1,721,576 research outputs found
Electricity supply: Corruption and reliability
No full textElectricity provision requires the combination of successive services into a bundle to be supplied to final consumers: power generation itself, electricity transmission, voltage and frequency control, and the sequence of tasks designated to ensure the necessary reliability. Because of these characteristics, it is considered to be a common pool resource (CPR) that has rival and non-excludable characteristics. Electricity provision is a rival good because individual consumption has an impact on the quantity available to the residual demand; it can also be considered non-excludable due to the difficulty in excluding those that do not pay for the service provided. Exploring the CPR features of electricity supply, Jacquelyn Pless from the University of Oxford, UK, and Harrison Fell from North Carolina State University, USA, evaluate the impact of bribes to secure electricity connection on the reliability of electric power supply
Energy consumption: Habits determine demand
No full textThe liberalization process in the electricity market dates back to 1982. Since then, a number of pro-competitive measures have been introduced to promote competition among producers. However, the downstream sector, and retail markets in particular, remains dominated by great inertia: consumers never face real-time price signals and have limited control over the true cost of their consumption habits. This is a legacy of the traditional business model, but the transition toward more flexible and increasingly decentralized systems requires a greater understanding of demand dynamics. To address this issue, Jacopo Torriti from the University of Reading, UK, studies how time-dependent social practices impact individual and aggregate demand profiles in the UK
Energy finance: Capital drives transition
No full textClimate scientists and policymakers often assume that energy markets and regulatory provisions are efficient tools where the right level of capital to sustain the transition to low-carbon-generation technologies will automatically materialize if only the right level of risk and allowed return on investment is offered to the investors. However, widespread evidence demonstrates that, despite the improved financial performance of most renewable energy sources, fossil fuel technologies are still attracting large investment, in particular in emerging economies. The economic literature is generally silent on the role that financial markets play in fostering the low-carbon transition. Rohan Best, from the Australian National University, fills this gap by studying the impact that financial capital stock plays in achieving energy transition
Adaptive mesh using non-conventional 1D and 2D finite elements based on CUF
No full textWhen dealing with complex structures with a several number of degrees of freedom (DOFs), it is useful trying to reduce the mesh for computational cost reasons, seeking not affecting the accuracy in results. The Finite Element Method can become very costly in calculations and time because of the use of very fine 3D meshes. A possible solution can be the application of the Adaptive Mesh (AM), which allows to concentrate the very fine mesh only in regions where critical conditions are present, in terms of geometrical or loads constrains. By exploiting the Node-Dependent Kinematic approach of the Carrera Unified Formulation and using Lagrange expanding functions, this work presents the application of non-conventional 1D and 2D elements for mesh refinement, offering a new and convenient technique to apply in the framework of AM. The static analysis of some typical study cases is performed and the results are provided in terms of displacements and stresses. The presented elements allow us to combine them in order to obtain a mesh refinement employing much less degrees of freedom with respect to the use of classical 3D finite elements
L’italiano dell’emigrazione: temi, approcci e metodologie d’indagine
No full textA century long history of Italian emigration all over the world has offered ample material for studying language contact. As the history unfolds linguistically, this article surveys the main works that analyse it. The survey is comprehensive in so far as it critically discusses the development of the field taking into account all major
theoretical paradigms and methodological tools devised and used to assess language loss and language shift, and their accompanying changes in attitudes and expressions of identity.
The survey must be also concise; yet an informed selection guarantees at least a mention of all major works and players in this field of research
Frictionally decaying frontal warm-core eddies
Get PDFPurpose. The dynamics of nonstationary, nonlinear, axisymmetric, warm-core geophysical surface frontal vortices affected by Rayleigh friction is investigated semi-analytically using the nonlinear, nonstationary reduced-gravity shallow-water equations. The scope is to enlarge the number of known (semi)analytical solutions of nonstationary, nonlinear problems referring to geophysical problems and even to pave the way to their extension to broader geometries and/or velocity fields. Methods and Results. The used method to obtain the solutions is based on the decomposition of the original equations in a part expressing their prescribed spatial structure, so that they can be trans-formed into ordinary differential equations depending on time only. Based on that analytical proce-dure, the solutions are then found numerically. In this frame, it is found that vortices characterized by linear distributions of their radial velocity and arbitrary structures of their section and azimuthal velocity can be described exactly by a set of nonstationary, nonlinear coupled ordinary differential equa-tions. The first-order problem (i. e., that describing vortices characterized by a linear azimuthal velocity field and a quadratic section) consists of a system of 4 differential equations, and each further order introduces in the system three additional ordinary differential equations and two algebraic equa-tions. In order to illustrate the behavior of the nonstationary decaying vortices and to put them in the context of observed dynamics in the World Ocean, the system's solution for the first-order and for the second-order problem is then obtained numerically using a Runge-Kutta method. The solutions demonstrate that inertial oscillations and an exponential attenuation dominate the vortex dynamics: expansions and shallowings, contractions and deepenings alternate during an exact inertial period while the vortex decays. The dependence of the vortex dissipation rate on its initial radius is found to be non-monotonic: it is higher for small and large radii. The possibility of solving (semi)analytically complex systems of differential equations representing observed physical phenomena is rare and very valuable. Conclusions. Our analysis adds realism to previous theoretical investigations on mesoscale vortices, represents an ideal tool for testing the accuracy of numerical models in simulating nonlinear, nonsta-tionary frictional frontal phenomena in a rotating ocean, and paves the way to further extensions of (semi-) analytical solutions of hydrodynamical geophysical problems to more arbitrary forms and more complex density stratifications
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