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World Journal of Nuclear Science and Technology 2016年第3期6卷 131-139页

作者： pedro Orrego José hernández Jorge manríquez Sección de Geología y minería Departamento de Materiales Nucleares Comisión Chilena de Energía Nuclear Santiago Chile Ingeniería Civil metalurgia Universidad de Santiago de Chile Santiago Chile

This article shows the modeling of a uranium dioxide production reactor using COmSOL multiphysics software program in its 4.3b version. The model was made using 3 kinds of studies: momentum, heat and mass transport, in order to determine the influence of the most important operational parameters: UO3 reaction rate, composition and flow of the reduction gas, the initial temperature reactor and the reducing gas. The operational parameters evaluated were the followings: constant gas flow of2.5 L/min, initial hydrogen concentration of 0.25, 0.50 and0.75 m, and initial temperature of 400°C. The obtained results allow to conclude that under these working conditions, uranium dioxide is obtained virtually instantaneous and, with concentrations close to 0.5 m H2 in the reducing gas, the process can operate continuously and autogenously, without applying additional energy and temperatures around 600°C.

关键词： Uranium Trioxide Uranium Dioxide Conversion modeling

Recruitment Age of Litopenaeus vannamei (Boone, 1931) (Decapoda: Penaeidae) in the Cabeza De Toro-La Joya Buenavista Lagoon System, Oaxaca-Chiapas, mexico

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Open Journal of marine Science 2017年第4期7卷 511-525页

作者： pedro Cervantes- hernández Pablo Torres- hernández mario Alejandro Gómez- Ponce Institutos de Recursos Universidad del Mar Carretera a Zipolite Puerto ángel México Instituto de Industrias Universidad del Mar Carretera a Zipolite Puerto ángel México Instituto de Ciencias del mar y Limnología Universidad Nacional Autónoma de México (Estación El Carmen) Ciudad del Carmen México

At present, the fishery of Litopenaeus vannamei continues overexploited in the Gulf of Tehuantepec (GT), mexico. From the available literature it was demonstrated that marine closure systems implemented in GT have not worked adequately since 1993, because these are completely protecting marine recruitment seasons, and reproductive seasons were only partially considered to protect. Due to these problems, new marine closure systems were proposed in the literature, but they were not accepted by fishermen from GT because they did not include marine and lagoon recruitment information. For this reason, in this study both recruitment types were analyzed with estimations on the recruitment age (RA), and its relationship with total length and weight. To the Cabeza de Toro la Joya Buenavista lagoon system (CTJB-LS), it was concluded that young recruits migration toward outside CTJB-LS elapsed between 3 and 5-m-olds, with the highest recruit flow in 4-m-olds. Thus, this last age was called the RA of L. vannamei (at 106 mm). maximum marine recruitment ranked from June to July, and maximum reproductive seasons were in October. In both recruitment seasons it was observed that biomass production was different. In marine season RA recorded 8.4 g more than lagoon season at the same size. Results were used in order to discus about atarraya nets uses, and to propose the implementation of a lagoon closure during July inside lagoon systems located in GT. With this proposal artisanal fishermen will be allowed to use atarraya nets with mesh opening of 25.4 mm during June, and they will obtain a good biomass production level as economic ***, with new marine closure systems shrimp reproductive seasons will be protected (from July to November).

关键词： Closure Systems Gulf of Tehuantepec Recruitment Age Recruitment Seasons White Shrimp

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考古植物遗存中的碳稳定同位素

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东方考古 2024年第1期 146-179页

作者： Juan pedro Ferrio mònica Aguilera Jordi Voltas José Luis Araus 褚黎明阿拉贡研究与发展机构(ARAID) 阿拉贡农业研究与技术中心(CITA)森林资源部 CTFC-AGROTECNIO联合研究单位莱里达大学农作物与森林科学系巴塞罗那大学生物学院植物生理学部综合作物生理生态学组农业技术研究中心(AGROTECNIO) 山东大学文化遗产研究院

考古植物遗存是了解关于过去社会经历的社会和环境条件的宝贵信息来源。植物遗存巨大潜力的充分开发需要分析技术的应用。在这一背景下,考古植物遗存的碳稳定同位素组成或许能够提供关于环境条件、农业管理、食物网和饮食偏好等多方面... 详细信息

考古植物遗存是了解关于过去社会经历的社会和环境条件的宝贵信息来源。植物遗存巨大潜力的充分开发需要分析技术的应用。在这一背景下,考古植物遗存的碳稳定同位素组成或许能够提供关于环境条件、农业管理、食物网和饮食偏好等多方面的线索。本文全面介绍了分析植物遗存的碳稳定同位素在考古学中的潜在应用。在对决定植物碳稳定同位素特性的广泛生理和环境因素进行解释之后,对最相关的方法问题进行了讨论。其中,本文对样品的前处理方式、与大气变化有关的不确定性以及植物遗存在土壤中沉积前后经历的潜在变化进行了评述。以选定的案例研究为例,为碳稳定同位素在考古学中的应用提供了方法和概念上的线索。同时,也强调了依旧存在的挑战。

关键词：碳稳定同位素植物考古环境农业

Reduction Kinetics of Uranium Trioxide to Uranium Dioxide Using Hydrogen

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World Journal of Nuclear Science and Technology 2015年第3期5卷 149-156页

作者： pedro Orrego Alfaro José hernández Torres Fernando Puchi Thiele Sección de Geología y minería Departamento de Materiales Nucleares Comisión Chilena de Energía Nuclear Santiago Chile Ingeniería Civil metalurgia Universidad Andrés Bello Santiago Chile

This article presents a study on the kinetics of the uranium conversion process, consisting in the reduction of uranium trioxide to uranium dioxide using hydrogen gas at temperatures of 500°C, 600°C and 700°C. Hydrogen concentrations used in the flow were 0.25 m, 0.50 m and 0.75 m. The mechanism established for the study of the kinetics of reduction of uranium trioxide was through the formation of an intermediate compound, U3O8. For this reason, these tests were divided into 2 stages: the first one the reduction from UO3 to U3O8, and second one from U3O8 to UO2. The results of each test were quantified by the release of H2O(g) produced by both reactions. Tests showed that the ideal working conditions are for hydrogen concentration flows of 0.75 m and temperatures in the range of 500°C - 600°C, with the intent to decrease the occurrence of side reactions that interfere with the process.

关键词： Conversion Uranium Oxides Nuclear Fuel Cycle

Hydrothermal Synthesis and Characterization of Europium-doped Barium Titanate Nanocrystallites

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Nano-micro Letters 2013年第1期5卷 57-65页

作者： margarita García-hernndez Geneviève Chadeyron Damien Boyer Antonieta García-murillo Felipe Carrillo-Romo Rachid mahiou Universidad Autónoma metropolitana Departamento de Ciencias NaturalesDCNIUnidad CuajimalpaPedro Antonio de los Santos 8411850 Mxico D.F. Mxico Clermont Universit Institut de Chimie de Clermont-Ferrand UMR 6296CNRS/UBP/ENSCCFBP 10448F-63000 Clermont-Ferrand Instituto Politcnico Nacional CIITEC IPNCerrada de Cecati S/N. Col. Santa CatarinaAzcapotzalco Mxico D.F. C.P. 02250Mxico

Barium titanate nanocrystallites were synthesized by a hydrothermal technique from barium chloride and tetrabutyl titanate. Single-crystalline cubic perovskite Ba TiO_3 consisting of spherical particles with diameters ranging from 10 to 30 nm was easily achieved by this route. In order to study the influence of the synthesis process on the morphology and the optical properties, barium titanate was also prepared by a solid-state reaction. In this case, only the tetragonal phase which crystallizes above 900 was observed. High-temperature X-ray diffraction measurements were performed to investigate the crystallization temperatures as well as the particle sizes via the Scherrer formula. The lattice vibrations were evidenced by infrared spectroscopy. Eu^(3+)was used as a structural probe, and the luminescence properties recorded from Ba TiO_3 :Eu^(3+)and elaborated by a solid-state reaction and hydrothermal process were compared. The reddish emission of the europium is increased by the nanometric particles.

关键词： BaTiO3 Europium Nanocrystallites Hydrothermal technique

Evaluation of multiplicative Weight of Covariance matrix on Hybrid Data Assimilation Schemes

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Atmospheric and Climate Sciences 2023年第2期13卷 255-281页

作者： pedro m. González-Jardines maibys Sierra-Lorenzo Adrián L. Ferrer-hernández Center for Atmospheric Physics Institute of Meteorology Havana Cuba

This research develops a comparative study between different multiplicative weights that are assigned to the covariance matrix that represents the background error in two hybrid assimilation schemes: 3DEnVAR and 4DEnVAR. These weights are distributed between the static and time-invariant matrix and the matrix generated from the perturbations of a previous ensemble. The assigned values are 25%, 50%, and 75%, always having as a reference the ensemble matrix. The experiments are applied to the short-range Prediction System (SisPI) that works operationally at the Institute of meteorology. The impact of Tropical Storm Eta on November 7 and 8, 2020 was selected as a study case. The results suggest that by giving the main weight to the ensemble matrix more realistic solutions are achieved because it shows a better representation of the synoptic flow. On the other hand, it is observed that 3DEnVAR method is more sensitive to multiplicative weight change of the first guess. more realistic results are obtained with 50% and 75% relations with 4DEnVAR method, whereas with 3DEnVAR a weight of 75% for the ensemble matrix is required.

关键词： SisPI WRFDA Hybrid-methods Covariance Weights

Structural studies of BaTiO_3:Er^(3+) and BaTiO_3:Yb^(3+) powders synthesized by hydrothermal method

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Journal of Rare Earths 2014年第11期32卷 1016-1021页

作者： Garrido-hernández A García-murillo A Carrillo-Romo F de J Cruz-Santiago L A Chadeyron G morales-Ramírez A de J Velumani S T.A. Post-graduate Student. Instituto Politécnico Nacional CIITEC IPN Cerrada de Cecati S/N. Col. Santa Catarina Azcapotzalco México D.F. C.P. 02250 México D.F México Instituto Politécnico Nacional CIITEC IPN Cerrada de Cecati S/N. Col. Santa Catarina Azcapotzalco México D.F. C.P. 02250 México D.F Departament of Engineering materials Tecnológico de Estudios Superiores de Coacalco (TESCo) Av. 16 de Septiembre # 54 Cabecera Municipal C.P. 55700 Coacalco de Berriozábal Estado de México Institut de Chimie de Clermont-Ferrand UMR 6296 CNRS / UBP / ENSCCF 24 avenue des Landais BP 80026 63171 Aubière Cedex – France Department of Electrical Engineering (SEES) Centro de Investigación y de Estudios Avanzados del IPN Av. Instituto Politécnico Nacional 2508 Col. San Pedro Zacatenco C.P. 07360 Mexico D.F. Mexico

Erbium and ytterbium doped barium titanate nanopowders were prepared using the hydrothermal method. A barium titanate structure doped with rare earth ions manifested new characteristics and improved the field of application of optical devices such as trichromatic tubes, LCD displays, lamps, and infrared lasers. In this work, BaTiO3：Er3＋ and BaTiO3：Yb3＋ were prepared using barium chloride [BaCl2], titanium butoxide [C16H36O4Ti], erbium chloride [ErCl3] and ytterbium chloride [YbCl3] as precursors. Anhydrous methanol was employed as a solvent. metallic potassium was used to promote solubility in the system and increase the pH to 13. This method yielded the formation of a predominantly cubic structure in both Er3＋ and Yb3＋ doped BaTiO3 powders. Characteristic bondings of BaTiO3 were observed with FT-IR spectroscopy. The predominantly cubic structure was confirmed by X-ray diffraction and micro-Raman analyses. The particle size（～30 nm） was estimated using the Scherrer equation and X-ray diffraction data. The results were presented and discussed.

关键词： nanopowders hydrothermal BaTiO3:Er3+ BaTiO3:Yb3+ rare earths

Local Stability of Curzon-Ahlborn Cycle with Non-Linear Heat Transfer for maximum Power Output Regime

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Journal of modern Physics 2013年第7期4卷 22-27页

作者： Delfino Ladino-Luna pedro Portillo-Díaz Ricardo T. Páez-hernández Universidad Autónoma metropolitana-Atzcapotzalco Física de Procesos Irreversibles Cd. México México

The study of local stability of thermal engines modeled as an endoreversible Curzon and Ahlborn cycle is shown. It is assumed a non-linear heat transfer for heat fluxes in the system (engine + environments). A semisum of two expressions of the efficiency found in the literature of finite time thermodynamics for the maximum power output regime is considered in order to make the analysis. Expression of variables for local stability and power output is found even graphic results for important parameters in the analysis of stability, and a phase plane portrait is shown.

关键词： Local Stability Thermal Engines Non-Linear Heat Transfer

On the Efficiency for Non-Endoreversible Stirling and Ericsson Cycles

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Journal of modern Physics 2013年第12期4卷 1-7页

作者： Delfino Ladino-Luna pedro Portillo-Díaz Ricardo T. Páez-hernández Universidad Autónoma metropolitana-Azcapotzalco Física de Procesos Irreversibles México D.F. México

An analysis of the Stirling and Ericsson cycles from the point of view of the finite time thermodynamics is made by assuming the existence of internal irreversibilities in an engine modeled by these cycles, and the ideal gas as working substance is considered. Expressions of efficiency in both regimes maximum power output and maximum ecological function are also shown. Appropriate variables are introduced so that the objective functions, namely power output, ecological function and efficiency can be functions of the reservoirs temperatures ratio and certain “measurable” parameters as a thermal conductance, the general constant of gases and the compression ratio of the cycle. Several results from the finite time thermodynamics literature are used, so that the developed methodology leads directly to appropriate expressions of the objective functions in order to simplify the optimization process.

关键词： Thermal Cycles Efficiency Power Output Ecological Function

Evaluation of Candidate Predictors for Seasonal Precipitation Forecasting

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Atmospheric and Climate Sciences 2023年第4期13卷 539-564页

作者： pedro m. González-Jardines maibys Sierra-Lorenzo Adrián L. Ferrer-hernández Arnoldo Bezanilla-morlot Center for Atmospheric Physics Institute of Meteorology Havana Cuba

This research proposes to carry out a principal component analysis using the maximum covariance method, with the aim of finding the most robust spatio-temporal relationships between several candidate predictors and the accumulated monthly precipitation recorded in Cuba during the period 1980-2020. This process will make it possible to establish quantitative relationships that, together with theoretical considerations, make it possible to reduce the list of predictors to be used for the purpose of obtaining seasonal predictions. The values of the predictors are represented through monthly averages obtained from ERA5 reanalysis, while monthly accumulated precipitation data were obtained from a national-scope grid with 4 km of spatial resolution, used as predictand. The results obtained reflect the highest spatio-temporal correlation values with the first variability mode in all cases, indicating that the usual regime conditions are predominant and have a greater coupling with the precipitation variability in the analyzed temporal scale. In addition, they suggest that the candidates that explain the transport of moisture at low levels, as well as the gradients between the middle and lower troposphere, show the most robust associations. In the same way, the surface temperature of tropical Atlantic Sea, the flow related to Quasi-Biennial Oscillation and the thermodynamic indices, K Index and Galvez-Davison Index, present good degrees of association, for which reason they can be considered the most recommendable for carrying out forecasting experiments.

关键词： Principal Component maximun Covariance Predictors ERA5