Effect Of Longitudinal Stress Research Articles

Simulation of Vatnajökull ice cap dynamics

We apply a coupled model of ice sheet dynamics and subglacial hydrology to investigate the dynamics and future evolution of the Vatnajökull ice cap, Iceland. In this paper we describe a new theoretical approach to introducing longitudinal stress coupling in the ice dynamics solution, and we analyze our ability to simulate the main features of Vatnajökull, with and without longitudinal stress effects. Equilibrium ice cap configurations exist for Vatnajökull but under a narrow range of climatic boundary conditions. Equilibrium reconstructions have an average ice thickness greater than what is observed at Vatnajökull, consistent with our inability to capture surge dynamics in Vatnajökull's outlet glaciers. Hydrological regulation of basal flow, longitudinal stress coupling, and a simple parameterization of the subglacial heat flux from Vatnajökull's geothermal cauldrons all help to reduce average ice thickness in the equilibrium reconstructions, but cases that reproduce the present‐day ice volume have an ice cap area that is 5–10% less than the actual ice cap. Present‐day reconstructions that adopt a realistic climate spin‐up for the period 1600–1990 provide improved fits to the modern‐day ice cap geometry. This indicates that climatic disequilibrium also plays a significant role in dictating Vatnajökull's morphology. Simulations for the period 1600–2300 illustrate that air temperature is the dominant control on Vatnajökull's volume and area. Longitudinal stress coupling and hydrological coupling both increase Vatnajökull's sensitivity to future warming.)

Magnetic domain demonstrations using the kerr magneto-optic effect

Abstract A new approach to the teaching of magnetic materials is afforded by a new teaching aid; the teaching aid enables magnetic domain changes for d.c. and a.c. magnetization to be shown on a television screen to large groups of students, demonstrating phenomena such as coercivity, remanence, hysteresis and saturation. Barkhausen noise is heard, accompanying the domain wall movements. Magnetostriction is demonstrated using a signal from a double piezo-electric transducer placed under the specimen, and the effects of longitudinal stress on all the above phenomena can be observed simultaneously.

Domain configuration under rotational flux and applied stress conditions in silicon-iron

Measurements of power loss have been made on individual grains in polycrystalline specimens of commercial 3% grain-oriented silicon-iron under longitudinal and transverse ac magnetization and rotational flux conditions. The domain configurations have also been observed using a stroboscopic Kerr magnetic-optic apparatus. The effect of longitudinal stress and dc bias fields on the domain patterns and power loss under these ac magnetization conditions has also been investigated. It can be concluded that the highest power loss occurs under pure rotational flux conditions and that the application of longitudinal compressive stress increases the power loss, but to a lesser extent when a transverse ac flux is present. The application of a longitudinal dc field increases the power loss for all ac magnetizing conditions, and it has been observed that a longitudinal tensile stress has the opposite effect on the domain configuration to the application of a transverse dc field.

The Effect of Longitudinal Stress on the Shear Stress at the Base of an Ice Sheet

Robin (1967) and Budd (1968, unpublished) have succeeded in connecting the variations in surface slope of an ice sheet with variations in the gradient of the longitudinal strain-rate. This paper tries to improve the theoretical basis of their work. By choice of a suitable coordinate system and suitable redefinition of the variables, Budd’s formula for the basal shear stress is derived with a minimum of restrictive assumptions. The resulting formula, containing the gradient of a longitudinal stress, is thought to be of high accuracy for the two-dimensional flow of cold ice sheets, and is valid for slopes of any magnitude.

The Effect of Longitudinal Stress on the Shear Stress at the Base of an Ice Sheet

Robin (1967) and Budd (1968, unpublished) have succeeded in connecting the variations in surface slope of an ice sheet with variations in the gradient of the longitudinal strain-rate. This paper tries to improve the theoretical basis of their work. By choice of a suitable coordinate system and suitable redefinition of the variables, Budd’s formula for the basal shear stress is derived with a minimum of restrictive assumptions. The resulting formula, containing the gradient of a longitudinal stress, is thought to be of high accuracy for the two-dimensional flow of cold ice sheets, and is valid for slopes of any magnitude.

Effect of Longitudinal Stress on the Magnetization of Volcanic Rocks

Effect of Longitudinal Stress on the Magnetization of Volcanic Rocks