Averaged current mode control for maximum power point tracking in high-gain photovoltaic applications

Romo, David de la Rosa,Loera-Palomo, Rodrigo,Rivero, Michel,Sellschopp-Sanchez, Francisco S. The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6

Efficient extraction of the maximum power from photovoltaic (PV) systems under inherently variable weather conditions is a key issue that has been tackled in recent years. Maximum power extraction techniques are relevant for increasing the penetration of PV systems into electric systems. This paper presents an averaged current mode control strategy as a maximum power extraction technique in a photovoltaic high step-up dc-dc converter, which can be applied to dc microgrids or ac networks through power inverters. Since the generated power of a photovoltaic system is related to the terminal voltage, power extraction is given through the regulation of the converter's input voltage. For this purpose, in the proposed averaged current mode control, the inner current loop uses the inductor current as a feedback signal, which improves the dynamic behavior of the converter with a simple gain. Meanwhile, the outer voltage loop is built with a proportional-integrative controller for regulation. The converter and control strategy are able to track rapid irradiance changes. They are also able to maintain the photovoltaic voltage regulation under dc bus voltage variations. The performance of the proposed control scheme is validated experimentally with a 100 W converter prototype.

Improving communication protocols in smart cities with transformers

Edgar Romo-Montiel,Ricardo Menchaca-Mendez,Mario Eduardo Rivero-Angeles,Rolando Menchaca-Mendez 한국통신학회 2022 ICT Express Vol.8 No.1

Adaptive medium access control (MAC) protocols are essential in the context of Vehicular AdHoc Networks (Vanets) because of the rapid changes in topology caused by the high mobility of nodes. In this work, we propose an adaptive version of the Slotted-ALOHA (S-ALOHA) protocol, where the transmission probability is constantly adjusted based on estimates of the number of vehicles in the coverage area. These values are computed using deep learning models for time series prediction. One challenge for implementing this approach is that the inputs to the models are noisy since they are also estimates based on the protocol’s operation itself. To address this problem, we propose a new training scheme where we add noise, similar to that produced by the protocol’s operation, to the inputs of the training examples as a form of regularization. Our experiments show that the regularized models perform close to the theoretical optimal where the number of vehicles in the area is always known.

Picasso, cognitivismo y lingüística

Francisco Romo Simon 부산외국어대학교 중남미지역원 2017 이베로아메리카 Vol.19 No.1

This paper outlines the general principles of some parallelisms that, from the Cognitive Linguistics’ field of study, we have appreciated between the thought and the work of Pablo Picasso, and the theoretical and methodological bases of Cognitive Science, in general, and Cognitive Linguistics in particular. The purpose of this comparative analysis is to use the work of Pablo Picasso to exemplify these connections and to reconsider the role of art (specially, in this case, painting and visual arts) in the construction and representation of knowledge, something particularly appropriated, when not necessary, according to the cognitive principles of research.

La linguistica cognitiva espanola y la teoria cognitivista: coincidencias y discrepancias

Francisco Romo Simon 고려대학교 스페인·라틴아메리카연구소 2017 스페인라틴아메리카연구 Vol.10 No.2

En este articulo proponemos una reflexion sobre la necesidad de unificar los criterios a la hora de apelar a los constructos analiticos y descriptivos de la linguistica cognitiva en el analisis la lengua espanola. Consideramos necesario este ejercicio porque, aunque en los ultimos anos ha aumentado el numero de publicaciones que se declaran cognitivistas, lo cierto es que rara vez se encuentran en ellas los planteamientos teoricos originales de esta rama de la linguistica tal como la definieron Rosch, Langacker o Lakoff, entre otros, y tal como si hacen autores que analizan otras lenguas, como el ingles. Consideramos que el alejamiento de las bases teoricas de la linguistica cognitiva en favor de una mayor difusion y una supuesta mejor aplicabilidad en los entornos de E/LE es el principal causante de que la teoria linguistica no haya prosperado en el ambito academico y de que las obras resultantes, en general, no puedan considerarse representativas de lo que la teoria linguistica si ha conseguido en el ambito internacional. En este articulo expondremos como hemos llegado a tal conclusion, cuales son las consecuencias de esta situacion, y propondremos algunas posibles soluciones para avanzar hacia una definicion de la lengua mas sistematica, coherente y alejada de percepciones subjetivas. In this paper, we will analyze and describe the characteristics of the Spanish Cognitive Linguistics. Despite the fact that, in the last years, the number of publications claiming to describe Spanish grammar phenomena by using Cognitive Linguistics has increased, it is hard to find among them any reference to the theoretical construals or analytic methods used by the original authors (i.e. Langacker or Lakoff), and thus, their theoretical impact has been minimal, at least in comparison with the advances made by general Cognitive Linguistics. It is the purpose of this article to analyze and expose the differences between the Spanish approach and the original theory to analyze the causes and consequences of the divergences between them.

Español, Spanglish y Portunhol : Una Aproximación Interpretativa

Francisco Romo Simon 한국라틴아메리카학회 2015 라틴아메리카연구 Vol.28 No.1

In the northern and southern limits of the Latin-American territory, the Spanish language is rapidly and uncontrolledly expanding, causing two linguistic hybridization phenomena: the well-known Spanglish (Spanish-English) and the incipient Portunhol (Spanish-Portuguese). Due to these regions’ actual relevance in the teaching of Spanish as a foreign language -which can be assumed to be greater in the future- these phenomena require attention in order to increase our comprehension of them and to decide whether they deserve to be included in the Spanish language classroom. Given the fact that the academic discussion concerning these phenomena seems to be focused on linguistic and macro-social issues, this research aims to offer a new ethnographic micro-subjective perspective of the topic based on the interpretative analysis of two interviews made with two natives of the regions where Spanglish and Portunhol exist. The analysis of such interviews reveals that the two phenomena are quite different, such that each demands a different approach in the Spanish as a foreign language classroom. While Portunhol is considered mainly to be an accident arisen from the contact of two languages in borderland regions, Spanglish is understood to be a symbolical linguistic identity device, with the range of its use going far beyond the border between the USA and Mexico.

Production, microstructural comparison and mechanical behavior of reinforced alumina composites containing zirconia, silicon carbide, nickel and titanium

Mario Romero-Romo,Enrique Pastorino-Chassale,Enrique Rocha-Rangel 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

Using a mix of Al2O3 powders to which other reinforcing materials such as: ZrO2, SiC, Ni and Ti were added up to 10 wt%,and the combination of conventional techniques known as milling-pressing-sintering, several composite samples were fabricated. The microstructures of the composites reinforced with (Ni or Ti) examined in the scanning electron microscope showed a slight metallic network formed between the alumina grains. The action of several mechanisms such as crack bridging, crack deflection and microcracking seems to be the cause of the improvement in the fracture toughness of the composites with respect to that of monolithic alumina. The experimental values of elastic modulus and hardness of the composites diminished, although, on the other hand, the compressive and flexural fracture strengths were increased when alumina was reinforced with the materials studied here.

Frequency spectra characterization of noncoding human genomic sequences

O. Paredes,Rebeca Romo‑Vázquez,Israel Román‑Godínez,Hugo Vélez‑Pérez,Ricardo A. Salido‑Ruiz,J. Alejandro Morales 한국유전학회 2020 Genes & Genomics Vol.42 No.10

Background Noncoding sequences have been demonstrated to possess regulatory functions. Its classifcation is challenging because they do not show well-defned nucleotide patterns that can correlate with their biological functions. Genomic signal processing techniques like Fourier transform have been employed to characterize coding and noncoding sequences. This transformation in a systematic whole-genome noncoding library, such as the ENCODE database, can provide evidence of a periodic behaviour in the noncoding sequences that correlates with their regulatory functions. Objective The objective of this study was to classify diferent noncoding regulatory regions through their frequency spectra. Methods We computed machine learning algorithms to classify the noncoding regulatory sequences frequency spectra. Results The sequences from diferent regulatory regions, cell lines, and chromosomes possessed distinct frequency spectra, and that machine learning classifers (such as those of the support vector machine type) could successfully discriminate among regulatory regions, thus correlating the frequency spectra with their biological functions Conclusion Our work supports the idea that there are patterns in the noncoding sequences of the genome.

Kinetic modeling of sorption–desorption cycles for phenol removal with a cyclodextrin polymer

Francisco J. Peñas,Ana Romo,José R. Isasi,María J. San José,Sonia Alvarez 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.75 No.-

This paper examines the long-term application of a cyclodextrin hydrogel sorbent in multiple sorption–desorption cycles. Aqueous phenol was the target pollutant, whilst methanol, ethanol and isopropanolwere chosen as eluents. The experimental results were well described by empirical models: thebreakthrough curves by a two-parameter dose–response equation, and the elution curves by a pulsepeakequation with two independent parameters. The differences in polarity of solvents producedsorbent fragmentation, particularly marked for isopropanol and considerably lower for methanol, andtherefore a progressive increase in mass-transfer coefficients. In addition, a dual approach was developedfrom the proposed breakthrough model to address the mass transport of sorbate within the packed beds. Thefirst one defines an average mass-transfer coefficient as representative for each complete sorptioncycle, whereas a time-profile of this coefficient is deduced in the second method. A sorption capacity of29.6 mg-phenol/g-sorbent was found in the working conditions.

Aspects of defects in 3d-3d correspondence

Gang, Dongmin,Kim, Nakwoo,Romo, Mauricio,Yamazaki, Masahito Institute of Physics Pub 2016 The journal of high energy physics Vol.2016 No.10

Microstructural evolution and fracture toughness of Al₂O₃/Ti composites

M. Vázquez-Villar,M. Romero-Romo,A. Altamirano-Torres,E. Rocha-Rangel 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.3

The effect of different additions of a metal (Ti) on the microstructure and fracture toughness of Al2O3-based ceramics, as well as the establishment of a route for their processing was analyzed in this study. The samples were prepared by means of mechanical milling and pressureless sintering in an argon atmosphere. Due to the fact of working with very small sizes of powders of both the metal and ceramic, it was possible to reach in sintered products greater values of densification than 95% of their relative density. Measurements of fracture toughness (KIC) evaluated by the fracture indentation method, indicate that this mechanical property had improved with some additions of Ti in the composite, for example KIC for pure alumina processed under the conditions of this study was 3.0MPa·m1/2, whereas, KIC for the composite with 3 vol % Ti was 4.1MPa·m1/2. The microstructure observed in a scanning electron microscopy shows the formation of small and fine metallic interpenetrating networks in the ceramic matrix, that improve in their formation with an increases of Ti in the composite. The effect of different additions of a metal (Ti) on the microstructure and fracture toughness of Al2O3-based ceramics, as well as the establishment of a route for their processing was analyzed in this study. The samples were prepared by means of mechanical milling and pressureless sintering in an argon atmosphere. Due to the fact of working with very small sizes of powders of both the metal and ceramic, it was possible to reach in sintered products greater values of densification than 95% of their relative density. Measurements of fracture toughness (KIC) evaluated by the fracture indentation method, indicate that this mechanical property had improved with some additions of Ti in the composite, for example KIC for pure alumina processed under the conditions of this study was 3.0MPa·m1/2, whereas, KIC for the composite with 3 vol % Ti was 4.1MPa·m1/2. The microstructure observed in a scanning electron microscopy shows the formation of small and fine metallic interpenetrating networks in the ceramic matrix, that improve in their formation with an increases of Ti in the composite.