, the cogeneration process appears as a solution seen with good eyes thanks to its great efficiency, which is why many institutions and companies have opted for the transition from the traditional system of energy production to cogeneration. This article develops the selection of the best alternative among different suppliers to implement a cogeneration system in an energy production plant, taking into account economic factors, selecting the one that represents the greatest profitability in the shortest time.

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Parametric Study of a Hybrid Renewable Energy Power Generation System in the Colombian Caribbean Region
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Rojas Suárez, Jhan Piero | 2022-03-20

The global environmental problems have increased the interest in renewable energies, in this article a wind-solar hybrid system is proposed as an alternative for energy production. To carry out this study, the research was divided into three stages, the first one consists of determining the behavior of a solar and wind system, the second stage focuses on determining the ideal location to implement the hybrid system and the third stage determines the composition of wind and PV devices that offers greater efficiency. After completing the three stages proposed above, the optimal locations for the implementation of a wind-solar hybrid system are Simón Bolívar and Puerto Bolívar.

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Autoregressive modelling of chromatographic signals from urine samples for prostate cancer diagnosis
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Soto Vergel, Angelo Joseph | 2021-06-09

This article evaluates autoregressive modeling as a feature extraction method in a database of chromatographic signals from urine samples for non-invasive diagnostic support of prostate cancer in response to the research question: Can chromatographic signals from urine be characterized and used as a non-invasive method for cancer diagnosis? For this purpose, a database of 18 patients, 9 diagnosed with prostate cancer and 9 control patients, is consolidated, statistical methods are implemented to generate autoregressive coefficients from the data signals, and finally, the principal component analysis technique is applied for crossclass classification. As a result, a correct classification was obtained in the total number of samples validating the autoregressive modelling as a feature extraction method in contrast to the conventional methodology usually followed in chromatographic signal processing.

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Investigation of Emission Characteristics and Lubrication Oil Properties in a Dual Diesel–Hydrogen Internal Combustion Engine
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Pardo García, Carlos Eduardo | 2022-04-05

: Hydrogen is considered one of the main gaseous fuels due to its ability to improve thermal performance in diesel engines. However, its influence on the characteristics of lubricating oil is generally ignored. Thus, in the present investigation, an analysis of the effect on the physical and chemical properties of lubricating oil with mixtures of diesel fuel–hydrogen was carried out, and the environmental impacts of this type of mixture were assessed. The development of the research was carried out using a diesel engine under four torque conditions (80 Nm, 120 Nm, 160 Nm and 200 Nm) and three hydrogen gas flow conditions (0.75 lpm, 1.00 lpm and 1.25 lpm). From the results, it was possible to demonstrate that the presence of hydrogen caused decreases of 3.50%, 6.79% and 4.42% in the emissions of CO, HC, and smoke opacity, respectively. However, hydrogen further decreased the viscosity of the lubricating oil by 26%. Additionally, hydrogen gas produced increases of 17.7%, 29.27%, 21.95% and 27.41% in metallic components, such as Fe, Cu, Al and Cr, respectively. In general, hydrogen favors the contamination and oxidation of lubricating oil, which implies a greater wear of the engine components. Due to the significantly negative impact of hydrogen on the lubrication system, it should be considered due to its influence on the economic and environmental cost during the engine’s life cycle.

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Study of the Cylinder Deactivation on Tribological Parameters and Emissions in an Internal Combustion Engine
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Orjuela Abril, Martha Sofia | 2022-04-07

In the present investigation, a study is carried out using numerical simulation on the effects of cylinder deactivation on tribological parameters and emissions in an internal combustion engine. For the development of the research, a tribological model was used to predict the characteristics of the lubrication film, friction conditions, blow-by gas, and deformation of the piston rings. Additionally, the construction of a CFD model was carried out to describe the kinematic movement of the engine piston. The analysis of results allowed for the demonstration of the active cylinders presenting an increase of 21.53% and 7.65% in the pressure and temperature in the cylinder wall. Additionally, the active cylinders present a reduction of 11.33% in the minimum thickness of the lubrication film and an increase in the friction force due to asperities, which implies an increase of 33% in power losses due to friction. The implementation of technologies such as cylinder deactivation causes an increase in combustion gas leaks caused by the increase in pressure of the active cylinders. However, the use of this technology allows reducing 9.09%, 8.26%, and 7.41% in CO, HC, and NO emissions. Although the use of technologies such as cylinder deactivation allows significant fuel savings, it is necessary to consider the negative effects caused by this technology, such as the increase in combustion gas leaks and the increase in power loss by the greatest frictional forces.

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CFD Analysis of the Effect of Dimples and Cylinder Liner Honing Groove on the Tribological Characteristics of a Low Displacement Engine
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Orjuela Abril, Martha Sofia | 2022-04-07

The contact between the piston rings and the cylinder liner is an interface with a strong influence on the tribological behavior and, therefore, directly affects the useful life of the engine components and fuel consumption. Due to this importance, the present investigation carried out an analysis of the effects of dimples and the honing groove in the cylinder liner on the tribological characteristics. A tribological model was developed to study the friction forces, minimum film thickness, and friction coefficient for the present investigation. Similarly, a computational fluid dynamics model was built to determine the dynamic movement of the piston. The validation of the numerical model showed a close similarity with the real behavior of the engine, obtaining an average relative error of 14%. The analysis of the results showed that a 3% increase in dimples’ density leads to a 3.79% increase in the minimum lubricant film and a 2.76% decrease in friction force. Additionally, it was shown that doubling the radius and depth of the dimple produces an increase of 3.86% and 1.91% in the thickness of the lubrication film. The most suitable distribution of the dimples on the surface of the cylinder liner corresponds to a square array. In general, the application of dimples and honing grooves in the cylinder liner are promising alternatives to reduce energy losses and minimize wear of engine components.

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Optimization of Phycobiliprotein Solubilization from a Thermotolerant Oscillatoria sp
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Barajas Solano, andres F | 2022-04-24

The present study evaluated the effect of multiple variables (drying time, drying temperature, biomass/solvent ratio, glass beads/biomass ratio, extraction time, and extraction speed) in the solubilization of three different phycobiliproteins (C-PC, APC, and PE) from a thermotolerant Oscillatoria sp. The strain was grown in BG11 media (28 ◦C, light: dark cycle of 12:12 h at 100 µmol·m−2 ·s −1 , 20 days) and the experiments were conducted according to a two-level randomized factorial design with six center points (38 runs). Results show that biomass/solvent ratio, glass beads/biomass ratio, and extraction time, are the most significant variables in the extraction of all three proteins, whereas the glass beads/biomass ratio and extraction time significantly affect their purity. The optimized conditions allow a statistical increase in the concentration of C-PC, APC, and PE extracted from the biomass; however, the purity was lower in comparison with the expected value. The latter occurs due to a larger biomass/solvent ratio and longer extraction times, which enhanced the solubility of other hydrophilic metabolites (proteins and carbohydrates, etc.).

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Bubble coalescence model effect on oxygen mass transfer using non-newtonian fluids
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Niño, Lilibeth | 2021-08

A modified bubble coalescence model including rheological conditions and shear forces in non-Newtonian fluids is evaluated using CFD (Computational Fluid Dynamics). Euler's model, along with population balance equations, was used to simulate bubble size distribution. Simultaneously, different bubble breakage and coalescence models were evaluated to investigate mass transfer and bubble diameter. A conventional aeration stirring system (Rushton turbine, ring sparger) was used and the results were validated by determining the experimental mass transfer coefficient. A 10-liter bioreactor operated under different operating conditions commonly used for non-Newtonian rheology was used. Xanthan Gum 0.25% was used to resemble the rheological conditions developed during fungal culture. CFD results were contrasted with tested data obtained from 𝑘�𝑘�𝐿�𝐿�𝑎�𝑎� measurements at different stirring speeds using the concordance d-index. A reasonable prediction was obtained comparing the modified model Luo-New to the most used conventional models Luo-Luo and Laakkonen-Luo. Therefore, model Luo-New shows the highest d values at 400-700 rpm with values of 0.83, 0.95, 0.98 and 0.69. By contrast, the model Luo-Luo showed less inaccurate values with levels lower than 0.62 in almost all comparisons. The latter concludes numerically that the inclusion of viscosity effects and shear on a bubble coalescence model improves the degree of prediction related to oxygen transfer. The latter being a critical factor in the design and testing of stirring and aeration devices.

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Enhancement of Metabolite Production in High-Altitude Microalgal Strains by Optimized C/N/P Ratio
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Suárez Quintana, William H. | 2022-07-04

: This study evaluated the role of C/N/P in the increase in the synthesis of carbohydrates, proteins, and lipids in two high-mountain strains of algae (Chlorella sp. UFPS019 and Desmodesmus sp. UFPS021). Three carbon sources (sodium acetate, sodium carbonate, and sodium bicarbonate), and the sources of nitrogen (NaNO3 ) and phosphate (KH2PO4 and K2HPO4 ) were analyzed using a surface response (3 factors, 2 levels). In Chlorella sp. UFPS019, the optimal conditions to enhance the synthesis of carbohydrates were high sodium carbonate content (3.53 g/L), high KH2PO4 and K2HPO4 content (0.06 and 0.14 g/L, respectively), and medium-high NaNO3 (0.1875 g/L). In the case of lipids, a high concentration of sodium acetate (1.19 g/L) coupled with high KH2PO4 and K2HPO4 content (0.056 and 0.131 g/L, respectively) and a low concentration of NaNO3 (0.075 g/L) drastically induced the synthesis of lipids. In the case of Desmodesmus sp. UFPS021, the protein content was increased using high sodium acetate (2 g/L), high KH2PO4 and K2HPO4 content (0.056 and 0.131 g/L, respectively), and high NaNO3 concentration (0.25 g/L). These results demonstrate that the correct adjustment of the C/N/P ratio can enhance the capacity of high-mountain strains of algae to produce high concentrations of carbohydrates, proteins, and lipids.

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Kinetic modeling of biosurfactant production from crude oil using Bacillus subtilis cells
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Alvarado, Kelly | 2022-06-23

Crude oil and its derivatives have high application in different industries, and unforeseen spills or overexploitation generate a significant threat in ecosystems, causing negative impacts on soil, water, and air. There are microorganisms capable of metabolizing hydrocarbons through the bioremediation process with biosurfactant production, but large-scale culturing and technification are still a significant challenge due to their high costs and optimization stage requirement. An unstructured kinetic model provides crucial information regarding improvements and process optimization at the first stages. Thereof prediction of bioprocess kinetic behavior is expected from mathematical expressions. Considering the above, biosurfactants’ bioprocess modeling tends to be an essential tool to increasingly focus on the efficiency and profitability of oil industries. That is why biosurfactant kinetics production from Bacillus subtilis is investigated in this research, implementing a mathematical model. Previous studies refereed experimental data to integrate into Monod, Contois, Haldane, Moser, Powell, Tessier, Aiba-Edward, Luong, Yano-Koga, and Chen-Hashimoto equations. Therefore, a nonlinear regression parameterization procedure is applied using the Matlab Fmincon Function. The best accuracy found between experimental and simulated data was achieved using the Chen-Hashimoto kinetic model with μmax, kd and ks values of 2.3239 d− 1 , 0.3748 d− 1 and 1.1619 g/L, respectively. This research suggests that biosurfactant production occurs under anaerobic conditions where hydrolysis controls microbial growth. These research results are a promising aim related to industrial biotechnology since computational modeling is essential for process efficiency from a technical and economic perspective.

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Analysis of the physicochemical process in the production of biogas from equine manure
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Sanchez-Beltrán, J M | 2021

. The present research aims to evaluate the physicochemical variables involved in the anaerobic digestion process to produce methane from manure on an agricultural farm; the farm has 2 equines that generate 12 Kg of manure per day. A manure sample was collected, and the following physicochemical parameters were determined: total solids, volatile solids, chemical oxygen demand, and pH. A tubular household biodigester was then implemented, consisting mainly of a polyethylene geomembrane that stores the organic matter and in which anaerobic digestion takes place. The performance of the biodigester was determined by the removal of organic matter quantified by volatile solids and chemical oxygen demand in the biodigester influent and digestate, of which removal of 82% of volatile solids and 74% of chemical oxygen demand was achieved. The average biogas production was 0.5 m3 /day, and its lower heating value was 26,000 kJ/m3 . The pH level of the biodigester was within the range of 6-7, in order to keep the methanogenic bacteria active, in charge of carrying out physicochemical process that guarantees anaerobic digestion and thus, the production of biogas.

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