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Computational studies on the seismic response of the State Route 99 bridge in Seattle with SmA/ECC plastic hinges

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 149-164页

作者： Jiping GE m.Saiid SAIIDI sebastian VARELA School of Urban Construction and Safety Engineering Shanghai Institute of TechnologyShanghai 201418China Department of Civil and Environmental Engineering University of NevadaRenoNV 89557USA Structural Engineering Group Freese and Nichols Inc.Fort WorthTX 76109USA

This paper reports a computational study on the seismic response of a three-span highway bridge system incorporating conventional and novel substructure details for improved seismic *** bridge has three continuous spans supported by two single-column piers and integral abutments founded on drilled *** will be the first full-scale highway bridge to use superelastic shape memory alloy bars (SmA)and engineered cementitious composite (ECC)to mitigate column plastic hinge damage and minimize residual displacements after a strong earthquake. A three-dimensional computational model capturing the nonlinear constitutive response of the novel materials and the effects of dynamic soil-structure interaction was developed to assess the seismic response of the bridge in finite-element software *** versions of the same bridge were analyzed and compared,one with conventional cast-in-place reinforced concrete columns,and the other with top plastic hinges incorporating Nickel-Titanium (NiTi)SmA reinforcing bars and *** novel SmA/ECC plastic hinges were found to substantially reduce damage and post-earthquake residual displacements in the bridge substructure,but led to larger maximum drifts relative to the bridge with conventional reinforced concrete plastic *** analysis results suggested that the novel plastic hinges could lead to improved post-earthquake serviceability of bridges after intense earthquakes.

关键词： seismic design analytical simulation near-fault earthquakes shape memory alloy engineered cementitious composite self-centering

Laser-induced thermal lens study of the role of morphology and hydroxyl group in the evolution of thermal diffusivity of copper oxide

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Chinese Physics B 2021年第6期30卷 588-593页

作者： Riya sebastian m S Swapna Vimal Raj S Sankararaman Department of Optoelectronics University of KeralaTrivandrum 695581KeralaIndia

The paper explores the evolution of thermal behavior of the material by studying the variations in thermal diffusivity using the single beam thermal lens(TL) technique. For this purpose, the decomposition of Cu(OH)_(2) into CuO is studied in a time range up to 120 h, by subjecting the sample to morphological, structural, and spectroscopic characterizations. The time evolution of thermal diffusivity can be divided into three regions for demonstrating the dynamics of the reaction. When the reaction is complete, the thermal diffusivity is also found to be saturated. In addition to the morphological modifications,from rods to flakes, the variations in the amount of hydroxyl group are attributed to be responsible for the enhancement of base fluid's thermal diffusivity by 165%. Thus the study unveils the role of hydroxyl groups in the thermal behavior of CuO.

关键词： thermal diffusivity CuO thermal lens morphology hydroxyl group

molecular dynamics simulation of the Stribeck curve: Boundary lubrication, mixed lubrication, and hydrodynamic lubrication on the atomistic level

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Friction 2023年第12期11卷 2342-2366页

作者： Simon STEPHAN sebastian SCHmITT Hans HASSE Herbert m.URBASSEK Laboratory of Engineering Thermodynamics(LTD) Department of Mechanical and Process EngieeringTU KaiserslauternRheinland-Pfalz 67663Germany Physics Department and Research Center(OPTImAS) TU KaiserslauternRheinland-Pfalz 67663Germany

Lubricated contact processes are studied using classical molecular dynamics simulations for determining the entire range of the Stribeck ***,the lateral movement of two solid bodies at different gap height are *** each simulation,a rigid asperity is moved at constant height above a flat iron surface in a lubricating *** methane and decane are considered as *** three main lubrication regimes of the Stribeck curve and their transition regions are covered by the study:Boundary lubrication(significant elastic and plastic deformation of the substrate),mixed lubrication(adsorbed fluid layer dominates the process),and hydrodynamic lubrication(shear flow is set up between the surface and the asperity).We find the formation of a tribofilm in which lubricant molecules are immersed into the metal surface—not only in the case of scratching,but also for boundary lubrication and mixed *** formation of a tribofilm is found to have important consequences for the contact ***,the two fluids are found to show distinctly different behavior in the three lubrication regimes:For hydrodynamic lubrication(large gap height),decane yields a better tribological performance;for boundary lubrication(small gap height),decane shows a larger friction coefficient than methane,which is due to the different mechanisms observed for the formation of the tribofilm;the mixed lubrication regime can be considered as a transition regime between the two other ***,it is found that the nature of the tribofilm depends on the lubricant:While methane particles substitute substrate atoms sustaining mostly the crystalline structure,the decane molecules distort the substrate surface and an amorphous tribofilm is formed.

关键词： boundary lubrication mixed lubrication hydrodynamic lubrication molecular dynamics simulation tribofilm

Wear dependent virtual flow rate sensor for progressing cavity pumps with deformable stator

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Petroleum Science 2024年第2期21卷 1346-1353页

作者： Jens müller sebastian Leonow Johannes Schulz Christian Hansen martin monnigmann Ruhr-Universitat Bochum Universit atsstraûe 150Bochum44801Germany SEEPEX GmbH Scharnh olzstraûe 344Bottrop46240Germany

This contribution presents a novel wear dependent virtual flow rate sensor for single stage single lobe progressing cavity pumps. We study the wear-induced material loss of the pump components and the impact of this material loss on the volumetric efficiency. The results are combined with an established backflow model to implement a backflow calculation procedure that is adaptive to wear. We use a laboratory test setup with a highly abrasive fluid and operate a pump from new to worn condition to validate our approach. The obtained measurement data show that the presented virtual sensor is capable of calculating the flow rate of a pump being subject to wear during its regular operation.

关键词： Backflow Progressing cavity pump Virtual sensor Wear

Robustness and efficiency of voting consensus protocols within byzantine infrastructures

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Blockchain(Research and Applications) 2021年第1期2卷 1-14页

作者： Angelo Capossele sebastian müller Andreas Penzkofer IOTA Foundation 10405BerlinGermany Aix-marseille Universitae CNRSCentrale MarseilleI2MUMR 737313453MarseilleFrance

This paper investigates several voting consensus protocols with low computational complexity in noisy Byzantine *** computer simulations,we show that explicit randomization of the consensus protocol can significantly increase the robustness towards faulty and malicious *** identify the optimal amount of randomness for various Byzantine attack strategies on different kinds of network topologies.

关键词： Distributed systems Consensus protocols Byzantine infrastructures Simulation studies

Design and Robust Performance Evaluation of a Fractional Order PID Controller Applied to a DC motor

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IEEE/CAA Journal of Automatica Sinica 2017年第2期4卷 304-314页

作者： J.Viola L.Angel J.m.sebastian Universidad Pontificia Bolivariana Universidad Politecnica de madrid Centre for Automation and Robotics (CAR) UPM-CSIC

This paper proposes a methodology for the quantitative robustness evaluation of PID controllers employed in a DC motor. The robustness analysis is performed employing a 2~3 factorial experimental design for a fractional order proportional integral and derivative controller(FOPID), integer order proportional integral and derivative controller(IOPID)and the Skogestad internal model control controller(SImC). The factors assumed in experiment are the presence of random noise,external disturbances in the system input and variable load. As output variables, the experimental design employs the system step response and the controller action. Practical implementation of FOPID and IOPID controllers uses the mATLAB stateflow toolbox and a NI data acquisition system. Results of the robustness analysis show that the FOPID controller has a better performance and robust stability against the experiment factors.

关键词： Factorial experimental design fractional-order PID controller robustness analysis SImC PID controller

Raman spectroscopy of isolated carbyne chains confined in carbon nanotubes:Progress and prospects

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Chinese Physics B 2022年第12期31卷 532-542页

作者： Johannes m.A.Lechner Pablo Hernández López sebastian Heeg Institut fur Physik and IRIS Adlershof Humboldt Universitat zu Berlin12489 BerlinGermany

Carbyne is an infinitely long linear chain of carbon atoms with sp1hybridization and the truly one-dimensional allotrope of *** obtaining freestanding carbyne is still an open challenge,the study of confined carbyne,linear chains of carbon encapsulated in carbon nanotubes,provides a pathway to explore carbyne and its remarkable properties in a well-defined *** this review,we discuss the basics and recent advances in studying single confined carbyne chains by Raman spectroscopy,which is their primary spectroscopic characterization *** highlight where single carbyne chain studies are needed to advance our understanding of confined carbyne as a material system and provide an overview of the open questions that need to be addressed and of those aspects currently under debate.

关键词： carbyne linear carbon chains carbon nanotubes Raman spectroscopy

Pauli Radius of the Proton

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Chinese Physics Letters 2021年第12期38卷 1-6页

作者： Zhu-Fang Cui Daniele Binosi Craig D.Roberts sebastian m.Schmidt School of Physics Nanjing UniversityNanjing 210093China Institute for Nonperturbative Physics Nanjing UniversityNanjing 210093China European Centre for Theoretical Studies in Nuclear Physics and Related Areas Villa TambosiStrada delle Tabarelle 286I-38123 Villazzano(TN)Italy Helmholtz-Zentrum Dresden-Rossendorf Dresden D-01314Germany RWTH Aachen University Ⅲ.Physikalisches Institut BAachen D-52074Germany

Using a procedure based on interpolation via continued fractions supplemented by statistical sampling,we analyze proton magnetic form factor data obtained via electron+proton scattering on Q^(2)∈[0.027,0.55]GeV^(2)with the goal of determining the proton magnetic *** approach avoids assumptions about the function form used for data interpolation and ensuing extrapolation onto Q^(2)■0 for extraction of the form factor *** this way,we find r_(m)=0.817(27)*** the difference between proton electric and magnetic radii calculated in this way,extant data are seen to be compatible with the possibility that the slopes of the proton Dirac and Pauli form factors,F1,2(Q^(2)),are not truly independent observables;to wit,the difference F_(1)’(0)-F_(2)’(0)/κp=[1+Kp]/[4 m_(p)^(2)],viz.,the proton Foldy term.

关键词： interpolation Pauli continued

multiscale Finite Elementmethods for Flows on Rough Surfaces

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Communications in Computational Physics 2013年第9期14卷 979-1000页

作者： Yalchin Efendiev Juan Galvis m.sebastian Pauletti Department of mathematics TAMUCollege StationTX 77843-3368USA Departamento de matematicas Universidad Nacional de ColombiaBogotaColombia

In this paper,we present the multiscale Finite Element method(msFEm)for problems on rough heterogeneous *** consider the diffusion equation on oscillatory *** objective is to represent small-scale features of the solution via multiscale basis functions described on a coarse *** problem arises in many applications where processes occur on surfaces or thin *** present a unified multiscale finite element framework that entails the use of transformations that map the reference surface to the deformed *** main ingredients of msFEm are(1)the construction of multiscale basis functions and(2)a global coupling of these basis *** the construction of multiscale basis functions,our approach uses the transformation of the reference surface to a deformed *** the deformed surface,multiscale basis functions are defined where reduced(1D)problems are solved along the edges of coarse-grid blocks to calculate nodalmultiscale basis ***,these basis functions are transformed back to the reference *** discuss the use of appropriate transformation operators that improve the accuracy of the *** method has an optimal convergence if the transformed surface is smooth and the image of the coarse partition in the reference configuration forms a quasiuniform *** this paper,we consider such transformations based on harmonic coordinates(following *** and ***[*** and Applied math.,LX(2007),pp.675-723])and discuss gridding issues in the reference *** results are presented where we compare the msFEm when two types of deformations are used formultiscale basis *** first deformation employs local information and the second deformation employs a global *** numerical results showthat one can improve the accuracy of the simulations when a global information is used.

关键词： multiscale finite elements on surfaces Laplace Beltrami resonance error harmonic maps