Soil–pipeline interaction along unstable slopes: a coupled three-dimensional approach. Part 1: Theoretical formulation

2009 ◽  
Vol 46 (11) ◽  
pp. 1289-1304 ◽  
Author(s):  
Giuseppe Cocchetti ◽  
Claudio di Prisco ◽  
Andrea Galli ◽  
Roberto Nova
Keyword(s):  
Piecewise Linear ◽  
Three Dimensional ◽  
Linear Formulation ◽  
Constitutive Relationship ◽  
Dimensional Approach ◽  
Theoretical Formulation ◽  
State Of Stress ◽  
Displacement Profile ◽  
Interaction Problem ◽  
Soil Movements

Pipelines buried along potentially unstable slopes are often monitored because soil movements can induce an evolution of the state of stress within the pipe that can eventually result in the loss of the serviceability of the system or even in its failure. In the present paper, the pipeline is discretised by means of a series of three-dimensional beam finite elements and the soil–pipeline interaction is reproduced by means of macroelements independent from each other, but characterized by a failure condition in which coupling among the different loading components is taken into account. The soil–pipeline interaction problem is formulated by accounting for the geometry of the slope, the soil and pipe mechanical properties, and the imposed soil displacement profile. A convenient piecewise linear formulation for the macroelement constitutive relationship is adopted and a large displacements scheme is also formulated.

Soil–pipeline interaction along unstable slopes: a coupled three-dimensional approach. Part 2: Numerical analyses

2009 ◽  
Vol 46 (11) ◽  
pp. 1305-1321 ◽  
Author(s):  
Giuseppe Cocchetti ◽  
Claudio di Prisco ◽  
Andrea Galli
Keyword(s):  
Piecewise Linear ◽  
Three Dimensional ◽  
Small Diameter ◽  
Structural Response ◽  
Companion Paper ◽  
Small Displacement ◽  
Beam Elements ◽  
Dimensional Finite Element ◽  
Displacement Profile ◽  
Three Dimensional Finite Element

The soil–pipe interaction constitutive model, based on the concept of the “macroelement” described in a companion paper, has been implemented according to a piecewise linear (PWL) formulation in a three-dimensional finite element code in which the pipe is discretised by means of beam elements. To draw an interpretative theoretical framework for the structural response of the system, some ideal problems in which the pipeline is assumed to be straight and the displacement profile simple are discussed. Both large and small displacement approaches are employed, and the problem of axial instability of pipelines is also analysed. Monitoring data from three real case studies have also been numerically simulated: the first two concern pipelines subject to transversal slow soil movements and the third one refers to a small diameter pipeline subject to failure due to axial instability.

Shifting perspectives: method, media and the complex image

1998 ◽  
Vol 10 (1-3) ◽  
pp. 100-108 ◽  
Author(s):  
Alicia Colson ◽  
Ross Parry
Keyword(s):  
Image Processing ◽  
Three Dimensional ◽  
Geographical Location ◽  
Spatial Relationship ◽  
Two Dimensional ◽  
Dimensional Approach ◽  
Complex Image ◽  
Cultural Resonance

This article argues that the analysis of a threedimensional image demanded a three-dimensional approach. The authors realise that discussions of images and image processing inveterately conceptualise representation as being flat, static, and finite. The authors recognise the need for a fresh acuteness to three-dimensionality as a meaningful – although problematic – element of visual sources. Two dramatically different examples are used to expose the shortcomings of an ingrained two-dimensional approach and to facilitate a demonstration of how modern (digital) techniques could sanction new historical/anthropological perspectives on subjects that have become all too familiar. Each example could not be more different in their temporal and geographical location, their cultural resonance, and their historiography. However, in both these visual spectacles meaning is polysemic. It is dependent upon the viewer's spatial relationship to the artifice as well as the spirito-intellectual viewer within the community. The authors postulate that the multi- faceted and multi-layered arrangement of meaning in a complex image could be assessed by working beyond the limitations of the two-dimensional methodological paradigm and by using methods and media that accommodated this type of interconnectivity and representation.

scholarly journals Curve and Surface Smoothing Using a Modified Cahn-Hilliard Equation

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Yongho Choi ◽  
Darea Jeong ◽  
Junseok Kim
Keyword(s):  
Piecewise Linear ◽  
Three Dimensional ◽  
Computational Results ◽  
Fourier Spectral Method ◽  
Splitting Scheme ◽  
Surface Smoothing ◽  
Three Dimensional Objects ◽  
Hilliard Equation ◽  
Stable Splitting ◽  
Cahn Hilliard Equation

We present a new method using the modified Cahn-Hilliard (CH) equation for smoothing piecewise linear shapes of two- and three-dimensional objects. The CH equation has good smoothing dynamics and it is coupled with a fidelity term which keeps the original given data; that is, it does not produce significant shrinkage. The modified CH equation is discretized using a linearly stable splitting scheme in time and the resulting scheme is solved by using a Fourier spectral method. We present computational results for both curve and surface smoothing problems. The computational results demonstrate that the proposed algorithm is fast and efficient.

scholarly journals A three-dimensional theory of wind pumping

1991 ◽  
Vol 37 (125) ◽  
pp. 89-96 ◽  
Author(s):  
Garry K. C. Clarke ◽  
Edwin D. Waddington
Keyword(s):  
Heat Source ◽  
Surface Pressure ◽  
Air Flow ◽  
Pressure Fluctuations ◽  
Normal Component ◽  
Three Dimensional ◽  
Lower Atmosphere ◽  
Dimensional Theory ◽  
Theoretical Formulation ◽  
Near Surface

AbstractQuantitative understanding of the processes that couple the lower atmosphere to the upper surface of ice sheets is necessary for interpreting ice-core records. Of special interest are those processes that involve the exchange of energy or atmospheric constituents. One such process, wind pumping, entails both possibilities and provides a possible mechanism for converting atmospheric kinetic energy into a near-surface heat source within the firn layer. The essential idea is that temporal and spatial variations in surface air pressure, resulting from air motion, can diffuse into permeable firn by conventional Darcy flow. Viscous friction between moving air and the solid firn matrix leads to energy dissipation in the firn that is equivalent to a volumetric heat source.Initial theoretical work on wind pumping was aimed at explaining anomalous near-surface temperatures measured at sites on Agassiz Ice Cap, Arctic Canada. A conclusion of this preliminary work was that, under highly favourable conditions, anomalous warming of as much as 2°C was possible. Subsequent efforts to confirm wind-pumping predictions suggest that our initial estimates of the penetration depth for pressure fluctuations were optimistic. These observations point to a deficiency of the initial theoretical formulation — the surface-pressure forcing was assumed to vary temporally, but not spatially. Thus, within the firn there was only a surface-normal component of air flow. The purpose of the present contribution is to advance a three-dimensional theory of wind pumping in which air flow is driven by both spatial and temporal fluctuations in surface pressure. Conclusions of the three-dimensional analysis are that the penetration of pressure fluctuations, and hence the thickness of the zone of frictional interaction between air and permeable firn, is related to both the frequency of the pressure fluctuations and to the spatial coherence length of turbulence cells near the firn surface.

A three dimensional approach for quantifying resultant loading at the knee

The Knee ◽  
2017 ◽  
Vol 24 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Ryan T. Lewinson ◽  
Chad P. Maag ◽  
Victor M.Y. Lun ◽  
J. Preston Wiley ◽  
Chirag Patel ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Dimensional Approach
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