Showing papers by "Instituto Tecnológico de Morelia published in 2018"
TL;DR: In this article, the green synthesis of silver nanoparticles (AgNPs) using Cynara cardunculus leaf extract in aqueous media was reported, where the silver ions reduction was carried out by the antioxidant component presents in the Cynara Cardunculus.
Abstract: The present study reports the green synthesis of silver nanoparticles (AgNP’s) using Cynara cardunculus leaf extract in aqueous media. The silver ions reduction was carried out by the antioxidant component presents in the Cynara cardunculus. Transmission electron micrographs revealed that the synthesized AgNP’s exhibits semi-spherical morphology and the particle size was less than 45 nm. The energy dispersive X-ray analysis (EDS) spectrum revealed the presence of silver. Complementary, The AgNP’s solution exhibited an absorption peak at 435 nm, corresponding to surface plasmon resonance of AgNP’s. Fourier transform infrared (FT-IR) spectra showed the presence of the organic components responsible for reduction and stabilizing the nanoparticles. X-ray photoelectron spectroscopy (XPS) was employed to elucidate the chemical state and near surface composition of the AgNP’s obtained from Cynara cardunculus leaf extract. The antibacterial effect of the AgNP’s synthesized was tested by the disk diffusion method against E. Coli and S. Aureus bacteria. The electrochemical response of the nanoparticles was evaluated by cyclic voltammogram. The antibacterial and electrochemical activity of the AgNP’s were described in this work.
47 citations
TL;DR: Both varieties of guava leaf extract showed excellent antioxidant properties, and total phenolics and total flavonoids showed a slightly positive correlation for ORAC-FL and hydroxyl radicals.
Abstract: Guava leaf (Psidium guajava L.) extracts are used in both traditional medicine and the pharmaceutical industry. The antioxidant compounds in P. guajava leaves can have positive effects including anti-inflammatory, anti-hyperglycemic, hepatoprotective, analgesic, anti-cancer effects, as well as protecting against cardiovascular diseases. In the present study, phenolic compounds and in vitro antioxidant capacity were measured in extracts obtained with polar and non-polar solvents from leaves of two varieties of guava, Calvillo Siglo XXI and Hidrozac. The quantity of total phenolics and total flavonoids were expressed as equivalents of gallic acid and quercetin, respectively. Hydroxyl radical, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Oxygen Radical Absorbance Capacity using fluorescein (ORAC-FL) in vitro tests were used to assess the radical scavenging abilities of the extracts. The total phenolics were higher in the aqueous fraction of the variety Calvillo Siglo XXI, while in the Hidrozac variety total phenolics were higher in the acetone and chloroform fractions. Total flavonoids were higher in all fractions in the variety Calvillo Siglo XXI. Total phenolics showed a highly positive correlation for ORAC-FL, and a moderately positive correlation with hydroxyl radicals. Finally, total flavonoids showed a slightly positive correlation for ORAC-FL and hydroxyl radicals. Both varieties of guava leaf extract showed excellent antioxidant properties.
35 citations
TL;DR: In this paper, the effects of avocado oil on kidney mitochondria were investigated in hypertensive rats with Nω-nitro- l -arginine methyl ester (L-NAME) and losartan.
27 citations
TL;DR: A high-throughput method based on exponential yeast growth to estimate the effects of concentration changes and nature of the carbon source on respiratory and fermentative metabolism and can be used as a preliminary screening of compounds/substances that may disturb or enhance fermentative or respiratory metabolism.
Abstract: Saccharomyces cerevisiae cells in the exponential phase sustain their growth by producing ATP through fermentation and/or mitochondrial respiration. The fermentable carbon concentration mainly governs how the yeast cells generate ATP; thus, the variation in fermentable carbohydrate levels drives the energetic metabolism of S. cerevisiae. This paper describes a high-throughput method based on exponential yeast growth to estimate the effects of concentration changes and nature of the carbon source on respiratory and fermentative metabolism. The growth of S. cerevisiae is measured in a microplate or shaken conical flask by determining the optical density (OD) at 600 nm. Then, a growth curve is built by plotting OD versus time, which allows identification and selection of the exponential phase, and is fitted with the exponential growth equation to obtain kinetic parameters. Low specific growth rates with higher doubling times generally represent a respiratory growth. Conversely, higher specific growth rates with lower doubling times indicate fermentative growth. Threshold values of doubling time and specific growth rate are estimated using well-known respiratory or fermentative conditions, such as non-fermentable carbon sources or higher concentrations of fermentable sugars. This is obtained for each specific strain. Finally, the calculated kinetic parameters are compared with the threshold values to establish whether the yeast shows fermentative and/or respiratory growth. The advantage of this method is its relative simplicity for understanding the effects of a substance/compound on fermentative or respiratory metabolism. It is important to highlight that growth is an intricate and complex biological process; therefore, preliminary data from this method must be corroborated by the quantification of oxygen consumption and accumulation of fermentation byproducts. Thereby, this technique can be used as a preliminary screening of compounds/substances that may disturb or enhance fermentative or respiratory metabolism.
25 citations
TL;DR: The proposed Matrix-Based System Reliability method can compute the failure probability of HVDC transmission systems by use of efficient matrix-based procedures and provides a straightforward way of handling the system events and estimating their probabilities.
25 citations
TL;DR: A novel methodology to assess structural vulnerability was proposed and applied in IEEE test system and high voltage transmission networks of 94 buses, by using graph theory to investigate various risk scenarios that can trigger cascading failures is validated.
Abstract: In previous research a novel methodology to assess structural vulnerability was proposed and applied in IEEE test system and high voltage transmission networks of 94 buses, by using graph theory to investigate various risk scenarios that can trigger cascading failures. In this paper we validate the application of this methodology in larger networks by applying a case study on the transmission network 230 and 400 kV of Mexico. The events of cascading failures are simulated through two elimination strategies: by deliberate attacks on critical nodes or by random errors. Iterations are performed by running successive N-1 contingencies on a network that is constantly changing its structure with the elimination of each node. The power flows are not necessary and only the calculation of the graph statistical parameter “geodesic vulnerability” is required. This reduces the computation time and leads to a comparative analysis of structural vulnerability.
22 citations
TL;DR: In this article, a frequency-based analytical approach is presented for dynamic analysis of three-phase balanced systems in the presence of harmonic distortion based on single-phase analysis, which is done by utilizing Dynamic Harmonic Domain (DHD) and defining a phase-shift matrix in frequency domain.
Abstract: In this paper, a frequency-based analytical approach is presented for dynamic analysis of three-phase balanced systems in the presence of harmonic distortion based on single-phase analysis. By providing mathematical foundation, this study proves that a three-phase balanced system (linear or non-linear, supplied by periodic balanced sinusoidal or non-sinusoidal sources) is completely balanced during both transient and steady-state conditions. This is done by utilizing Dynamic Harmonic Domain (DHD) and defining a phase-shift matrix in frequency domain. As the most noteworthy application of the proposed methodology, single-phase modeling approach is put forward. Therefore, during the transient period, one can analyze only one phase of a three-phase balanced system and calculate exact quantities of the other phases without performing extra simulations, which is not possible through time domain. The introduced concept has been applied to different test cases including three-phase transformer inrush current. In addition, the proposed approach has been utilized to obtain a single-phase model of VSC-based power electronic devices for dynamic harmonic analysis, followed by discussion on results.
18 citations
TL;DR: In this article, an advanced current-sensorless control scheme for voltage source converter-power factor correction rectifiers is proposed, which is aimed at reducing the complexity of the control while maintaining desirable features for ac/dc conversion, such as unity power factor, low total harmonic distortion in input current, continuous regulation of the dc voltage even facing ac voltage sags and dynamic load changes.
Abstract: This paper presents the design, modeling, implementation, and experimental results of an advanced current-sensorless control scheme for voltage source converter–power factor correction rectifiers. This proposal is aimed to reduce the complexity of the control while maintaining desirable features for ac/dc conversion, such as unity power factor, low total harmonic distortion in input current, continuous regulation of the dc voltage even facing ac voltage sags and dynamic load changes. Unlike other proposals, this scheme has a single feedback proportional-integral loop, uses few mathematical operations, and the dq 0 reference frame is not included in the control scheme. These characteristics simplify the implementation of the proposed control thus improving its efficiency. The theoretical analysis and simulation validate the technical feasibility of the proposed control, and finally, various cases of study and experimental results obtained with a laboratory scale-down prototype are presented to confirm the viability and performance of the control.
17 citations
01 Nov 2018
TL;DR: In this paper, the authors present the theory and design of the control system used to mitigate harmonic problems in three-phase four-wire systems based on a split capacitor topology.
Abstract: The electrical power quality in three phase four wire systems, feeding nonlinear loads, can be improved by using active power filters (APF) in order to mitigate the total harmonic distortion. Harmonic currents and voltages produced by single phase, non-linear loads, which are connected phase to neutral in a three phase, four wire system, are third order, zero sequence harmonics. These third order, zero sequence harmonic currents, unlike positive and negative sequence harmonic currents, do not cancel but add up arithmetically at the neutral bus, and can be greater than the current of each of the phases. The danger that arises is an excessive overheating of the neutral, since there is no circuit breaker in this conductor, which limits the current, as occurs with the phase conductors. An excessive current in the neutral can also cause an excessive voltage difference between the neutral conductor and ground. This paper presents the theory and design of the control system used to mitigate harmonic problems in three-phase four-wire systems based on a split capacitor topology. Due to split capacitor topology has midpoint between the capacitors, this point can be used for the neutral return path, and thus, the entire neutral current flows through the DC bus capacitors reducing the number of switching devices. Simulation results are shown to validate the proposed procedures.
16 citations
TL;DR: The existence of synergic and diverse roles of carbon and nitrogen sources that are affected by RIM15, influencing the fermentative and respiratory growth of S. cerevisiae is revealed and the usefulness of a threshold in doubling time values as an indicator of fermentativeand respiratory growth is endorsed.
Abstract: Nutritional homeostasis is fundamental for alcoholic fermentation in Saccharomyces cerevisiae. Carbon and nitrogen have been related to this metabolic process; nevertheless, little is known about their interactions with the media and the energetic metabolism. Rim15p kinase is a point of convergence among different nutrient-activated signaling pathways; this makes it a target to investigate the relationship between nutritional status and energetic metabolism. To improve the current knowledge of nutrient interactions and their association with RIM15, we validated the doubling time as an indicator of growth phenotype, confirming that this kinetic parameter can be related to the cellular bioenergetic status. This endorses the usefulness of a threshold in doubling time values as an indicator of fermentative (≤ 6.5 h) and respiratory growth (≥ 13.2 h). Using the doubling time as response variable, we find that (i) two second-order interactions between type and concentration of carbon and nitrogen sources significantly affected the growth phenotype of S. cerevisiae; (ii) these metabolic interactions changed when RIM15 was deleted, suggesting a dependence on this gene; (iii) high concentration of ammonium (5% w/v) is toxic for S. cerevisiae cells; (iv) proline prompted fermentative growth phenotype regardless presence or absence of RIM15; (v) RIM15 deletion reverted ammonium toxicity when cells were grown in glucose (10% w/v); and (vi) RIM15 deletion improves fermentative metabolism probably by a partial inhibition of the respiration capacity. This study reveals the existence of synergic and diverse roles of carbon and nitrogen sources that are affected by RIM15, influencing the fermentative and respiratory growth of S. cerevisiae.
14 citations
TL;DR: In this paper, the growth and characterization of doped molecular semiconductor metallophthalocyanine-tetracyanoquinodimethane (MPc-TCNQ) films, with MÕ= Fe, Zn, Cu.
TL;DR: In this paper, a finite element (FE) model was applied to evaluate the deformation during welding process in TWIP-Ti steel 5.8mm thickness plates. Butty joints were used to evaluate deformation in high and low heat input welds.
TL;DR: Data indicate that glutathione exhaustion impact negatively both the electron transport chain function and the chronological life span of yeast, the latter occurring when a low threshold level of this antioxidant is reached, independently of the H2O2 levels.
Abstract: Diet plays a key role in determining the longevity of the organisms since it has been demonstrated that glucose restriction increases life span whereas a high-glucose diet decreases it. However, the molecular basis of how diet leads to the aging process is currently unknown. We propose that the quantity of glucose that fuels respiration influences reactive oxygen species generation and glutathione levels, and both chemical species impact in the aging process. Herein, we provide evidence that mutation of the gene GSH1 in Saccharomyces cerevisiae diminishes glutathione levels. Moreover, glutathione levels were higher with 0.5% than in 10% glucose in the gsh1Δ and wild-type strains. Interestingly, the chronological life span was lowered in the gsh1Δ strain cultured with 10% glucose but not under dietary restriction. The gsh1Δ strain also showed inhibition of the mitochondrial respiration in 0.5 and 10% glucose but only increased the H2 O2 levels under dietary restriction. These results correlate well with the GSH/GSSG ratio, which showed a decrease in gsh1Δ strain cultured with 0.5% glucose. Together, these data indicate that glutathione exhaustion impact negatively both the electron transport chain function and the chronological life span of yeast, the latter occurring when a low threshold level of this antioxidant is reached, independently of the H2 O2 levels.
TL;DR: The results show that additional transmission capacity may be required to satisfy the flexibility requirements caused by net load ramps and the effect on investment and operational costs of including operational constraints of generators, transmission losses, and N-1 security constraints on the TEP problem.
Abstract: This paper discusses the impact that different approximations have on the Transmission Expansion Planning (TEP) problem. Due to the long decision horizons involved, the number of variables can make the problem intractable if approximations to the problem are not made. Furthermore, new emerging technologies and changes in the way we operate our systems are putting under scrutiny some of the approximations usually made to the problem. In this context, this paper evaluates the effect on investment and operational costs of including operational constraints of generators (ramping), transmission losses, and N-1 security constraints on the TEP problem. TEP is formulated as a mixed-integer linear program (MILP). We first validate our analysis using the Garver test system. Then, the importance of including the aforementioned constraints to TEP is tested with the 24-bus and 118-bus IEEE systems. Our results show that additional transmission capacity may be required to satisfy the flexibility requirements caused by net load ramps.
TL;DR: The use of the Peaucellier–Lipkin mechanism, its transformation from one to three degrees of freedom, and the incorporation of the stability system are the main innovations and contributions of this novel nonanthropomorphic exoskeleton.
Abstract: This article presents the principles upon which a new nonanthropomorphic biped exoskeleton was designed, whose legs are based on an eight-bar mechanism. The main function of the exoskeleton is to a...
TL;DR: In this article, a new method for mean life evaluation of power system equipment, based on the two-parameter Weibull distribution, is presented for complete and right-censored failure data.
TL;DR: In this article, a pair of welds were made in austenitic stainless steel AISI 304L and the novel twinning-induced plasticity (TWIP) steel microalloyed with titanium.
Abstract: In this study, a pair of welds was made in austenitic stainless steel AISI 304L and the novel twinning-induced plasticity (TWIP) steel microalloyed with titanium. Microstructural characterization and mechanical assessment were conducted with the aim to compare the weldability of both materials. The weld joints were performed in two passes by means of the autogenous gas tungsten arc welding (GTAW) process. The operating parameters were defined with the aid of penetration depth predictions carried out by a finite element (FE) numerical model. The results indicated that the weldability of TWIP-Ti steel compared to that of the AISI 304L steel had some advantages as the lower extension of the heat affected zone (HAZ) and a lower mechanical properties loss with respect to the base material. The ferritic solidification mode towards the outer of the FZ in the AISI 304L steel avoided hot cracking in the HAZ. Conversely, the HAZ of TWIP-Ti steel did not present hot cracking despite the austenitic solidification mode. The higher thermal diffusivity of the TWIP-Ti steel had a positive effect in the HAZ conditions improvement, which in turn was correlated with the welding cooling rates and microstructural aspects through the FEM model.
TL;DR: Correlation analysis showed that the fruitiness/sweetness description of the mezcal produced using the ATF1-engineered K. marxianus yeast correlated with the content of the esters, whose presence improved the organoleptic properties of the craft mez cal beverage.
Abstract: Mezcal, a traditional beverage that originated in Mexico, is produced from species of the Agavaceae family. The esters associated with the yeasts utilized during fermentation are important for improving the organoleptic properties of the beverage. We improved the ester contents in a mezcal beverage by using the yeast Kluyveromyces marxianus, which was engineered with the ATF1 gene. ATF1 expression in the recombinant yeast significantly increased compared with that in the parental yeast, but its fermentative parameters were unchanged. Volatile-organic-compound-content analysis showed that esters had significantly increased in the mezcal produced with the engineered yeast. In a sensory-panel test, 48% of the panelists preferred the mezcal produced from the engineered yeast, 30% preferred the mezcal produced from the wild type, and 15 and 7% preferred the two mezcal types produced following the routine procedure. Correlation analysis showed that the fruitiness/sweetness description of the mezcal produced using the ATF1-engineered K. marxianus yeast correlated with the content of the esters, whose presence improved the organoleptic properties of the craft mezcal beverage.
18 Jul 2018
TL;DR: In this article, the authors studied the expansion-contraction phenomenon and residual stress distribution in the seal welding of a 12Cr-1Mo steel band-blade assembly and found that the complex distribution of the transversal residual stresses generated by temperature gradients in the assembly are responsible for the expansion contraction phenomenon occurring during the welding process.
TL;DR: It is shown that using equivalent circuit for triplen harmonics is essential to find a relation between residual components since if sequences are connected in parallel, it is not possible to modify results of classical symmetrical components and this equivalent circuit should be directly analyzed.
Abstract: In this paper, a frequency-based analytical approach for dynamic analyzing of unbalanced three-phase systems in the presence of harmonic distortion using sequence domain is put forward. As will be shown, classical symmetrical components proposed by Fortescue is not applicable under nonsinusoidal periodic condition. In such cases, generalized symmetrical components proposed by Tenti et al. can be used to calculate sequences from phase domain values. However, it introduces a new sequence component called residual component, which has a different value for each phase and cannot be directly obtained based on sequence networks. To such aim, using dynamic harmonic domain, an approach that makes it possible to use features of classical symmetrical components and modify the outputs to compute sequences based on the concept of generalized symmetrical components is proposed. Moreover, it is shown that using equivalent circuit for triplen harmonics is essential to find a relation between residual components since if sequences are connected in parallel, it is not possible to modify results of classical symmetrical components and this equivalent circuit should be directly analyzed. Time domain software is used to perform conventional lumped circuit simulation and validate the time domain responses resulted from DHD.
TL;DR: An algorithm to detect, localize and classify fault events in overhead transmission lines compensated with a thyristor-controlled series capacitor (TCSC) using the discrete wavelet transform combined with a probabilistic neural network to determine whether a fault condition exists in the line, the fault type and also the fault distance.
Abstract: This paper describes an algorithm to detect, localize and classify fault events in overhead transmission lines compensated with a thyristor-controlled series capacitor (TCSC). During a fault event, a complex pattern of traveling wave reflections and refractions is generated at the point of fault inception. The proposed algorithm uses the discrete wavelet transform combined with a probabilistic neural network to analyze all this information and determine whether a fault condition exists in the line, the fault type and also the fault distance. In order to assess the algorithm performance, several studies were carried out under varied conditions. The obtained results demonstrate that the algorithm accuracy for calculating the fault distance is smaller than 1% of the total line length, and a 100% efficiency for determining the fault type. The algorithm is also immune to harmonic interaction due to low-frequency harmonics generated by the TCSC. A comparative advantage over previous algorithms for TCSC-compensated transmission lines is the fact that the proposed algorithm not only identifies the faulted line section but also localizes accurately the distance to the fault, using only measurements at one end of the line.
TL;DR: In this paper, multiwalled carbon nanotubes (MWCNTs), functionalized and pristine, were incorporated in polycaprolactam matrix; hydrochloric acid (19 and 38%) and formic acid(88%) were used as polymer solvents.
Abstract: Several electronic applications have been developed through the use of carbon nanotubes and polymer composites. Multiwalled carbon nanotubes (MWCNTs), functionalized and pristine, were incorporated in polycaprolactam matrix; hydrochloric acid (19 and 38%) and formic acid (88%) were used as polymer solvents. Mechanical stirring method was employed to dissolve the polymer and achieve the dispersion of MWCNTs in polymer matrix. The obtained composites were characterized by scanning electron microscopy, confirming the presence of MWCNTs in polymer. Raman and Fourier transformed infrared spectra were used to identify the interaction between MWCNTs and polycaprolactam. Hardness improvements were proved through microhardness test, reaching values over 100 Hv units. The electrical conductivity in composites with the highest MWCNTs content (4 wt%) was confirmed. The results described in this manuscript confirm the possibility to develop a new material using MWCNTs dispersion in polycaprolactam matrix and possible applications in electronical and mechanical fields.
TL;DR: The characteristics of a sprawling robotic leg inspired by the limb postures of certain reptilian animals known as sprawling-legged creatures are shown, which can trace concave or convex curves, as well as straight lines, making it a reptile-like robotic limb that is very similar to the natural one.
Abstract: This article shows the characteristics of a sprawling robotic leg inspired by the limb postures of certain reptilian animals known as sprawling-legged creatures. The main part of the robotic limb i...
01 Nov 2018
TL;DR: Ferroresonance is a phenomenon that is present in voltage signals in the form of aperiodic oscillations that cause transient overvoltages, mainly in transformers, which makes it important to consider in the design of electrical systems as discussed by the authors.
Abstract: Ferroresonance is a phenomenon that is present in voltage signals in the form of aperiodic oscillations that cause transient overvoltages, mainly in transformers. This phenomenon must be considered in the design of electrical systems, since it presents high levels of distorted voltages causing damage to equipment, which makes it important to study. In this paper ferroresonance simulations are shown in ATP (Alternative Transient Program), presenting serial type ferroresonances through different scenarios, observing the behavior of voltage signals. For the presence of ferroresonance, certain capacitive values are considered in cables and power supply voltage levels of the system, in addition, the impact on the location of switches is analyzed, observing how ferroresonance behaves under different operating conditions.
TL;DR: The article presents an illustrative example describing a detailed procedure concerning the configurations and collaboration of their legs according to an imposed center of rotation around of which the six-legged robot walks.
Abstract: This article describes the way in which six nontraditional legs collaborate to provide locomotion to a walking machine when it moves along a path Such legs are based on the one-degree-of-freedom P
TL;DR: In this paper, the effect of hydrogen on fatigue crack growth was studied using rotary bending fatigue tests using martensitic-bainitic microalloyed steel, and cracks propagated along high-shear-stress planes.
Abstract: In a martensitic-bainitic microalloyed steel, the effect of hydrogen on fatigue crack growth was studied using rotary bending fatigue tests. The steel was subjected to a rapid thermal cycle to get a microstructure similar to that which would be formed within the coarse-grained heat-affected zone of a weld. Crack growth was monitored as a function of the number of cycles applied during fatigue tests on three types of specimens: 1) those without hydrogen charge, 2) those charged with hydrogen and 3) those charged with hydrogen which was then discharged through low-temperature heat treatment. All types showed persistent slip marks, and cracks propagated along high-shear-stress planes. In the presence of hydrogen, crack growth was affected by microstructural defects caused by the hydrogen charging process, and the persistent slip marks developed in an area closer to the crack tip and crack path. On the contrary, without hydrogen, crack growth occurred perpendicular to the applied force, and the persistent slip marks were fewer in number and further from the crack tip and crack path. This indicates that the plasticity increased (i.e., the damage that occurred in the presence of hydrogen matched the hydrogen-enhanced local plasticity mechanism).
TL;DR: In this paper, the results of a numerical simulation, in the transient 3D state, of heating a block of stainless steel AISI 304 in continuous movement in the interior of an experimental vertical furnace were presented.
Abstract: The present work shows the results of a numerical simulation, in the transient 3D state, of heating a block of stainless steel AISI 304 in continuous movement in the interior of an experimental vertical furnace. The model considers the heat transfer by radiation between the furnace walls and the surface of the block using the model P-1, implemented in CFD Fluent® commercial software. The thermal boundary conditions were experimentally determined by sectioning and recording the furnace wall temperatures at different heights. In turn, the conditions were implemented through a user-defined function. The displacement of the block was modeled using two methods: the field assignment method and the layering dynamic mesh method. The simulated thermal histories obtained with both methods were compared with the experimental thermal history of the block during continuous movement in the interior of the furnace. The results show that the layering dynamic mesh method predicts the thermal history of the block heating during continuous movement more accurately than the field assignment method, providing a viable alternative for the simulation of continuous processes at high temperatures, such as the process of reheating a steel billet.
01 Sep 2018
TL;DR: The core-losses of a single-phase wound core transformer are computed using the “CORELOSS” application and they are compared with results obtained with a commercial FE package.
Abstract: This paper describes a finite-element (FE) based application for the numerical evaluation of core-losses in distribution transformer. The specific application is centered around a method that permits the generation of software applications for a variety of user/customer defined problems and makes use of the FE method in order to solve them. A variety of problems are considered such as electromagnetic or thermal, steady state or transient, linear or non-linear, and two-dimensional (2-D) or three-dimensional (3-D). The present manuscript focuses on one such application and more specifically on the problem of core-losses evaluation in oil-immersed, wound core, distribution transformers, both single-phase and three-phase. Finally, the core-losses of a single-phase wound core transformer are computed using the “CORELOSS” application and they are compared with results obtained with a commercial FE package.
TL;DR: In this article, a significant increase in electrical conductivity and microhardness was observed in all the nanocomposites with different MWCNTs addition (5, 7 and 9 wt %), resulting in improvement properties in contrast to pristine polymers.
Abstract: PA6 and PMMA polymers with different MWCNTs addition (5, 7 and 9 wt %) were synthetized through casting solution, resulting in improvement properties in contrast to pristine polymers. SEM images showed the MWCNTs embedded into polymeric matrices. D, G and G´ bands of MWCNTs were confirmed by Raman spectroscopy and functional groups observed in both nanocomposites by FTIR demonstrated a strong interaction. A significant increasing in electrical conductivity and microhardness was observed in all the nanocomposites. Major microhardness values were obtained in MWCNTs/PA6 (50 HV) however the MWCNTs/PMMA nanocomposites showed the highest electrical conductivity value (6.4×10−4 S/cm).