Search results for "parametric model"
showing 10 items of 63 documents
A comparative study of SPCTRAL2 and SMARTS2 parameterised models based on spectral irradiance measurements at Valencia, Spain
1998
Abstract Results obtained using the parametric models SPCTRAL2 and SMARTS2 for the urban area of Valencia, Spain, have been analysed and compared with experimental measurements at ground level obtained with two Li-cor 1800 spectroradiometers with a 6 nm resolution. The study used two different input parameters in both models for the aerosol characterisation: the aerosol optical thickness at 0.5 μ m, τ a λ (0.5) , and the Angstrom turbidity coefficient β . The results obtained show that both algorithms reproduce quite correctly the spectral irradiance experimental values when an urban aerosol model parameterised by the τ a λ (0.5) value is considered. In all the cases the deviations are low…
Model Analysis of Hydrometeor Scattering Effects on Free Space Near-Infrared Links
2012
A promising technology for peer-to-peer connections and urban area networks is represented by wireless communications through free space using optical carrier (Free Space Optics, FSO). This technology ensures high data rates, with relatively low error rates, low power consumption and inherent security. Nevertheless FSO links are quite sensitive to atmospheric condition. Fog droplets, but also raindrops and snowflakes, may introduce severe path attenuation which drastically reduces the channel availability. A parametric model to simulate droplets scattering effects over the FSO link in terms of extinction coefficient, albedo factor and asymmetry coefficient as function of the particle water …
Maiolica bricks spires and domes in Sicily.Tipology, constructive and decorative elements
2018
The use of maiolica bricks as artefact for surface decoration is widespread both in monumental and ordinary architectures in the Mediterranean regions, harmonizing the local construction traditions with the Islamic influences. This study presents an in-depth analysis of examples of spires and domes in Sicily featuring earthenware maiolica cladding serving both as decoration and structural element. Due to the limited knowledge of these artefacts, incautious construction operations led to an alteration of their material and technical features, putting at risk a centuries-old heritage. The systematic investigation on more than a hundred samples categorises these architectural polychrome elemen…
Wedge-shaped bricks spires and domes. Construction and decorative aspects
2018
The use of maiolica bricks as artefact for surface decoration is widespread both in monumental and ordinary architectures in the Mediterranean regions, harmonizing the local construction traditions with the Islamic influences. This study presents an in-depth analysis of examples of spires and domes in Sicily featuring earthenware maiolica cladding serving both as decoration and structural element. Due to the limited knowledge of these artefacts, incautious construction operations led to an alteration of their material and technical features, putting at risk a centuries-old heritage. The systematic investigation on more than a hundred samples categorises these architectural polychrome elemen…
A probabilistic framework for automatic prostate segmentation with a statistical model of shape and appearance
2011
International audience; Prostate volume estimation from segmented prostate contours in Trans Rectal Ultrasound (TRUS) images aids in diagnosis and treatment of prostate diseases, including prostate cancer. However, accurate, computationally efficient and automatic segmentation of the prostate in TRUS images is a challenging task owing to low Signal-To-Noise-Ratio (SNR), speckle noise, micro-calcifications and heterogeneous intensity distribution inside the prostate region. In this paper, we propose a probabilistic framework for propagation of a parametric model derived from Principal Component Analysis (PCA) of prior shape and posterior probability values to achieve the prostate segmentatio…
A comparison of different one-diode models for the representation of I–V characteristic of a PV cell
2014
Predictive performance tools are an important factor in the success of any new technology because they permit demonstration of whether a system will be efficient and economically feasible. A reliable predictive tool should allow the designer to optimise system performance and to maximise the cost effectiveness of a system prior to installation. This article discusses the five main parametric models for photovoltaic (PV) systems available in the literature. The current–voltage characteristics of a photovoltaic module can be reproduced modelling the PV panel as an equivalent electrical circuit made of linear and non-linear components. The parameters describing such components are directly rel…
Multi-parametric GIS analysis to assess gully erosion susceptibility: a test in southern Sicily, Italy
2011
: A GIS-analysis was carried out in a test basin of southern Sicily, the Magazzolo River basin, in order to assess susceptibility conditions to gully erosion phenomena. The linear density of ephemeral and permanent gullies computed within each class of nine environmental variables was used to generate a gully erosion susceptibility map for the area. A validation procedure carried out in order to test the reliability of the adopted method highlighted a clear correlation between the occurrence of gullies and the computed susceptibility levels
Algorithmic modeling and prototyping of a structural joint for freeform surfaces
2016
This paper describes a parametric approach in architectural design through the elaboration of a process for generating non-standard structural joints particularly suitable for the arrangement of freeform surfaces in which maximum adaptability of the system is required to join a different number of members converging in a node from generic directions. The algorithmic definitions, developed using the graphical editor Grasshopper integrated with Rhinoceros, allow the management of an integrated workflow from the conceptual design of freeform surface to the prototyping of a structural joint with 3D printing techniques.
Il mattone cuneiforme maiolicato. Procedure algoritmico-parametriche digitali come strumento di indagine e progettazione: dall'architettura storica a…
2020
The study focuses on the cuneiform in majolica brick that has been widespread in Sicily since the 16th century for the construction of spires and domes. A unifying element that has constituted a particular identity contribution to the island’s brick tradition; an original solution able to combine aesthetics with structural and durability. On the basis of more than a hundred examined cases, the different geometrical-formal peculiarities detected in relation to the characteristics of the shell are described. Some analyses and checks of the traditional geometrical composition patterns of the wall facade are reported. Through the definition of digital tools of algorithmic-parametric design, new…