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Selim Ciraci - One of the best experts on this subject based on the ideXlab platform.

  • Elastic and plastic deformation of graphene silicene and boron nitride honeycomb nanoribbons under uniaxial tension a first principles density functional theory study
    Physical Review B, 2010
    Co-Authors: M. Topsakal, Selim Ciraci
    Abstract:

    Department of Physics, Bilkent University Ankara 06800, Turkey(Dated: January 26, 2010)This study of Elastic and plastic deformation of graphene, silicene and boron nitride (BN) honey-comb nanoribbons under uniaxial tension determines their Elastic constants and reveals interestingfeatures. In the course of stretching in the Elastic Range, the electronic and magnetic properties canbe strongly modi ed. In particular, it is shown that the band gap of a speci c armchair nanoribbonis closed under strain and highest valance and lowest conduction bands are linearized. This way,the massless Dirac fermion behavior can be attained even in a semiconducting nanoribbon. Un-der plastic deformation, the honeycomb structure changes irreversibly and o ers a number of newstructures and functionalities. Cage like structures, even suspended atomic chains can be derivedbetween two honeycomb akes. Present work elaborates on the recent experiments by Jin et al.,Phys. Rev. Lett. 102, 205501 (2009) deriving carbon chains from graphene. Furthermore, thesimilar formations of atomic chains from BN and Si nanoribbons are predicted.

  • Elastic and plastic deformation of graphene, silicene, and boron nitride honeycomb nanoribbons under uniaxial tension: A first-principles density-functional theory study
    Physical Review B - Condensed Matter and Materials Physics, 2010
    Co-Authors: M. Topsakal, Selim Ciraci
    Abstract:

    This study of Elastic and plastic deformation of graphene, silicene, and boron nitride (BN) honeycomb nanoribbons under uniaxial tension determines their Elastic constants and reveals interesting features. In the course of stretching in the Elastic Range, the electronic and magnetic properties can be strongly modified. In particular, it is shown that the band gap of a specific armchair nanoribbon is closed under strain and highest valance and lowest conduction bands are linearized. This way, the massless Dirac fermion behavior can be attained even in a semiconducting nanoribbon. Under plastic deformation, the honeycomb structure changes irreversibly and offers a number of new structures and functionalities. Cagelike structures, even suspended atomic chains can be derived between two honeycomb flakes. Present work elaborates on the recent experiments [C. Jin, H. Lan, L. Peng, K. Suenaga, and S. Iijima, Phys. Rev. Lett. 102, 205501 (2009)] deriving carbon chains from graphene. Furthermore, the similar formations of atomic chains from BN and Si nanoribbons are predicted.

  • the response of mechanical and electronic properties of graphane to the Elastic strain
    arXiv: Materials Science, 2009
    Co-Authors: M. Topsakal, Seymur Cahangirov, Selim Ciraci
    Abstract:

    Based on first-principles calculations, we resent a method to reveal the Elastic properties of recently synthesized monolayer hydrocarbon, graphane. The in-plane stiffness and Poisson's ratio values are found to be smaller than those of graphene, and its yielding strain decreases in the presence of various vacancy defects and also at high ambient temperature. We also found that the band gap can be strongly modified by applied strain in the Elastic Range.

M. Topsakal - One of the best experts on this subject based on the ideXlab platform.

  • Elastic and plastic deformation of graphene silicene and boron nitride honeycomb nanoribbons under uniaxial tension a first principles density functional theory study
    Physical Review B, 2010
    Co-Authors: M. Topsakal, Selim Ciraci
    Abstract:

    Department of Physics, Bilkent University Ankara 06800, Turkey(Dated: January 26, 2010)This study of Elastic and plastic deformation of graphene, silicene and boron nitride (BN) honey-comb nanoribbons under uniaxial tension determines their Elastic constants and reveals interestingfeatures. In the course of stretching in the Elastic Range, the electronic and magnetic properties canbe strongly modi ed. In particular, it is shown that the band gap of a speci c armchair nanoribbonis closed under strain and highest valance and lowest conduction bands are linearized. This way,the massless Dirac fermion behavior can be attained even in a semiconducting nanoribbon. Un-der plastic deformation, the honeycomb structure changes irreversibly and o ers a number of newstructures and functionalities. Cage like structures, even suspended atomic chains can be derivedbetween two honeycomb akes. Present work elaborates on the recent experiments by Jin et al.,Phys. Rev. Lett. 102, 205501 (2009) deriving carbon chains from graphene. Furthermore, thesimilar formations of atomic chains from BN and Si nanoribbons are predicted.

  • Elastic and plastic deformation of graphene, silicene, and boron nitride honeycomb nanoribbons under uniaxial tension: A first-principles density-functional theory study
    Physical Review B - Condensed Matter and Materials Physics, 2010
    Co-Authors: M. Topsakal, Selim Ciraci
    Abstract:

    This study of Elastic and plastic deformation of graphene, silicene, and boron nitride (BN) honeycomb nanoribbons under uniaxial tension determines their Elastic constants and reveals interesting features. In the course of stretching in the Elastic Range, the electronic and magnetic properties can be strongly modified. In particular, it is shown that the band gap of a specific armchair nanoribbon is closed under strain and highest valance and lowest conduction bands are linearized. This way, the massless Dirac fermion behavior can be attained even in a semiconducting nanoribbon. Under plastic deformation, the honeycomb structure changes irreversibly and offers a number of new structures and functionalities. Cagelike structures, even suspended atomic chains can be derived between two honeycomb flakes. Present work elaborates on the recent experiments [C. Jin, H. Lan, L. Peng, K. Suenaga, and S. Iijima, Phys. Rev. Lett. 102, 205501 (2009)] deriving carbon chains from graphene. Furthermore, the similar formations of atomic chains from BN and Si nanoribbons are predicted.

  • the response of mechanical and electronic properties of graphane to the Elastic strain
    arXiv: Materials Science, 2009
    Co-Authors: M. Topsakal, Seymur Cahangirov, Selim Ciraci
    Abstract:

    Based on first-principles calculations, we resent a method to reveal the Elastic properties of recently synthesized monolayer hydrocarbon, graphane. The in-plane stiffness and Poisson's ratio values are found to be smaller than those of graphene, and its yielding strain decreases in the presence of various vacancy defects and also at high ambient temperature. We also found that the band gap can be strongly modified by applied strain in the Elastic Range.

Anil Sethi - One of the best experts on this subject based on the ideXlab platform.

  • Monoaxial Pedicle Screws Are Superior to Polyaxial Pedicle Screws and the Two Pin External Fixator for Subcutaneous Anterior Pelvic Fixation in a Biomechanical Analysis
    Hindawi Limited, 2013
    Co-Authors: Rahul Vaidya, Ndidi Onwudiwe, Matthew Roth, Anil Sethi
    Abstract:

    Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the Elastic Range. Once that was completed, 3 components were tested in torsion within the Elastic Range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113 Nmm monoaxial, 3.638 ± 0.108 Nmm Click-x; 3.634 ± 0.147 Nmm Pangea) than the exfix system (2.882 ± 0.054 Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360 N) than exfixes (160 N) and polyaxial devices which failed if distracted greater than 4 cm (157 N Click-x or 138 N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360 N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems

  • Research Article Monoaxial Pedicle Screws Are Superior to Polyaxial Pedicle Screws and the Two Pin External Fixator for Subcutaneous Anterior Pelvic Fixation in a Biomechanical Analysis
    2013
    Co-Authors: Rahul Vaidya, Ndidi Onwudiwe, Matthew Roth, Anil Sethi
    Abstract:

    Copyright © 2013 Rahul Vaidya et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distractionwithin the Elastic Range. Once that was completed, 3 components were tested in torsion within the Elastic Range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113Nmmmonoaxial, 3.638 ± 0.108Nmm Click-x; 3.634 ± 0.147Nmm Pangea) than the exfix system (2.882 ± 0.054Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360N) than exfixes (160N) and polyaxial devices which failed if distracted greater than 4 cm (157N Click-x or 138N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems. 1

Changyu Chen - One of the best experts on this subject based on the ideXlab platform.

  • shaking table study on displacement based design for seismic retrofit of existing buildings using nonlinear viscous dampers
    Journal of Structural Engineering-asce, 2008
    Co-Authors: Kuo-chun Chang, Yuyuan Lin, Changyu Chen
    Abstract:

    This paper presents the experimental and analytical results of a shaking-table study on the Elastic and inElastic behavior of a 2/3-scale three-story steel structure retrofitted by the nonlinear viscous dampers. The properties of the dampers used in the test are designed based on the displacement-based design procedure. The retrofitted frame exhibits moderate inElastic behavior under the design ground motion of the 275% El Centro earthquake. The lateral floor displacements, story drifts, floor accelerations, story shears, and damper axial forces measured from the frame tested are compared with those obtained from the displacement-based method as well as the nonlinear time-history analysis. It is shown from the study that the addition of nonlinear viscous dampers to the structure results in displacement and force reduction by about 68 to 80% under the 30% El Centro earthquake (PGA ≈ 0.1 g). Higher-mode responses are significantly diminished. In addition, the displacement and acceleration responses of the structure with dampers are appropriately captured by analytical models in the Elastic Range. The differences between the experimental and analytical results become noticeable in the inElastic Range. The displacement-based evaluation procedure tends to underestimate the responses of the damped structure in the Elastic Range and overestimate them in the inElastic Range.

M D Symans - One of the best experts on this subject based on the ideXlab platform.

  • SUSTAINABILITY IN SOFT WEAK OPEN FRONT BUILDINGS SUSTAINABILITY IN SOFT WEAK OPEN FRONT BUILDINGS
    2020
    Co-Authors: F H Schott, D A Lee, J Karns, M D Symans
    Abstract:

    ABSTRACT Soft weak open front (SWOF) buildings often perform poorly in earthquakes. Two examples are buildings with a street facing garage, or commercial facilities with extensive open display windows. The poor performance of SWOF structures can consist of complete loss of use or even total collapse. This paper presents an approach to protecting such structures via the addition of an energy dissipation system (viscous dampers) such that peak inter-story drifts are limited to about 1% under relatively severe seismic events, thus keeping the deformations within the Elastic Range. With this addition of damping, earthquake survivability of this class of structures increases significantly. A series of seismic analyses are presented herein to demonstrate the potential performance of the damping system. In addition, a variety of damper installation configurations that provide enhanced energy dissipation are discussed. 10NCEE Tenth U.S. National Conference on Earthquake Engineering Frontiers of Earthquake Engineering July 21-25, 2014 Anchorage ABSTRACT Soft weak open front (SWOF) buildings often perform poorly in earthquakes. Two examples are buildings with a street facing garage, or commercial facilities with extensive open display windows. The poor performance of SWOF structures can consist of complete loss of use or even total collapse. This paper presents an approach to protecting such structures via the addition of an energy dissipation system (viscous dampers) such that peak inter-story drifts are limited to about 1% under relatively severe seismic events, thus keeping the deformations within the Elastic Range. With this addition of damping, earthquake survivability of this class of structures increases significantly. A series of seismic analyses are presented herein to demonstrate the potential performance of the damping system. In addition, a variety of damper installation configurations that provide enhanced energy dissipation are discussed