Search

Your search keyword '"Rivera, Marco"' showing total 456 results
Start Over Author "Rivera, Marco" Search Limiters Full Text
456 results on '"Rivera, Marco"'

1. Hopf and Bautin bifurcations in a 3D model for pest leafhopper with stage structure and generalist predatory mite

Author

Ramírez, Martha Alvarez, Rivera, Marco Polo García, and Santos, Ahida Ortiz

Subjects
Mathematics - Dynamical Systems, Mathematics - Classical Analysis and ODEs, 34C23, 92D25
Abstract

In a recent paper of Yuan and Zhu (J. Differential Equations 321(2022) 99-129), the nature of dynamics of a generalist predator and prey with stage structure is modeled as a three-dimensional coupled nonlinear differential system. A detailed analysis of the bifurcation shows that the model exhibits a high complexity in its dynamics, which arises from the use of predatory mites as agent for controlling stage structures of tea green leafhopper pest. Unfortunately, there is a mistake in Proposition 2.2, item (3), also the hypothesis in Proposition 3.3 is incorrect. In this paper, we revisit the model and straighten those mentioned errors as in item (3), changed the existing hypothesis by a suitable one and give a corrected proof of Proposition 3.3 in its new form. Also, we show that the model does undergo both Hopf bifurcation and Bautin bifurcation, and numerical examples are given to support the analytic results.

Published
2024

2. Measurable Parameter Combinations of Environmentally-dephased EMRI Gravitational-Wave Signals

Author

Rivera, Marco Immanuel B. and Reyes, Reinabelle C.

Subjects
General Relativity and Quantum Cosmology
Abstract

The future space-borne Laser Interferometer Space Antenna (LISA) is expected to detect gravitational waves (GW) from Extreme Mass Ratio Inspiral (EMRI) binaries which may live in nontrivial environments such as accretion disks. In this work, we apply the Fisher matrix Principal Component Analysis (PCA) method to assess how well LISA observations can jointly constrain the source parameters and environmental densities around EMRIs. Specifically, we calculate the Fisher matrix from the post-Newtonian parameters of an EMRI binary embedded in a fluid with a constant density profile. We determine that the most dominant measurable parameter combination is dominated by contributions from environmental effects, namely, gravitational drag, accretion, and gravitational pull (in order of contribution). The proposed reparameterization of the PN parameters can be used to improve the power and efficiency of future detection and parameter estimation methods., Comment: Matches accepted version in New Astronomy; 8 pages, 2 figures

Published
2024
Full Text
View/download PDF

9. Geological evidence of extensive N-fixation by volcanic lightning during very large explosive eruptions

Author

Aroskay, Adeline, primary, Martin, Erwan, additional, Bekki, Slimane, additional, Le Pennec, Jean-Luc, additional, Savarino, Joël, additional, Temel, Abidin, additional, Manrique, Nelida, additional, Aguilar, Rigoberto, additional, Rivera, Marco, additional, Guillou, Hervé, additional, Balcone-Boissard, Hélène, additional, Phelip, Océane, additional, and Szopa, Sophie, additional

Published
2024
Full Text
View/download PDF

16. Polymerised type I collagen modifies the physiological network of post‐acute sequelae of COVID‐19 depending on sex: a randomised clinical trial

Author

Furuzawa‐Carballeda, Janette, primary, Olguín‐Rodríguez, Paola Vanessa, additional, Torres‐Villalobos, Gonzalo, additional, Barajas‐Martínez, Antonio, additional, Martínez‐Garcés, Vania Jocelyn, additional, Fossion, Ruben, additional, Martínez‐Rivera, Marco Antonio, additional, Ibarra‐Coronado, Elizabeth, additional, Tello‐Santoyo, Geraldine, additional, Bureos Lecona, Octavio Abraham, additional, Méndez‐Flores, Silvia, additional, Ilian Rivas‐Redonda, Kenia, additional, Ochoa‐Hein, Eric, additional, Olivares‐Martínez, Elizabeth, additional, Hernández‐Ramírez, Diego Francisco, additional, and Rivera, Ana Leonor, additional

Published
2023
Full Text
View/download PDF

17. Step potentials for Dark Energy

Author

Cardenas, Victor H. and Rivera, Marco

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics, General Relativity and Quantum Cosmology
Abstract

We consider a reconstructing scheme using observational data from SNIa, BAO and CMB, based on a model of dark unification using a single non-minimally coupled scalar field. We investigate through a reconstruction program, the main features the current observational data imposes to the scalar field potential. We found that the form suggested by observations implies a step feature in the potential, where the kinetic and potential energy becomes of the same order of magnitude., Comment: Proceedings of I CosmoSul - Cosmology and Gravitation in Southern Cone (Rio de Janeiro, 2011). Eds: J. S. Alcaniz, S. Carneiro, L. P. Chimento, S. del Campo, J. C. Fabris, J. A. S. Lima and W. Zimdahl

Published
2012
Full Text
View/download PDF

18. The role of curvature in the slowing down acceleration scenario

Author

Cardenas, Victor H. and Rivera, Marco

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology
Abstract

We introduce the curvature $\Omega_k$ as a new free parameter in the Bayesian analysis using SNIa, BAO and CMB data, in a model with variable equation of state parameter $w(z)$. We compare the results using both the Constitution and Union 2 data sets, and also study possible low redshift transitions in the deceleration parameter $q(z)$. We found that, incorporating $\Omega_k$ in the analysis, it is possible to make all the three observational probes consistent using both SNIa data sets. Our results support dark energy evolution at small redshift, and show that the tension between small and large redshift probes is ameliorated. However, although the tension decreases, it is still not possible to find a consensus set of parameters that fit all the three data set using the Chevalier-Polarski-Linder CPL parametrization., Comment: 6 pages, 8 figures

Published
2012
Full Text
View/download PDF

29. Efecto de la labranza y fertilización nitrogenada en los cultivos de fréjol y maíz sobre indicadores biológicos de la calidad de un suelo andino del Ecuador

Author

Llanga, Leyda, primary, Avila-Salem, María Eugenia, additional, Montesdeoca, Fabián, additional, Aponte, Humberto, additional, Ron-Garrido, Lenin, additional, Espinosa, José, additional, Rivera, Marco, additional, Borie, Fernando, additional, Cornejo, Pablo, additional, and Alvarado Ochoa, Soraya, additional

Published
2023
Full Text
View/download PDF

34. Effect of tillage and nitrogen fertilization in bean and corn crops on biological indicators of the quality of an Andean soil of Ecuador

Author

Llanga, Leyda, Avila-Salem, María Eugenia, Montesdeoca, Fabián, Aponte, Humberto, Ron-Garrido, Lenin, Espinosa, José, Rivera, Marco, Borie, Fernando, Cornejo, Pablo, and Alvarado Ochoa, Soraya

Subjects
microbial biomass, microbial respiration, Siembra directa, acid phosphatase, actividad enzimática, enzymatic activity, direct sowing, fosfatasa ácida, respiración microbiana, biomasa microbiana
Abstract

Biological parameters are used as early indicators of the quality of an agricultural soil (ICS), due to their quick response to the anthropic soil management. The main objective of this research was to determine the effect of the tillage system: no-till (SD) and conventional tillage (LC), and to the nitrogen fertilization in bean and corn crop on certain biological indicators of soil quality. The study was carried out on a mollisol from the Andean region of Ecuador. Microbial biomass (MB), microbial respiration (RM), and enzyme activity (acid phosphatase, hydrolysis of fluorescein diacetate [FDA], and β-glucosidase [β-G]) were determined. The results showed that the phosphatase presented the highest activity under LC, the FDA responded to the effect of high nitrogen levels application (N), the activity of the β-G enzyme was higher under LC. Additionally, the principal component analysis selected these biological indicators studied as ICS. It is concluded that the biological indicators of the soil were affected by the management practices studied. Los parámetros biológicos son usados como indicadores tempranos en la calidad de un suelo (ICS) agrícola, ya que responden rápidamente al manejo antrópico. El objetivo de esta investigación fue determinar el efecto del sistema de labranza: siembra directa (SD) y labranza convencional (LC), y de la fertilización nitrogenada después de los cultivos de fréjol y maíz, sobre ciertos indicadores biológicos de la calidad del suelo. El estudio se realizó sobre un molisol de la región andina del Ecuador. Se determinó la biomasa microbiana (BM), respiración microbiana (RM), y actividad enzimática (fosfatasa ácida, hidrólisis de la fluoresceína-diacetato [FDA], y β-glucosidasa [β-G]). Los resultados mostraron que la fosfatasa presentó la mayor actividad bajo LC, la FDA respondió al efecto de los niveles altos de nitrógeno (N), la actividad de la enzima β-G fue mayor en LC. Adicionalmente, el análisis de componentes principales seleccionó a los indicadores biológicos estudiados, como ICS. Se concluye que los indicadores biológicos del suelo fueron afectados por las prácticas de manejo estudiadas.

Published
2023
Full Text
View/download PDF

35. A Detailed dSPACE-Based Implementation of Modulated Model Predictive Control for AC Microgrids.

Author

Villalón, Ariel, Muñoz, Carlos, Muñoz, Javier, and Rivera, Marco

Subjects
MICROGRIDS, PREDICTION models, CLEAN energy, IDEAL sources (Electric circuits), COMPUTER software testing
Abstract

Microgrids represent a promising energy technology, because of the inclusion in them of clean and smart energy technologies. They also represent research challenges, including controllability, stability, and implementation. This article presents a dSPACE-control-platform-based implementation of a fixed-switching-frequency modulated model predictive control (M 2 PC) strategy, as an inner controller of a two-level, three-phase voltage source inverter (VSI) working in an islanded AC microgrid. The developed controller is hierarchical, as it includes a primary controller to share the load equally with the other power converter with its own local modulated predictive-based controller. All details of the implementation are given for establishing the dSPACE-based implementation of the control on a dSPACE ds1103 control platform, using MATLAB/Simulink for the controller design, I/O implementation and configuration with the embedded dSPACE's real-time interface in Simulink, and then using the ControlDesk software for monitoring and testing of the real plant. The latter consists of the VSI operating with  L C L  filters, and sharing an  R L  load with a paralleled VSI with exactly the same controller. Finally, the obtained experimental waveforms are shown, with our respective conclusions representing this work, which is a very valuable tool for helping microgrid researchers implement dSPACE-based real-time simulations. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

41. Evaluación geofísica de la actividad eruptiva actual del volcán Sabancaya y formación de un domo de lava

Author

Centeno, Riky, Lazarte, Ivonne, Vargas, Katherine, Llerena, Jean Pierre, Rivera, Marco, Del Carpio Calienes, José Alberto, and Tavera, Hernando

Subjects
Monitoreo volcánico, Vulcanología, Erupciones volcánicas, purl.org/pe-repo/ocde/ford#1.05.07 [https], Volcán Sabancaya
Abstract

El Instituto Geofísico del Perú (IGP) informa que la actividad eruptiva del volcán Sabancaya ubicado en la región Arequipa se mantiene en niveles moderados, presentando, desde abril de 2022, la ocurrencia y registro promedio de 42 explosiones volcánicas diarias y la consecuente emisión de cenizas y gases que eventualmente alcanzan alturas de 3500 m sobre la cima del volcán. En este tiempo, las cenizas generadas fueron dispersadas en todo el valle del Colca hasta distancias de 30 km. Asimismo, durante los meses de abril y mayo del presente año, se ha observado en superficie un aporte importante de magma que ha dado lugar al crecimiento de un domo preexistente en el cráter del volcán. Este domo de lava puede dar origen en los próximos días o semanas a dos escenarios: 1) la actividad explosiva puede continuar con su nivel habitual y; 2) se puede producir un ligero incremento de la actividad explosiva, por la sobrepresurización del sistema magmático.

Published
2022

42. Measurements of Electron Density, Temperature, and Absolute Metastable 1s3 and 1s5 States of Ar in Ar–CO DC Discharge Employing Emission Spectroscopy

Author

Legorreta, J. R., Yousif, Farook Bashir, Escalona, Joaquin, Rivera, Marco, Lopez-Patino, J., Fuentes, B. E., and Martinez, Horacio

Abstract

This article deals with the investigation of dc plasma discharge of Ar–CO gas mixture in which the relative electron density and absolute temperature were measured. Relative electron density and absolute temperature were obtained for the mixture at discharge powers between 200 and 12 000 mW, and pressures between 0.1 and 0.5 mbar employing the radiative collisional model for several Ar–CO mixtures. Behavior of the electron temperature and relative number density are discussed. The absolute number density of the 1s5 was found to be higher than that of the 1s3 level.

Published
2023
Full Text
View/download PDF

43. Pesticide misuse among small Andean farmers stems from pervasive misinformation by retailers

Author

Struelens, Quentin François, primary, Rivera, Marco, additional, Alem Zabalaga, Mariana, additional, Ccanto, Raúl, additional, Quispe Tarqui, Reinaldo, additional, Mina, Diego, additional, Carpio, Carlos, additional, Yumbla Mantilla, María Rosa, additional, Osorio, Mélany, additional, Roman, Soraya, additional, Muñoz, Diego, additional, and Dangles, Olivier, additional

Published
2022
Full Text
View/download PDF

44. Response to the comments by the authors Hamed Jalilian et al. On: “What is the radiation before 5G? A correlation study between measurements in situ and in real time and epidemiological indicators in Vallecas, Madrid”, by I. López, N. Félix, M. Rivera, A. Alonso, and C. Maestú. Environmental Health 10.1016/j.envres.2021.110734

Author

López, Isabel, primary, Félix, Nazario, additional, Rivera, Marco, additional, Alonso, Adrián, additional, and Maestú, Ceferino, additional

Published
2022
Full Text
View/download PDF

47. Evaluación de la deformación estructural y distribución de esfuerzos en el volcán Misti (Arequipa)

Author

Antayhua Vera, Yanet Teresa, Velarde Quispe, Lizbeth, Tavera, Hernando, Rivera, Marco, and Centeno Quico, Riky

Subjects
Monitoreo volcánico, Vulcanología, Deformación estructural, Volcán Misti, purl.org/pe-repo/ocde/ford#1.05.07 [https]
Abstract

La deformación estructural y distribución de esfuerzos en el volcán Misti (Arequipa) es evaluada utilizando datos sísmicos registrados durante el periodo 2017 a 2020 por una red local compuesta por 6 estaciones distribuidas en el entorno de dicha estructura volcánica. En total, se seleccionaron y relocalizaron 180 sismos volcano-tectónicos (VT) con magnitudes entre M0.8 y M2.9. En profundidad, la sismicidad se distribuye por debajo del cráter del volcán Misti, donde se distingue un domo de lava andesítido, siguiendo una distribución casi vertical hasta una profundidad de 3 km, pero que en superficie define un área de 2 km². Estos resultados sugieren que la actividad sísmica del Misti tendría posible correlación con los esfuerzos generados por los siguientes procesos: a) la interacción de fluidos magmáticos (principalmente gases) provenientes de un reservorio magmático profundo R1 ubicado entre 7 y 15 km por debajo del cráter (Tepley et al., 2013; Rivera et al., 2017) con otro reservorio superficial R2 ubicado a ~3 km (Tepley et al., 2013); b) la interacción de estos fluidos magmáticos con el sistema hidrotermal del volcán Misti ubicado entre 1 y 5 km de profundidad por debajo del cráter (Finizola et al., 2004). En ambos casos, estos procesos estarían generando o reactivando fallas y/o fracturas en el conducto volcánico rocoso y frágil. Asimismo, la interconexión de dichas fallas y fracturas, incluso visibles en el domo de lava, estaría permitiendo el paso de estos fluidos magmáticos y su posterior desgasificación hacia la superficie.

Published
2022

48. Morfología del cráter del volcán Ubinas y peligro potencial de colapso en su flanco sur – Región Moquegua

Author

Vargas, Katherine, Cruz, John, Villegas Lanza, Juan Carlos, Rivera, Marco, and Tavera, Hernando

Subjects
Monitoreo volcánico, Volcán Ubinas, Cráter, Vulcanología, Peligros volcánicos, Erupciones volcánicas, purl.org/pe-repo/ocde/ford#1.05.07 [https]
Abstract

A partir de 883 imágenes obtenidas en un levantamiento aerofotogramétrico, se ha elaborado un Modelo de Elevación Digital (DEM) para el cráter y flanco sur del volcán Ubinas con una resolución de 60 cm. Analizando esta información, se ha identificado en el fondo del cráter del volcán una capa de relleno más de 100 m de espesor compuesta de cenizas, lapilli y fragmentos de lava, constituyendo un volumen de 2´640,000 m³. Con ayuda del DEM y en base al modelamiento numérico se han elaborado tres escenarios de peligro por descenso de lahares (flujos de lodo). En el escenario más frecuente, serían afectadas las vías de acceso a Ubinas, Tonohaya, Huarina, Matalaque. En otros escenarios, se suman áreas de cultivo, canales de agua, puentes peatonales, y obras de infraestructura de Tonohaya, San Miguel y Huatagua, así como la generación de derrumbes en ambas márgenes del río Ubinas, ocasionando eventualmente el represamiento del río Tambo en inmediaciones de la localidad de Huarina. La información del DEM ha permitido identificar una zona de potencial colapso en la parte superior del flanco sur del volcán Ubinas abarcando un área de 292,000 m² y un volumen aproximado de 3.7x10⁷ m³. De producirse un detonante, se generaría una avalancha de escombros que se emplazaría en el valle de Ubinas a lo largo de 8 km afectando a las localidades de Querapi (con población reasentada), Ubinas, Tonohaya y San Miguel.

Published
2022

49. Improvement of two grid power factor control methods for matrix converter open‐end‐winding drive with common‐mode voltage elimination supplied by unbalanced grid.

Author

Stanić, Luka, Ristić, Leposava, Bebić, Milan, and Rivera, Marco

Subjects
MATRIX converters, ELECTRIC power distribution grids, AC DC transformers, VOLTAGE, VECTOR spaces
Abstract

This paper investigates space‐vector‐modulation (SVM) technique that uses only rotating space vectors to drive a direct matrix converter (DMC) with zero common‐mode voltage (CMV). Two methods for controlling grid power factor have been proposed in the literature for such a drive. Until now, analysis has been limited to balanced grid conditions. However, total harmonic distortion (THD) of grid currents significantly increases under unbalanced conditions. Hence, the aims of this paper are: (1) derivation of DMC model consisting of general equations for output voltages and input currents, written in the complex form. (2) Analysis and comparison of two existing methods for grid power factor control under balanced grid conditions, by using the previously derived model. (3) Proposal of extended versions of both methods in order to improve converter's performance under unbalanced grid conditions. The proposed control strategy aims to achieve sinusoidal currents and maintain the same power factor on the grid side while completely compensating grid unbalance on the load side. (4) Determination of the maximum transfer ratio under balanced and unbalanced grid conditions. Experimental results with Hardware In the Loop (HIL) are provided to verify the theoretical analysis and effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

50. Optimal Location and Sizing of Distributed Generators and Energy Storage Systems in Microgrids: A Review.

Author

Grisales-Noreña, Luis Fernando, Restrepo-Cuestas, Bonie Johana, Cortés-Caicedo, Brandon, Montano, Jhon, Rosales-Muñoz, Andrés Alfonso, and Rivera, Marco

Subjects
ENERGY storage, MICROGRIDS, POWER resources
Abstract

This article reviews the main methodologies employed for the optimal location, sizing, and operation of Distributed Generators (DGs) and Energy Storage Systems (ESSs) in electrical networks. For such purpose, we first analyzed the devices that comprise a microgrid (MG) in an environment with Distributed Energy Resources (DERs) and their modes of operation. Following that, we examined the planning and operation of each DER considered in this study (DGs and ESSs). Finally, we addressed the joint integration of DGs and ESSs into MGs. From this literature review, we were able to identify both the objective functions and constraints that are most commonly used to formulate the problem of the optimal integration and operation of DGs and ESSs in MGs. Moreover, this review allowed us to identify the methodologies that have been employed for such integration, as well as the current needs in the field. With this information, the purpose is to develop new mathematical formulations and approaches for the optimal integration and operation of DERs into MGs that provide financial and operational benefits. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results