385 research outputs found
Neural network approach to parton distributions fitting
We will show an application of neural networks to extract information on the
structure of hadrons. A Monte Carlo over experimental data is performed to
correctly reproduce data errors and correlations. A neural network is then
trained on each Monte Carlo replica via a genetic algorithm. Results on the
proton and deuteron structure functions, and on the nonsinglet parton
distribution will be shown.Comment: 4 pages, 5 eps figures. Talk given by Andrea Piccione at the "X
International Workshop on Advanced Computing and Analysis Techniques in
Physics Research", ACAT 2005, DESY-Zeuthen, Germany, 22-27 May 2005.
Corrected fig.
Exploring life forms for linking Orthopteran assemblage and grassland plant community:
AbstractOrthopterans are well known to represent the majority of insect biomass in many grassland ecosystems. However, the verification of a relationship between the traditional descriptors of orthopteran assemblage structure and plant community patterns is not straightforward. We explore the usefulness of the concept of life forms to provide insights on such ecosystem level relationship. For this purpose, thirty sample sites in semi-natural calcareous grasslands were classified according to the relative proportion of dominant herbaceous plant life forms. Orthopteran species were grouped in four categories, based on the Bei-Bienko's life form categorization. The association among plant communities, orthopteran assemblages and environmental factors was tested by means of canonical correspondence analysis. Orthoptera groups were found to be associated with distinct plant communities, also indicating the effect of vegetation change on orthopteran assemblages. In particular, geobionta species were associated with all the most disturbed plant communities, while chortobionta and thamnobionta seemed to be dependent on better preserved grassland types. Therefore, the use of life forms could help informing on the relationships of orthopteran assemblages with grassland conservation state. Information on such community relationships at the local scale could also assist managers in the interpretation of habitat change maps in terms of biodiversity changes
Brecht, "Fatzer" e la "grande pedagogia"
Fatzer Fragment goes once more to show that traditional realistic drama cannot sucessfully represent the world as it is, but rather that drama must portray the image of a world which will allow change and transformation. Brecht, "Fatzer" e la "grande pedagogia
Neural network determination of parton distributions: the nonsinglet case
We provide a determination of the isotriplet quark distribution from
available deep--inelastic data using neural networks. We give a general
introduction to the neural network approach to parton distributions, which
provides a solution to the problem of constructing a faithful and unbiased
probability distribution of parton densities based on available experimental
information. We discuss in detail the techniques which are necessary in order
to construct a Monte Carlo representation of the data, to construct and evolve
neural parton distributions, and to train them in such a way that the correct
statistical features of the data are reproduced. We present the results of the
application of this method to the determination of the nonsinglet quark
distribution up to next--to--next--to--leading order, and compare them with
those obtained using other approaches.Comment: 46 pages, 18 figures, LaTeX with JHEP3 clas
VR WebGIS: an OpenSource approach to 3D real-time landscape management
OpenSource philosophy has reached to
unexpected goals. The diffusion of
OpenSource tools is increased quite a
lot, but also the quality of the tools is improving.
Their usability is slowing going
even towards communities not exactly
skilled in advanced programming. Open
movement is penetrated in many sectors,
often subverting, thank to its social impact,
the traditional rules of companies
and research institutions, pulling down
sometimes hierarchies and pushing on
innovative ideas because of their validity
and values. [...]Peer Reviewe
VR WebGIS: an OpenSource approach to 3D real-time landscape management
OpenSource philosophy has reached to
unexpected goals. The diffusion of
OpenSource tools is increased quite a
lot, but also the quality of the tools is improving.
Their usability is slowing going
even towards communities not exactly
skilled in advanced programming. Open
movement is penetrated in many sectors,
often subverting, thank to its social impact,
the traditional rules of companies
and research institutions, pulling down
sometimes hierarchies and pushing on
innovative ideas because of their validity
and values. [...]Peer Reviewe
Geomorphological Evolution of Volcanic Cliffs in Coastal Areas: The Case of Maronti Bay (Ischia Island)
The morphoevolution of coastal areas is due to the interactions of multiple continental and marine processes that define a highly dynamic environment. These processes can occur as rapid catastrophic events (e.g., landslides, storms, and coastal land use) or as slower continuous processes (i.e., wave, tidal, and current actions), creating a multi-hazard scenario. Maronti Bay (Ischia Island, Southern Italy) can be classified as a pocket beach that represents an important tourist and environmental area for the island, although it has been historically affected by slope instability, sea cliff recession, and coastal erosion. In this study, the historical morphoevolution of the shoreline was analysed by means of a dataset of aerial photographs and cartographic information available in the literature over a 25-year period. Furthermore, the role of cliff recession and its impact on the beach was also explored, as in recent years, the stability condition of the area was worsened by the occurrence of a remarkable landslide in 2019. The latter was reactivated following a cloudburst on the 26th of November 2022 that affected the whole Island and was analysed with the Dem of Difference technique. It provided an estimate of the mobilised volumes and showed how the erosion and deposition areas were distributed and modified by wave action. The insights from this research can be valuable in developing mitigation strategies and protective measures to safeguard the surrounding environment and ensure the safety of residents and tourists in this multi-hazard environment
DETC2003/PTG-48000 APPLICATION OF A MULTIAXIAL FATIGUE CRITERION FOR THE EVALUATION OF LIFE OF GEARS OF COMPLEX GEOMETRY
ABSTRACT Gears can show significant biaxial stress state at tooth root fillet, due to the way they are loaded and their particular geometry. This biaxial stress state can show a significant variability in principal axes during meshing. Moreover loads may have non predictable components that can be evaluated with the aid of recorded data from complex spectra. In these conditions, commonly adopted approaches for fatigue evaluation may be unsuitable for a reliable fatigue life prediction. This work is aimed at discussing a computer implementation of a fatigue life prediction method suitable for multiaxial stress states and constant amplitude or random loading. For random loading a counting procedure to extract cycles from complex load histories is discussed. This method, proposed by Vidal et al., is based on the r.m.s. value of a damage indicator over all the planes through the point where the fatigue life calculation is made. Miner's rule is used for the evaluation of the overall damage. The whole fatigue life of the component is evaluated in terms of the numbers of repetitions of the loading block. FEM data are used to evaluate stresses under load. The implementation was validated using test data found in the technical literature. Examples of applications to gears are finally discussed
Parton distributions: determining probabilities in a space of functions
We discuss the statistical properties of parton distributions within the
framework of the NNPDF methodology. We present various tests of statistical
consistency, in particular that the distribution of results does not depend on
the underlying parametrization and that it behaves according to Bayes' theorem
upon the addition of new data. We then study the dependence of results on
consistent or inconsistent datasets and present tools to assess the consistency
of new data. Finally we estimate the relative size of the PDF uncertainty due
to data uncertainties, and that due to the need to infer a functional form from
a finite set of data.Comment: 11 pages, 8 figures, presented by Stefano Forte at PHYSTAT 2011 (to
be published in the proceedings
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