1,073 research outputs found
Dealing with Interaction Between Bipolar Multiple Criteria Preferences in PROMETHEE Methods
In this paper, we consider the bipolar approach to Multiple Criteria Decision
Analysis (MCDA). In particular we aggregate positive and negative preferences
by means of the bipolar PROMETHEE method. To elicit preferences we consider
Robust Ordinal Regression (ROR) that has been recently proposed to derive
robust conclusions through the use of the concepts of possible and necessary
preferences. It permits to take into account the whole set of preference
parameters compatible with the preference information provided by the Decision
Maker (DM)
Effects of Irrigation and Tree Spacing on Soil and Air Temperature Profiles of Olive Orchards
Changes on the climate of the boundary layer occur when a vegetation cover
above a bare soil is introduced, namely on temperatures and humidity profiles,
above and under soil surface. Since air and soil temperatures affect crop growth and
development and also soil moisture, they have been used as driving variables in
numerous crop growth and development models as well as in those referred to soil
mineralization, evaporation, transpiration, etc. The aim of this work was to evaluate
(a) the soil thermal behavior in two olive orchards (Olea europaea sp. europaea),
both grown on soils with little profile development (Regosol and Cambisol) and
subject to drip irrigation but with different spacing between trees, and (b) the air
thermal profile over olive rows. Experiments were performed from April to June
2012 in Southern Portugal. Soil and air temperatures were measured by
thermocouples. The two orchards changed spatial distribution of soil surface
temperature, soil temperature profiles and air temperature within the canopy, either
on a daily or hourly basis. Olive tree spacing and irrigation affected both the soil
thermal behavior and air thermal profiles. Tree spacing affected the horizontal
gradients established along the interrows (intensity and rhythm). Irrigation reduced
hourly and daily mean soil surface temperatures and daily thermal amplitudes of
both profiles. Differences were also found on damping depths of the thermal wave
estimated for the driest and the wettest profiles. Along the row, the effect of shading
seems to overlap that of irrigation in a hourly basis
Forme di devozione nei luoghi di culto dell’Abruzzo antico
The paper is dealing with the forms of votive religion in a region of Italy, corresponding
to the modern Abruzzo, which during ancient times had been inhabited by Italic people,
such as Pretuzi, Vestini, Equi, Marsi, Peligni and Marrucini. It addresses chronological
issues, (i.e., the onset of votive offerings, their relationship with cult places and sacred
buildings, and the moment on their disappearence), problems related to the meaning to
be attributed to the different types of supply (bronze, terracotta, pottery) and historicalideological
issues, particularly with regard to theme of the Romanization of the territory
and of the adhesion of different social classes to a model of religious import. Finally,
some examples illustrate the problem of the relationship between a votive offering and
the worship of a particular deity
Silicon Nanowires the Route from Synthesis towards Applications
This work provides an overview on the silicon nanowires synthesis scenario by introducing the most employed bottom-up and top-down strategies, exploiting their main advantages and drawbacks. The impressive structural, optical and electrical properties of these nanostructures promote their implementation in low power consumption nanodevices with improved performances. Some representative examples of Si NW applications in field-effect transistors, broadband photodetectors, low-cost solar cells with improved light absorption and for selective and ultrasensitive biological detectors are reported. The realization of Si NWs by metal assisted chemical etching (MACE) by the use of discontinuous Au layers and the relationship among structural features and growth conditions are here discussed in detail. Indeed, the NW length, diameter, crystalline structure and doping can be precisely defined by using this low cost and industrially compatible process. Si NWs with quantum confined size are realized by MACE leading to the observation of room temperature light emission from Si. According to quantum confinement theory, the emission wavelength can be red-shifted by tuning the NW diameter opening the routes towards low-cost, Si-based photonics. Moreover, the realization of innovative multiwavelength light sources operating at room temperature is investigated by embedding a carbon nanotube (CNT) dispersion inside Si nanowire arrays using a low cost and Si technology compatible technology. The NW/CNT hybrid system exhibits a tunable emission both in the visible and in the infrared which is strategic for telecommunication applications. The conditions leading to the prevalence of the visible or the IR signal have been identified and are herein discussed. The design of 2D random fractal arrays of Si nanowires is here described. Indeed, the structural arrangement of MACE synthesized Si NWs can be engineering by the deposition of a thin Au layer that superimposes its complimentary fractal arrangement onto the Si NW arrays. Si NW fractal arrays display strong self-similarities over a wide range of length scales and the correlation among the fractal parameters and the optical properties are demonstrated. In fact, the ability to control the scattering, absorption and emission properties is investigated as a function of fractal dimension and lacunarity for different designs. A strong light trapping behavior in the visible range due to the efficient in-plane multiple scattering occurring in the Si NW layer has a promising potential for both photovoltaics and photonics. Furthermore, the first experimental observation of a constructive interference effect in the backscattered Raman light from strongly diffusing Si nanowires is reported. Coherent backscattering of light (CBS) is observed when electromagnetic waves undergo multiple scattering within a disordered optical medium. CBS effect arising from the interference of inelastic scattered Raman radiation has been demonstrated in random Si NW arrays. The results are interpreted within the theoretical model of mixed Rayleigh-Raman random walks, exploiting the role of phase coherence in multiple scattering phenomena. In conclusion, the decoration of MACE-synthesized Si NWs by Ag nanoparticles (NPs) produced by pulsed laser deposition (PLD) is an appealing strategy in order to couple the huge aspect ratio of NWs to plasmonic effects leading to the realization of ultrasensitive surface enhanced Raman spectroscopy (SERS) sensors. PLD conditions have been optimized to guarantee the uniform decoration of NW sidewall along all their length without the need of any post-deposition annealing by using a low-cost and Si implementable technology. The Ag NP morphology can be precisely tuned as a function of the NW length or the number of laser pulses and the correlation among the structural and optical properties of Si NWs decorated is reported, demonstrating a great potentiality for SERS applications
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