Effect of temperature-dependent multiple reflections in crystals using a high-accuracy universal polarimeter

2000 ◽  
Author(s):  
Pedro Gomez-Garrido ◽  
Cecilio Hernandez-Rodriguez
Keyword(s):  
High Accuracy ◽  
Effect Of Temperature ◽  
Multiple Reflections ◽  
Temperature Dependent

Temperature-dependent gyration tensor of LiIO3single crystal using the high-accuracy universal polarimeter

2002 ◽  
Vol 35 (2) ◽  
pp. 228-232 ◽  
Author(s):  
J. Herreros-Cedrés ◽  
C. Hernández-Rodríguez ◽  
R. Guerrero-Lemus
Keyword(s):  
Optical Activity ◽  
High Accuracy ◽  
Multiple Reflections ◽  
Temperature Dependent ◽  
Temperature Range ◽  
High Degree

The gyration tensor of LiIO3has been measured in the temperature range between 293 and 493 K at a wavelength of 632.8 nm. Optical activity and birefringence for the (010) plane were determined by using a high-accuracy universal polarimeter (HAUP). Likewise, optical activity for the (001) plane was studied by using a conventional polarimeter in the same temperature range at 632.8 nm wavelength. In the latter case, a modulation of the optical activity was observed. This effect can be explained by multiple reflections within the slab with a high degree of plane parallelism.

The effect of temperature-dependent thermal parameters in thermal models of subduction zones

2021 ◽  
Author(s):  
Iris van Zelst ◽  
Timothy J. Craig ◽  
Cedric Thieulot
Keyword(s):  
Subduction Zones ◽  
Thermal Parameters ◽  
Dislocation Creep ◽  
Seismogenic Zone ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Thermal Models ◽  
Intermediate Depth ◽  
Dehydration Reactions ◽  
Model Setup

<p>The thermal structure of subduction zones plays an important role in the seismicity that occurs there with e.g., the downdip limit of the seismogenic zone associated with particular isotherms (350 °C - 450 °C) and intermediate-depth seismicity linked to dehydration reactions that occur at specific temperatures and pressures. Therefore, accurate thermal models of subduction zones that include the complexities found in laboratory studies are necessary. One of the often-ignored effects in models is the temperature-dependence of the thermal parameters such as the thermal conductivity, heat capacity, and density.<span> </span></p><p>Here, we build upon the model setup presented by Van Keken et al., 2008 by including temperature-dependent thermal parameters to an otherwise clearly constrained, simple model setup of a subducting plate. We consider a fixed kinematic slab dipping at 45° and a stationary overriding plate with a dynamic mantle wedge. Such a simple setup allows us to isolate the effect of temperature-dependent thermal parameters. We add a more complex plate cooling model for the oceanic plate for consistency with the thermal parameters.<span> </span></p><p>We test the effect of temperature-dependent thermal parameters on models with different rheologies, such as an isoviscous wedge, diffusion and dislocation creep. We find that slab temperatures can change by up to 65 °C which affects the location of isotherm depths. The downdip limit of the seismogenic zone defined by e.g., the 350 °C isotherm shifts by approximately 4 km, thereby increasing the maximum possible rupture area of the seismogenic zone. Similarly, the 600 °C isotherm is shifted approximately 30 km deeper, affecting the depth at which dehydration reactions and hence intermediate-depth seismicity occurs. Our results therefore show that temperature-dependent thermal parameters in thermal models of subduction zones cannot be ignored when studying subduction-related seismicity.<span> </span></p>

The Effect of Temperature Dependent Yield Strength on Upper Bounds for Creep Ratcheting

2006 ◽  
Author(s):  
Timothy E. McGreevy ◽  
Frederick A. Leckie ◽  
Peter Carter ◽  
Douglas L. Marriott
Keyword(s):  
Yield Strength ◽  
Upper Bounds ◽  
Effect Of Temperature ◽  
Strain Accumulation ◽  
Core Concept ◽  
Temperature Dependent ◽  
Inelastic Analysis ◽  
Asme Code ◽  
Inelastic Design ◽  
Very High

The Bree model and the elastic core concept have been used as the foundation for the simplified inelastic design analysis methods in the ASME Code for the design of components at elevated temperature for nearly three decades. The methodology provides upper bounds for creep strain accumulation and a physical basis for ascertaining if a structure under primary and secondary loading will behave elastically, plastically, shakedown, or ratchet. Comparisons of the method with inelastic analysis results have demonstrated its conservatism in stainless steel at temperatures representative of those in LMBR applications. The upper bounds on creep accumulation are revisited for very high temperatures representative of VHTR applications, where the yield strength of the material is strongly dependent upon temperature. The effect of the variation in yield strength on the evolution of the core stress is illustrated, and is shown to extend the shakedown regions, and affects the location of the boundaries between shakedown, ratcheting, and plasticity.

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