Saddle Configurations Research Articles

Vergence and facing patterns in large-scale sheath folds

The careful geometric analysis of minor structural detail elucidates the relationships and evolution of associated large-scale curvilinear hinge geometries, developed during WNW-directed Caledonian thrusting exposed in Neoproterozoic Moine psammites of the Moine Nappe. Reversals in the polarity of structural facing associated with minor folding, mark the position of major sheath folds which parallel transport. Upwardly convex sheaths (closing in the direction of thrust transport) cored by older gneissose basement inliers are termed culminations, whilst those opening in the transport direction (and cored by Moine psammites) are termed depressions. Sheath folds are bisected by transport parallel and foliation normal (culmination/depression) surfaces which separate not only the reversals in facing, but also delineate zones of minor fold hinge obliquity into clockwise and anticlockwise domains relative to the transport direction. The sense of obliquity of minor Z and S folds is thus dependent on position with respect to the surfaces of culmination and depression and not the fold axial surfaces. Surfaces of culmination and depression may be superimposed on original overturned antiformal and synformal folds to produce a variety of dome (culmination on antiform), saddle (depression on antiform), inverted saddle (culmination on synform) and basin (depression on synform) configurations. The curvilinear hinges of minor folds may also be asymmetrical about the transport direction and within the plane of the regional foliation to define patterns of fold hinge-line vergence. Classical concepts of fold limb vergence may thus relate to larger antiformal and synformal hinges, whilst the fold hinge-line vergence defines major curvilinear hinges associated with culminations and depressions. Major sheath folds may therefore be interpreted in terms of both minor fold hinge-line and limb vergence, coupled with fold axis obliquity and reversals in the polarity of structural facing. The ability to recognise consistent and reliable structural relationships between facing and hinge obliquity at small scales indicates that the regional deformation process forms a linked and coherent system through several orders of magnitude.

The Support of Horizontal Vessels Containing High-Temperature Fluids—A Design Study

This paper investigates the behavior of horizontal cylindrical vessels, subjected to thermal loading by high-temperature fluid, where the saddles are fixed to the supporting structure. In order to determine an optimum saddle design, three widely used saddle configurations, with differing saddle heights and top saddle plate extensions, are explored. Thereafter, one of the saddle designs is selected to illustrate a decoupling procedure, for the radial and axial expansions, whereby design charts are obtained to derive the maximum stress values for a range of vessel geometries. The finite element approach, using linear elastic, small displacement analysis, is used throughout.

Static aspects of the fission and fusion of3He drops

Using an effective3He-3He interaction, we have investigated the fission and fusion of3He drops from a static point of view. Our calculations show that a fission barrier develops for these neutral systems, and that their saddle configurations are rather elongate. The transition from oblate to prolate shapes as a function of the angular momentumL, as well as critical values for fission and fusion are discussed for some selected cases. We show that a kind of proximity potential can be extracted from the drop-drop interaction potentials.

Fission and fusion of3He drops

We have investigated the static fission and fusion of3He drops using a density functional. Our calculations show that a fission barrier develops for these neutral systems, and that their saddle configurations are rather elongate. We show that a kind of proximity potential can be extracted from the drop-drop interaction potentials.