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Bivariate Analysis of Pollutants Monthly Maxima in Mexico City Using Extreme Value Distributions and Copula

j.urnal of Environmental Protection 2024年第7期15卷 796-826页

作者： j.an A. Vazquez-Morales Eliane R. Rodrigues hortensia j. reyes-cervantes Facultad de Ciencias Fsico-Matemticas Benemrita Universidad Autnoma de Puebla Puebla Mexico Instituto de Matemticas Universidad Nacional Autnoma de Mxico Mexico City Mexico

In the present work, we are interested in studying the j.int distributions of pairs of the monthly maxima of the pollutants used by the environmental authorities in Mexico City to classify the air quality in the metropolitan area. In order to obtain the j.int distributions a copula will be considered. Since we are analyzing the monthly maxima, the extreme value distributions of Weibull and Fréchet are taken into account. Using these two distributions as marginal distributions in the copula a Bayesian inference was made in order to estimate the parameters of both distributions and also the association parameters appearing in the copula model. The pollutants taken into account are ozone, nitrogen dioxide, sulphur dioxide, carbon monoxide, and particulate matter with diameters smaller than 10 and 2.5 microns obtained from the Mexico City monitoring network. The estimation was performed by taking samples of the parameters generated through a Markov chain Monte Carlo algorithm implemented using the software OpenBugs. Once the algorithm is implemented it is applied to the pairs of pollutants where one of the coordinates of the pair is ozone and the other varies on the set of the remaining pollutants. Depending on the pollutant and the region where they were collected, different results were obtained. Hence, in some cases we have that the best model is that where we have a Fréchet distribution as the marginal distribution for the measurements of both pollutants and in others the most suitable model is the one assuming a Fréchet for ozone and a Weibull for the other pollutant. Results show that, in the present case, the estimated association parameter is a good representation to the correlation parameters between the pair of pollutants analyzed. Additionally, it is a straightforward task to obtain these correlation parameters from the corresponding association parameters.

关键词： Copula Extreme Value Distribution Bayesian Inference Air Pollution Mexico City

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Air Quality Estimation Using Nonhomogeneous Markov Chains: A Case Study Comparing Two Rules Applied to Mexico City Data

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j.urnal of Environmental Protection 2023年第7期14卷 561-582页

作者： Eliane R. Rodrigues j.an A. Cruz-j.árez hortensia j. reyes-cervantes Guadalupe Tzintzun Instituto de Matemáticas Universidad Nacional Autónoma de México Mexico City Mexico Facultad de Ciencias Fsico-Matemáticas Benemérita Universidad Autónoma de Puebla Puebla Mexico Instituto Nacional de Ecologa y Cambio Climático Secretara de Medio Ambiente y Recursos Naturales Mexico City Mexico

A nonhomogeneous Markov chain is applied to the study of the air quality classification in Mexico City when the so-called criterion pollutants are used. We consider the indices associated with air quality using two regulations where different ways of classification are taken into account. Parameters of the model are the initial and transition probabilities of the chain. They are estimated under the Bayesian point of view through samples generated directly from the corresponding posterior distributions. Using the estimated parameters, the probability of having an air quality index in a given hour of the day is obtained.

关键词： Air Quality Index Air Pollution Mexico City Nonhomogeneous Markov Chains Bayesian Inference

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Analysis of Ozone Behaviour in the City of Puebla-Mexico Using Non-Homogeneous Poisson Models with Multiple Change-Points

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j.urnal of Environmental Protection 2016年第12期7卷 1886-1903页

作者： j.an Antonio Cruz-j.árez hortensia reyes-cervantes Eliane R. Rodrigues Facultad de Ciencias Fisico-Matemáticas Benemérita Universidad Autónoma de Puebla Puebla Mexico Instituto de Matemáticas Universidad Nacional Autónoma de México Mexico City Mexico

In this work, some non-homogeneous Poisson models are considered to study the behaviour of ozone in the city of Puebla, Mexico. Several functions are used as the rate function for the non-homogeneous Poisson process. In addition to their dependence on time, these rate functions also depend on some parameters that need to be estimated. In order to estimate them, a Bayesian approach will be taken. The expressions for the distributions of the parameters involved in the models are very complex. Therefore, Markov chain Monte Carlo algorithms are used to estimate them. The methodology is applied to the ozone data from the city of Puebla, Mexico.

关键词： Non-Homogeneous Poisson Model Markov Chain Monte Carlo Methods Bayesian Inference Ozone Air Pollution City of Puebla

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Consolidation of AA 7075-2 wt% ZrO2 Composite Powders by Severe Plastic Deformation via ECAP

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Acta Metallurgica Sinica(English Letters) 2016年第10期29卷 895-901页

作者： S. E. Hernandez-Martinez j. j. Cruz-Rivera R. Martinez-Sanchez C. G. Garay-reyes j. A. Mufioz-Bolanos j. M. Cabrera j.L.Hernández-Rivera Instituto de Metalurgia Universidad Autonoma de San Luis Potosi Sierra Leona 550 78210 San Luis Potosi Mexico Centro de Investigacion en Materiales Avanzados (CIMAV) Miguel de Cervantes 120 31109 Chihuahua Mexico Departamento de Ciencia de Materiales e Ingenieria Metalurgica Universitat Politecnica de Catalunya Av Diagonal 647 08028 Barcelona Spain Fundacion CTM Centro Tecnologico Plaza de la Ciencia 208243 Manresa Spain CONACYT Research Fellow-Instituto de Metalurgia Universidad Autonoma de San Luis Potosi- Sierra Leona 550 78210 San Luis Potosf Mexico

The powders of the AA 7075-ZRO2 were mixed by mechanical milling, but it was found that the system presents a few disadvantages when processed by conventional sintering and hot extrusion, since intermetallic phases between ZrO2 particles and alloying elements were formed. Equal channel angular pressing （ECAP） processing was proposed as an alternative method to consolidate the composite where there is no intermetallic formation. The analysis of the ECAP process showed that the intermediate temperature （220℃） produced a higher consolidation level than conventional sintering and hot extrusion （400 and 500℃, respectively）. This fact was supported by relative density analysis. In the case of the sintered and hot-extruded sample, the relative density exhibited a value of 0.95, while ECAP sample showed a value of 0.98. Hardness values show that microstructural refinement obtained during mechanical milling was preserved during ECAP processing even when it was carded out at 220℃.

关键词： Metal matrix composites (MMCs) Powder consolidation Severe plastic deformation (SPD)

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Nucleation and growth kinetics of La0.7Sr0.3Cr0.4Mn0.6O3-δ SOFC perovskite:Symmetry alteration evolution induced by Cu2+ and Ni2+ impregnation

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Progress in Natural Science:Materials International 2016年第6期26卷 665-670页

作者： A.Concha-Balderrama G.Roj.s-George j.Alvarado-Flores H.Esparza-Ponce M.H.Bocanegra-Bernal A.reyes-Roj.s Centro de Investigación en Materiales Avanzados S.C.(CIMAV) Laboratorio Nacional de NanotecnologíaMiguel de Cervantes 120 Complejo Industrial ChihuahuaCd.de Chihuahua

La0.7Sr0.3Cr0.4Mn0.6O3-δperovskite nanoparticles have been synthetized using an ethylene glycol modified solgel method and impregnated by Cu0.75Ni0.25nanoparticles. The phase transitions and nucleation kinetics were studied by time resolved x-ray diffraction, Rietveld, Raman spectroscopy and high resolution transmission electron microscopy. Findings have shown that, an atomic disorder dominates from room temperature to 400 °C. Nanoparticles with crystal size j.hnson-Mehl-Avrami model had described the whole process, where the existence of two phases was shown before it reached its complete D3d6point group symmetry.

关键词： Perovskite structure Sol-gel method Composite Kinetics Rietveld

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