scholarly journals Tectonic plate coupling and elastic thickness derived from the inversion of a steady state viscoelastic model using geodetic data: Application to southern North Island, New Zealand

2003 ◽  
Vol 108 (B3) ◽  
Author(s):  
Steven C. Cohen ◽  
Desmond J. Darby
Keyword(s):  
Steady State ◽  
New Zealand ◽  
Viscoelastic Model ◽  
Geodetic Data ◽  
Tectonic Plate ◽  
Data Application ◽  
Plate Coupling

scholarly journals Studies on dielectric relaxation in relation to viscosity of some anilines, phenol, and their binary mixtures at microwave frequencies

2019 ◽  
Vol 97 (2) ◽  
pp. 210-215
Author(s):  
C.V. Maridevarmath ◽  
G.H. Malimath
Keyword(s):  
Relaxation Time ◽  
Steady State ◽  
Dynamic Viscosity ◽  
Room Temperature ◽  
Viscoelastic Model ◽  
Frictional Resistance ◽  
Nonlinear Behaviour ◽  
Viscoelastic Relaxation ◽  
Microwave Frequencies ◽  
Loss Formula

In the present work, the study of variation of relaxation time (τ) with viscosity of the medium (η) is carried out on four polar samples: 2-Nitroaniline, 4-Bromoaniline, 4-Chloroaniline, 4-Chlorophenol, and also on the binary mixture of 2-Nitroaniline + 4-Bromoaniline at room temperature by using microwave bench operating at a frequency of 9.59 GHz. In this regard, the different parameters like dielectric constant ([Formula: see text]), dielectric loss ([Formula: see text]), relaxation time (τs), macroscopic steady state viscosity (ηs), dynamic viscosity (ηd), and viscoelastic relaxation time (τve) were determined for all the systems. It is observed that the relaxation time (τs) increases with the increase in the viscosity of the medium for all the systems. Plots of log(τs) versus log(ηs) for all the systems show that variation of relaxation time is found to be nonlinear in the higher viscosity regions. This suggests the failure of Debye’s theory at these regions. Further, the nonlinear behaviour of relaxation time with the viscosity is explained by using the viscoelastic model suggested by Barlow et al. (Proc. R. Soc. A 309, 473 (1969). doi: 10.1098/rspa.1969.0053 ). It is also observed that macroscopic steady state viscosity (ηs) values are greater than the dynamic viscosity (ηd), and viscoelastic relaxation time (τve) values were found to be lower compared to the relaxation time (τs). These results suggest that the effective frictional resistance experienced by the molecules during reorientation is lower and the measured values of macroscopic steady state viscosity (ηs) are frequency dependent.

A mechanical model for adjustable passive stiffness in rabbit detrusor

2006 ◽  
Vol 101 (4) ◽  
pp. 1189-1198 ◽  
Author(s):  
John E. Speich ◽  
Kevin Quintero ◽  
Christopher Dosier ◽  
Lindsey Borgsmiller ◽  
Harry P. Koo ◽  
...  
Keyword(s):  
Steady State ◽  
Mechanical Model ◽  
Strain Softening ◽  
Slow Component ◽  
Viscoelastic Model ◽  
Passive Force ◽  
Passive Stiffness ◽  
Cross Link ◽  
Force Relaxation ◽  
Adjustable Passive Stiffness

Strips of rabbit detrusor smooth muscle (DSM) exhibit adjustable passive stiffness characterized by strain softening: a loss of stiffness on stretch to a new length distinct from viscoelastic behavior. At the molecular level, strain softening appears to be caused by cross-link breakage and is essentially irreversible when DSM is maintained under passive conditions (i.e., when cross bridges are not cycling to produce active force). However, on DSM activation, strain softening is reversible and likely due to cross-link reformation. Thus DSM displays adjustable passive stiffness that is dependent on the history of both muscle strain and activation. The present study provides empirical data showing that, in DSM, 1) passive isometric force relaxation includes a very slow component requiring hours to approach steady state, 2) the level of passive force maintained at steady state is less if the tissue has previously been strain softened, and 3) tissues subjected to a quick-release protocol exhibit a biphasic response consisting of passive force redevelopment followed by force relaxation. To explain these and previously identified characteristics, a mechanical model for adjustable passive stiffness is proposed based on the addition of a novel cross-linking element to a hybrid Kelvin/Voigt viscoelastic model.

scholarly journals On the Isotopic Composition of Dissolved Inorganic Carbon in Rivers and Shallow Groundwater: A Diagrammatic Approach to Process Identification and A More Realistic Model of the Open System

Radiocarbon ◽  
1997 ◽  
Vol 39 (3) ◽  
pp. 251-268 ◽  
Author(s):  
C. B. Taylor
Keyword(s):  
Steady State ◽  
New Zealand ◽  
Isotopic Composition ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Dynamic Balance ◽  
Shallow Groundwater ◽  
Realistic Model ◽  
Essential Information ◽  
Aquifer Systems

Rivers and shallow groundwater are deep groundwater precursors. Their dissolved inorganic carbon content (DIC) and its isotopic composition are end members in the evolution of these properties in confined situations, and are therefore essential information when applying carbon isotopes as tracers of groundwater processes and determining aquifer residence times using 14C.During studies of regional aquifer systems in New Zealand, a simple model has been developed to explain the isotopic compositions of DIC encountered in rivers and shallow groundwater. The model format incorporates a diagrammatic approach, providing a framework for tracing the subsequent evolution of DIC in both precipitation- and river-recharged aquifers under closed conditions.DIC concentration of rivers continuously adjusts toward chemical and isotopic equilibrium between direct addition of CO2 to the water (via plant respiration and decay of dead organic material) and exchange of CO2 across the river-air interface. In the shallow groundwater situation, the gaseous reservoir is soil CO2, generally at significantly higher partial pressure. In both cases, calcite dissolution or other processes may be an additional source of DIC directly added to the bicarbonate and dissolved CO2 components; while these may add or remove DIC, steady-state isotopic concentrations are considered to be determined only by the dynamic balance between directly added CO2 and gas exchange. This model allows the calculation of steady states, using selectable parameters in river or groundwater situations. These appear as straight lines in 13C or 14C vs. 1/DIC, or total 14C vs. DIC plots, into which the experimental data can be inserted for interpretation. In the case of 14C, the steady-state balance is very often complicated by the presence of an old component in the directly added DIC; the understanding achieved via the 13C patterns is helpful in recognizing this.Data from four contrasting aquifer systems in New Zealand. The success of the approach has depended crucially on DIC concentrations measured very accurately on the isotope samples, rather than separate chemical analyses.

Electrical resistivity imaging of the inter-plate coupling transition at the Hikurangi subduction margin, New Zealand

2019 ◽  
Vol 524 ◽  
pp. 115710
Author(s):  
Wiebke Heise ◽  
Yasuo Ogawa ◽  
Edward A. Bertrand ◽  
T. Grant Caldwell ◽  
Ryokei Yoshimura ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
New Zealand ◽  
Electrical Resistivity Imaging ◽  
Resistivity Imaging ◽  
Plate Coupling
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