检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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)

Six forests in one:Tree species diversity in the Bosque Protector Chongón Colonche,a lowland mountain range in coastal Ecuadorian

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2022年第6期9卷 725-733页

作者： Oswaldo jadan David ADonoso Edwin Ponce-Ramírez Franz Pucha-Cofrep Omar cabrera Facultad de Ciencias Agropecuarias Universidad de Cuenca12 de Octubre y Diego de TapiaCuenca010107Ecuador Programa de Doctorado en Conservacion de Recursos Naturales Escuela Internacional de DoctoradoUniversidad Rey Juan CarlosMostolesMadridES-28933Spain Departamento de Biología Escuela Politecnica NacionalLadron de Guevara E11⋅253Quito170525Ecuador Geoforest S.A 12 de febrero y Av.Franklin VegaMacas140150Ecuador Grupo de Investigacion Hidrología y Climatología Universidad Tecnica Particular de LojaSan Cayetano Alto S/NLoja110101Ecuador Brandenburg University of Technology(BTU)Cottbus-Senftenberg 03044CottbusGermany Departamento de Ciencias Biologicas y Agropecuarias Universidad Tecnica Particular de LojaSan Cayetano Alto S/NLoja110101Ecuador

Tropical mountain ranges shape the structure of tree communities and promote highly diverse natural ***“Bosque Protector Chong on-Colonche”(BPCC),an 86,000-ha mountain formation situated on the coast of Ecuador,is biogeographically important for the region by connecting floristic elements of the wet Choco and the dry Tumbesian *** understanding of the factors that model tree and palm diversity and distribution in this mountain range are *** measured and identified all trees and palms(DBH≥10 cm)in 289 plots of0.2 ha,distributed throughout *** used generalized linear models to explain the relationship between forest diversity and structure and climatic variables(temperature,rain,aridity),and *** then used cluster and non-metric multidimensional scale(NMDS)analyses to search for distinct forest communities within the *** partition(varpart)was used to determine which predictor variables best explained these distinct forest communities.A species indicator analysis identified the species most likely to define these distinct forest ***,we carried out a niche modeling approach to identify the potential distribution of these forest communities within *** total,we identified 220 tree and palm species in our *** average number of species per plot was 17.8±5.8,ranging from 3 to 40 *** methods sorted the 289study plots into six different forest communities,three communities in the dry forest and three in the semi-humid Garúa *** and temperature,but not altitude or aridity,explained floristic *** results emphasize the high but little cataloged diversity in the lowland mountain rainforests of coastal Ecuador.

关键词： Chongón-Colonche Climatic variables Dry forest Forest communities Garúa forest

Reflectivity and thickness analysis of epiretinal membranes using spectral-domain optical coherence tomography

在线全文

学校读者我要写书评

暂无评论

International journal of Ophthalmology(English edition) 2016年第1期9卷 93-98页

作者： Ajay E.Kuriyan Delia cabrera DeBuc William E.Smiddy Department of Ophthalmology Bascom Palmer Eye InstituteMiller School of Medicine University of Miami

AIM：To compare thickness and reflectivity spectral domain optical coherence tomography（SD-OCT）findings in patients with idiopathic epiretinal membranes（ERMs）,before and after ERM peeling surgery,with normal controls.·METHODS：A retrospective study analyzing SD-OCTs of eyes with ERMs undergoing ERM peeling surgery by one surgeon from 2008 to 2010 and normal control ***-OCTs were analyzed using a customized algorithm to measure reflectivity and *** relationship between the SD-OCT findings and best corrected visual acuity（BCVA）outcomes was also studied.·RESULTS：Thirty-four ERM eyes and 12 normal eyes were *** eyes had high reflectivity and thickness of the group of layers from the internal limiting membrane（ILM）to the retinal pigment epithelium（RPE）and the group of layers from the ILM to the external limiting membrane（ELM）.The values of reflectivity of these two groups of layers decreased postoperatively,but were still higher than normal *** contrast,preoperative eyes had lower reflectivity of two10×15 pixel regions of interest（ROIs）incorporating：1）ELM＋outer nuclear layer（ONL）and 2）photoreceptor layer（PRL）＋RPE,compared to *** values of reflectivity of these ROIs increased postoperatively,but were still lower than normal controls.A larger improvement in BCVA postoperatively was correlated with a greater degree of abnormal preoperative reflectivity and thickness findings.·C ONCLUSION：Quantitative differences in reflectivity and thickness between preoperative,postoperative,and normal SD-OCTs allow assessment of changes in the retina secondary to *** study identified hyperreflective inner retina changes and hyporeflective outer retina changes in patients with ***-OCT quantitative measures of reflectivity and/or thickness of specific groups of retinal layers and/or ROIs correlate with improvement in BCVA.

关键词： epiretinal membranes optical coherencetomography reflectivity retina imaging vitrectomy

High-throughput Phenotyping and Genomic Selection:The Frontiers of Crop Breeding Converge

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

journal of Integrative Plant Biology 2012年第5期54卷 312-320页

作者： Lloren cabrera-Bosquet jos Crossa jarislav von Zitzewitz María Dolors Serret jos Luis Araus French National Institute for Agricultural Research (INRA UMR759)Ecophysiology Laboratory of Plants under Environmental StressMontpellier F-34060France International Maize and Wheat Improvement Center (CIMMYT) El BatnTexcoco CP 56130Mexico National Research Program on Rainfed Crops National Institute for Agricultural ResearchEst.Exp.La EstanzuelaColonia 70000Uruguay Unit of Plant Physiology Faculty of BiologyUniversity of BarcelonaAv.Diagonal643Barcelona 08028Spain

Genomic selection （GS） and high-throughput phenotyping have recently been captivating the interest of the crop breeding com- munity from both the public and private sectors world-wide. Both approaches promise to revolutionize the prediction of complex traits, including growth, yield and adaptation to stress. Whereas high-throughput phenotyping may help to improve understanding of crop physiology, most powerful techniques for high-throughput field phenotyping are empirical rather than analytical and compa- rable to genomic selection. Despite the fact that the two method- ological approaches represent the extremes of what is understood as the breeding process （phenotype versus genome）, they both consider the targeted traits （e.g. grain yield, growth, phenology, plant adaptation to stress） as a black box instead of dissectingthem as a set of secondary traits （i.e. physiological） putatively related to the target trait. Both GS and high-throughput phenotyping have in common their empirical approach enabling breeders to use genome profile or phenotype without understanding the underlying biology. This short review discusses the main aspects of both approaches and focuses on the case of genomic selection of maize flowering traits and near-infrared spectroscopy （NIRS） and plant spectral reflectance as high-throughput field phenotyping methods for complex traits such as crop growth and yield.

关键词： Genomic selection high-throughput phenotyping NIRS quantitative traits SNPs.

Single-atom catalysts with anionic metal centers: Promising electrocatalysts for the oxygen reduction reaction and beyond

在线全文

学校读者我要写书评

暂无评论

journal of Energy Chemistry 2021年第12期30卷 285-293,I0006页

作者： jinxing Gu Yinghe Zhao Shiru Lin jingsong Huang Carlos R.cabrera Bobby G.Sumpter Zhongfang Chen Department of Chemistry University of Puerto Rico.Rio Piedras Campus.San Juan.Puerto Rico 00931USA Center for Nanophase Materials Sciences Oak Ridge National LaboratoryOak RidgeTennessee 37831USA Department of Chemistry and Biochemistry The University of Texas at El PasoEl PasoTexas 79968USA

Ongoing efforts to develop single-atom catalysts(SACs) for the oxygen reduction reaction(ORR) typically focus on SACs with cationic metal centers,while SACs with anionic metal centers(anionic SACs) have been generally ***,anionic SACs may offer excellent active sites for ORR,since anionic metal centers could facilitate the activation of O_(2) by back donating electrons to the antibonding orbitals of O_(2).In this work,we propose a simple guideline for designing anionic SACs:the metal centers should have larger electronegativity than the surrounding atoms in the substrate on which the metal atoms are *** means of density functional theory(DFT) simulations,we identified 13 anionic metal centers(Co,Ni,Cu,Ru,Rh,Pd,Ag,Re,Os,Ir,Pt,Au,and Hg) dispersed on pristine or defective antimonene substrates as new anionic SACs,among which anionic Au and Co metal centers exhibit limiting potentials comparable to,or even better than,conventional Pt-based catalysts towards *** also found that anionic Os and Re metal centers on the defective antimonene can electrochemically catalyze the nitrogen reduction reaction(NRR) with a limiting potential close to that of stepped Ru(0001).Overall,our work shows promise towards the rational design of anionic SACs and their utility for applications as electrocatalysts for ORR and other important electrochemical reactions.

关键词： Single-atom catalysts Anionic metal centers Antimonene Oxygen reduction reaction Nitrogen reduction reaction

THE SHAPE FACTOR:A PARAMETER TO ASSESS THE EFFECT OF PULVERISED FUEL ASH ON THE FLOW PROPERTIES OF CEMENT PASTES AND CONCRETE

在线全文

学校读者我要写书评

暂无评论

THE SHAPE FACTOR:A PARAMETER TO ASSESS THE EFFECT OF PULVERI...

Intelligent collision risk detection in medium-sized cities of developing countries,using naturalistic driving:A review

1985北京国际水泥及混凝土学术会议

作者： C.j.Hopkins j.G.cabrera Departmeat of Civil Engineering University of Leeds LS2 9JTUK

Pulverised fuel ash (pfa) is the British name for the low calcium content, inorganic material remaining after the combustion of powdered coal. Other countries use the term "fly ash". Considerable differences exist between pfas. When pfa is added to a cement paste its flow properties are modified. As a consequence of this, the workability of a pfa-concrete is affected. Changes in workability depend on the properties of the particular pfa incorporated in the concrete mix. A reliable system of classifying pfas is necessary. Research has shown that the most important characteristics of pfa in terms of its ability to affect the flow behaviour of cement paste are its shape and surface properties. This paper presents the development of a method which characterises pfas by using the "shape factor" parameter. This parameter can be determined in minutes using the particle size distribution of the pfa and the specific surface area of the pfa. A chart is proposed which will classify pfa in zones. The zones indicate the pfa particle shape and its suitability for use in concrete.

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

journal of Traffic and Transportation Engineering(English Edition) 2022年第6期9卷 912-929页

作者： juan jose Paredes Santiago Felipe Yepes Ricardo Salazar-cabrera Alvaro Pachon dela Cruz juan Manuel Madrid Molina Telematics Engineering Research Group(GIT) Telematics DepartmentUniversidad Del CaucaPopayanColombia Information Technology and Telecommunications Research Group(12T) Universidad IcesiCaliColombia

Traffic accidents are one of the most serious problems worldwide,being one of the leading causes of death and economic loss in the ***-and middle-income countries,mainly their medium-sized cities,are among the most affected by this problem.93%of traffic accidents occur in low and middle-income countries,even though these countries have approximately 60%of the world’s *** occurs mainly because in these types of countries,especially in medium-sized cities(target context),there are no ideal conditions for driving,such as adequate road infrastructure,good condition of vehicles,and rigorous safety *** data analysis techniques including machine learning(ML)have increasingly been used to solve this *** driving(ND)can be applied as a data collection method that provides information on traffic *** commonly uses a vehicle’s kinematic data to detect high-risk driving behaviors that could cause an *** objectives of this document are to present a review of different alternatives that help in data collection and creation of intelligent solutions related to detection of possible traffic accidents,principally using ND;and to propose an intelligent collision risk detection system(ICRDS)for identification of areas with a high probability of TA in the target *** the review,it was possible to analyze and evaluate the devices,variables and algorithms that help characterize a risk event in driving,considering the target *** development of a prototype of an ICRDS for a medium-sized city in a developing country is considered viable,considering the identified components,with the aim of identifying risk events in driving,and areas of high probability of accidents in the city.

关键词： Naturalistic driving Near-crash Traffic accident Vehicle data collection

Acoustic contamination assessment during the transition between the COVID-19 restrictions and reactivation:A exploratory analysis in Guayaquil

在线全文

学校读者我要写书评

暂无评论

Geography and Sustainability 2023年第2期4卷 138-149页

作者： Andrés Velastegui-Montoya Geancarlo Guerrero-cabrera Sandra Gonzalez-Camba Yadira jaramillo-Lindao Ricardo Murillo-Portillo j.Hidalgo-Crespo Luis Encalada-Abarca Centro de Investigación y Proyectos Aplicados a las Ciencias de la Tierra(CIPAT) ESPOL Polytechnic UniversityP.O.Box 09-01-5863GuayaquilEcuador Facultad de Ingeniería en Ciencias de la Tierra(FICT) ESPOL Polytechnic UniversityP.O.Box 09-01-5863GuayaquilEcuador Geoscience Institute Federal University of Pará66075-110BelémBrazil Facultad de Ciencias Naturales y Matemáticas(FCNM) ESPOL Polytechnic UniversityP.O.Box 09-01-5863GuayaquilEcuador Sciences pour la Conception l’Optimisation et la Production(G-SCOP)Centre National de la Recherche Scientifique(CNRS)UniversitéGrenoble Alpes38000GrenobleFrance Facultad de Ingeniería Industrial Universidad de Guayaquil090150GuayaquilEcuador Centre of Geographical Studies Institute of Geography and Spatial PlanningUniversity of Lisbon1600-276LisbonPortugal Universidad Espíritu Santo SamborondónEcuador

Noise pollution is becoming a critical health risk for city *** 2020,the COVID-19 pandemic forced many cities to implement several mobility *** restrictions changed human activity patterns and decreased the noise levels and noise pollution that often affect urban *** the number of infections decreased,so did the outdoor activities,influencing the population’s perception of *** paper aims to evaluate the changes in noise levels associated with mobility restrictions between 2020 and 2021 in Guayaquil,*** study used crowdsourcing with the help of smartphones and mobile applications to collect geo-referenced environmental noise *** data was used to generate noise maps in different time ***,noise level maps were created using GIS-based tools to identify the urban areas that experienced the highest noise level variation during the study *** results show that the most significant noise increase occurred at ***,when analyzing noise level changes in different urban areas,the western area of Guayaquil was the one that experienced the most significant noise level *** inform the perception of noise pollution and could potentially serve as a reference for decision-makers during the proposal of public policies that ensure a better quality of life for its citizens.

关键词： Acoustic contamination Crowdsourcing Data scrubbing Kriging Noise map

Relativistic charged stellar modeling with a perfect fluid sphere

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第9期75卷 113-121页

作者： joaquin Estevez-Delgado joel Arturo Rodríguez Ceballos jorge Mauricio Paulin-Fuentes joséVega cabrera Antonio Rendón Romero Facultad de Ciencias Físico Matemáticas de la Universidad Michoacana de San Nicolás de Hidalgo Edificio BCiudad UniversitariaMorelia MichoacánCP 58040Mexico Facultad de Químico Farmacobiología de la Universidad Michoacana de San Nicolás de Hidalgo Tzintzuntzan No.173Col.MatamorosMorelia MichoacánC.P.58240Mexico División Académica de Ciencias Básicas de la Universidad juárez Autónoma de Tabasco Carretera Cunduacán-Jalpa Km.1Col.La Esmeralda86690CunduacánTabascoMexico Facultad de Ingenieria Mecanica de la Universidad Michoacana de San Nicolás de Hidalgo Edificio W Ciudad UniversitariaCP 58030Morelia MichoacánMexico

In this report we present the generalization of a solution to Einstein's equations with perfect fluid for the case of Einstein–Maxwell with perfect *** effect of the charge is reflected by a parameter,ν,and its interval is determined by the positivity condition from the pressure in the interior of the *** is shown that the solution is stable according to the Zeldovich criteria as well as in relation to the criteria of the adiabatic *** compactness,u=GM/c^(2)R,of this charged model is greater than it is for the chargeless case as a result of the effect of the presence of the *** allows it to represent stars with a high compactness,in particular a graphic analysis is presented for the star SAX j1808.4-3658 with mass M=1.435M_(⊙)and radius R=7.07 *** these data and employing the solution,we obtain that the total maximum charge for the star is Q=2.4085×10^(20)C.

关键词： general relativity exact solutions charged fluid stars models