The emission/absorption FE 2 spectrum of HD 45677

The complex behavior of the emission/absorption spectrum of Fe II is analyzed. The far UV spectrum is characterized almost solely by absorption lines, while, in the near UV, strong emissions are predominant. Radiative excitation from the ground to the highest levels (chi is approximately 10 eV) with re-emission in the near UV, visible and I.R. seems to be the main mechanism capable of explaining the observed spectral features

Ecosystem management: Evaluating the impact of Marine Protected Areas on local communities in Kia, Fiji. A case study

More than one billion people, mostly from developing countries, rely on fish as their primary source of income and protein. With fishing pressure increasing rapidly, fish stocks across the world are fast declining. The consequences are already visible; nearly two-thirds of the global fish stocks have been overexploited, leaving disruption to food webs and marine ecosystems, and declining income for fishermen dependent on fisheries for their livelihoods. With predictions of further decline in fish stocks in the near future, it is crucial to reinforce marine environment protection. Marine Protected Areas (MPAs) have been recognized as an effective management tool to protect fish populations, showing benefits beyond areas delimited by the MPA, thus adding further valuable support to local fisheries. The presence of MPAs is particularly important in areas with coral reef systems. With more than 30% of the world’s coral reefs negatively affected by ocean acidification, combined with the broader effect of global climate change and overfishing, resulting predictions indicate that 60% of the world’s reefs will be lost by 2030. MPAs are regarded as a useful tool in mitigating these impacts. With the prominent role MPAs play in marine conservation, monitoring and evaluating their status is necessary to ensure that marine management measures are effective and efficient. This research explores the role of an MPA established in the vicinity of Kia Island, a remote island off the North coast of Vanua Levu, Fiji, and enveloped by the world’s third longest continuous barrier reef system. Semi- structured interviews and focus groups were conducted in the 3 villages of Daku, Ligau, and Yaro, in order to investigate stakeholders’ perceptions on ecological, financial, and social changes occurring after the establishment of the MPA. Participants observed that since its establishment, the marine environment appears to be healthier inside and outside the MPA. Fish species, previously absent from the area have been observed, fish populations appear more abundant, and fish size may also have increased. Stakeholders also reported that they believe corals are recovering, and sea grass is now more prosperous. The improved health of the ecosystem means that fish catches are more abundant, and fishermen’s income has consequently increased. The access to better finances has driven women to undertake fishing on a regular basis, empowering them to become breadwinners alongside their family’s men. The role of women is slowly changing both within their family structure and at community level. However, in a society like the Fijian’s, where patriarchy has strong roots, it is currently too early to assess what the consequences of women’s new role may be within the traditional society. Recommendations to further assess the impact of the MPA include an assessment of income versus expenditure, landing site surveys, and ecological sampling to monitor change occurring inside and outside the MPA. Combined, these assessments will support efficient planning of future resource management. Social research on the change in women’s role and consequences on the family and wider community should also be developed

IUE observations of blue halo high luminosity stars

Two high luminosity population II blue stars of high galactic latitude, BD+33 deg 2642 and HD 137569 were observed at high resolution. The stellar spectra show the effect of mass loss in BD+33 deg 2642 and abnormally weak metallic lines in HD 137569. The interstellar lines in the direction of BD+33 deg 2642, which lies at a height z greater than or equal to 6.2 kpc from the galactic plane, are split into two components. No high ionization stages are found at the low velocity component; nor can they be detected in the higher velocity clouds because of mixing with the corresponding stellar/circumstellar lines

I valori di fronte al cambiamento

«Nessuna epoca storica ha consegnato all’educazione compiti di così vasta portata come la nostra. Uscita dal privato, dove era stata confinata per secoli, l’educazione è stata proiettata nel sociale, nell’economico, nel professionale acquistando dimensioni e funzioni ignote nel passato». Così Claudio Desinan nel 1984, quasi anticipando la realtà odierna, evocava l’urgenza di prendere atto di una società in continuo divenire dove la mutevolezza della cultura e della popolazione fanno sì che l’educazione non possa più essere considerata un’attività relativamente definita come lo era stata in passato

Direct numerical simulation of turbulent forced convection in a wavy channel at low and order one Prandtl number

Turbulent forced convection in a channel with one planar wall and one wall of sinusoidal shape is investigated by Direct Numerical Simulation. The flow is fully developed and the Reynolds number based on the mean bulk velocity and the average hydraulic diameter is Re ≈ 18,900; in this weakly turbulent flow regime three different Prandtl number values are investigated, Pr = 0.025, 0.20, 0.71. The fluid is in contact with the colder channel walls at an equal, uniform temperature. The main statistical quantities, like the root-mean-square of temperature fluctuations and the turbulent heat fluxes, the local heat transfer coefficient and turbulent Prandtl number values are reported. Effects of flow separation and reattachment on the local heat transfer rate and turbulent Prandtl number distribution are also presented and discussed. An a priori analysis of the behavior of the simple gradient diffusion model of turbulent heat fluxes is performed in the low Prandtl number, separated flow conditions of the present work. While the low Prandtl number effect can be accounted for by an appropriate selection of the turbulent Prandtl number value to be provided to the model, deviations form the expected behavior of turbulent heat fluxes are seen to occur in the flow separation region and downstream reattachment

Development and implementation of turbulence models in the combustion code Ares

This report describes the R&D activities carried out under the ENEA-MURST programme , objective 4. Three more turbulence models (the RNG K – ε, the one-equation Spalart & Allmaras and the Wilcox K – ω) have been implemented into the Ares combustion code. They represent state-of-the-art models that have demonstrated over the past decade their superior accuracy , robustness as well as ease of implementation with respect to the class of K – ε models. The first chapter describes the models formulations. In chapter 2 the three models have been validated against three well known test cases. Particular attention has been dedicated to coupling the one-equation turbulence model by Spalart & Allmaras to the TFC premixed combustion model, for two computed turbulence scales are needed to evaluate the turbulent flame velocity and one-equation models provide one turbulent scale only. For validating the correct models implementations, two simple cold test cases have been chosen, namely the turbulent boundary layer over a flat plate, and a well documented turbulent flow over a backward facing step. Finally the Moreau combustor test case have been used for the validation of the models for premixed combustion flow. The state-of-the-art turbulence models implemented should allow the combustion code Ares to increase its ability to correctly compute complex turbulent premixed reactive flows in real combustors, which is the objective of the next project tasks

On wind-wave interaction phenomena at low Reynolds numbers

After decades of research efforts, wind-wave interaction mechanisms have been recognized as extremely elusive. The reason is the complex nature of the problem, which combines complex coupling mechanisms between turbulent wind and water waves with the presence of multiple governing parameters, such as the friction Reynolds number of the wind, the water depth and the wind fetch. As shown unequivocally here, the use of suitable flow settings allows us to reduce the complex problem of wind-wave interaction to its essential features, mainly as a function of the sole friction Reynolds number of the wind. The resulting numerical solution allows us to study the interactions between water and air layers with their own fluid properties, and to unveil very interesting features, such as an oblique wave pattern travelling upstream and a wave-induced Stokes sublayer. The latter is responsible for a drag reduction mechanism in the turbulent wind. Despite the simulated flow conditions being far from the intense events occurring at the ocean-atmosphere interface, the basic flow phenomena unveiled here may explain some experimental evidence in wind-wave problems. Among other things, the wave-induced Stokes sublayer may shed light on the large scatter of the drag coefficient data in field measurements where swell waves of arbitrary directions are often present. Hence the present results and the developed approach pave the way for the understanding and modelling of the surface fluxes at the ocean-atmosphere interface, which are of overwhelming importance for climate science

Thermal management of a Formula E electric motor: Analysis and optimization

The thermal analysis of a high performance brushless synchronous electric motor with permanent magnets and water jacket cooling is presented. The analysis is carried out following a lumped parameter thermal network approach which allows to identify the most important thermal paths in the motor and the main parameters influencing them. Thanks to its simplicity, the solution of such a thermal network model is very fast, allowing a large number of what-if scenarios to be computed over a short amount of time. For this reason, the model is coupled with external tools for performing systematic sensitivity analyses and optimizations. Goal of the investigation is the reduction of the windings temperature being this temperature inversely proportional to the efficiency and the power delivered by the motor. The sensitivity analysis, performed over a series of material, geometric, and operational factors, leads to the identification of the most relevant parameters influencing the thermal behaviour of the motor. A series of optimizations, focusing on these parameters and including suitable constraints granting the well-posedness of the problem and the feasibility of the solution, bring to the definition of an optimum layout of the water jacket and of the stator geometries. The optimized geometry allows a significant reduction of the windings temperature to be achieved