102,014 research outputs found
Advanced well simulation in a multilayered reservoir
No full textPaper 71st Western Regional Meeting, Bakersfield (CA
Optimization of the production strategy with a dual flow horizontal completion technique
No full textDispersion Processes and Residence Times in a Semi-Enclosed Basin with Recirculating Gyres: an Application to the Tyrrhenian Sea
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Dispersion processes and residence times in a semi-enclosed basin with recirculating gyres: An application to the Tyrrhenian Sea
No full textIn this paper we investigate the dispersion of a tracer in a semi-enclosed basin characterized by a steady flow with recirculations. In particular, we focus on the macroscopic behavior of the system, characterized by the total concentration of the tracer in the basin, C(t), and by its residence time T. As a case study, the circulation in an idealized basin mirroring some of the major characteristics of the Tyrrhenian Sea is considered, with a northward current connecting the inflow and the outflow regions of the basin, and with a main cyclonic gyre in the northern part of it. Numerical simulations are performed from several release points in the basin and for two different values of the diffusivity coefficient K. Two independent models for dispersion are used, an Eulerian and a Lagrangian one, allowing us to validate both the basic formalism and the numerical results. The experiments show that the macroscopic properties of dispersion are largely influenced by the presence of the main gyre, while they do not depend strongly on K in the considered range. Namely, after a first phase which depends on the initial conditions, the tracer tends to be concentrated in the region of the northern gyre, and this influences the trend of C(t) versus time and the value T. For almost all the simulations, the decrease of C(t) in time can be approximated by an exponential decay, indicating a constant probability of tracer escaping the basin. The e-folding timescale of the decay is the inverse of the principal eigenvalue of the advection-diffusion operator, and it can be computed a priori knowing the flow field; this allows us to compute also an a priori estimate for the residence time T. Only when the initial release is very close to the outflow, is the initial decay of C(t) distinctly different from an exponential, and a more detailed analysis is necessary. The basic results appear generalizable to a number of other similar systems with recirculations
Dispersion Processes and Residence Time in a Semi Enclosed Basin with Recirculating Gyres. The case of the Tyrrhenian Sea
No full textEnvironmental benefits of a universal mobile charger, How much energy should mobile-phone chargers really consume?
No full textNearly two billion new mobile phones are sold worldwide every year, and most of them are bought to replace obsolete models. If the old phone chargers are not compatible with the new devices, then they are thrown away too, even if still operational. With more than a billion devices becoming e‐waste each year and a huge quantity of potentially unnecessary new chargers being produced, the environmental implications are enormous.
This article looks at the outcome of a study on mechanical, electrical and life-cycle assessment characteristics of a wide range of mobile-phone chargers and highlights similarities, differences and improvement opportunities.
A sample of more than 50 chargers from official brands and compatible part suppliers was used in the study. The chargers were selected to represent the most recent and widespread models on offer from mobile-phone brands, plus some older models to gauge historical trends
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