Landscape and Environmental Impact Evaluation of Roundabouts

The interest of researchers and practitioners on roundabout solutions has been growing increasingly in the last decades. The often large areas occupied by this type of intersections require special attention on the use of ground and the preservation of the natural, environmental and architectural heritage. This aim also presents the opportunity for evaluating their impact on the landscape and environment. The paper proposes a new method developed for roundabout evaluation (but generalizable to other infrastructures and fields) borrowed from building technology and based on the needs, requirements and performance expected from an object rather than on prescriptions for and descriptions of its dimensions and quality. Applications on two roundabouts are presented in order to highlight practical developments. Their final evaluation sheets are presented and through them it is relatively easy to single out the problems and drawbacks of the roundabouts from the landscape point of view

Case studies of landscape and environmental impact evaluation of roundabouts

This paper is a follow-up to a previous one that presented a new method for evaluating the landscape and environmental impact of roundabouts borrowed from building technology and based on the needs, requirements and performance expected from an object rather than on prescriptions for and descriptions of its dimensions and quality. The proposed method aims at defining criteria to set up an information structure based on a need and performance approach capable of evaluating impacts on the landscape and environmental integration. After a brief résumé of the above-mentioned principles, two applications are presented in order to highlight two practical developments. The roundabouts on which the applications are focused are located in an urban and in a rural environment respectively in the Northern part of Italy. Obviously their analysis cannot be considered comprehensive of all possible cases but it covers a large proportion of them. Differences between the two roundabouts are many and they concern, besides the landscape and environment, geometrical dimensions, type of flow, presence of weekday users (pedestrians and bikers). The final evaluation sheets are presented and through them it is relatively easy to single out the problems and drawbacks of the roundabouts from the landscape point of view

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM