bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and simulation of techniques for mitigation of harmonic distortion in a three-phase rectifier
Authors: Garrido-Arévalo V M , Pérez-Camargo W J , López Quintero J G 
Published: March 2020

Abstract
Rectifiers are electrical devices that receive an alternating signal and deliver a direct current signal at their output, this process by which they transform one type of energy to another is known as rectification. This type of device incorporates a phenomenon called harmonic distortion into the electrical network, which consists of malformations presented in the waveform of the alternating signal from which it feeds, which generate unwanted effects on electrical systems. Because of this, this work presents the combination of two harmonic distortion mitigation strategies (12-pulse multilevel converter and harmonic frequency tuned filtering stage) in order to reduce total harmonic distortion levels generated by a three-phase rectifier.
Development of heat transfer and pressure drop correlations in twisted tube heat exchangers
Authors: Ardila M J G , Valdes M , Cabal M R , Castro A , Quintero J G 
Published: March 2020

Abstract
Heat transfer in concentric twisted tubes exchangers has several applications in the chemical and food industry mainly due to its compact structure and high transport coefficients, however, its use has been limited as a consequence of drop pressure. This study reports Nusselt number and friction factor correlations as a function of the dimensionless Dean number as well as Prandtl number, and a torsional step parameter. Simulations were carried out using ANSYS CFX® V16.0 software at workstations belonging to Grupo de Investigación en Materiales Avanzados y Energía of Instituto Tecnológico Metropolitano. Six geometries were developed with SolidEdge® ST9 academic license. Geometry modification, cleanup, and repair were made although DesignModeler® 2019 academic license. Finally Meshing® for discretization. The mesh size independence, and incidence of the turbulence model, and twisting step validated the computational tools use. Correlation numerically showed an increase of 60% average respect to smooth bending tube.
On the nonlinear control of a single-phase current source converter for sinusoidal voltage generation
Authors: Montoya O D , Acevedo O , Gil-González W , Holguín M , Serra F M 
Published: March 2020

Abstract
Colombian power system is being transformed for the large-scale integration of renewable energy resources and energy storage systems; all of these are integrated by power electronic converters controlled by voltage and current sources. In addition, for regulatory policies it is required that the alternating current networks that feeds linear and nonlinear loads, can provide pure sinusoidal voltage and current forms in terms of frequency and amplitude. To guarantee it, in this paper the design of a nonlinear controller for a single-phase current source converter is explored, which is switched through a pulse-width modulated signal for providing sinusoidal voltages on linear loads. It is applied a feedback nonlinear control design on the dynamical model of the converter by using its averaged representation. The proposed control strategy allows guaranteeing asymptotic stability in the sense of Lyapunov for closed-loop operation. In steady state conditions the voltage behavior on the linear load evidences a sinusoidal form with an estimation error lower than 0.667%, which can be considered negligible for any practical power system application. All the simulations are conducted via MATLAB software 2017b licensed by Universidad Tecnologica de Bolívar, Colombia.
Application of the backward/forward sweep method for solving the power flow problem in DC networks with radial structure
Authors: Grisales-Noreña L F , Garzon-Rivera O D , Ramírez-Vanegas C A , Montoya O D , Ramos-Paja C A 
Published: March 2020

Abstract
This paper presents the application of the backward/forward sweep iterative method for solving the power flow problem in direct current networks with radial structure, considering resistive and constant power loads. The validation of the effectiveness and robustness of the proposed method is made by using six comparative methods proposed in literature for power flow analysis in radial direct current networks: Gauss-Jacobi, Gauss-Seidel, Newton-Raphson, linear approximation based on Taylor series, successive approximations, and the triangular matrix formulation. Those methods are evaluated using four test systems formed by 10, 21, 33 and 69 nodes. Simulation results, obtained in MATLAB, show that the proposed approach is efficient for radial direct current grids in terms of solution quality and processing time, increasing the efficiency for larger number of nodes increases.
Solution of the optimal power flow problem in direct current grids applying the hurricane optimization algorithm
Authors: Arteaga J A , Montoya O D , Grisales-Noreña L F 
Published: March 2020

Abstract
The Colombian electrical power system is being transformed by the large-scale integration of energy storage systems and renewable energy resources to the power system. These technologies can be integrated using alternating current or direct current technologies via power electronic converters. Here we analyze the direct current paradigm by proposing a master-slave optimizer for solving the problem of optimal power flow considering nonlinear loads. The master stage covers the dispatch of all distributed generators using the hurricane optimization algorithm. In the slave stage, a power flow method based on successive approximations is used to determine the voltage variables and evaluate the objective function of the problem, which is the minimization of power loss. A 69-nodes direct current network is used as a test case to compare the numerical performance of the hurricane optimization algorithm with a nonlinear optimization package and a metaheuristic approach called black hole optimizer. All simulations are performed using MATLAB software version 2017a licensed by Universidad Tecnológica de Bolívar, Colombia.
The effects of the contacts on the electronic localization properties of DNA
Authors: Páez C J , Quintero J H , Garcia-Castro A C 
Published: March 2020

Abstract
In this numerically work, we investigate the electronic transport along model deoxyribonucleic acid molecules using an effective tight-binding approach that includes the backbone onsite energies. The transmission probability, localization length and participation number are examined as a function of system size, energy dependence, and the contact coupling between the leads and the deoxyribonucleic acid molecule. On one hand, the transition from an diffusive regime for short systems to a localized regime is identified, suggesting the necessity of a further length scale revealing the system borders sensibility. On the other hand, we show that the localization length and participation number, do not depended of system size and contact coupling in the thermodynamic limit. Finally we discuss possible length dependent origins for the large discrepancies among experimental results for the electronic transport in deoxyribonucleic acid sample.
New anisotropic diffusion operator in images filtering
Authors: Vera M , Gonzalez E , Huérfano Y , Gelvez E , Valbuena O 
Published: March 2020

Abstract
The anisotropic diffusion filters have become in the fundamental bases to address the medical images noise problem. The main attributes of these filters are: the noise removal effectiveness and the preservation of the information belonging to the edges that delimit the objects of an image. Due to these excellent attributes, through this article, a comparative study is proposed between a new diffusion operator and the Lorentz operator, proposed by the pioneers of anisotropic diffusion. For this, a strategy consisting of two phases is designed. In the first, called operator construction, the composition of functions is used to generate a new diffusion operator that meets with the conditions reported for this kind of the mathematical object. In the second phase, denominated filtering, a synthetic cardiac images database, based on computed tomography, is filtered using the aforementioned operators. According with the value obtained for the peak of the signal-to-noise ratio, the new operator shows similar performance to the Lorentz operator. The implementation of this new operator contributes to the generation of new knowledge in digital image processing context.
Regular time series for physical-chemical water parameters: Total suspended solids and hydrogen potential
Authors: Ortiz J F , Mesa M J , Molina O E 
Published: March 2020

Abstract
The Quindío river is the main water source of the Quindío department, Colombia, which supplies water to 410000 people. Therefore, the study of its water quality is extremely important. If pollution is not monitored and controlled in this water source, diseases could affect the population of people that use the river as a source of water. For this reason, fieldwork was carried out in an area of the Quindío river where the total suspended solid and hydrogen potential parameters were studied. In order to analyze the data that was obtained in the fieldwork, the spine interpolation needed to be performed to generate a new sample where the spatial data was equidistant. To determine the relationship between the total suspended solid and hydrogen potential parameters, two regular time series were built and the second-order vector autoregressive model was adjusted. The model order was suggested by the statistical package Eviews.
Effect of concentration of starch in the properties morphological and structural of porous ceramic based on expansive clays
Authors: Suarez M , Bermudez D , Peña-Rodriguez G , Ferrer M , Dulce-Moreno H J 
Published: March 2020

Abstract
In this article is used the sacrificial material method to generate different porosities between 44.42% and 69.14% in ceramics based on expansive clays from San Jose de Cúcuta metropolitan area, Colombia, to analyze the effect of concentration of starch (porogenic agent) in the morphological and structural properties using calcium carbonate as a stabilizer. The porous ceramics was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Finally, the images were analyzed with the software Image J, Image Tool and Origin. The results showed that the weight concentration of starch has a relationship with the average pore size, the number of pores and the porous area of the samples where the percentage of porous area and the average pore size of the mixtures increases as starch is added due to the decay of the sacrificial material. The number of pores of the mixtures decreased by increasing the weight concentration of the starch due to the agglomeration of the starch.
Comparison of statistical forecasting techniques for Colombian coffee demand in South Korea
Authors: Rincón R D , Palacios W , Paipa H O 
Published: March 2020

Abstract
This article shows a comparison of various methods as a statistical technique for making applied forecasts of Colombian coffee demand in South Korea. The aim is to model the demand behavior in the most adjusted and efficient way possible. To do this, the correlation factor between demand and different macroeconomic variables was analyzed, the one with the greatest relationship is selected and the autocorrelation factor is evaluated. Later, different deterministic methods are used such as linear regression by least squares, simple moving average, weighted moving average, simple exponential smoothing, and exponential smoothing with trend. As a result, a multiple linear regression analysis is obtained, an evaluation of the predictive capacity of the regression model was made through analysis of variance, and the calculation of the standard error of multiple estimation, multiple determination coefficient and the adjusted determination coefficient.
Geometry optimization studies on nonplanar wingtip devices for typical transport aircraft
Authors: Manjunath I B , Kulkarni Venkatesh M , Balaraman P 
Published: March 2020

Abstract
Wings are the main lift generating sources for an aerospace system. Wing design is a complex process that involves selection of many aerofoil design parameters, wing design requirements and considerations. The main focus in this study is to validate nonplanar wingtip design methodologies and make a numerical estimation and comparison of aerodynamic characteristics of non planar wing tip devices and the associated induced drag. Naturally the high pressure on the bottom surface of the wing causes streamlines from underneath the wing to wrap around the tip to the top, thereby equalizing the pressure difference at the tip. This creates the rotating flow commonly known as a wing tip vortex. The current study investigates and assesses the possibility of retrofitting a non planar wing tip device for the rectangular tapered wing configuration without adding any additional weight to the main wing structure. There are basically three case studies. The first one is a validation of predicted experimental data against numerical simulation using FLUENT® tool for classical NACA 23015 aerofoil.
The second one involves taking into consideration possible mounting location of the nonplanar wingtip device on the main wing for smooth operation and gradual lift generation process.
A third case study is comparison of ‘wing alone experimental data’ against ‘wing with nonplanar winglet’data computed using FLUENT® in three dimensional space. Additionally estimation of numerical optimum load distribution is done for one of the optimum nonplanar winglet geometry using MATLAB tool. Finally comparison of MATLAB results with experimental loading is done for clarity.
Numerical modelling of solid hydrogen flow through an extruder die
Authors: Prashanth S R , Arumugam Senthil Kumar , Gangradey Ranjana , Mukherjee Samiran , Kasthurirengan S , Behera Upendra 
Published: March 2020

Abstract
Harnessing energy by nuclear fusion has progressed into technological developments as a result of sufficient progress made in the theoretical investigations. Fueling a tokamak by pellet injection is reported to be most efficient among other fueling techniques. It is thus important to produce a solid hydrogen filament by extrusion process using an extruder-die setup. It is required to arrive at an optimum configuration of the die as the pressure drop in the die decides the load on the extruder. The present analysis focuses on developing a CFD model of a die taking into account the complex rheological behavior of solid hydrogen. A systematic parametric analysis is performed to study the influence of die geometry on the flow behavior. The un-yielded regions are identified from the simulation results. It has been found that the un-yielded region decreases as the contraction ratio and contraction angle is decreased. The un-yielded zone is predominantly present in the region before contraction. However, at lower flow rates, the un-yielded zone appears even after the contraction.
Numerical modelling of right circular cylindrical fin of finite length subjected to conduction and convection losses in transient state
Authors: Boosala Swathi , Darapu Srikanth Satish Kumar 
Published: March 2020

Abstract
Fins are employed for the purpose of enhancing heat transfer from the base of the component, a known fact. In this paper, the performance calculation for uniform cross-sectional circular fin was done by transient analysis. The necessary numerical equations were derived by applying energy balance. Obtained results were compared with standard results. Variation of temperature over the surface of the fin is assumed to be in one dimension only. The equations were checked for forced convection. Stability criteria were obtained for different boundary conditions. Steady state analysis eliminates the influence of temperature increase when subjected to constant heat flow. This condition was considered, and calculations were done for nodes as well as the complete system. The performance parameters for extended surfaces such as effectiveness and efficiency also vary from steady state to transient state. In this context the energy balance for fin was made at macro and micro levels i.e., by finite difference method employing nodes and overall energy balance.
Analytical Approximate Solutions of Non Linear Partial Differential Equations using VIM, VIADM and New Modified KVIADM
Authors: Sheth Shruti S , Singh Twinkle R 
Published: March 2020

Abstract
This paper examines the Analytical Approximate Solutions of the Non Linear Partial Differential Equations such as Non Linear Wave Equations and In viscid Burgers’ Equation using Variational Iteration Method (VIM), Variational Iteration Adomian Decomposition Method (VIADM) and New Modified Kamal Variational Iteration Adomian Decomposition Method (New MKVIADM). VIM is a powerful tool to solve the differential equations which gives fast consecutive approximations without any conditional assumptions or any further transformations which may change the physical behaviour of the problem. Adomian Decomposition method is also an efficient method which handles the linear and non linear differential and integral equations with Initial and Boundary Conditions. It provides an efficient numerical solution in the form of an infinite series which is obtained iteratively. It usually converges to the exact solution using Adomian polynomials. Kamal Transform is a very recent new arrival of an integral transform which is commanding to solve the linear initial value problems. To check the efficiency of these methods, we have illustrated two non linear wave equations and one In Viscid Burgers’ equation. Objective of this paper is that, how rapidly these methods converge to the exact solution in the closed form, in the given domain for the given initial conditions, and still how it sustains the high accuracy and precision. Our aim in this paper is try to employ the combination of three different kinds of methods. The strategy of the methods is outlined and in view of the convergence of the methods and to show how it fulfils the objectives.
An approximate analytical solution of non linear partial differential equation for water infiltration in unsaturated soils by combined Elzaki Transform and Adomian Decomposition Method
Authors: Varsoliwala A C , Singh T R 
Published: March 2020

Abstract
The aim of the concerned paper is to describe the behaviour of the water infiltration problems in unsaturated soils. Governing equation of this phenomenon is known as Richards’ equation. The solution of the Richards’ equation has been found by Elzaki Adomian Decomposition Method. This method gives a solution in terms of convergent series. Comparison of the approximate solutions and exact solutions have been found here. MATLAB and MATHEMATICA are used to obtain numerical and graphical representation.
Curved domain discretization with boundary defined by polar equations
Authors: Vijayakumar Kallur V , Hariprasad A S 
Published: March 2020

Abstract
A domain discretisation procedure for a planar curved domain with boundary in polar equations is presented. The curved domain is split into curved triangles and then to a fine mesh of linear triangles in the interior and curved triangles or linear triangles near to the boundary. Later by inserting midside nodes to these triangles 6-node triangles obtained further each one into four triangles. The mesh conformity is preserved by applying similar procedure to every triangle of the domain. This procedure is applied to discretize the star shaped curved domain or cracked convex curved domains into all triangles and then into all quadrilaterals. Thus we generate a triangular and a quadrangular finite element mesh. The refinements to the mesh are obtained by increasing the number of divisions of the boundary curve. This discretization of curved domains will reduce the computational complications in the evaluation of integrals, which has lot of practical applications.
Influence of magnetic field on a curved circular plate and flat plate lubricated with non-Newtonian fluid
Authors: Hiremath A G , Hanumagowda B N , Siddharama P , Jagadish P 
Published: March 2020

Abstract
This paper presents a Analytical study of the effect of magnetic field on the performance of flat and curved circular plate with Non-Newtonian fluids. From the Stokes theory a Modified Reynolds equation is derived. The solution for pressure, load capacity and squeeze time is obtained to study the influence of transverse magnetic field and couple stress parameter on these characteristics. The non-dimensional pressure, load and squeeze film time is computed numerically and presented graphically. The results predicts that, the effect of Hartmann number M
0 and Non-Newtonian fluid l
* is improved in pressure, load carrying capacity significantly whereas delay in squeezing time as compared to the non-magnetic(NMC) and Newtonian(NC) cases.
Numerical Study of Heat Transfer Performance of Pin Fin by Shape Modification
Authors: Bharath S , Rakesh R , Ponangi Babu Rao , Ananthu M , Raj Ashwin , Majumder Aritra 
Published: March 2020

Abstract
Rate of heat transfer is an important parameter of heat exchangers, mostly it is affected by fins geometry. To achieve maximum heat transfer, shape of the fins plays a major role. In the present work an attempt is made to study the heat transfer performance in terms of temperature difference and pressure drop of pin fin heat sink with constant base heat flux is studied using commercial CFD software (ANSYS). Three geometries of pin fin have been designed by keeping the same cross-sectional area. CFD analysis have been carried out in both free and forced convection with transient formulation. Results have been compared with circular shape fin.
Development and testing of in-stream domestic turbine at building scale
Authors: Puneeth S , Chethana K Y , Anup T J , Kaushik S 
Published: March 2020

Abstract
All In stream turbine may be a source of renewable energy that empower mechanical, metropolitan and rural areas to generate clean, dependable, low-cost power from their potential available. Here the core rotating part of the turbine is fabricated by 3D printing and fixed to turn axially inside a round and hollow pipe beneath the control of liquid streaming either heading there through the liquid will strike the edges of the turbine and in this way giving the rotating movement to the generator shaft. The edges of the turbine are turned in a plane that is slanted at a relative point to the rotational pivot of the central shaft. The edges of the turbine are outlined and analyzed by computational fluid dynamics considering the aero-foil section to optimize and decrease the resistance of the hydrodynamic flow also experimental work has done to find out the power output and electricity generation.