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Impact of surface roughness on the coefficient of friction of polymer-on-polymer contacts for deflection pulley-rope systems in the lift industry

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Friction 2024年第9期12卷 2126-2138页

作者： Ainhoa GUINEA Andrea AGINAGALDE Wilson TATO Iñigo LLAVORI Pablo GARCIA Leire ARRAIAGO Alaitz ZABALA Mechanical and Industrial Production Department Mondragon UnibertsitateaMondragon 20500Spain Orona EIC Orona IdeoHernani 20120Spain

The coefficient of friction(CoF)between the deflection pulley and rope in a lift strongly affects the life span of the *** surface roughness is a key factor affecting the metallic pulley–rope CoF,its effect on polymeric pulleys is *** present study analyses the effect of roughness and working conditions on cast polyamide 6(PA6G)deflection pulley–thermoplastic polyurethane(TPU)-coated rope *** statistical analysis revealed that the effect of surface roughness on the CoF for low-load tests was *** present study contributes significantly to parameter selection in deflection pulley machining to minimise friction between the pulley and rope.

关键词： polymer-on-polymer friction roughness dry sliding

High-temperature tribological performance of functionally graded Stellite 6/WC metal matrix composite coatings manufactured by laser-directed energy deposition

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Friction 2024年第3期12卷 522-538页

作者： Marta OSTOLAZA Alaitz ZABALA Jon Inaki ARRIZUBIETA Iñigo LLAVORI Nagore OTEGI Aitzol LAMIKIZ Department of Mechanical Engineering University of the Basque Country UPV/EHUPlaza Torres Quevedo 1Bilbo 48013Spain Faculty of Engineering Mechanics and Industrial ProductionMondragon UnibertsitateaLoramendi 4Mondragon 20500Spain

Wear-driven tool failure is one of the main hurdles in the *** issue can be addressed through surface coating with ceramic-reinforced metal matrix ***,the maximum ceramic content is limited by *** this work,the tribological behaviour of the functionally graded WC-ceramic-particlereinforced Stellite 6 coatings is *** that end,the wear resistance at room temperature and 400°C is ***,the tribological analysis is supported by crack sensitivity and hardness evaluation,which is of utmost importance in the processing of composite materials with *** indicate that functionally graded materials can be employed to increase the maximum admissible WC content,hence improving the tribological behaviour,most notably at high ***,a shift from abrasive to oxidative wear is observed in high-temperature wear testing.

关键词： friction coating metal matrix composite functionally graded materials high temperature laserdirected energy deposition

Woody plant taxonomic,functional,and phylogenetic diversity decrease along elevational gradients in Andean tropical montane forests:Environmental filtering and arrival of temperate taxa

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Plant Diversity 2024年第4期46卷 491-501页

作者： Guillermo Bañares-de-Dios Manuel J.Macía Gabriel Arellano Íñigo Granzow-de la Cerda Julia Vega-álvarez Itziar Arnelas Carlos I.Espinosa Norma Salinas Luis Cayuela Departamento de Biología y Geología Física y Química InorgánicaUniversidad Rey Juan CarlosCalle Tulipán s/nMóstolesMadridES-28933Spain Departamento de Biología Área de BotánicaUniversidad Autónoma de MadridCalle Darwin 2MadridES-28049Spain Centro de Investigación en Biodiversidad y Cambio Global(CIBC-UAM) Universidad Autónoma de MadridCalle Darwin 2MadridES-28049Spain Ecology and Evolutionary Biology University of MichiganAnn ArborMI 48109USA Oikobit LLC ***AlbuquerqueNM87120USA Real Jardín Botánico–CSIC Plaza Murillo 2MadridES-28014Spain Departamento de Biología Animal EcologíaParasitologíaEdafología y Química AgrícolaUniversidad de SalamancaCalle Donantes de Sangre s/nSalamancaES-37007Spain Departamento de Biodiversidad Ecología y EvoluciónUniversidad Complutense de MadridCalle JoséAntonio Nováis 12Ciudad UniversitariaES-28040Spain Departamento de Ciencias Biológicas y Agropecuarias Universidad Técnica Particular de LojaA.P.11-01-608 LojaEcuador Sección Química Pontificia Universidad Católica del PerúA.P.Lima 32LimaPeru ECI School of Geography and EnvironmentUniversity of OxfordOX13QYOxfordshireUnited Kingdom Instituto de Investigación en Cambio Global(IICG-URJC) Universidad Rey Juan CarlosCalle Tulipán s/nMóstolesMadridES-28933Spain

Mountains are paramount for exploring biodiversity patterns due to the mosaic of topographies and climates encompassed over short *** research has traditionally focused on taxonomic diversity when investigating changes along elevational gradients,but other facets should be *** first time,we simultaneously assessed elevational trends in taxonomic,functional,and phylogenetic diversity of woody plants in Andean tropical montane forests and explored their underlying ecological and evolutionary *** investigation covered four transects(traversing ca.2200 m a.s.l.) encompassing 114 plots of 0.1 ha across a broad latitudinal range(ca.10°).Using Hill numbers to quantify abundance-based diversity among 37,869 individuals we observed a consistent decrease in taxonomic,functional,and phylogenetic diversity as elevation increased,although the decrease was less pronounced for higher Hill *** exception was a slight increase in phylogenetic diversity when dominant species were *** decrease in taxonomic and functional diversity might be attributed to an environmental filtering process towards highlands,where the increasingly harsher conditions exclude species and functional ***,the differences in steepness decrease between Hill orders suggest that rare species disproportionately contribute to functional *** phylogenetic diversity the shifting elevational trend between Hill orders indicates a greater than previously considered influence in central Andean highlands of tropical lowlands originated species with strong niche conservatism relative to distantly related temperate *** could be explained by a decreasing presence and abundance of temperate,extratropical taxa towards the central Andes relative to northern or southern Andes,where they are more prevalent.

关键词： Altitudinal gradients Andes Environmentalﬁltering Out of the Tropical Lowlands Functional rarity Tropical Niche Conservatism

Debaryomyces hansenii supplementation in low fish meal diets promotes growth,modulates microbiota and enhances intestinal condition in juvenile marine fish

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Journal of Animal Science and Biotechnology 2024年第1期15卷 253-276页

作者： Ignasi Sanahuja Alberto Ruiz Joana P.Firmino Felipe E.Reyes-López Juan B.Ortiz-Delgado Eva Vallejos-Vidal Lluis Tort Dariel Tovar-Ramírez Isabel M.Cerezo Miguel A.Moriñigo Carmen Sarasquete Enric Gisbert Aquaculture Program Institute of Agrifood Research and Technology(IRTA)La Rapita 43540Spain Centro de Biotecnologia Acuicola Universidad de Santiago de ChileSantiagoChile Instituto de Ciencias Marinas de Andalucia(ICMAN-CSIC) Avda.Republica Saharaui no 2Campus Universitario Rio San PedroPuerto RealCadiz 11510Spain Nucleo de Investigaciones Aplicadas en Ciencias Veterinarias y Agronomicas Facultad de Medicina Veterinaria y AgronomiaUniversidad de Las AmericasSantiagoChile Department of Cell Biology Physiologyand ImmunologyUniversitat Autonoma de BarcelonaBarcelonaSpain Centro de Investigaciones Biologicas del Noroeste SC CIBNORLa PazMexico Department of Microbiology Instituto de Biotecnologia Y Desarrollo Azul(IBYDA)Faculty of SciencesUniversity of Malaga29010 MalagaSpain SCBI Bioinformatic UnitUniversity of Malaga29590 MalagaSpain

Background The development of a sustainable business model with social acceptance,makes necessary to develop new strategies to guarantee the growth,health,and well-being of farmed *** hansenii is a yeast species that can be used as a probiotic in aquaculture due to its capacity to i)promote cell proliferation and differen-tiation,ii)have immunostimulatory effects,iii)modulate gut microbiota,and/or iv)enhance the digestive *** provide inside into the effects of *** on juveniles of gilthead seabream(Sparus aurata)condition,we inte-grated the evaluation of the main key performance indicators coupled with the integrative analysis of the intestine condition,through histological and microbiota state,and its transcriptomic *** After 70 days of a nutritional trial in which a diet with low levels of fishmeal(7%)was supplemented with 1.1%of ***(17.2×10^(5) CFU),an increase of ca.12%in somatic growth was observed together with an improve-ment in feed conversion in fish fed a yeast-supplemented *** terms of intestinal condition,this probiotic modu-lated gut microbiota without affecting the intestine cell organization,whereas an increase in the staining intensity of mucins rich in carboxylated and weakly sulphated glycoconjugates coupled with changes in the affinity for certain lectins were noted in goblet *** in microbiota were characterized by the reduction in abundance of several groups of Proteobacteria,especially those characterized as opportunistic *** microarrays-based transcrip-tomic analysis found 232 differential expressed genes in the anterior-mid intestine of ***,that were mostly related to metabolic,antioxidant,immune,and symbiotic *** Dietary administration of *** enhanced somatic growth and improved feed efficiency param-eters,results that were coupled to an improvement of intestinal condition as histochemical and transcriptomic tools *** probiotic ye

关键词： Debaryomyces hansenii Intestine condition Low fish meal diet Microbiota Transcriptomics Yeast probiotic

A Comparative Study of the L2 Pragmatic Competence of University Students in Hong Kong and the Chinese Mainland:The Contributions of Sociocultural Context and Linguistic Proficiency

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Chinese Journal of Applied Linguistics 2024年第3期47卷 371-392,524页

作者： Scott AUBREY rod ELLIS Faculty of Education Chinese University of Hong Kong School of Education Curtin UniversityAustralia

This study investigates the differences in pragmatic competence between Hong Kong and Chinese mainland university *** included 19 native speakers of English,115 Chinese mainland students,divided into those who had spent time abroad in an English-speaking country(CM A)and those who had not(CM NA),and 97 Hong Kong students,divided into those from an English-medium secondary school(Hong Kong EMI)and those from a Chinese-medium school(Hong Kong CMI).Linguistic proficiency was measured by a C-test,and pragmatic competence by a Metapragmatic Knowledge Test,an Irony Test and a Monologic Role *** scores were compared using ANCOVAs to control for differences in *** results point to a continuum of pragmatic competence—EMI>CMI>CM A>CM NA—reflecting the groups’access to English in real-life *** differences between the Hong Kong groups and the Chinese mainland groups were clearest in those tests measuring processing capacity(i.e.,Irony Response Time and the Monologic Role Play).CM A,but not CM NA,performed as well as the Hong Kong groups on measures of metapragmatic *** results are discussed in terms of Bialystok’s(1993)distinction between analyzed representation and control of processing.

关键词： pragmatic competence social context Hong Kong the Chinese mainland metapragmatic knowledge processing capacity

Multiphysics Simulation of a Novel Concept of MEMS-based Solid Propellant Thruster for Space Propulsion

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Journal of Thermal Science 2011年第6期20卷 527-533页

作者： José A.Moríigo José Hermida-Quesada Dept.of Space Programmes National Institute for Aerospace Technology Ctra.Ajalvir km.4Torrejón de Ardoz 28850 MadridSpain Propulsion EngineerPh.D. Dept.of Aerodynamics and Propulsion National Institute for Aerospace Technology Ctra.Ajalvir km.4Torrejón de Ardoz 28850 MadridSpain

This work analyzes a novel MEMS-based architecture of submillimeter size thruster for the propulsion of small spacecrafts,addressing its preliminary characterization of *** architecture of microthruster comprises a setup of miniaturized channels surrounding the solid-propellant reservoir filled up with a high-energetic *** channels guide the hot gases from the combustion region towards the nozzle entrance located at the opposite side of the *** simulations of the transient response of the combustion gases and wafer heating in thruster firings have been conducted with FLUENT under a multiphysics modelling that fully couples the gas and solid parts *** approach includes the gas-wafer and gas-polymer thermal exchange,burnback of the polymer with a simplified non-reacting gas pyrolysis model at its front,and a slip-model inside the nozzle portion to incorporate the effect of gas-surface and rarefaction onto the gas ***,accurate characterization of thruster operation requires the inclusion of the receding front of the polymer and heat transfer in the moving gas-solid *** study stresses the improvement attained in thermal management by the inclusion of lateral micro-channels in the *** particular,the temperature maps reveal the significant dependence of the thermal loss on the instantaneous surface of the reservoir wall exposed to the heat flux of hot ***,the simulations stress the benefit of implementing such a pattern of micro-channels connecting the exit of the combustion reservoir with the *** results prove that hot gases flowing along the micro-channels exert a sealing action upon the heat flux at the reservoir wall and partly mitigate the overall thermal loss at the inner-wall vicinity during the *** analysis shows that propellant decomposition rate is accelerated due to surface preheating and it suggests that a delay of the flame extinction into the reservoir

关键词： micronozzles spacecraft micropropulsion solid propellant thrusters

Electro-tribological properties of diamond like carbon coatings

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Friction 2020年第2期8卷 451-461页

作者： Iñigo BRACERAS Iñigo IBÁNEZ Santiago DOMINGUEZ-MEISTER Xabier VELASCO Marta BRIZUELA Iñaki GARMENDIA Tecnalia Research&Innovation Mikeletegi Pasealekua 2Donostia-San Sebastian 20009Spain Mechanical Engineering Department University of the Basque Country UPV/EHUPlaza de Europa1Donostia-San Sebastian 20018Spain

Diamond like carbon(DLC)coatings typically present good self-lubricating tribological properties that could be of interest in sliding dielectric contacts in multiple electrical *** this work electro-tribological studies have been performed on several DLC coatings against aluminum in different humidity conditions,in which the coefficients of friction(CoFs)and electrical contact resistance(ECR)were continuously *** show that CoF and ECR data can be linked to the properties of the coatings(thickness,finishing,microstructure,residual stresses,and wettability)and the degradation modes of their tribological and electrical ***,electro-tribological data can provide valuable information about the performance of dielectric coatings,the reasons behind it,and assist in the development of the *** also shows potential for on-line monitoring of coated parts in operation.

关键词： DLC electro-tribology ECR-electrical contact resistance coefficient of friction

Analysis of Viscous Heating in a Micro-Rocket Flow and Performance

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Journal of Thermal Science 2008年第2期17卷 116-124页

作者： José A.Moríigo José Hermida Quesada Dept.of Space Programmes National Institute for Aerospace Technology Dept.of Aerodynamics and Propulsion National Institute for Aerospace Technology

Micro-rockets for propulsion of small spacecrafts exhibit significant differences with regard to their macroscale counterparts,mainly caused by the role of the viscous dissipation and heat transfer processes in the micron-sized *** goal of this work is to simulate the transient operation of a micro-rocket to investigate the effects of viscous heating on the flow and performance for four configurations of the expanding gas and wafer *** modelling follows a multiphysics approach that solves the fluid and solid regions fully coupled.A contin- uum-based description that incorporates the effects of gas rarefaction through the micro-nozzle,viscous dissipa- tion and heat transfer at the solid-gas interface is ***-equilibrium is addressed with the implementa- tion of a 2nd-order slip-model for the velocity and temperature at the *** results stress that solid-fluid cou- pling exerts a strong influence on the flowfield and performance as well as the effect of the wafer during the first instants of the transient in micro-rockets made of low and high thermal conductivity materials.

关键词： Micronozzles propulsion MEMS slip flow viscous heating

Slip-model Performance for Underexpanded Micro-scale Rocket Nozzle Flows

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Journal of Thermal Science 2007年第3期16卷 223-230页

作者： JoséA.Morí■igo JoséHermidaQuesada Francisco Caballero Requena Dept.of Space Programmes Dept.of

In aerospace Micro-Electro Mechanical Systems （MEMS）, the characteristic length scale of the flow approaches the molecular mean free path, thus invalidating the continuum description and enforcing the use of particle methods, like the Direct Simulation Monte Carlo （DSMC）, to deal with the non-equilibrium regions. Within the slip-regime （0.01〈Kn〈-0.1） both approaches, continuum and particle-based, seem to behave well in terms of accuracy. The present study summarizes the implementation and results obtained with a 2nO-order slip boundary condition in a Navier-Stokes solver to address the rarefaction near the nozzle walls. Its assessment and application to a cold-gas micro-scale conical nozzle of 300μm throat diameter, discharging into the low-pressure freestream, constitutes the major aim of the work. The slip-model incorporates the velocity slip with thermal creep and temperature jump, thus permitting to deal with non-isothermal flows as well. Results show that the gas experiences an intense rarefaction in the lip vicinity, pointing to the limits of model validity. Furthermore, a strong Mach deceleration is observed, attributed to the rather thick subsonic boundary layer and supersonic bulk heating caused by the viscous dissipation, in contrast with the expansion to occur in large rocket nozzles during underexpanded operation.

关键词： Slip flow MEMS micronozzles