Showing papers on "Deformation (meteorology) published in 1989"

The influence of formation material properties on the response of water levels in wells to Earth tides and atmospheric loading

Abstract: The water level in an open well can change in response to deformation of the surrounding material, either because of applied strains (tidal or tectonic) or surface loading by atmospheric pressure changes. Under conditions of no vertical fluid flow and negligible well bore storage (static-confined conditions), the sensitivities to these effects depend on the elastic properties and porosity which characterize the surrounding medium. For a poroelastic medium, high sensitivity to applied areal strains occurs for low porosity, while high sensitivity to atmospheric loading occurs for high porosity; both increase with decreasing compressibility of the solid matrix. These material properties also influence vertical fluid flow induced by areally extensive deformation and can be used to define two types of hydraulic diffusivity which govern pressure diffusion, one for applied strain and one for surface loading. The hydraulic diffusivity which governs pressure diffusion in response to surface loading is slightly smaller than that which governs fluid flow in response to applied strain. Given the static-confined response of a water well to atmospheric loading and Earth tides, the in situ drained matrix compressibility and porosity (and hence the one-dimensional specific storage) can be estimated. Analysis of the static-confined response of five wells to atmospheric loading and Earth tides gives generally reasonable estimates for material properties.

Water-pressure coupling of sliding and bed deformation: II. Velocity- depth profiles

Abstract: Basal motion of a glacier resting on an unconsolidated bed can arise from sliding between ice and bed, ploughing of clasts through the upper layer of the bed, pervasive deformation of the bed, or shearing across discrete planes in the bed. Theoretical analyses and limited observations of soft-bedded glaciers not dominated by supply of channelized melt water from the surface suggest that sliding will be slow if the bed contains abundant clasts in the 1–10 mm size range, and that high velocities by ploughing are unlikely though possible. Pervasive deformation usually will account for 60–100% of the basal velocity, and the strain-rate will be proportional to the basal shear stress and inversely proportional to the square or cube of the effective pressure. These hypotheses are based on results of part I in this series, and allow modeling of Ice Stream B, West Antarctica, in part III of this series.

Active deformation of the continents

Abstract: Whereas relatively narrow bands of deformation define oceanic plate boundaries, in continental situations deformation is shown to be distributed over much broader zones. The complex and heterogeneous nature of boundary regions between major plates is outlined with reference to the Mediterranean and the Himalayas. Relatively aseismic regions have traditionally been defined as microplates but although they are presently acting as rigid blocks undergoing slow deformation, it is argued that this need not always have been the case, and that deformation may simply have moved elsewhere. Broad zones of deformation surrounding rigid blocks are highlighted as fundamental to the analysis and interpretation of continental tectonics. Detailed theoretical consideration is given to the kinematics of distributed formation and the dynamics of continental deformation. -A.J.Barker

Deformation and breakup of drops in simple shear flows

Abstract: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.

Deformation of the so-called Gorda Plate

Abstract: A new compilation of magnetic anomaly identifications, recent side scan sonar data, and other data provide constraints on the mechanism of deformation of the area commonly known as the Gorda plate. A sharp boundary between the rigid Juan de Fuca plate and deformed material trends southeast from the northern part of the Gorda ridge. In material older than 2–3 Ma, the boundary is gradational and trends more to the east. Previous observations that the anomalies east of the ridge are shorter than their counterparts on the Pacific plate are confirmed. There is no evidence for subduction or obduction along the Mendocino transform. Adjacent to the ridge, the deformation is interpreted to be distributed NW-SE right-lateral simple shear, possibly controlled by ductile deformation of the lower crust. Deformation of this sense is capable of producing the observed shortening the anomalies. Away from the ridge, apparently in crust of age 2–3 Ma, there must be a transition to deformation on observed NE-SW left-lateral faults parallel to the original spreading fabric.

Geodynamic model for Alpine intra-plate compressional deformation in Western and Central Europe

Abstract: Summary The Mesozoic grabens and wrench induced troughs of Western and Central Europe developed in response to Triassic to Early Cretaceous intra-plate tensional stresses which affected the Arctic — North Atlantic and the Tethys borderlands during the rifting phases preceding the opening of the respective oceans. During the Alpine orogeny, collision-related compressive stresses exerted on the foreland induced the reactiviation of pre-existing fracture systems, and caused the inversion of Mesozoic grabens and the uplifting of major basement blocks at distances up to 1300 km to the north of the present Alpine deformation front. The structural style of these inversion structures is indicative of compression and transpression. Total crustal shortening is unlikely to exceed a few tens of kilometres. These displacements require a coupling between the foreland and the orogen at the Alpine A-subduction zones and, within the foreland, a decoupling at intra-crustal levels between the crust and mantle and/or at deeper lithospheric levels.

On the deformation of Artin-Schreier to Kummer

Abstract: © Gauthier-Villars (Éditions scientifiques et médicales Elsevier), 1989, tous droits réservés. L’accès aux archives de la revue « Annales scientifiques de l’É.N.S. » (http://www. elsevier.com/locate/ansens) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.

Basal ice formation and deformation: a review

Abstract: A distinction is often made between the ice which constitutes the major part of glaciers and ice sheets and a relatively thin layer of debris-rich ice which is present at their base. This ’basal ice’, which has a vertical extent of up to tens of metres, is produced at and interacts with the glacier bed, while the overlying ’glacier ice’ is a product of firnification processes occurring at or near the upper surface of the ice mass (Paterson, 1981). As a result of its different mode and environment of formation, basal ice may differ from glacier ice in terms of its overall extent and structure and in the properties of the ice, debris, solutes and gases of which it is composed. In general, basal ice sequences have a much higher debris content than glacier ice and an anisotropic structure, consisting of individual layers, lenses and pods of variable lateral extent and distinctive chemical and isotopic composition. Several workers have combined study of these characteristics with theoretical considerations to postulate mechanisms for the formation of basal ice (Weertman, 1961; 1964; Kamb and LaChapelle, 1964; Boulton, 1970; Shaw, 1977; Tison and Lorrain, 1987). Given this compositional variability, basal ice may behave in a very different way rheologically from glacier ice or polycrystalline ’laboratory’ ice. A number of recent studies have reported field observations which indicate that strain rates in debris-rich basal ice or frozen subglacial sediments may be well in excess of those expected from theoretical or laboratory-based studies. This is of signicance since, although much of the internal deformation of ice masses occurs in layers close to the bed, most models of glacier and ice-sheet behaviour are based on assumptions of the uniform deformation of isotropic, polycrystalline ice based on Glen’s (1955) power flow law (see Weertman and Birchfield, 1984). This is no less the case today than in 1967, when Theakstone called for a greater comprehension of the response to stress of ice ’such as actually exists at glacier beds’, without which he felt that ’an adequate theory of glacier sliding is unlikely to be developed’ (Theakstone, 1967). The aim of this paper is to identify some of the processes responsible for the formation of basal ice sequences and to demonstrate the links likely to exist between these processes and the characteristics of the resultant sequences. The postulated rheological consequences of these properties are also discussed in the

Mechanism of Grain Orientation During Hot-Pressing of Bismuth Titanate

Abstract: Grain-oriented Bi4Ti3O12 ceramics have been prepared by hot-pressing. Platelike grains align during hot-pressing; the long-axis direction perpendicular to the crystal c axis is oriented perpendicular to the pressing direction. The effects of hotpressing conditions such as temperature, pressure, time, and type of filler on the density, orientation degree, and deformation of hot-pressed compacts were examined. Sharp increases in the density, deformation, and grain orientation occurred during the early stage; the density decreased, and the latter two incresed on prolonged hot-pressing. The grain orientation is closely related to the deformation in the radial direction. The grain-orientation mechanism is discussed referring to mechanisms proposed for high-temperature deformation in ceramics. The compact is deformed by two processes: one accompaines grain orientation, and the other does not. Grain-boundary sliding is proposed for the former process. The contribution of grain-boundary sliding to the deformation increases with increasing temperature and pressure. The filler also influences the contribution. The decrease in density is caused by cavity formation during prolonged hot-pressing.

Rubber toughening of plastics: Part 12 Deformation mechanisms in toughened nylon 6,6

Abstract: Etude comparative du comportement en traction de polyamide 66 renforcee ou non par 20% d'elastomere

Shear band analysis for granular materials: The question of incremental non-linearity

Abstract: Shear band analysis is a theoretical approach for the phenomenon of deformation localization, a characteristic aspect of rupture in geomaterials. It is closely related to advanced soil modelling, because the constitutive equations describing the material behaviour play the central role in that analysis. One of the basic features of geomaterials' behaviour is non-reversibility. Soil models have to incorporate some kind of incremental non-linearity to take irreversibility into account. Depending on the actual type of the considered non-linearity shear band analysis must be conducted in different ways. The basic equations of shear band analysis are presented, introducing a comprehensive discussion of the different cases to be considered with respect to the different types of non-linearity incorporated in the formulation of constitutive equations.

Micromechanics of Fracture in Structural Adhesive Bonds

Abstract: The high mode-I fracture surface energies, GIC , of structural adhesives can be attributed to their ability to form large crack-tip deformation zones prior to failure. It has been suggested that this feature also controls the dependence of the adhesive bond GIC on bond thickness. The proposed explanation asserted that the physical constraint of the adherents and the nature of the crack-tip stress field in an adhesive joint alter the size and shape of the deformation zone, and this in turn changes the fracture behaviour. To examine this hypothesis, motion pictures were taken of fracture specimens during loading, and the stress whitening that occurred at the crack tip was used to judge the relative dimensions of the deformation zone. The results generally support the hypothesis. Moreover, the pictures furnish a clear image of the deformation zone's growth patterns during loading, and this provides a critical test for future modelling efforts.

Ovalized label panel for round hot filled plastic containers

Abstract: A plastic container for use in receiving product in a hot state the sealing of which creates a negative pressure therein after the product cools, an ovalized portion of the container disposed between a bottom and shoulder having circular cross sections wherein the negative pressure causes a uniform deformation of the ovalized portion allowing the container to remain aesthetically pleasing in appearance.