The role of the spectrum in the cyclic behavior of composition operators

2004 ◽  
Vol 167 (791) ◽  
pp. 0-0 ◽  
Author(s):  
Eva A. Gallardo-Gutiérrez ◽  
Alfonso Montes-Rodríguez
Keyword(s):  
Composition Operators ◽  
Cyclic Behavior

scholarly journals Low-Cycle Fatigue of FRP Strips Glued to a Quasi-Brittle Material

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7753
Author(s):  
Enzo Martinelli ◽  
Antonio Caggiano
Keyword(s):  
Bond Length ◽  
Low Cycle Fatigue ◽  
Cyclic Behavior ◽  
Pure Mode ◽  
Geometric Quantity ◽  
Bond Slip ◽  
Frp Strips ◽  
Interface Bond ◽  
Fracture Processes

This paper aims at further advancing the knowledge about the cyclic behavior of FRP strips glued to quasi-brittle materials, such as concrete. The results presented herein derive from a numerical model based on concepts of based on fracture mechanics and already presented and validated by the authors in previous works. Particularly, it assumes that fracture processes leading to debonding develop in pure mode II, as is widely accepted in the literature. Starting from this assumption (and having clear both its advantages acnd shortcomings), the results of a parametric analysis are presented with the aim of investigating the role of both the mechanical properties of the interface bond–slip law and a relevant geometric quantity such as the bond length. The obtained results show the influence of the interface bond–slip law and FRP bond length on the resulting cyclic response of the FRP-to-concrete joint, the latter characterized in terms of S-N curves generally adopted in the theory of fatigue. Far from deriving a fully defined correlation among those parameters, the results indicate general trends that can be helpful to drive further investigation, both experimental and numerical in nature.

Monotonic and Cyclic Behavior of Ultrafine Grain Metals:Overview

2006 ◽  
Vol 503-504 ◽  
pp. 267-274 ◽  
Author(s):  
Alexei Vinogradov
Keyword(s):  
Plastic Deformation ◽  
Cyclic Stress ◽  
Grain Boundary Sliding ◽  
Cyclic Behavior ◽  
Ultrafine Grain ◽  
Strain Behavior ◽  
Fine Grain ◽  
Boundary Sliding ◽  
The Common

The available to date experimental results are reviewed with regard to the common aspects and features of monotonic and cyclic stress-strain behavior of various ultra-fine grain materials produced by severe plastic deformation (SPD). Some possible mechanisms of plastic flow and degradation during monotonic and cyclic testing are discussed from the standpoint of initial SPD structure and its evolution upon loading. The role of two strengthening mechanisms – dislocation accumulation and grain reduction - is highlighted. The key importance of grain boundaries for the mechanical behavior, strain localization and fracture of ultra-fine grain metals is argued and the experimental evidence is presented on the significance of grain boundary sliding in their plastic deformation. The results of phenomenological modeling of the monotonic and cyclic response of ultra-fine grain metals are presented in terms of dislocation kinetics and a satisfactory agreement with experimental data is demonstrated.

scholarly journals Dynamics of Dalk Glacier in East Antarctica Derived from Multisource Satellite Observations Since 2000

2020 ◽  
Vol 12 (11) ◽  
pp. 1809
Author(s):  
Yiming Chen ◽  
Chunxia Zhou ◽  
Songtao Ai ◽  
Qi Liang ◽  
Lei Zheng ◽  
...  
Keyword(s):  
East Antarctica ◽  
Surface Velocity ◽  
Cyclic Behavior ◽  
Glacier Terminus ◽  
Digital Elevation ◽  
Ice Velocity ◽  
Velocity Changes ◽  
Elevation Model ◽  
Surface Ice

Monitoring variability in outlet glaciers can improve the understanding of feedbacks associated with calving, ocean thermal forcing, and climate change. In this study, we present a remote-sensing investigation of Dalk Glacier in East Antarctica to analyze its dynamic changes. Terminus positions and surface ice velocities were estimated from Landsat and Sentinel-1 data, and the high-precision Worldview digital elevation model (DEM) was generated to determine the location of the potential ice rumple. We detected the cyclic behavior of glacier terminus changes and similar periodic increases in surface velocity since 2000. The terminus retreated in 2006, 2009, 2010, and 2016 and advanced in other years. The surface velocity of Dalk Glacier has a 5-year cycle with interannual speed-ups in 2007, 2012, and 2017. Our observations show the relationship between velocity changes and terminus variations, as well as the driving role of the ice rumple. Ice velocity often increases after calving events and continuous retreats. The loss of buttressing provided by an ice rumple may be a primary factor for increases in ice velocity. Given the restriction of the ice rumple, the surface velocity remains relatively stable when the glacier advances. The calving events may be linked to the unstable terminus caused by the ice rumple.

Transient Contact of Two Sliding Half-Planes With Wear

1987 ◽  
Vol 109 (4) ◽  
pp. 598-603 ◽  
Author(s):  
A. Azarkhin ◽  
J. R. Barber
Keyword(s):  
Contact Area ◽  
Material Removal ◽  
Frictional Heating ◽  
The Other ◽  
Cyclic Behavior ◽  
Governing Equations ◽  
Simple Geometry ◽  
Transient Contact ◽  
Two Bodies

We study the transient contact of two sliding bodies with a simple geometry. The model employs the Archard law of wear in which the rate of material removal is proportional to pressure and speed of sliding. The problem is formulated in terms of two governing equations with unknown pressure and heat flux at the interface. The equations are solved numerically, using appropriately chosen Green’s functions. We start with a single area of contact. As a result of frictional heating and thermal expansion, the contact area shrinks, which leads to further localization of pressure and temperature. The role of wear is twofold. By removing protruding portions of the two bodies, wear tends to smoothen out pressure and temperature. On the other hand, it causes the contact area to grow sufficiently large to become unstable and bifurcate. Areas carrying load are eventually removed by wear, and the contact moves elsewhere. The system develops a cyclic behavior in which contact and non-contact areas interchange.

On Bounded and Compact Composition Operators in Polydiscs

1990 ◽  
Vol 42 (5) ◽  
pp. 869-889 ◽  
Author(s):  
F. Jafari
Keyword(s):  
Carleson Measure ◽  
Composition Operators ◽  
Bergman Spaces ◽  
Sufficient Conditions ◽  
Extensive Study ◽  
Weighted Bergman Spaces ◽  
Carleson Measures ◽  
Angular Derivatives ◽  
Necessary And Sufficient

Recently MacCluer and Shapiro [6] have characterized the compact composition operators in Hardy and weighted Bergman spaces of the disc, and MacCluer [5] has made an extensive study of these opertors in the unit ball of Cn. Angular derivatives and Carleson measures have played an essential role in these studies. In this article we study composition operators in poly discs and characterize those operators which are bounded or compact in Hardy and weighted Bergman spaces. In addition to Carleson measure theorems resembling those of [5], [6], we give necessary and sufficient conditions satisfied by the maps inducing bounded or compact composition operators. We conclude by considering the role of angular derivatives on the compactness question explicitly.

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