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Effects of inner sleeves on the inner frictional resistance of open-ended piles driven into sand

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frontiers of Structural and Civil Engineering 2016年第4期10卷 499-505页

作者： janaka j. KUMARA Yoshiaki KIKUCHI Takashi KURASHINA Takahiro YAjIMA Department of Civil Engineering Tokyo University of Seience Noda 278-8510 Japan Maeda Corporation Tokyo 102-8151 Japan

In open-ended piles, inner friction is developed between inner pile shaf and the inner soil. Inner frictional resistance depends largely on the degree of soil plugging, which is influenced by many factors including pile diameter, relative density and end conditions of piles. In this paper, effects of inner sleeves on inner frictional resistance are discussed. The experiments were conducted on a medium-dense sandy ground using laboratory-scale piles. It was observed that the piles penetrated under partially-plugged or unplugged state. The results suggest that inner fiictional resistance, Qin increases with sleeve height, l linearly and requires 2D （D is pile outer diameter） of l to produce a large as 50% of Qt by Qin （Qt is total resistance）. The results also indicate that bearing capacity increases with wall thickness at the pile tip, which can be attributed to the increase in annular area. The results also indicate that soil plug height is independent of sleeve height. The results also reveal that the penetration of straight piles is closer to unplugged state than the sleeved piles. The results of incremental filling ratio and plug length ratio also indicate that the degree of soil plugging is affected by the sleeve height.

关键词： bearing capacity inner frictional resistance inner sleeve open-ended piles soil plugging

Stability of Projection Methods for Incompressible flows Using High Order Pressure-Velocity Pairs of Same Degree:Continuous and Discontinuous Galerkin formulations

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Communications in Computational Physics 2014年第8期16卷 817-840页

作者： E.ferrer D.Moxey R.H.j.Willden S.j.Sherwin ETSIA–School of Aeronautics Universidad Politecnica de MadridPza.Cardenal Cisneros 3MadridE-28040Spain. Department of Aeronautics Imperial College LondonLondonSW72AZUK. Department of Engineering Science University of OxfordParks RoadOxfordOX13PJUK.

This paper presents limits for stability of projection type schemes when using high order pressure-velocity pairs of same *** high order h/p variational methods encompassing continuous and discontinuous Galerkin formulations are used to explain previously observed lower limits on the time step for projection type schemes to be stable[18],when h-or p-refinement strategies are *** addition,the analysis included in this work shows that these stability limits do not depend only on the time step but on the product of the latter and the kinematic viscosity,which is of particular importance in the study of high Reynolds number *** show that high order methods prove advantageous in stabilising the simulations when small time steps and low kinematic viscosities are *** upon this analysis,we demonstrate how the effects of this instability can be reduced in the discontinuous scheme by introducing a stabilisation term into the global ***,we show that these lower limits are compatible with Courantfriedrichs-Lewy(CfL)type restrictions,given that a sufficiently high polynomial order or a mall enough mesh spacing is selected.

关键词： Incompressible Navier-Stokes equations projection methods velocity-correction continuous Galerkin discontinuous Galerkin inf-sup LBB condition.

Study on Characteristics of Co-firing Ammonia/Methane fuels under Oxygen Enriched Combustion Conditions

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journal of Thermal Science 2018年第3期27卷 270-276页

作者： XIAO Hua WANG Zhaolin VALERA-MEDINA Agustin BOWEN Philip j School of Engineering Cardiff University College of Energy Xiamen University

Having a background of utilising ammonia as an alternative fuel for power generation, exploring the feasibility of co-firing ammonia with methane is proposed to use ammonia to substitute conventional natural gas. However, improvement of the combustion of such fuels can be achieved using conditions that enable an increase of oxygenation, thus fomenting the combustion process of a slower reactive molecule as ammonia. Therefore, the present study looks at oxygen enriched combustion technologies, a proposed concept to improve the performance of ammonia/methane combustion. To investigate the characteristics of ammonia/methane combustion under oxygen enriched conditions, adiabatic burning velocity and burner stabilized laminar flame emissions were studied. Simulation results show that the oxygen enriched method can help to significantly enhance the propagation of ammonia/methane combustion without changing the emission level, which would be quite promising for the design of systems using this fuel for practical applications. furthermore, to produce low computational-cost flame chemistry for detailed numerical analyses for future combustion studies, three reduced combustion mechanisms of the well-known Konnov's mechanism were compared in ammonia/methane flame simulations under practical gas turbine combustor conditions. Results show that the reduced reaction mechanisms can provide good results for further analyses of oxygen enriched combustion of ammonia/methane. The results obtained in this study also allow gas turbine designers and modellers to choose the most suitable mechanism for further combustion studies and development.

关键词： Ammonia/Methane Oxygen-enriched Combustion Reduced Mechanism Gas Turbine

EffECT Of ELECTROLESS PLATING COBALT UPON CHARACTERISTICS Of NICKEL HYDROXIDE ELECTRODEfORRECHARGEABLEALKALINEBATTERIES

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中国有色金属学会会刊：英文版 1998年第4期8卷 135-141页

作者： Wang, XY Zhang, YS Yan, j Yuan, HT Song, DY Nankai Univ Inst New Energy Mat Chem Tianjin 300071 Peoples R China

ＩＮＴＲＯＤＵＣＴＩＯＮＮｉｃｋｅｌｈｙｄｒｏｘｉｄｅｅｌｅｃｔｒｏｄｅｓｈａｖｅｂｅｅｎｗｉｄｅｌｙｕｓｅｄａｓｐｏｓｉｔｉｖｅｅｌｅｃｔｒｏｄｅｉｎＮｉＣｄ，ＮｉＨ２ａｎｄＮｉＭＨｓｅｃｏｎｄａｒｙｂａｔ... 详细信息

ＩＮＴＲＯＤＵＣＴＩＯＮＮｉｃｋｅｌｈｙｄｒｏｘｉｄｅｅｌｅｃｔｒｏｄｅｓｈａｖｅｂｅｅｎｗｉｄｅｌｙｕｓｅｄａｓｐｏｓｉｔｉｖｅｅｌｅｃｔｒｏｄｅｉｎＮｉＣｄ，ＮｉＨ２ａｎｄＮｉＭＨｓｅｃｏｎｄａｒｙｂａｔｅｒｉｅｓ．Ｉｍｐｒｏｖｅｍｅｎｔ...

关键词： nickel hydroxide electrode electroless plating cobalt electrode performance electrochemical impedance conductivity

Theoretical assessment of the impact of environmental contamination on the dynamical transmission of polio

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International journal of Biomathematics 2019年第2期12卷 1-35页

作者： C.Balde M.Lam A.Bah S.Bowong j.j.Tewa Department of Mathematics Faculty of Science and Technic University Cheikh Anta DiopDakarSenegal Department of Computer Engineering National Advanced School of Engineering University Cheikh Anta Diop DakarSenegal Laboratory of Mathematics Department of Mathematics and Computer Science faculty of Science University of Douala P.O.Box 24157 DoualaCameroon National Advanced School of Engineering University of Yaounde I P.O.Box 8390 YaoundeCameroon IRD Sorbonne UniversityUHH1SCOF-93143BondyFrance Team GRIMCAPEYaoundeCameroon The African Center of Excellence in Information and Communication Technologies(CETIC)University of Yaounde 1Cameroon

A mathematical model for the dynamical transmission of polio is considered,with the aim of investigating the impact of environment *** model captures two infection pathways through both direct human-to-human transmission and indirect human-to-environment-to-human transmission by incorporating the environment as a transition and/or reservoir of *** derive the basic reproduction number R0^env We show that the disease free equilibrium is globally asymptotically stable(GAS)if R0^envf R0^env>1,there exists a unique endemic equilibrium which is locally asymptotically stable(LAS).Similar results hold for environmental contamination free sub-model(without the incorporation of the indirect transmission).At the endemic level,we show that the number of infected individuals for the model with the environ mental-related contagion is greater than the corresponding number for the environmental contamination free *** conjunction with the inequality R0for the environmental contamination free sub-model,our finding suggests that the contaminated environment plays a detrimental role on the transmission dynamics of polio disease by increasing the endemic level and the severity of the ***,it is natural to implement control strategies to reduce the severity of the disease by providing adequate hygienic living conditions,educate populations at risk to follow rigorously those basic hygienic rules in order to avoid adequate contacts with suspected contaminated ***,we perform numerical simulations to support the theory.

关键词： Poliovirus environment contamination human shedding rate mathematical models stability

Application of laser scanning for rock mass characterization and discrete fracture network generation in an underground limestone mine

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International journal of Mining Science and Technology 2019年第1期29卷 131-137页

作者： j.an j.Monsalve jon Baggett Richard Bishop Nino Ripepi Mining and Minerals Department Virginia Polytechnic Institute&State University

Terrestrial laser scanning(TLS) is a useful technology for rock mass characterization. A laser scanner produces a massive point cloud of a scanned area, such as an exposed rock surface in an underground tunnel,with millimeter precision. The density of the point cloud depends on several parameters from both the TLS operational conditions and the specifications of the project, such as the resolution and the quality of the laser scan, the section of the tunnel, the distance between scanning stations, and the purpose of the scans. One purpose of the scan can be to characterize the rock mass and statistically analyze the discontinuities that compose it for further discontinuous modeling. In these instances, additional data processing and a detailed analysis should be performed on the point cloud to extract the parameters to define a discrete fracture network(DfN) for each discontinuity set. I-site studio is a point cloud processing software that allows users to edit and process laser scans. This software contains a set of geotechnical analysis tools that assist engineers during the structural mapping process, allowing for greater and more representative data regarding the structural information of the rock mass, which may be used for generating DfNs. This paper presents the procedures used during a laser scan for characterizing discontinuities in an underground limestone mine and the results of the scan as applied to the generation of DfNs for further discontinuous modeling.

关键词： Rock mass characterization Laser scanning Discrete fracture network I-site studio

On continuum modeling using kinetic-frictional models in high shear granulation

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Particuology 2014年第2期12卷 124-127页

作者： P.j.abrahamsson S.Sasic A.Rasmuson Department of Chemical Engineering Chalmers University of TechnologySE-412 96 GothenburgSweden Department of Applied Mechanics Division of Fluid DynamicsChalmers University of TechnologySE-412 96 GothenburgSweden

This short communication demonstrates why extreme caution has to be taken when applying conven- tional kinetic-frictional closures to continuum modeling of high shear granulation （HSG）, Conventional models refer to closure laws where the kinetic and frictional stresses are summed up to obtain the total stress field, In the simple, dense, and sheared system ofa Couette shear cell, the effect of the lack of scale separation on the model predictions is examined, both quantitatively and qualitatively. It is observed that the spatial resolution has a significant effect on the magnitude of the kinetic and frictional contributions to the solid phase stresses. With this new investigation and previous studies of HSG, it is concluded that conventional kinetic-frictional models are inadequate for continuum modeling of HSG.

关键词： Kinetic theory of granular flowfrictional stressSeparation of scalesHigh shear granulationCouette shear cell

Synaptic electronics and neuromorphic computing

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Science China(Information Sciences) 2016年第6期59卷 56-81页

作者： Navnidhi K.UPADHYAY Saumil jOSHI j.joshua YANG Department of Electrical and Computer Engineering University of Massachusetts

In order to map the computing architecture and intelligent functions of the human brain on hardware, we need electronic devices that can emulate biological synapses and even neurons, preferably at the physical level. Beginning with the history of neuromorphic computation, in this article, we will briefly review the architecture of the brain and the learning mechanisms responsible for its plasticity. We will also introduce several memristive devices that have been used to implement electronic synapses, presenting some important milestones in this area of research and discussing their advantages, disadvantages, and future prospects.

关键词： memristors neuromorphic engineering RRAM synapses synaptic devices

INTRASPINAL CONNECTIONS Of DORSAL COLUMN POSTSYNAPTIC NEURONS IN THE CAT——A PHYSIOLOGICAL ANALYSIS

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Science China Chemistry 1985年第9期28卷 972-978页

作者：吕国蔚,GARY j.BENNETT,NOZOMU NISHIKAWA,MARVIN j.HOffERT,RONALD DUBNER Department of Neurophysiology Beijing Second Medical College China Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA Department of Anesthesiology Shiga University of Medical Seience Shiga japan Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA Department of Neurology Univeraity of Wisenonsin Medieal School Madison Wisconsin 53792 U.S.A Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA

Dorsal column postsynaptic (DCPS) neurons in the dorsal horn of the spinal cord have been identified by antidromic stimulation and intracellularly recorded in anesthetized cats. In about one-half of the cells, the antidromic stimulus evokes only an antidromic potential. This potential sometimes has an atypical shape due to penetration-induced depolarization. Atypieal potentials arc converted into typical antidromic spike potentials after intracellular injection of hyperpolarizing current. In the other one-half, the antidromic potentials are followed by postsynaptic activity. Intracellular analysis indicates that this postsynaptic activity is generated largely by activation of the intraspinal collaterals of A-beta primary afferents that are ascending the dorsal columns. Part of this postsynaptic activity has been produced monosynaptically. Polysynaptic responses are also evident; these are thought to be initiated by A-beta axons, desending axons from neurons in the dorsal column nuclei, or the local coll

关键词： A PHYSIOLOGICAL ANALYSIS