On the accuracy of surface spline interpolation on the unit sphere

This paper considers a novel modification to the surface splines that have previously been used on the unit sphere. The surface splines considered are a natural analogue of surface splines in IRd and possess a unique Fourier expansion in terms of an orthonormal basis of spherical harmonics. Knowing the decay of the associated Fourier coefficients is important because they enable error estimates for spherical interpolation. In this paper we explicitly compute the Fourier coefficients of the surface splines and employ a recent theoretical result [8] to provide a useful error bound. We illuminate our theoretical findings by performing numerical experiments on the sphere and also on the hemisphere

Polyharmonic approximation on the sphere

The purpose of this article is to provide new error estimates for a popular type of SBF approximation on the sphere: approximating by linear combinations of Green's functions of polyharmonic differential operators. We show that the $L_p$ approximation order for this kind of approximation is $\sigma$ for functions having $L_p$ smoothness $\sigma$ (for $\sigma$ up to the order of the underlying differential operator, just as in univariate spline theory). This is an improvement over previous error estimates, which penalized the approximation order when measuring error in $L_p$, p>2 and held only in a restrictive setting when measuring error in $L_p$, p<2.Comment: 16 pages; revised version; to appear in Constr. Appro

Readings in the UK energy security

Over the last few decades, the debate about 'Peak Oil' became increasingly common and frustrating to governments, oil companies and individuals. Also in the last decade or so, some unusual events took places, which have raised the concern about the future of energy resources.i These events lead policy makers to consider what is known today as 'Energy Security'. The UK is one of these countries that fears the unknown future should petroleum resources worldwide become scarce or vanish. After the dwindling of the North Sea production, the UK found itself on the brink of losing its energy self-sufficiency (Macalister, 2010). This paper sets the following questions: has the UK’s oil and gas production peaked yet? If so, does the UK have a serious energy security problem? and if so, how this problem may be solved and what are the possible short, medium and long-term solutions for such a concern? In answering these questions, the paper discusses the concerns and challenges to the UK energy security and brings about the Government plans for tackling these concerns. It is found that the UK does not experience an energy security problem on the short to medium-term, but it may suffer energy insecurity on the longer-term

On the Dynamics of the Deployment of Renewable Energy Production Capacities

This chapter falls within the context of modeling the deployment of renewable en-ergy production capacities in the scope of the energy transition. This problem is addressed from an energy point of view, i.e. the deployment of technologies is seen as an energy investment under the constraint that an initial budget of non-renewable energy is provided. Using the Energy Return on Energy Investment (ERoEI) characteristics of technologies, we propose MODERN, a discrete-time formalization of the deployment of renewable energy production capacities. Be-sides showing the influence of the ERoEI parameter, the model also underlines the potential benefits of designing control strategies for optimizing the deployment of production capacities, and the necessity to increase energy efficiency.Peer reviewe

Bovine Embryo Transfer–Present and Future

Bovine embryo transfer (ET) has evolved in the past few decades from basic research, to applied research, to its presence as a multimillion- dollar industry. ET is a technique for genetic manipulation which allows the producer to improve the production capacity of his livestock. This article describes some of the current techniques of ET being used and some of the techniques of genetic manipulation being researched which may find future commercial application in the field of ET. Currently used techniques include superovulation, nonsurgical recovery of embryos\u27 splitting of embryos and cryopreservation of embryos

The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect

X-ray micro-tomography and pore network modeling of single-phase fixed-bed reactors.

A three-dimensional (3D) irregular and unstructured pore network was built using local topological and geometrical properties of an isometric bead pack imaged by means of a high-resolution X-ray computed micro-tomography technique. A pore network model was developed to analyze the 3D laminar/inertial(non-Darcy) flows at the mesoscopic (pore level) and macroscopic (after ensemble-averaging) levels. The non-linear laminar flow signatures were captured at the mesoscale on the basis of analogies with contraction and expansion friction losses. The model provided remarkably good predictions of macroscopic frictional loss gradient in Darcy and non-Darcy regimes with clear-cut demarcation using channel-based Reynolds number statistics. It was also able to differentiate contributions due to pore and channel linear losses, and contraction/expansion quadratic losses. Macroscopic mechanical dispersion was analyzed in terms of retroflow channels, and transverse and longitudinal Péclet numbers. The model qualitatively retrieved the Péclet-Reynolds scaling law expected for heterogeneous networks with predominance of mechanical dispersion. Advocated in watermark is the potential of pore network modeling to build a posteriori constitutive relations for the closures of the more conventional macroscopic Euler approaches to capture more realistically single-phase flow phenomena in fixed-bed reactor applications in chemical engineering

Interpretation of porosity and LWD resistivity from the Nankai accretionary wedge in light of clay physicochemical properties: Evidence for erosion and local overpressuring

International audienceIn this study, we used porosity to assess the compaction state of the Nankai accretionary wedge sediments and any implications for stress and pore pressure. However, hydrous minerals affect porosity measurements, and accounting for them is essential toward defining the interstitial porosity truly representative of the compaction state. The water content of sediments was measured in core samples and estimated from logging data using a resistivity model for shale. We used the cation exchange capacity to correct the porosity data for the amount of water bound to clay minerals and to correct the porosity estimates for the surface conductivity of hydrous minerals. The results indicate that several apparent porosity anomalies are significantly reduced by this correction, implying that they are in part artifacts from hydrous minerals. The correction also improves the fit of porosity estimated from logging-while-drilling (LWD) resistivity data to porosity measured on cores. Low overall porosities at the toe of the accretionary wedge and in the splay fault area are best explained by erosion, and we estimated the quantity of sediments eroded within the splay fault area by comparing porosity-effective stress relationships of the sediments to a reference curve. Additionally, a comparison of LWD data with core data (resistivity and P wave velocity) obtained at Site C0001 landward of the mega-splay fault area, suggested a contribution from the fracture porosity to in situ properties on the formation

The role of rock joint frictional strength in the containment of fracture propagation

The fracturing phenomenon within the reservoir environment is a complex process that is controlled by several factors and may occur either naturally or by artificial drivers. Even when deliberately induced, the fracturing behaviour is greatly influenced by the subsurface architecture and existing features. The presence of discontinuities such as joints, artificial and naturally occurring faults and interfaces between rock layers and microfractures plays an important role in the fracturing process and has been known to significantly alter the course of fracture growth. In this paper, an important property (joint friction) that governs the shear behaviour of discontinuities is considered. The applied numerical procedure entails the implementation of the discrete element method to enable a more dynamic monitoring of the fracturing process, where the joint frictional property is considered in isolation. Whereas fracture propagation is constrained by joints of low frictional resistance, in non-frictional joints, the unrestricted sliding of the joint plane increases the tendency for reinitiation and proliferation of fractures at other locations. The ability of a frictional joint to suppress fracture growth decreases as the frictional resistance increases; however, this phenomenon exacerbates the influence of other factors including in situ stresses and overburden conditions. The effect of the joint frictional property is not limited to the strength of rock formations; it also impacts on fracturing processes, which could be particularly evident in jointed rock masses or formations with prominent faults and/or discontinuities