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Reconstruction of debris-flow activity in a temperate mountain forest catchment of central Mexico

Journal of Mountain Science 2019年第9期16卷 2096-2109页

作者： osvaldo franco-ramos Markus STOFFEL Juan Antonio BALLESTEROS-CANOVAS Instituto de Geografia. Universidad NacionalAutonoma de Mexico Ciudad Universitaria Coyoacan 04510 Mexico Dendrolab.ch Department of Earth Sciences University of Geneva 13 rue des Maraichers CH-1205 Geneva Switzerland Climate Change Impacts and Risks in the Anthropocene (C-CIA) Institute for Environmental Sciences University of Geneva 66 Boulevard Carl-Vogt CH-1205 Geneva Switzerland Department F.-A. Forelfor Environmental and Aquatic Sciences University of Geneva 66 Boulevard Carl-Vogt CH- 1205 Geneva Switzerland

The use of dendrochronology to study and date geomorphic processes in volcanic environments is still incipient, even more so on the volcanic slopes covered by temperate forests in central Mexico. Mass movements, such as debris flows, often impact forest stands where they cause damage to individual trees, thereby generating growth disturbances(GD) in the tree-ring records. The identification and dating of GD enables reconstruction of the age of trees colonizing bare surfaces after major events, but also allows the assessment of the frequency or spatial distribution of past geomorphic process activity. Here we used increment cores from 65 Pinus leiophylla, Abies religiosa, and Alnus jorullensis trees growing in the Axal gorge, on the southern slopes of La Malinche volcano, to unravel past debris-flow activity both temporally and spatially. Based on the combination of GD records, a weighted tree response index(Wit), field evidence and hydrometeorological records, we reconstructed 23 debris flows since ***, almost two-thirds of the reconstructed years with debris-flow activity in Axal gorge match with events recorded in Axaltzintle gorge located on the NE slopes of La Malinche. These findings suggest a regional triggering mechanism, most likely related to the occurrence of hurricanes. This research could be useful for disaster risk management of the La Malinche National Park.

关键词： Debris flows La Malinche volcano Dendrogeomorphology Temperate forest Hydrometeorological phenomena

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Weighted Weak-type Estimates for Multilinear Commutators of Fractional Integrals on Spaces of Homogeneous Type

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Acta Mathematica Sinica,English Series 2007年第10期23卷 1813-1826页

作者： osvaldo GOROSITO Gladis PRADOLINI Oscar SALINAS Department of Mathematics Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina

We obtain weighted distributional inequalities for multilinear commutators of the fractional integral on spaces of homogeneous type, The techniques developed in this work involve the behavior of some fractional maximal functions. In relation to these operators, as a main tool, we prove a weighted weak type boundedness result, which is interesting in itself.

关键词： commutators fractional integral operator multilinear operators

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Seismic response of deep circular tunnels subjected to S-waves:Axial bending

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Underground Space 2024年第4期17卷 267-279页

作者： Chatuphat Savigamin Antonio Bobet osvaldo P.M.Vitali HR Engineering Services Inc.MedleyFL 33166United States Lyles School of Civil Engineering Purdue UniversityWest LafayetteIN 47907United States Department of Civil Environmentaland Construction EngineeringUniversity of Hawaii at ManoaHonoluluHI 96822United States

Ovaling deformation of circular tunnels has received great interest from the tunneling community because this mode of seismicinduced deformation is considered the most ***,there is growing evidence that other deformation modes can also be important and thus need to be considered in *** study presents a new analytical solution to estimate axial bending(snaking),a mode of deformation caused by S-waves impinging on a tunnel parallel to the tunnel *** solution is developed using the soilstructure interaction approach with the assumption that the interface between the ground and the tunnel lining is frictionless(fullslip).Full dynamic numerical simulations are conducted to verify the new full-slip solution,together with the existing no-slip *** of dynamic amplification are also explored for both full-slip and no-slip interface conditions by changing the wavelength(or frequency)of the seismic input motions.

关键词： Seismic response of tunnels Analytical solutions Soil-structure interaction Axial bending Snaking S-waves

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Construction of Dulac functions for mathematical models in population biology

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International Journal of Biomathematics 2015年第3期8卷 135-154页

作者： osvaldo Osuna Cruz Vargas-De-Leon Instituto de Fisica y Matematicas Universidad MichoacanaEdif. C-3 Cd. Universitaria CP 58040 Morelia Michoacan Mexico Unidad de Medicina Experimental Hospital General de Mexico "Dr. Eduardo Liceaga" DF 06726 Mdxieo

In this paper, we present a method for constructing a Dulac function for mathematical models in population biology, in the form of systems of ordinary differential equations in the plane.

关键词： Population models epidemic models chemostat models Dulac function nonexistence of periodic orbits.

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Brain angiotensin Ⅱ in dopaminergic imbalance-derived pathologies:neuroinflammation and vascular responses

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Neural Regeneration Research 2021年第3期16卷 504-505页

作者： Victoria Belén Occhieppo osvaldo Martin Basmadjian Claudia Bregonzio Instituto de Farmacología Experimental Córdoba(IFEC-CONICET) Departamento de FarmacologíaFacultad de Ciencias Químicas Universidad Nacional de CórdobaCórdobaArgentina

Brain angiotensinⅡ(ANGⅡ)as a pleiotropic player:Mental disorders have been commonly associated with an imbalance in many neurotransmitter systems,such as dopamine,glutamate,and gamma-aminobutyric *** the complexity of brain functioning,all components of the neurovascular unit should be considered in studies for a better comprehension of the physiopathology and possible therapeutics.

关键词： player comprehension imbalance

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Catalytic combustion of soot over ceria-zinc mixed oxides catalysts supported onto cordierite

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Journal of Environmental Sciences 2014年第3期26卷 694-701页

作者： Leandro Fontanetti Nascimento Renata Figueredo Martins Rodrigo Ferreira Silva osvaldo Antonio Serra Department of Chemistry FFCLRP University of Sao Paulo

Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. The unique storage properties of ceria （CeO2） makes it one of the most efficient catalysts available to date. Here, we proposed that ceria-based catalysts can lower the temperature at which soot combustion occurs; more specifically, from 610℃ to values included in the diesel exhausts operation range （300-450℃）. The sol-gel method was used to synthesize mixed oxide-based catalysts （CeO2：ZnO）; the resulting catalysts were deposited onto cordierite substrates. In addition, the morphological and structural properties of the material were evaluated by XRD, BET, TPR-H2, and SEM. Thermogravimetric （TG/DTA） analysis revealed that the presence of the catalyst decreased the soot combustion temperature by 200℃ on average, indicating that the oxygen species arise at low temperatures in this situation, promoting highly reactive oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy （DRS） showed that catalyst-impregnated cordierite samples efficiently oxidized soot in a diesel/biodiesel stationary motor： soot emission decreased by more than 70%.

关键词： soot oxidation mixed oxides ceria

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Behavior of tunnels excavated with dip and against dip

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Underground Space 2021年第6期6卷 709-717页

作者： osvaldo P.M.Vitali Tarcisio B.Celestino Antonio Bobet Lyles School of Civil Engineering Purdue UniversityWest LafayetteIN 47907USA Sao Carlos School of Engineering University of Sao PauloSao CarlosSP 13566Brazil

Rock masses with remarked rock structure are likely to be highly anisotropic;thus,the relative orientation of the tunnel with respect to the rock structure will affect the tunnel *** measured at the walls of tunnels in highly anisotropic rock masses often reveal an asymmetric deformation pattern around the tunnel perimeter,which is often interpreted as the result of rock heterogeneity or changing ***,numerical and analytical investigation of tunnels in anisotropic rock masses show that the tunnel axis misalignment with the principal directions of stress and material anisotropy induce anti-symmetric axial displacements(i.e.,axial distortion of the tunnel cross section)far behind the tunnel *** the face,the axial distortion is partially constrained,causing asymmetric radial *** this study,tunnels excavated with and against dip of the major rock mass discontinuity are explored using 3D FEM modeling.A detailed analysis on the mechanisms associated with the direction of excavation is *** is shown that the asymmetric displacements near the face may strongly affect the displacements measured at the tunnel walls,which may explain the asymmetric displacements commonly observed on tunnels in anisotropic rock.

关键词： Tunnel Tunnel misalignment Anisotropic rock Face effects

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3D finite element modelling optimization for deep tunnels with material nonlinearity

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Underground Space 2018年第2期3卷 125-139页

作者： osvaldo P.M.Vitali Tarcisio B.Celestino Antonio Bobet Lyles School of Civil Engineering Pwrdue UniversityWest LafayetteIN 47907USA Sao Carlos School of Engineering.Univerity of Sao Paulo Sao CarlosSP 13566Brazil

3D modeling of tunnels using a nonlinear ground model is still a time-consuming task because it usually requires a large number of incremental phases with iterative processes,to ensure accuracy while minimizing computational *** of theﬁnite element mesh is of utmost *** the current tendency towards 3D modeling of tunnels,few publications are concerned with mesh optimization considering model size,grid reﬁnement and order of *** paper improves the understanding of key issues that affect 3D modeling of *** results shown that:(1)2nd order elements are more effcient when material nonlinearity is present and should be preferred;(2)the plastic zone size has a strong inﬂuence on the model dimensions and may require discretizations much larger than those currently *** paper provides recommendations for mesh reﬁnement and model dimensions(width and length)as a function of the plastic zone size,for accurate 3D models with reduced computational cost.

关键词： Tunnel Numerical modeling Finite element method Mesh optimization Nonlinear material

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Life cycle assessment of low impact development technologies combined with conventional centralized water systems for the City of Atlanta, Georgia

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Frontiers of Environmental Science & Engineering 2016年第6期10卷 3-15页

作者： Hyunju Jeong osvaldo A. Broesicke Bob Drew Duo Li John C. Crittenden Department of Civil and Environmental Engineering South Dakota School of Mines and Technology Rapid City SD 57701 USA Brook Byers Institute for Sustainable Systems School of Civil and Environmental Engineering Georgia Institute of Technology 828 West Peachtree Street Suite 320 Atlanta GA 30332-0595 USA ECOVIE Rainwater Collection Systems 4287 Club Drive N.E. Atlanta GA 30319 USA Crittenden and Associates C-305 Building E Wangjing High-tech Park LizezhongEr Road Chaoyang District Beijing 100102 China

Low-impact development （LID） technologies, such as bioretention areas, rooftop rainwater harvesting, a_nd xeris_caping can co_ntrol stormwater runoff, supply non-potable water, and landscape open *** study examines a hybrid system （HS） that combines LID technologies with a centralized water system to lessen the burden on a conventional system （CS）. CS is defined as the stormwater collection and water supply infrastructure, and the conventional landscaping choices in the City of Atlanta. The study scope is limited to five single-family residential zones （SFZs）, classified R-1 through R-5, and four multi-family residential zones （MFZs）, classified RG-2 through RG-5. Population density increases from 0.4 （R-1） to 62.2 （RG-5） persons per 1,000 m2. We performed a life cycle assessment （LCA） comparison of CS and HS using TRACI 2.1 to simulate impacts on the ecosystem, human health, and natural resources. We quantified the impact of freshwater consumption using the freshwater ecosystem impact （FEI） indicator. Test results indicate that HS has a higher LCA single score than CS in zones with a low population density; however, the difference becomes negligible as population density increases. Incorporating LID in SFZs and MFZs can reduce potable water use by an average of 50%. and 25%,respectively.; however, water savings are negligible in zones with high population density （i.e., RG-5） due to the diminished surface area per capitaavailable for LID technoogies. The results demonstrate that LID technologies effectively reduce outdoor water demand and therefore would be a good choice to decrease the water consumption impact in the City of Atlanta.

关键词： Life cycle assessment (LCA) Low impact development (LID) Bioretention area Rainwater harvesting Xeriscaping

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Stable Combustion under Carbon Dioxide Enriched Methane Blends For Exhaust Gas Recirculation(EGR)

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Journal of Thermal Science 2021年第6期30卷 2186-2195页

作者： OKON Aniekan VIGUERAS-ZUNIGA Marco-osvaldo AGWU Ogbonnaya CHONG Cheng Tung VALERA-MEDINA Agustin Department of Mechanical Engineering University of UyoUyo PMB1017Nigeria Department of Mechanical Engineering Universidad VeracruzanaVeracruz 942940Mexico College of Physical Sciences and Engineering Cardiff UniversityQueen's BuildingCardiff CF243AAUK China-UK Low Carbon College Shanghai Jiao Tong UniversityShanghai 201306China

Exhaust gas recirculation(EGR)is one of the main techniques to enable the use of oxyfuel combustion for carbon capture and storage(CCS).However,the use of recirculated streams with elevated carbon dioxide poses different ***,more research is required about the cumulative effects on the desirable outcomes of the combustion processes such as thermal efficiency,reduced emissions and system operability,when fuels with high CO_(2) concentration for CCS exhaust gas recirculation or biogas are ***,this study evaluates the use of various CO_(2) enriched methane blends and their response towards the formation of a great variety of structures that appear in swirling flows,which are the main mechanism for combustion control in current gas turbines *** study uses 100 kW acoustically excited swirl-stabilised burner to investigate the flow field response to the resultant effects of the variation in the swirl strength,excitation under isothermal condition and the corresponding effects during combustion with different fuels at various CO_(2) *** show changes in size and location of flow structures as a result of the changes in the mean and turbulent velocities of the flow field,consequence of the imposition of different swirl and forcing *** thermal efficiency is also observed in the system when using high swirl and forcing while the blend of CO_(2) with methane balanced the heat release fluctuation with a corresponding reduction in the acoustic amplitudes of the combustion response,suggesting that certain CO_(2) concentrations in the fuel can provide more stable *** between 10%to 15%CO_(2) volume show great promise for stability improvement,with the potential of using these findings in larger units that employ CCS technologies.

关键词： thermoacoutics swirl coherent structures carbon dioxide fuel blends stability

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