检索结果-南通市图书馆

International journal of Mining Science and Technology 2019年第5期29卷 731-737页

作者： M.O.Bustamante Rúa A.j.daza Aragón P.Bustamante Baena j.d.osorio botero school mines national university of colombiamedellín 050036colombia

Spontaneous combustion of coal seams in open pit mines is a problem that occurs in coal mines around the *** have been developed that express several factors which generate self-heating in the coal and favor *** synergy of these factors contributes to the increase in the temperature of oxidation reactions,facilitating the culmination of the activation energy of the system,in which the ignition develops and the reaction is ***,the incidence of each variable’s susceptibility to coal combustion is unknown,so in this work a methodology was developed to determine statistically which of the variables has the greatest contribution in the *** statistics,atypical values detection,principal component determination,cluster analysis,and logistic regression were used to determine how many indicator variables are necessary to describe susceptibility to coal *** the analysis,21,000 data from different seams of two open-pit coal mines in endwalls and abandoned pits were processed with consideration given to extrinsic and intrinsic *** temperature,atmospheric pressure,wind speed,oxygen,methane,height,ash,volatile matter,heat power,vitrinite,liptinite and the Hardgrove Index are the most influential variables in the phenomenon.

关键词： Coal fire Self-ignition Statistics analysis Open pit mines Spontaneous combustion

A cleaner production strategy for acid mine drainage prevention of waste rock:A porphyry copper case

在线全文

学校读者我要写书评

暂无评论

International journal of Mining Science and Technology 2024年第8期34卷 1163-1177页

作者： Yesica L.botero Isabelle demers Luis A.Cisternas ArnoldoÁvila Mostafa Benzaazoua departamento de Ingeniería Química y Procesos de Minerales Universidad de AntofagastaAntofagasta1240000Chile Research Institute on Mines and Environment Universitédu Québec en Abitibi-TémiscamingueRouyn-NorandaQC J9X5E4Canada Eriez Flotation Group Chile S.A. Santiago1240000Chile Geology and Sustainable Mining Institute University Mohammed Ⅵ PolytechnicLot 660 Hay Moulay RachidBen Guerir 43150Morocco

An in-process technology approach is proposed to identify the source of acid mine drainage(AMd)generation and prevent its formation in a porphyry copper waste rock(WR).Adopting actions before stockpiling the WR enables the establishment of potential contaminants and predicts the more convenient method for AMd prevention.A WR sample was separated into size fractions,and the WR’s net acidgenerating potential was quantified using chemical and mineralogical *** diameter of physical locking of sulfides(dPLS)was determined,and the fractions below the dPLS were desulfurized using ***,the WR fractions and tailing from the flotation test were submitted to acid-base accounting and weathering tests to evaluate their acid-generating *** show that the WR’s main sulfide mineral is pyrite,and the dPLS was defined as 850μm.A sulfide recovery of 91%was achieved using a combination of HydroFloat^(®)and denver cells for a size fraction lower than *** grinding was *** results show that size fractions greater than dPLS and the desulfurized WR are unlikely to produce *** outcomes show that in-processing technology can be a more proactive approach and an effective tool for avoiding AMd in a porphyry copper WR.

关键词： Waste rock Porphyry copper ore desulfurization Acid mine drainage HydroFloat^(®) In-process technology Cleaner production

A New Approach to State Estimation for Uncertain Linear Systems in a Moving Horizon Estimation Setting

在线全文

学校读者我要写书评

暂无评论

International journal of Automation and computing 2016年第6期13卷 653-664页

作者： j.Garcia-Tirado H.botero F.Angulo Faculty of Economic and Administrative Sciences QualityMetrology and Production Research GroupMetropolitan Institute of Technology of Medellin (ITM) KALMAN Research Group Faculty of MinesElectric Energy and Automatics DepartmentNational University of Colombia (MedelliCampus) Perception and Intelligent Control Research Group Department of ElectricalElectronicsand Computational EngineeringFaculty of Engineering and ArchitectureNational University of Colombia (Manizales)Q buildingLa Nubia campus

This paper addresses the state estimation problem for linear systems with additive uncertainties in both the state and output equations using a moving horizon approach. Based on the full information estimation setting and the game-theoretic approach to the H∞filtering, a new optimization-based estimation scheme for uncertain linear systems is proposed, namely the H∞-full information estimator, H∞-FIE in short. In this formulation, the set of processed data grows with time as more measurements are received preventing recursive formulations as in Kalman filtering. To overcome the latter problem, a moving horizon approximation to the H∞-FIE is also presented, the H∞-MHE in short. This moving horizon approximation is achieved since the arrival cost is suitably defined for the proposed scheme. Sufficient conditions for the stability of the H∞-MHE are derived. Simulation results show the benefits of the proposed scheme when compared with two H∞filters and the well-known Kalman filter.

关键词： uncertain processed overcome estimator latter horizon filtering recursive weighting constraints

A geomorphological model of susceptibility to the effect of human interventions for environmental licensing determination(SHIELd)

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2022年第2期13卷 284-294页

作者： Cristina I.Pereira Celene B.Milanes Ivan Correa Enzo Pranzini Benjamin Cuker Camilo M.botero EAFIT University Earth Sciences DepartmentMedellínColombia Coastal Systems Research Group Playas Corporation Ltda.BogotáColombia Civil and Environmental department Universidad De La CostaBarranquillaColombia department of Earth Sciences University of FlorenceFirenzeItaly department of Marine and Environmental Science Hampton UniversityHamptonUnited States University Sergio Arboleda School of LawSanta

Almost every country requires some form of environmental licensing prior to the inception of development projects that may affect the integrity of the environment and its social *** developed a new conceptual and methodological model to instruct the assessment of the potential impacts posed by proposed *** to Human Interventions for Environmental Licensing determination(SHIELd)includes a novel geomorphological interpretation of the Environmental Impact Assessment(EIA).It considers the impact of human interventions on geomorphological processes and landscape functioning in the context of the entire ecosystem,going further than the classical concept of *** susceptibility of the site informs the screening stage,allowing local conditions to help define the criteria used in the ***,the level of detail of the environmental baseline is scoped by considering the degree of disturbance of natural processes posed by human *** this geomorphological susceptibility model on different kinds of environments would allow shifting the environmental licensing practices from the prevailing anthropocentric and static conception of the environment towards an Ecosystem *** addresses the need to improve the screening and scoping stages that form the basis of the rest of any *** introduces several innovations to EIA including the incorporation of fuzzy logic,a preassembled database of contributions form experts,and a shifting of emphasis from the type of proposed intervention to the type of environment and its relative susceptibility.

关键词： Processes and landforms Expert knowledge Ecosystem approach Screening Scoping

Tribological Properties and Corrosion Resistance Enhancement of H13 Hot Work Steel by Means of CrN/TiN Multilayers

在线全文

学校读者我要写书评

暂无评论

材料科学与工程（中英文版） 2010年第6期4卷 51-59页

作者： Bejarano Gaitan Gilberto Gomez botero Maryory osorio Alberto jaime Caicedo Anguio julio Aperador Chaparro William Grupo de Corrosion y Proteccion de la Universidad de Antioquia Calle 67 No 53-108 Medellin Colombia Grupo de Estado Solido de la Universidad de dntioquia Calle 67 No 53-108 Medellin Colombia Grupo de Peliculas delgadas Dpto de Fisica Universidad del Valle Calle 13 No 100-000 Cali Colombia lngenieria Mecanica Escuela Colombiana de Ingenieria AK 45 No. 205-59 Bogota Colombia

Steel AISI H13 is used mainly for fabrication of hardened hot work tools; however life time of this steel is limited by its relatively low wear and corrosion resistance, if it would be exposed to an aggressive environment. It is widely known that the performance of tools and parts that undergo high mechanical load can be enhanced by the use of monolayer hard thin coatings. However, the use of such coatings as corrosion barriers is often unsatisfactory, since the deposition processes usually generate small pores and pinholes, which negatively affect the electrochemical behaviour of the coating/substrate system. On the other hand, if a hard thin film covers a less noble material, such as steel, small anodic areas could be generated and exposed to an aggressive environment a galvanic corrosion would take place. Therefore, it is also necessary to optimize the design of the coating system used in order to achieve the better relationship between mechanical and electrochemical properties for the whole system. The intention of the presented work was to enhance the tribological properties and corrosion resistance of steel AISI H13 through the use of a CrN/TiN multilayer coatings system, which were deposited by using the balanced magnetron sputtering technique.

关键词：热作模具钢摩擦学性能耐腐蚀性氮化钛 H13 性能增强多层膜 CrN

A robust new metric of phenotypic distance to estimate and compare multiple trait differences among populations

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

Current Zoology 2012年第3期58卷 426-439页

作者： Rebecca SAFRAN Samuel FLAXMAN Michael KOPP darren E. IRWIN derek BRIGGS Matthew R. EVANS W. Chris FUNK david A. GRAY Eileen A. HEBETS Nathalie SEddON Elizabeth SCORdATO Laurel B. SYMES joseph A. TOBIAS david P. L. TOEWS j. Albert C. UY department of Ecology and Evolutionary Biology University of Colorado Boulder CO 80309 U.S.A. Mathematics and B iosciences Group Faculty of Mathematics University of Vienna A-1090 Vienna Austria Current address Evolutionary Biology and Modeling Group Faculty of Sciences Aix-Marseille University 13331 Marseille France. department of Zoology University of British Columbia 6270 University Boulevard Vancouver BC Canada V6T 1Z4. Research ＆ Evaluation Methodology School of Education University of Colorado Boulder CO 80309 U.S.A. School of Biological and Chemical Sciences Queen Mary University of London London E1 4NS department of Biology Colorado State University Fort Collins CO 80523 U.S.A. department of Biology California State University Northridge CA 91330 U.S.A. School of Biological Sciences University of Nebraska Lincoln NE 68588 U.S.A. Edward Grey Institute Department of Zoology University of Oxford Oxford OX1 3PS UK Committee on Evolutionary Biology The University of Chicago Chicago IL 60637U.S.A. department of Biology Dartmouth College Hanover NH 03755 U.S.A. department of Biology University of Miami Coral Gables FL 33146 U.S.A.

Whereas a rich literature exists for estimating population genetic divergence, metrics of phenotypic trait divergence are lacking, particularly for comparing multiple traits among three or more populations. Here, we review and analyze via simula- tion Hedges＇ g, a widely used parametric estimate of effect size. Our analyses indicate that g is sensitive to a combination of unequal trait variances and unequal sample sizes among populations and to changes in the scale of measurement. We then go on to derive and explain a new, non-parametric distance measure, ＇Aft＇, which is caiculated based upon a joint cumulative distribution function （CdF） from all populations under study. More precisely, distances are measured in terms of the percentiles in this CdF at which each population＇s median lies. Ap combines many desirable features of other distance metrics into a single metric; namely, compared to other metrics, p is relatively insensitive to unequal variances and sample sizes among the populations sam- pied. Furthermore, a key feature of Ap--and our main motivation for developing it--is that it easily accommodates simultaneous comparisons of any number of traits across any number of populations. To exemplify its utility, we employ Ap to address a ques- tion related to the role of sexual selection in speciation： are sexual signals more divergent than ecological traits in closely related taxa？ Using traits of known function in closely related populations, we show that traits predictive of reproductive performance are indeed, more divergent and more sexually dimorphic than traits related to ecological adaptation [Current Zoology 58 （3）： 426-439 2012].

关键词： Effect size Phenotype divergence Sexual dimorphism Sexual selection Speciation