Статті в журналах: "Framed sheaves"

1

Bruzzo, Ugo, Francesco Sala, and Mattia Pedrini. "Framed sheaves on projective stacks." Advances in Mathematics 272 (February 2015): 20–95. http://dx.doi.org/10.1016/j.aim.2014.11.019.

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2

Scalise, Jacopo Vittorio. "Framed symplectic sheaves on surfaces." International Journal of Mathematics 29, no. 01 (January 2018): 1850007. http://dx.doi.org/10.1142/s0129167x18500076.

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Анотація:

A framed symplectic sheaf on a smooth projective surface [Formula: see text] is a torsion-free sheaf [Formula: see text] together with a trivialization on a divisor [Formula: see text] and a morphism [Formula: see text] satisfying some additional conditions. We construct a moduli space for framed symplectic sheaves on a surface, and present a detailed study for [Formula: see text]. In this case, the moduli space is irreducible and admits an ADHM-type description and a birational proper map onto the space of framed symplectic ideal instantons.

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3

Hurtubise, Jacques, Lisa Jeffrey, and Reyer Sjamaar. "Moduli of Framed Parabolic Sheaves." Annals of Global Analysis and Geometry 28, no. 4 (November 2005): 351–70. http://dx.doi.org/10.1007/s10455-005-1941-6.

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4

Bruzzo, Ugo, and Dimitri Markushevish. "Moduli of framed sheaves on projective surfaces." Documenta Mathematica 16 (2011): 399–410. http://dx.doi.org/10.4171/dm/336.

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5

HENNI, AMAR ABDELMOUBINE. "MONADS FOR FRAMED TORSION-FREE SHEAVES ON MULTI-BLOW-UPS OF THE PROJECTIVE PLANE." International Journal of Mathematics 25, no. 01 (January 2014): 1450008. http://dx.doi.org/10.1142/s0129167x14500086.

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Анотація:

We construct monads for framed torsion-free sheaves on blow-ups of the complex projective plane at finitely many distinct points. Using these monads we prove that the moduli space of such sheaves is a smooth algebraic variety. Moreover, we construct monads for families of such sheaves parametrized by a noetherian scheme S of finite type. A universal monad on the moduli space is introduced and used to prove that the moduli space is fine.

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6

KIM, BUMSIG, and HWAYOUNG LEE. "WALL-CROSSINGS FOR TWISTED QUIVER BUNDLES." International Journal of Mathematics 24, no. 05 (May 2013): 1350038. http://dx.doi.org/10.1142/s0129167x13500389.

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Given a double quiver, we study homological algebra of twisted quiver sheaves with the moment map relation using the short exact sequence of Crawley-Boevey, Holland, Gothen, and King. Then in a certain one-parameter space of the stability conditions, we obtain a wall-crossing formula for the generalized Donaldson–Thomas invariants of the abelian category of framed twisted quiver sheaves on a smooth projective curve. To do so, we closely follow the approach of Chuang, Diaconescu and Pan in the ADHM quiver case, which makes use of the theory of Joyce and Song. The invariants virtually count framed twisted quiver sheaves with the moment map relation and directly generalize the ADHM invariants of Diaconescu.

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7

Nevins, Thomas A. "Representability for some moduli stacks of framed sheaves." manuscripta mathematica 109, no. 1 (September 1, 2002): 85–91. http://dx.doi.org/10.1007/s00229-002-0290-z.

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8

Bartocci, Claudio, Valeriano Lanza, and Claudio L. S. Rava. "Moduli spaces of framed sheaves and quiver varieties." Journal of Geometry and Physics 118 (August 2017): 20–39. http://dx.doi.org/10.1016/j.geomphys.2016.10.011.

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9

Franco, Emilio, Marcos Jardim, and Simone Marchesi. "Branes in the moduli space of framed sheaves." Bulletin des Sciences Mathématiques 141, no. 4 (June 2017): 353–83. http://dx.doi.org/10.1016/j.bulsci.2017.04.002.

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10

Sala, Francesco. "Restriction theorems for μ-(semi)stable framed sheaves". Journal of Pure and Applied Algebra 217, № 12 (грудень 2013): 2320–44. http://dx.doi.org/10.1016/j.jpaa.2013.03.010.

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11

Oprea, Dragos. "Framed sheaves over treefolds and symmetric obstruction theories." Documenta Mathematica 18 (2013): 323–42. http://dx.doi.org/10.4171/dm/399.

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12

HENNI, ABDELMOUBINE AMAR, MARCOS JARDIM, and RENATO VIDAL MARTINS. "ADHM CONSTRUCTION OF PERVERSE INSTANTON SHEAVES." Glasgow Mathematical Journal 57, no. 2 (December 18, 2014): 285–321. http://dx.doi.org/10.1017/s0017089514000305.

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AbstractWe present a construction of framed torsion free instanton sheaves on a projective variety containing a fixed line which further generalises the one on projective spaces. This is done by generalising the so called ADHM variety. We show that the moduli space of such objects is a quasi projective variety, which is fine in the case of projective spaces. We also give an ADHM categorical description of perverse instanton sheaves in the general case, along with a hypercohomological characterisation of these sheaves in the particular case of projective spaces.

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13

Jardim, Marcos. "Atiyah–Drinfeld–Hitchin–Manin construction of framed instanton sheaves." Comptes Rendus Mathematique 346, no. 7-8 (April 2008): 427–30. http://dx.doi.org/10.1016/j.crma.2008.02.014.

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14

Eyssidieux, Philippe, and Francesco Sala. "Instantons and framed sheaves on Kähler Deligne–Mumford stacks." Annales de la faculté des sciences de Toulouse Mathématiques 27, no. 3 (2018): 599–628. http://dx.doi.org/10.5802/afst.1579.

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15

Bruzzo, Ugo, Dimitri Markushevich, and Alexander Tikhomirov. "Uhlenbeck–Donaldson compactification for framed sheaves on projective surfaces." Mathematische Zeitschrift 275, no. 3-4 (June 13, 2013): 1073–93. http://dx.doi.org/10.1007/s00209-013-1170-9.

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16

Sala, Francesco. "Symplectic structures on moduli spaces of framed sheaves on surfaces." Central European Journal of Mathematics 10, no. 4 (May 2, 2012): 1455–71. http://dx.doi.org/10.2478/s11533-012-0063-1.

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17

Henni, Abdelmoubine Amar. "On the fixed locus of framed instanton sheaves on ℙ3". Pacific Journal of Mathematics 308, № 1 (3 грудня 2020): 41–72. http://dx.doi.org/10.2140/pjm.2020.308.41.

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18

Toda, Yukinobu. "Non-commutative thickening of moduli spaces of stable sheaves." Compositio Mathematica 153, no. 6 (April 26, 2017): 1153–95. http://dx.doi.org/10.1112/s0010437x17007047.

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We show that the moduli spaces of stable sheaves on projective schemes admit certain non-commutative structures, which we call quasi-NC structures, generalizing Kapranov’s NC structures. The completion of our quasi-NC structure at a closed point of the moduli space gives a pro-representable hull of the non-commutative deformation functor of the corresponding sheaf developed by Laudal, Eriksen, Segal and Efimov–Lunts–Orlov. We also show that the framed stable moduli spaces of sheaves have canonical NC structures.

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19

von Flach, Rodrigo A., and Marcos Jardim. "Moduli spaces of framed flags of sheaves on the projective plane." Journal of Geometry and Physics 118 (August 2017): 138–68. http://dx.doi.org/10.1016/j.geomphys.2017.01.019.

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20

Bartocci, Claudio, Valeriano Lanza, and Claudio L. S. Rava. "Corrigendum and addendum to “Moduli spaces of framed sheaves and quiver varieties”." Journal of Geometry and Physics 121 (November 2017): 176–79. http://dx.doi.org/10.1016/j.geomphys.2017.07.008.

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21

Bruzzo, Ugo, Mattia Pedrini, Francesco Sala, and Richard J. Szabo. "Framed sheaves on root stacks and supersymmetric gauge theories on ALE spaces." Advances in Mathematics 288 (January 2016): 1175–308. http://dx.doi.org/10.1016/j.aim.2015.11.005.

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22

Bruzzo, Ugo, Rubik Poghossian, and Alessandro Tanzini. "Poincaré Polynomial of Moduli Spaces of Framed Sheaves on (Stacky) Hirzebruch Surfaces." Communications in Mathematical Physics 304, no. 2 (April 8, 2011): 395–409. http://dx.doi.org/10.1007/s00220-011-1231-z.

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23

NEVINS, THOMAS A. "MODULI SPACES OF FRAMED SHEAVES ON CERTAIN RULED SURFACES OVER ELLIPTIC CURVES." International Journal of Mathematics 13, no. 10 (December 2002): 1117–51. http://dx.doi.org/10.1142/s0129167x02001599.

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Fix a ruled surface S obtained as the projective completion of a line bundle L on a complex elliptic curve C; we study the moduli problem of parametrizing certain pairs consisting of a sheaf ℰ on S and a map of ℰ to a fixed reference sheaf on S. We prove that the full moduli stack for this problem is representable by a scheme in some cases. Moreover, the moduli stack admits an action by the group C*, and we determine its fixed-point set, which leads to explicit formulas for the rational homology of the moduli space.

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24

Ben-Zvi, David, and Thomas Nevins. "Perverse bundles and Calogero–Moser spaces." Compositio Mathematica 144, no. 6 (November 2008): 1403–28. http://dx.doi.org/10.1112/s0010437x0800359x.

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AbstractWe present a simple description of moduli spaces of torsion-free 𝒟-modules (𝒟-bundles) on general smooth complex curves, generalizing the identification of the space of ideals in the Weyl algebra with Calogero–Moser quiver varieties. Namely, we show that the moduli of 𝒟-bundles form twisted cotangent bundles to moduli of torsion sheaves on X, answering a question of Ginzburg. The corresponding (untwisted) cotangent bundles are identified with moduli of perverse vector bundles on T*X, which contain as open subsets the moduli of framed torsion-free sheaves (the Hilbert schemes T*X[n] in the rank-one case). The proof is based on the description of the derived category of 𝒟-modules on X by a noncommutative version of the Beilinson transform on P1.

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25

Licata, Anthony, and Alistair Savage. "Vertex operators and the geometry of moduli spaces of framed torsion-free sheaves." Selecta Mathematica 16, no. 2 (December 11, 2009): 201–40. http://dx.doi.org/10.1007/s00029-009-0015-1.

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26

Li, Yiqiang. "A class of perverse sheaves on framed representation varieties of the Jordan quiver." Journal of Algebra 386 (July 2013): 113–30. http://dx.doi.org/10.1016/j.jalgebra.2013.04.011.

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27

von Flach, Rodrigo A., Marcos Jardim, and Valeriano Lanza. "Obstruction theory for moduli spaces of framed flags of sheaves on the projective plane." Journal of Geometry and Physics 166 (August 2021): 104255. http://dx.doi.org/10.1016/j.geomphys.2021.104255.

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28

Licata, Anthony M. "Framed torsion-free sheaves on CP2, Hilbert schemes, and representations of infinite dimensional Lie algebras." Advances in Mathematics 226, no. 2 (January 2011): 1057–95. http://dx.doi.org/10.1016/j.aim.2010.06.005.

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29

Garbali, Alexandr, and Andrei Neguţ. "Computing the R-matrix of the quantum toroidal algebra." Journal of Mathematical Physics 64, no. 1 (January 1, 2023): 011702. http://dx.doi.org/10.1063/5.0120003.

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We consider the problem of the R-matrix of the quantum toroidal algebra [Formula: see text] in the Fock representation. Using the connection between the R-matrix R( u) ( u being the spectral parameter) and the theory of Macdonald operators, we obtain explicit formulas for R( u) in the operator and matrix forms. These formulas are expressed in terms of the eigenvalues of a certain Macdonald operator, which completely describe the functional dependence of R( u) on the spectral parameter u. We then consider the geometric R-matrix (obtained from the theory of K-theoretic stable bases on moduli spaces of framed sheaves), which is expected to coincide with R( u) and thus gives another approach to the study of the poles of the R-matrix as a function of u.

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30

Wang, Shi-bo, Shijia Wang, and Zhaoliang Ge. "A Mathematical Model and Error Analysis of Shearer Cutting Path Based on Its Attitude." Mathematical Problems in Engineering 2018 (September 17, 2018): 1–8. http://dx.doi.org/10.1155/2018/1790602.

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The horizon control system is the key technology in the automation of a shearer. The achievement of accurate shearer cutting path plays an important role for horizon control. A mathematical model of cutting path in the local geographic coordinate frame was built. Error analysis based on genetic algorithm (GA) was studied to guarantee the accuracy of the shearer cutting path. Parameters from a MG1000/2660-WD shearer and data from a working face were used to obtain the shearer cutting path with reference to the local geographic coordinate frame. Also, with error analysis based on GA, the desired sensors were chosen, which allowed coordinate position errors of a shearer’s cutting path to be less than 0.01 m. The desired accuracies of the inertial navigation system and encoders mounted on the different shearers used in thin seam, medium-thickness seam, and thick seam were calculated.

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31

He, Guifang, Chunfu Sheng, Hongwei He, Rong Zhou, Ding Yuan, Xin Ning, and Fanggang Ning. "Mathematical and geometrical modeling of braided ropes bent over a sheave." Journal of Engineered Fibers and Fabrics 15 (January 2020): 155892502093972. http://dx.doi.org/10.1177/1558925020939726.

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As soft elements for force transmission, braided fiber ropes play important roles in many fields where the fiber ropes are used bent over sheaves, while the relevant experiments are time-consuming and expensive. Computational simulation is a promising choice for evaluating the performance of fiber ropes when bent over a sheave. This article presents two methods that could be employed to build a model of braided rope bent over a sheave. One is the mathematical method which deduces the exact mathematical equations of braiding curves based on the Frenet–Serret frame. The spatial equations, considering the phase difference of strands in the same direction and the difference of strands’ projection in different directions, are discussed carefully. The final equation of braided strands is confirmed by modeling the braided rope in Maple® 17. The other method, which is inspired by the analysis of braiding movements, is based on the intersection of surfaces of braiding surface and helical surface which are introduced and defined based on the motion analysis of bobbins and take-up roller. The SolidWorks® 2018 is successfully employed to realize the modeling process.

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32

Cvetko-Vah, Karin, Jens Hemelaer, and Lieven Le Bruyn. "What is a noncommutative topos?" Journal of Algebra and Its Applications 18, no. 06 (May 27, 2019): 1950107. http://dx.doi.org/10.1142/s021949881950107x.

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In [Cvetko-Vah, Non-commutative frames, J. Algebra Appl. (2018), https://doi.org/10.1142/S0219498819500117 ] noncommutative frames were introduced, generalizing the usual notion of frames of open sets of a topological space. In this paper, we extend this notion to noncommutative versions of Grothendieck topologies and their associated noncommutative toposes of sheaves of sets.

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33

Payandehjoo, Barash, Saeid Sabouri-Ghomi, and Parviz Ebadi. "Seismic Behavior of X-Shaped Drawer Bracing System (DBS) and X-Braced Frames with Heavy Central Core." Journal of Earthquake and Tsunami 10, no. 04 (October 2016): 1650004. http://dx.doi.org/10.1142/s1793431116500044.

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In this work, seismic performance of conventional X-braced frames is enhanced by using Drawer Bracing Systems (DBS). DBS is an innovative structure, which increases ductility and energy absorption capacity of the X-braces through elimination of the harmful effects of local and global buckling and by converting the induced axial forces inside diagonal arms to flexural moments. Two half-scale specimens are tested under cyclic loading and the seismic performance of an X-shaped DBS is compared to that of an X-braced frame. Both braced frames are designed for equal nominal base shears and have similar frame sizes and dimensions. Test results confirm that converting the axial force to flexural moments in rational dissipative elements inside braces helps prevent the global and local buckling of braces in X-shaped DBS. Consequently, ductility and energy absorption capacity of the Concentrically Braced Frames (CBFs) is increased remarkably.

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34

Iliadis, S. D., and Yu V. Sadovnichy. "On sheaves of Abelian groups and universality." Applied General Topology 22, no. 1 (April 1, 2021): 149. http://dx.doi.org/10.4995/agt.2021.14422.

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<p>Universal elements are one of the most essential parts in research fields, investigating if there exist (or not) universal elements in different classes of objects. For example, classes of spaces and frames have been studied under the prism of this universality property. In this paper, studying classes of sheaves of Abelian groups, we construct proper universal elements for these classes, giving a positive answer to the existence of such elements in these classes. </p>

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35

Kassinos, S. C., E. Akylas, and C. A. Langer. "Rapidly sheared homogeneous stratified turbulence in a rotating frame." Physics of Fluids 19, no. 2 (February 2007): 021701. http://dx.doi.org/10.1063/1.2710291.

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36

Bahrami, Alireza, and Mahmood Heidari. "Evaluation of structural response of composite steel-concrete eccentrically buckling-restrained braced frames." Journal of Applied Engineering Science 18, no. 4 (2020): 591–600. http://dx.doi.org/10.5937/jaes0-25497.

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The main purpose of this paper is to evaluate the structural response of composite steel-concrete eccentrically buckling-restrained braced frames (BRBFs). The finite element (FE) software ABAQUS is employed to nonlinearly analyse the BRBFs. Comparing the modelling and experimental test results validates the FE modelling method of the BRBF. Three different strong earthquake records of Tabas, Northridge, and Chi-Chi are selected for the nonlinear dynamic analyses. A BRBF is then designed having a shear link. Afterwards, the designed BRBF is analysed under the selected earthquake records using the validated modelling method. The lateral displacements, base shears, and energy dissipations of the frame and shear link rotations are achieved from the analyses of the BRBF. The results are compared and discussed. The obtained BRBF results are also compared with their corresponding steel eccentrically braced frame (EBF) results. It is concluded that the BRBF can generally accomplish the improved structural response compared with the EBF under the earthquake records. Meanwhile, the BRBF has larger base shear capacity than the EBF. Moreover, the BRBF dissipates more energy than the EBF.

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37

Pronina, Polina, Ying Sun, and Olga Tushavina. "Mathematical modelling of high-intensity heat flux on the elements of heat-shielding composite materials of a spacecraft." Journal of Applied Engineering Science 18, no. 4 (2020): 693–98. http://dx.doi.org/10.5937/jaes0-28086.

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Анотація:

The main purpose of this paper is to evaluate the structural response of composite steel-concrete eccentrically buckling-restrained braced frames (BRBFs). The finite element (FE) software ABAQUS is employed to nonlinearly analyse the BRBFs. Comparing the modelling and experimental test results validates the FE modelling method of the BRBF. Three different strong earthquake records of Tabas, Northridge, and Chi-Chi are selected for the nonlinear dynamic analyses. A BRBF is then designed having a shear link. Afterwards, the designed BRBF is analysed under the selected earthquake records using the validated modelling method. The lateral displacements, base shears, and energy dissipations of the frame and shear link rotations are achieved from the analyses of the BRBF. The results are compared and discussed. The obtained BRBF results are also compared with their corresponding steel eccentrically braced frame (EBF) results. It is concluded that the BRBF can generally accomplish the improved structural response compared with the EBF under the earthquake records. Meanwhile, the BRBF has larger base shear capacity than the EBF. Moreover, the BRBF dissipates more energy than the EBF.

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38

Sun, Shu Li, Chun Sheng Liu, Jun Zhang, and Jin Guo Chen. "Mathematical Modeling and Numerical Simulation of Hydraulic Lifting System on Shearer." Advanced Materials Research 566 (September 2012): 664–68. http://dx.doi.org/10.4028/www.scientific.net/amr.566.664.

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In order to improve the reliability of hydraulic lifting system of Shearer, based on the establishment of the mathematical models for drum hydraulic lifting system, we adopt the Matlab and Automation Studio to simulate the lifting system on shearer, to simulate the real state of working of the lifting system, to analyze the flow, pressure, acceleration impact on working performance of the system, given the basis to evaluation of system reliability. To provide a theoretical frame of reference for the design of the Shearer drum lifting institutions.

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39

Fatahi, Behzad, and S. Hamid Reza Tabatabaiefar. "Effects of Soil Plasticity on Seismic Performance of Mid-Rise Building Frames Resting on Soft Soils." Advances in Structural Engineering 17, no. 10 (November 2014): 1387–402. http://dx.doi.org/10.1260/1369-4332.17.10.1387.

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In this study, the effects of Plasticity Index (PI) variation on the seismic response of mid-rise building frames resting on soft soil deposits are investigated. To achieve this goal, three structural models including 5, 10, and 15 storey buildings are simulated in conjunction with a clayey soil representing soil class Ee according to the classification of AS1170.4–2007 (Earthquake actions in Australia) and then varying the Plasticity Index. Structural sections of the selected frames were designed according to AS3600–2009 (Australian Standard for Concrete Structures) after undertaking dynamic analysis under the influence of four different earthquake ground motions. The frame sections are modelled and analysed, employing finite difference method adopting FLAC 2D software under two different boundary conditions: (i) fixed base (no Soil-Structure Interaction), and (ii) flexible base considering soil-structure interaction. Fully nonlinear dynamic analyses under the influence of different earthquake records are conducted and the results in terms of maximum lateral displacements and inter-storey drifts for the above mentioned boundary conditions are obtained, compared, and discussed. Base on the results of the numerical investigations, it becomes apparent that as the Plasticity Index of the subsoil increases, the base shears of mid-rise building frames resting on soft soil deposits increase, while the lateral deflections and corresponding inter-storey drifts decrease. It is concluded that reduction of the Plasticity Index could noticeably amplify the effects of soil-structure interaction on the seismic response of mid-rise building frames.

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40

Smith, Bryan Stafford, and Young‐Soo Yoon. "Estimating Seismic Base Shears of Tall Wall‐Frame Buildings." Journal of Structural Engineering 117, no. 10 (October 1991): 3026–41. http://dx.doi.org/10.1061/(asce)0733-9445(1991)117:10(3026).

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41

Wang, Shijia. "Research on shearer positioning with double-INS." Sensor Review 39, no. 4 (July 15, 2019): 577–85. http://dx.doi.org/10.1108/sr-12-2018-0318.

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Purpose This paper aims to improve shearer positioning accuracy. Shearer positioning using an inertial navigation system (INS) is a highly useful technology; however, positioning accuracy is seriously hindered by INS attitude error, particularly heading drift. Design/methodology/approach A shearer positioning model with double-INS based on extended Kalman filter was proposed. The constant distance between two INSs (INS 1 and INS 2) was selected as the observation vector. Allan variance was used to identify the noise type of the vertical-axis gyroscope, and the stochastic process of heading drift for two INSs was obtained and divided into incongruous drift and concurrent drift. Findings Simulation was then carried out to determine the optimal arrangement of the two INSs. For incongruous drift, the optimal arrangement satisfied the condition that the line connecting INS 1 and INS 2 was perpendicular to the shearer lateral axis (in the shearer coordinate frame) and parallel to the east-north plane (in the east-north-up coordinate frame). Under optimal arrangement, the positioning accuracy increased against the distance between INS 1 and INS 2. For concurrent drift, the double-INS positioning model had no effect. Under the circumstances, the number of INSs should be increased so that the uncertainty of INS drift was reflected as much as possible. Originality/value A new double-INS positioning model was proposed with the constant distance between the two INSs. The optimal arrangement for double-INS was obtained.

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42

Zhao, Li Juan, and Zhen Tian. "Application of Co-Simulation in Noise and Vibration Analysis of Shearer." Advanced Materials Research 619 (December 2012): 172–75. http://dx.doi.org/10.4028/www.scientific.net/amr.619.172.

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In order to investigate the noise and vibration characteristics of shearer, through the analysis of shearer found that the nonlinear instantaneous impact loading caused by cutting pick in the cutting process is the main disturbance source of the noise and vibration,the simulation pro- gramme of cutting pick momentary load was worked out by the implementation of MATLAB. The vibration of the key parts was obtained through the analysis of the rigid-flex coupled model of shearer which was established based on a co-simulation virtual prototype frame,and found that the vibration of the shell stretched out side is more severe, the shell subjacent ear under a larger dynamic stress, the planet carrier has a evident torsional deformation. According to analysis results, the optimized shell vibration significantly weakened, mechanical performance improved drama- tically. The analysis results provide an important basis for improving the shearer cutting unit design and reducing the noise level of coal face.

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43

ROACH, D. C., and A. G. L. HOLLOWAY. "Combined effects of flow curvature and rotation on uniformly sheared turbulence." Journal of Fluid Mechanics 628 (June 1, 2009): 371–94. http://dx.doi.org/10.1017/s0022112009006296.

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This paper describes an experiment in which a uniformly sheared turbulence was subjected to simultaneous streamwise flow curvature and rotation about the streamwise axis. The distortion of the turbulence is complex but well defined and may serve as a test case for turbulence model development. The uniformly sheared turbulence was developed in a straight wind tunnel and then passed into a curved tunnel section. At the start of the curved section the plane of the mean shear was normal to the plane of curvature so as to create a three-dimensional or ‘out of plane’ curvature configuration. On entering the curved tunnel, the flow developed a streamwise mean vorticity that rotated the mean shear about the tunnel centreline through approximately 70°, so that the shear was nearly in the plane of curvature and oriented so as to have a stabilizing effect on the turbulence. Hot wire measurements of the mean velocity, mean vorticity, mean rate of strain and Reynolds stress anisotropy development along the wind tunnel centreline are reported. The observed effect of the mean shear rotation on the turbulence was to diminish the shear stress in the plane normal to the plane of curvature while generating non-zero values of the shear stress in the plane of curvature. A rotating frame was identified for which the measured mean velocity field took the form of a simple shear flow. The turbulence anisotropy was transformed to this frame to estimate the effects of frame rotation on the structure of sheared turbulence.

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44

Fragiadakis, Michalis, Dimitrios Vamvatsikos, and Mark Aschheim. "Application of Nonlinear Static Procedures for the Seismic Assessment of Regular RC Moment Frame Buildings." Earthquake Spectra 30, no. 2 (May 2014): 767–94. http://dx.doi.org/10.1193/111511eqs281m.

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The applicability of nonlinear static procedures for estimating the seismic demands of typical regular RC moment-resisting frames is evaluated. This work, conducted within the framework of the ATC-76-6 project, shows the degree to which nonlinear static methods can characterize global and local response demands vis-à–vis those determined by nonlinear dynamic analysis for three RC moment-frame buildings. The response quantities (engineering demand parameters) considered are peak story displacements, story drifts, story shears, and floor overturning moments. The single-mode pushover methods evaluated include the N2 and the ASCE-41 coefficient methods. Multi-modal pushover methods, such as modal pushover analysis and the consecutive modal pushover method, were also evaluated. The results indicate that the relatively good performance of the single-mode methods observed for low-rise buildings rapidly deteriorates as the number of stories increases. The multi-modal techniques generally extend the range of applicability of pushover methods, but at the cost of additional computation and without ensuring the reliability of the results.

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45

WINTERS, K. B. "Growth of inertia–gravity waves in sheared inertial currents." Journal of Fluid Mechanics 601 (April 25, 2008): 85–100. http://dx.doi.org/10.1017/s0022112008000621.

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The linear stability of inviscid non-diffusive density-stratified shear flow in a rotating frame is considered. A temporally periodic base flow, characterized by vertical shear S, buoyancy frequency N and rotation frequency f, is perturbed by infinitesimal inertia–gravity waves. The temporal evolution and stability characteristics of the disturbances are analysed using Floquet theory and the growth rates of unstable solutions are computed numerically. The global structure of solutions is addressed in the dimensionless parameter space (N/f, S/f, φ) where φ is the wavenumber inclination angle from the horizontal for the wave-like perturbations. Both weakly stratified rapidly rotating flows (N<f) and strongly stratified slowly rotating flows (N>f) are examined. Distinct families of unstable modes are found, each of which can be associated with nearby stable solutions of periodicity T or 2T where T is the inertial frequency 2π/f. Rotation is found to be a destabilizing factor in the sense that stable non-rotating shear flows with N2/S2>1/4 can be unstable in a rotating frame. Morever, instabilities by parametric resonance are found associated with free oscillations at half and integer multiples of the inertial frequency.

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46

Pannier, Yannick, Henry Proudhon, Cristian Mocuta, Dominique Thiaudière, and Sabine Cantournet. "In situmulti-axial loading frame to probe elastomers using X-ray scattering." Journal of Synchrotron Radiation 18, no. 6 (September 14, 2011): 907–11. http://dx.doi.org/10.1107/s0909049511024861.

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Anin situtensile–shear loading device has been designed to study elastomer crystallization using synchrotron X-ray scattering at the Synchrotron Soleil on the DiffAbs beamline. Elastomer tape specimens of thickness 2 mm can be elongated by up to 500% in the longitudinal direction and sheared by up to 200% in the transverse direction. The device is fully automated and plugged into theTANGOcontrol system of the beamline allowing synchronization between acquisition and loading sequences. Experimental results revealing the evolution of crystallization peaks under load are presented for several tension/shear loading sequences.

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47

Jia, Yigang, Guangyu Wu, Yaxi Zhong, WenGuo Ren, Cheng Yu, and Bao Wan. "Nonlinear Simulation Analysis on Loaded-Bearing Performance of Multistory Infilled R.C. Frame Structure with Openings Under Horizontal Force." Journal of Computational and Theoretical Nanoscience 14, no. 1 (January 1, 2017): 497–504. http://dx.doi.org/10.1166/jctn.2017.6351.

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The influence of infill walls on the mechanical property of RC frame structures is distinct, the rational lateral stiffness of infilled frame structures and the design method of filler wall which are considered in resistance urgently need to be discussed. A group of single-span single-story infilled frame models (three) are nonlinear simulation analyzed by using ANSYS program, and verify the results of ANSYS by comparing with their experimental results. Then, establish a group of single-span three-stories infilled frame models (seven) with different opening sizes and different opening locations to simulate and analyze the lateral performance of multistory infilled frame structure with openings. And the following conclusions are drawn: the frame beam is in the unfavorable condition of “short beam sheared” with the existence of the openings in up and down stories; the lower the location of story is, the bigger the lateral stiffness of infilled frame is, and the quicker the degradation speed of stiffness is and so on.

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48

Fenwick, R. C., and B. J. Davidson. "Comparative analyses of a multi-storey frame and wall using the current and draft loadings codes." Bulletin of the New Zealand Society for Earthquake Engineering 22, no. 4 (December 31, 1989): 181–92. http://dx.doi.org/10.5459/bnzsee.22.4.181-192.

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The two draft loadings codes, DZ 4203-86 and 89, introduced major changes in both the response spectra used for seismic design and the methods of analysis. In this paper a wall and a frame, which have been proportioned to provide the seismic lateral load resistance for a 24 storey structure, are analysed by the methods given in these codes to highlight the differences. To simplify the comparison torsional effects have been omitted. The technique of finding a set of lateral loads, by taking the differences of the combined modal storey shears and using these to find the design structural actions, is shown to be inappropriate for structures analysed for the response spectra given in the draft loadings code (DZ 4203, 86 or 89), if the second or higher modes make a significant contribution to the combined modal storey shears.

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49

Santo, H., D. Stagonas, E. Buldakov, and P. H. Taylor. "Current blockage in sheared flow: Experiments and numerical modelling of regular waves and strongly sheared current through a space-frame structure." Journal of Fluids and Structures 70 (April 2017): 374–89. http://dx.doi.org/10.1016/j.jfluidstructs.2017.02.010.

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50

Bahrami, Alireza, and Mahmood Heidari. "Investigation of Steel Frames Equipped with Steel Eccentric Braces and Steel-Concrete Buckling-Restrained Braces Having Moment Link." Open Construction and Building Technology Journal 15, no. 1 (May 6, 2021): 55–69. http://dx.doi.org/10.2174/1874836802115010055.

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Background: Different bracing systems of steel Eccentric Braces (EBs) and steel-concrete Buckling-Restrained Braces (BRBs) can be used in steel frames in order to make the frames stronger in resisting lateral loads. These steel frames with EBs or BRBs are generally called Eccentrically Braced Frames (EBFs) or Buckling-Restrained Braced Frames (BRBFs), respectively. Objective: This study aims to investigate steel frames with bracing systems of steel EBs and steel-concrete BRBs having moment link. Methods: The EBFs and BRBFs are nonlinearly analysed employing the finite element software ABAQUS. Experimental tests of the EBF and BRB are utilised for the validation of their modelling. The modelling is validated by comparing the modelling results with experimental tests results. Then, an EBF and a BRBF are designed having moment link. The extreme earthquake records of Tabas, Chi-Chi, and Northridge are selected for the dynamic analyses of the EBF and BRBF. The validated modelling method is applied to analyse the designed EBF and BRBF under the selected earthquake records. Results: The achieved results from the analyses are lateral displacements, base shears, and energy dissipations of the EBF and BRBF and moment link rotations. These results are compared and discussed. Conclusion: It is concluded that the hierarchy of the lateral displacements of the analysed EBF and BRBF, having moment link, is related to the Tabas, Chi-Chi, and Northridge records because the lateral displacements of the frames are directly proportional to the peak ground accelerations of the records, and there is the same hierarchy for the records in terms of their peak ground accelerations. Lower lateral displacements are witnessed for the BRBF than the EBF subjected to the Tabas and Chi-Chi records. However, larger lateral displacement is observed for the BRBF than the EBF under the Northridge record. The same procedure as the lateral displacements is also revealed for the effectiveness of the BRBF with regard to its link rotations compared with the EBF. Moreover, the BRBF improves the base shear capacities and energy dissipations of the frame compared with the EBF. Consequently, the BRBF is generally demonstrated to be superior to the EBF from the structural performance point of view. Thus, the BRBF can be used more efficiently in structures subjected to large lateral loads compared with the EBF.

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