3,045 research outputs found
QCD analysis of near-to-planar 3-jet events
Perturbative QCD analysis is presented of the cumulative out-of-plane
momentum distribution in the near-to-planar e+e- annihilation events, K_out <<
Q. In this kinematical region multiple gluon radiation effects become
essential. They are resummed with the single-logarithmic accuracy, which
programme includes the 2-loop treatment of the basic radiation and matching
with the exact O(alpha_s^2) result.
Dedicated experimental analyses of 3-jet event characteristics are of special
interest for the study of the non-perturbative confinement effects.Comment: 32 pages, 1 figure, JHEP class include
Calibration of the ATLAS electromagnetic calorimeter using calibration hits
In the present note a method to determine the electron energy from the energies measured in an electron cluster is discussed. The method is based on a detailed Monte-Carlo simulation (labeled \textit{Calibration Hits}) of electrons in the ATLAS detector in which also the energies deposited in the passive and dead materials are recorded. It allows also to compute the different contributions (energy deposited in front, in and behind the Accordion) to the total electron energy. To better understand the various contributions to the energy reconstruction three rounds of simulations have been performed: electrons hitting the middle cell centre, electrons spread uniformly over a cell in absence of magnetic field and electrons spread uniformly over a cell in presence of magnetic field. The method is applied to the Barrel calorimeter and to electrons. Its extension to the End Caps and to photons does not pose problems. In the operative ATLAS conditions an energy resolution sampling term varying from 9.9 at =0.3 and 16.8 at =1.2 is obtained. The linearity varies between 0.1 and 0.4 in the energy interval 10-100GeV over the same range
BIM and GIS: WHEN PARAMETRIC MODELING MEETS GEOSPATIAL DATA
Geospatial data have a crucial role in several projects related to infrastructures and land management. GIS software are able to perform advanced geospatial analyses, but they lack several instruments and tools for parametric modelling typically available in BIM. At the same time, BIM software designed for buildings have limited tools to handle geospatial data. As things stand at the moment, BIM and GIS could appear as complementary solutions, notwithstanding research work is currently under development to ensure a better level of interoperability, especially at the scale of the building. On the other hand, the transition from the local (building) scale to the infrastructure (where geospatial data cannot be neglected) has already demonstrated that parametric modelling integrated with geoinformation is a powerful tool to simplify and speed up some phases of the design workflow. This paper reviews such mixed approaches with both simulated and real examples, demonstrating that integration is already a reality at specific scales, which are not dominated by "pure" GIS or BIM. The paper will also demonstrate that some traditional operations carried out with GIS software are also available in parametric modelling software for BIM, such as transformation between reference systems, DEM generation, feature extraction, and geospatial queries. A real case study is illustrated and discussed to show the advantage of a combined use of both technologies. BIM and GIS integration can generate greater usage of geospatial data in the AECOO (Architecture, Engineering, Construction, Owner and Operator) industry, as well as new solutions for parametric modelling with additional geoinformation
HBIM challenge among the paradigm of complexity, tools and preservation: The Basilica di Collemaggio 8 years after the earthquake (L'Aquila)
In December 2012 ENIservizi (the Italian multi-national energy agency operating in many countries), after the Earthquake that occurred in April 2009, decided to undertake the project 'Re-start from Collemaggio' with the aim of giving new hope to the L'Aquila community, funding around 14 million Euro to restore the Basilica di Collemaggio. The Superintendence Office carried on the restoration project with the scientific support of the Università degli Studi de L'Aquila and the Università La Sapienza di Roma, under the coordination of the Politecnico di Milano. ENIservizi, aware of the BIM potential in the complex building and infrastructure domain in the world, required an advanced HBIM from the laser scanner and photogrammetric surveying to support the diagnostic analysis, the design project, the tender and the restoration itself, today still on course. Plans and vertical sections were delivered (2012) starting from the surveying campaigns (February and June 2013), together with the first HBIM advancement from the end of 2012 in support of the preliminary-definitive-executive steps of the restoration design project (2013-14-15). Five years later, this paper tries to make a synthesis of the different lessons learnt, in addition to the positive and critical aspects relating HBIM feasibility, sustainability and usefulness to the challenging restoration work. In particular, the Collemaggio BIM experience anticipated the new Italian Public Procurement Legislation (D.Lgs 50/2016, Nuovo Codice degli Appalti pubblici) aligned with to the EUPPD 24/2014: The EU Directive on Public Procurement asked all the 28 EU countries to adopt building informative modelling by February 2016 in order to support the whole LCM (Life Cycle Management), starting from the project and the intervention, through rewarding scores or mandatory regulations. Many analyses foresees to save from around 5% to 15% of the overall investment by adopting mature BIM (Level 3 to 5), particularly 4D remotely controlled BIM in support of the LCM, as in the case of maintenance and management process. The tender for Basilica restoration was published in 2015: The process was not developed enough to introduce selective criteria based on BIM adoption by the Construction Industry due to the lack of legislation at that time and the lack of BIM skills among the companies. Nevertheless ENIservizi also separately funded aside the HBIM of the Basilica to tackle an advanced BIM able to address decision-making processes in the heritage domain among the different actors: To support operators, architects, structural engineers, economic computation, construction site management and restoration, the theoretical and practical approach adopted by the HBIM, overcame the current logic based on sequential LoD (from simplex to complex, from the preliminary to the executive design) that is typical of new constructions in favour of a complex LoD approach that could guarantee management of the richness, unicity and multiplicity of each component and the maximum degree of knowledge in order to derive the decisions from the starting phases of the project. On the lesson learnt from this experience, the process of updating the current codification criteria (UNI11337-2009) was started with a draft proposal stimulating a debate for the future of HBIM adoption
Historic bim: A new repository for structural health monitoring
Recent developments in Building Information Modelling (BIM) technologies are facilitating the management of historic complex structures using new applications. This paper proposes a generative method combining the morphological and typological aspects of the historic buildings (H-BIM), with a set of monitoring information. This combination of 3D digital survey, parametric modelling and monitoring datasets allows for the development of a system for archiving and visualizing structural health monitoring (SHM) data (Fig. 1). The availability of a BIM database allows one to integrate a different kind of data stored in different ways (e.g. reports, tables, graphs, etc.) with a representation directly connected to the 3D model of the structure with appropriate levels of detail (LoD). Data can be interactively accessed by selecting specific objects of the BIM, i.e. connecting the 3D position of the sensors installed with additional digital documentation. Such innovative BIM objects, which form a new BIM family for SHM, can be then reused in other projects, facilitating data archiving and exploitation of data acquired and processed. The application of advanced modeling techniques allows for the reduction of time and costs of the generation process, and support cooperation between different disciplines using a central workspace. However, it also reveals new challenges for parametric software and exchange formats. The case study presented is the medieval bridge Azzone Visconti in Lecco (Italy), in which multi-Temporal vertical movements during load testing were integrated into H-BIM
OBJECT-ORIENTED APPROACH FOR 3D ARCHAEOLOGICAL DOCUMENTATION
Documentation on archaeological fieldworks needs to be accurate and time-effective. Many features unveiled during excavations can be recorded just once, since the archaeological workflow physically removes most of the stratigraphic elements. Some of them have peculiar characteristics which make them hardly recognizable as objects and prevent a full 3D documentation. The paper presents a suitable feature-based method to carry on archaeological documentation with a three-dimensional approach, tested on the archaeological site of S. Calocero in Albenga (Italy). The method is based on one hand on the use of structure from motion techniques for on-site recording and 3D Modelling to represent the three-dimensional complexity of stratigraphy. The entire documentation workflow is carried out through digital tools, assuring better accuracy and interoperability. Outputs can be used in GIS to perform spatial analysis; moreover, a more effective dissemination of fieldworks results can be assured with the spreading of datasets and other information through web-services
Ataxia with oculomotor apraxia type 2: a clinical, pathologic, and genetic study
BACKGROUND: Ataxia with oculomotor apraxia type 2 (AOA2) is characterized by
onset between age 10 and 22 years, cerebellar atrophy, peripheral neuropathy,
oculomotor apraxia (OMA), and elevated serum alpha-fetoprotein (AFP) levels.
Recessive mutations in SETX have been described in AOA2 patients.
OBJECTIVE: To describe the clinical features of AOA2 and to identify the SETX
mutations in 10 patients from four Italian families.
METHODS: The patients underwent clinical examination, routine laboratory tests,
nerve conduction studies, sural nerve biopsy, and brain MRI. All were screened
for SETX mutations.
RESULTS: All the patients had cerebellar features, including limb and truncal
ataxia, and slurred speech. OMA was observed in two patients, extrapyramidal
symptoms in two, and mental impairment in three. High serum AFP levels, motor and
sensory axonal neuropathy, and marked cerebellar atrophy on MRI were detected in
all the patients who underwent these examinations. Sural nerve biopsy revealed a
severe depletion of large myelinated fibers in one patient, and both large and
small myelinated fibers in another. Postmortem findings are also reported in one
of the patients. Four different homozygous SETX mutations were found (a
large-scale deletion, a missense change, a single-base deletion, and a
splice-site mutation).
CONCLUSIONS: The clinical phenotype of oculomotor apraxia type 2 is fairly
homogeneous, showing only subtle intrafamilial variability. OMA is an inconstant
finding. The identification of new mutations expands the array of SETX variants,
and the finding of a missense change outside the helicase domain suggests the
existence of at least one more functional region in the N-terminus of senataxin
On large angle multiple gluon radiation
Jet shape observables which involve measurements restricted to a part of
phase space are sensitive to multiplication of soft gluon with large relative
angles and give rise to specific single logarithmically enhanced (SL) terms
(non-global logs). We consider associated distributions in two variables which
combine measurement of a jet shape V in the whole phase space (global) and that
of the transverse energy flow away from the jet direction, Eout (non-global).
We show that associated distributions factorize into the global distribution in
V and a factor that takes into account SL contributions from multi-gluon
``hedgehog'' configurations in all orders. The latter is the same that
describes the single-variable Eout distribution, but evaluated at a rescaled
energy VQ.Comment: 16 page
Thermo-mechanical behavior of surface acoustic waves in ordered arrays of nanodisks studied by near infrared pump-probe diffraction experiments
The ultrafast thermal and mechanical dynamics of a two-dimensional lattice of
metallic nano-disks has been studied by near infrared pump-probe diffraction
measurements, over a temporal range spanning from 100 fs to several
nanoseconds. The experiments demonstrate that, in these systems, a
two-dimensional surface acoustic wave (2DSAW), with a wavevector given by the
reciprocal periodicity of the array, can be excited by ~120 fs Ti:sapphire
laser pulses. In order to clarify the interaction between the nanodisks and the
substrate, numerical calculations of the elastic eigenmodes and simulations of
the thermodynamics of the system are developed through finite-element analysis.
At this light, we unambiguously show that the observed 2DSAW velocity shift
originates from the mechanical interaction between the 2DSAWs and the
nano-disks, while the correlated 2DSAW damping is due to the energy radiation
into the substrate.Comment: 13 pages, 10 figure
Soft gluons at large angles in hadron collisions
A general discussion is presented of the single logarithmic soft factor that
appears in two scale QCD observables in processes involving four partons. We
treat it as the ``fifth form factor'', accompanying the four collinear singular
Sudakov form factors attached to colliding and outgoing hard partons. The fifth
form factor is expressed in terms of the Casimir operators (squared colour
charges) of irreducible representations in the crossing - and -channels.
As an application we revisit the problem of large angle radiation in
and give a relatively simple solution and interpretation of the results. We
found an unexpected symmetry of the soft anomalous dimension under exchange of
internal and external variables of the problem whose existence calls for
explanation.Comment: 29 pages, pictures generated with feynmf graphic packag
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