检索结果-南通市图书馆

Potential Use of Strain Hardening ECC in Permanent Formwork with Small Scale Flexural Beams

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2009年第3期24卷 482-487页

作者：李贺东 christopher k.y.l.ung Department of Civil Engineering Hong Kong University of Science and Technology

Utilizing pre-cast ECC panels as participating permanent formwork of concrete members, and the validity of using ECC to disperse the single crack in concrete into multiple ones in ECC were studied. In the process, totally two kinds of ECC with different tensile properties, 7 series of flat panels with different top surface figures and 3 U-shape panels with different inner surface forms were investigated. To evaluate the performance of the permanent formworks, small ECC-concrete composite beams were cast and tested mechanically. The 4-point bending test results show that the use of pre-cast ECC panels as permanent formwork can significantly improve the load capacity and toughness of a concrete member, effectively dispersing single widely opened crack in concrete into multiple ones in ECC. Most permanent formworks show perfect bond with the concrete cast on them, while the ones with partially debonded zone achieve the best mechanical performance. The U-shape permanent formworks show better performances than the flat ones, achieving much betler improvements in both the load capacity and toughness, together with better crack width control.

关键词： pseudo strain hardening cementitious composites permanent formwork toughness crack

Compressive properties of a novel slurry-infiltrated fiber concrete reinforced with arc-shaped steel fibers

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第6期24卷 543-556页

作者： Hedong lI yabiao lI yunfeng PAN P.l.NG christopher k.y.l.ung Xin ZHAO School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Civil Engineering The University of Hong KongHong Kong 999077China Faculty of Civil Engineering Vilnius Gediminas Technical UniversityVilnius LT-10223Lithuania Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China School of Civil Engineering and Architecture Zhejiang University of Science and TechnologyHangzhou 310023China

Slurry-infiltrated fiber concrete(SIFCON)is a sort of strain hardening cement-based composite material,typically made with 5%–20%steel *** study focused on a novel type of SIFCON in which hooked-end steel fibers were replaced by arc-shaped steel *** quasi-static compressive properties of the SIFCON were first *** results suggested that using arc-shaped steel fibers in lieu of hooked-end steel fibers increased the quasi-static compressive strength by 47.1%and the strain at peak stress by 56.3%.We attribute these improvements to new crack-resisting mechanisms,namely“fiber crosslock”,“dual bridging”,and“confinement loops”,when the arc-shaped steel fibers are introduced into *** high impact resistance is a special property of SIFCON that is of practical significance,the dynamic compressive properties of arc-shaped steel fiber SIFCON were studied by using an 80-mm-diameter split Hopkinson pressure bar(SHPB).The results showed that the dynamic compressive strength,dynamic increase factor(DIF),and dynamic toughness of SIFCON all increased with the strain *** SIFCON incorporating arc-shaped steel fibers proved to have significant advantages in structural applications requiring high impact resistance.

关键词： Slurry-infiltrated fiber concrete(SIFCON) Arc-shaped steel fiber Quasi-static compressive properties Spilt Hopkinson pressure bar(SHPB) Dynamic compressive properties

Early Paleogene stratigraphic sequences,mammalian evolution and its response to environmental changes in Erlian Basin,Inner Mongolia,China

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

Science China Earth Sciences 2010年第12期53卷 1918-1926页

作者： christopher k.BEARD Daniel l.GEBO Section of Vertebrate Paleontology Carnegie Museum of Natural History4400 Forbes AvenuePittsburghPA 15213USA Department of Anthropology Northern Illinois UniversityDeKalbIL 60115USA

Paleogene strata in the Huheboerhe area,Erlian Basin,Inner Mongolia,China have been subdivided into three lithological units:the Nomogen Formation,the Arshanto Formation,and the Irdin Manha *** least 12 mammal-bearing horizons have been recognized in these formations,of which 4 in the Nomogen Formation,6 in the Arshanto Formation,and 2 in the Irdin Manha *** investigation proved that the "Houldjin Formation" recognized in this area by the Central Asiatic Expeditions(CAE) of the American Museum Natural History in the 1920s is actually the Irdin Manha Formation,while the "Irdin Manha Formation" of CAE is the Arshanto Formation.A recent paleomagnetic study suggests that the upper part of the Nomogen Formation is early Eocene in age and the Arshanto Formation is mainly early Eocene rather than middle Eocene as previously *** Gashatan,Bumbanian,and Arshantan land mammal ages are correlated respectively to the Thanetian,the early ypresian,and the middle ypresian through earliest lutetian of the Geological Time *** land mammal ages are also correlated with the late Tiffanian through Clarkforkian,the early Wasatchian,and the middle-late Wasatchian and most of the Bridgerian of the North American land Mammal *** the early Paleogene,the mammalian history of the Erlian Basin was dominated by the appearance of new mammalian families and the replacement of a variety of genera and species,corresponding to the gradual climatic changes during this time *** abrupt emergence of several modern mammalian orders at the beginning of the Eocene is probably related to extreme climatic warming in relation to the Paleocene-Eocene Thermal Maximum.

关键词： Erlian Basin Paleogene mammal faunal turnover biochronology environmental response

Assessing volcanic origins within detrital zircon populations——A case study from the Mesozoic non-volcanic margin of southern Australia

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2019年第4期10卷 1371-1381页

作者： Milo Barham christopher l. kirkland Martin Danisík Centre for Exploration Targeting (CET)- Curtin Node The Institute for Geoscience Research (TIGeR)School of Earth and Planetary SciencesCurtin UniversityGPO Box U1987PerthWA 6845Australia GeoHistory Facility John de Laeter CenterCurtin UniversityGPO Box U1987PerthWA 6845Australia

Detrital zircon U/Pb geochronology is a common tool used to resolve stratigraphic questions,inform basin evolution and constrain regional geological *** favourable circumstances,detrital zircon populations can contain a concomitant volcanic contribution that provides constraints on the age of ***,for non-volcanic settings,proving isolated detrital zircon grains are from contemporaneous and potentially remote volcanism is *** we use same grain(U-Th)/He thermochronology coupled with U/Pb geochronology to identify detrital zircon grains of contemporary volcanic origin.(U-Th)/He ages from Cretaceous zircon grains in southern Australia define a single population with a weighted mean age of 104±6.1 *** from zircon U/Pb geochronology and palynology(~104.0-107.5 Ma).Detrital zircon trace-element geochemistry is consistent with a continental signature for parent rocks and coupled with detrital grain ages,supports derivation from a>2000 km distant early-to mid-Cretaceous Whitsunday Volcanic Province in eastern ***,integration of biostratigraphy,single-grain zircon double-dating(geochronology and thermochronology)and grain geochemistry enhances fingerprinting of zircon source region and transport history.A distal volcanic source and rapid continental-scale transport to southern Australia is supported here.

关键词： Provenance Grain history Thermochronology Geochronology Source to sink Trace-elements

Comparative analysis of empirical and deep learning models for ionospheric sporadic E layer prediction

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2025年第1期9卷 10-19页

作者： Bingkun yu PengHao Tian XiangHui Xue christopher JScott Hailun ye JianFei Wu Wen yi TingDi Chen Xiankang Dou Institute of Deep Space Sciences Deep Space Exploration LaboratoryHefei 230088China CAS key laboratory of Geospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Hefei National laboratory University of Science and Technology of ChinaHefei 230088China Department of Meteorology University of ReadingReading RG66BBUK

Sporadic E(Es)layers in the ionosphere are characterized by intense plasma irregularities in the E region at altitudes of 90-130 *** they can significantly influence radio communications and navigation systems,accurate forecasting of Es layers is crucial for ensuring the precision and dependability of navigation satellite *** this study,we present Es predictions made by an empirical model and by a deep learning model,and analyze their differences comprehensively by comparing the model predictions to satellite RO measurements and ground-based ionosonde *** deep learning model exhibited significantly better performance,as indicated by its high coefficient of correlation(r=0.87)with RO observations and predictions,than did the empirical model(r=0.53).This study highlights the importance of integrating artificial intelligence technology into ionosphere modelling generally,and into predicting Es layer occurrences and characteristics,in particular.

关键词： ionospheric sporadic E layer radio occultation ionosondes numerical model deep learning model artificial intelligence

Effect of cylinder wall parameters on the final packing density of mono-disperse spheres subject to three-dimensional vibrations Author links open overlay panel

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第8期91卷 211-225页

作者： Jack R.Grogan Andrei l.Nicuşan christopher R.k.Windows-yule School of Chemical Engineering The University of BirminghamEdgbastonBirminghamB152TTUK

Achieving densely packed particles is desirable within the industries of ceramics,pharmaceuticals,defence and additive *** this work,we use the discrete element method(DEM)to determine the effect of wall parameters on the final packing density of mono-disperse spheres subject to 4 varying three-dimensional vibration and fill *** focus specifically on the impact of the container wall parameters on the particles'final packing *** on from the validation of the DEM simulation the particle-wall coefficient of restitution,the particle-wall coefficient of rolling friction and the particle-wall coefficient of sliding friction were varied individually and the effect on the final packing density *** relatively low particle-particle friction glass beads,the effect of these wall properties had no discernible effect on the final packing density *** on from these findings the particle-wall properties were varied at the extreme values of particle-particle coefficient of rolling friction and particle-particle coefficient of sliding *** a particle-particle coefficient of sliding friction=1,increases in particle-wall coefficient of restitution resulted in a minor increase in the final packing density of particles though this was not statistically *** a particle-particle coefficient of sliding friction=1,increases in particle-wall coefficient of rolling friction resulted in a minor decrease in the final packing density of the particles though again not to a degree where the trend can,with complete certainty,be distinguished from the random error across the ***,when the particle-particle coefficient of sliding friction=1,increases in particle-wall coefficient of sliding friction resulted in a significant decrease in the final packing density of *** decrease was attributed to the propagation of force chains throughout the *** significant decrease in final packing density with

关键词： Vibropacking Packing Densification Vibration Discrete element method Friction Wall friction Restitution

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

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

Friction 2021年第3期9卷 583-597页

作者： Florian kÖNIG christopher SOUS Georg JACOBS Institute for Machine Elements and Systems Engineering Rheinisch-Westfälische Technische Hochschule Aachen UniversitySchinkelstraße 10Aachen 52062Germany

With the increased use of automotive engine start-stop systems,the numerical prediction and reduction of frictional losses in sliding bearings during starting and stopping procedures has become an important *** engineering practice,numerical simulations of sliding bearings in automotive engines are performed with statistical asperity contact models with empirical values for the necessary surface *** aim of this study is to elucidate the applicability of these approaches for the prediction of friction in sliding bearings subjected to start-stop *** this purpose,the friction performance of sliding bearings was investigated in experiments on a test rig and in transient mixed elasto-hydrodynamic simulations in a multi-body simulation environment(mixed-EHl/MBS).In mixed-EHl/MBS,the extended Reynold’s equation with flow factors according to Patir and Cheng has been combined on the one hand with the statistical asperity contact model according to Greenwood and Tripp and on the other hand with the deterministic asperity contact model according to *** detailed comparison of simulation and experimental results clarifies that the application of statistical asperity contact models with empirical values of the necessary inputs leads to large deviations between experiment and *** actual distribution and position of surface roughness,as used in deterministic contact modelling,is necessary for a reliable prediction of the frictional losses in sliding bearings during start-stop operation.

关键词： sliding bearing friction wearing-in contact model,mixed elasto-hydrodynamic simulation