44,483 research outputs found
Seismic vulnerability of industrial steel structures with masonry infills using a numerical approach
No full textRecent earthquakes have highlighted the high vulnerability of the industrial structures that are not specifically designed for accounting seismic forces. Among them, a widespread typology is characterised by steel structures without bracing or other anti-seismic details and with masonry infills. With the aim of increasing the knowledge on the seismic behaviour of these structures, this work focuses on a mechanical-based approach for the evaluation of fragility curves for industrial areas. The exposure data are obtained by in-situ survey and acquiring information available in existing databases, like the Italian Cartis-GL one that is specifically devised for industrial structures. The variability of geometrical and mechanical data and the presence of epistemic uncertainties are considered by constructing a population of structures using the Monte Carlo method. Each structure is analysed through static-nonlinear simulations adopting mixed finite elements accounting for geometrical and constitutive nonlinearities. The approach is tested for infilled steel structures in the industrial area of the municipality of Spezzano Albanese (Italy). Results show that the presence of masonry infill drastically modifies the seismic behaviour of this structural typology. In particular, it turns out that if the mechanical contribution of the infill is neglected, the structures exhibit high damages even for low intensities of the seismic action
Koiter analysis of folded structures using a corotational approach
No full textAbstractThe paper deals with geometrically nonlinear finite element analysis of folded-plate and shell structures. A Koiter asymptotic approach is proposed, based on the reuse of a linear element in the nonlinear context through a corotational formulation.The corotational approach represents a simple and effective way to satisfy the basic requirement of Koiter analysis, i.e. full objectivity in the finite element modeling. In fact, starting simply from a suitable linear finite element and implementing the corotational algebra proposed in Garcea et al. (2009), Zagari (2009) lead to objective explicit expressions for the first four variations of the strain energy which are needed by asymptotic analysis.The shell element used here is the flat shell quadrangular element with 4 nodes and 6 dofs per node proposed in Madeo et al. (2012) and called MISS-4: a mixed element, based on the Reissner–Mindlin plate theory, with an Allman-like quadratic interpolation for displacements and an equilibrated isostatic interpolation for the stress resultants. The element is free from locking and spurious zero-energy modes, so it appears a suitable candidate for nonlinear corotational analysis.The results of the numerical validation show the effectiveness and accuracy of the proposed approach, and its excellent overall robustness for both mono- and multi-modal buckling problems, also in the presence of strong nonlinear pre-critical behavior
The Approach to a Child with Dysmorphic Features: What the Pediatrician Should Know
No full textThe advancement of genetic knowledge and the discovery of an increasing number of genetic disorders has made the role of the geneticist progressively more complex and fundamental. However, most genetic disorders present during childhood; thus, their early recognition is a challenge for the pediatrician, who will be also involved in the follow-up of these children, often establishing a close relationship with them and their families and becoming a referral figure. In this review, we aim to provide the pediatrician with a general knowledge of the approach to treating a child with a genetic syndrome associated with dysmorphic features. We will discuss the red flags, the most common manifestations, the analytic collection of the family and personal medical history, and the signs that should alert the pediatrician during the physical examination. We will offer an overview of the physical malformations most commonly associated with genetic defects and the way to describe dysmorphic facial features. We will provide hints about some tools that can support the pediatrician in clinical practice and that also represent a useful educational resource, either online or through apps downloaded on a smartphone. Eventually, we will offer an overview of genetic testing, the ethical considerations, the consequences of incidental findings, and the main indications and limitations of the principal technologies
A hybrid virtual element formulation for 2D elasticity problems
No full textIn this paper, a hybrid variational framework for the Virtual Element Method (VEM) is proposed and a family of polygonal elements for plane elasticity is developed. Under specific assumptions, it is proved that the minimization of Total Potential Energy and the projection operation typical of enhanced VEM can be deduced from the stationary condition of the Hellinger–Reissner mixed functional. Since the designed elements can be regarded as either enhanced VEM or hybrid finite elements, they are named as Hybrid Virtual Element Method (HVEM). The primary variables are the displacements along the element boundary and the stress field within the element domain.
The assumed stress field is expressed on a polynomial basis that satisfies the divergence-free condition. In the HVEM formulation, stabilization-free elements can be obtained using two concepts, namely hyper-stability and iso-stability. In particular, the iso-stable cases show the best solution in recovering both displacement and stress fields. Several numerical applications are developed, assessing the stability for a single distorted element. The proposed family of HVEM proves to be accurate, also if coarse meshes are used. Additionally, the effectiveness of the proposed HVEM is demonstrated for typical structural elements, testing the convergence rate and comparing the results with analytic or other numerical solutions
Growth hormone deficiency and hypobetalipoproteinemiin a patient with Kabuki syndrome: A case report
No full textKabuki syndrome (KS) is a rare condition characterized by facial features (eversion of the lower lateral eyelid, arched eyebrows with the lateral one-third dispersed or sparse, depressed nasal tip, and prominent ears), skeletal anomalies, dermatoglyphic abnormalities, short stature, and mental retardation. We described a case of KS clinically diagnosed at 7 years of life based on typical facial features, neurodevelopmental delay, and growth failure; the diagnosis was genetically confirmed later on in adolescence. Endocrinology investigations performed for short stature, revealed growth hormone deficiency (GHD). The treatment with rhGH from 8 years of life, initially improved height velocity and stature, however the catch-up growth was only transient and final height was disappointing. The patient investigated also for the presence of altered lipid profile showed hypobetalipoproteinemia (HBL). At the best of our knowledge, this is the first case of KS with both GHD and genetic hypobetalipoproteinemia in the literature. This case reinforces the awareness for the necessity to take in account that in many cases syndromes can combine with different unexpected genetic conditions. (www.actabiomedica.it)
Numerical Model and Seismic Vulnerability of Infilled Industrial Steel Structures
No full textA numerical framework for the seismic vulnerability assessment of industrial steel structures with masonry infills is presented. This peculiar structural typology has been extensively observed in many industrial areas in the Italian territory and is commonly characterized by the absence of bracings or any anti-seismic design criteria. As such, masonry infills represent the main seismic resistant structural component which, then, cannot be neglected in the vulnerability analyses. An efficient finite element model is adopted to simulate the structural nonlinear behaviour, considering both geometrical and constitutive nonlinearities. Epistemic uncertainties related to the geometric data and the mechanical characteristics of steel and masonry are considered. The approach is tested for infilled steel structures in the industrial area of Spezzano Albanese, in southern Italy. Fragility curves are constructed considering or not considering the presence of infills and the results show that the seismic behaviour is drastically different in the two cases. In particular, it turns out that if the mechanical contribution of the infill is neglected, the structures exhibit high damage even for low intensities of the seismic action
Intelligent Agents For Pandemic Modeling
No full textPandemic scenarios are very complex due to the wide
number of variables and critical aspects which have to
be considered. In fact these phenomena evolve quickly
with strong inertia and influence of stochastic
components (i.e. mutation, human decisions, etc.).
Therefore, Modeling & Simulation is often the only
approach able to reproduce effectively pandemic
dynamics in a realistic way.
A methodology for developing such types of models,
taking into consideration open-issues generated by
pandemic threats is proposed in the paper and human
factors are consider as critical element to mode. A
methodology that supports quick development of
models and fast result achievement is elaborated and
described; at the same time, particular attention is
given to validation and verification of models
WORKLOAD FORECAST ALGORITHM OPTIMIZATION FOR RE-ORGANIZING RETAIL NETWORK
No full textThis research is focused on developing an innovative approach for optimizing workload forecast algorithms in point of sale for retailers; this paper proposes a real case as validation framework and the procedures for optimizing and fine tuning the predictive algorithms for improving their performances. The analysis is based on different time series (i.e. sales, customers, working hours, etc.) correlated by the predictive algorithms. The paper proposes a metrics devoted to measure the performances considering the multivariable framework and the different target functions
A mechanical-based seismic vulnerability assessment method with an application to masonry structures in Cosenza (Italy)
No full textThe paper presents a mechanical-based framework for the evaluation of local-scale seismic
fragility curves. The approach is oriented to a seismic vulnerability assessment of unrein-
forced masonry buildings and makes use of basic exposure data easily obtained from sur-
vey or available in existing database. An efficient finite element model and static nonlinear
analyses are employed to assess the structural behaviour. The mechanical-based fragility
curves are evaluated using Monte Carlo simulations that allow to account for the uncer-
tainties propagation. The proposed approach is tested on a case-study regarding the city
centre of Cosenza, in southern Italy, using exposure information available from CARTIS
database
Seismic vulnerability of masonry structures through a mechanical-based approach
No full textEnhancing the territorial resilience to natural events, such as earthquakes, is assuming a primary role in the current political debate. In the context of Disaster Risk Management, developing reliable vulnerability models for the seismic risk assessment at a territorial scale is an aspect of crucial importance. In this perspective, the paper presents a mechanical-based method for the evaluation of local-scale seismic fragility curves for unreinforced masonry buildings, based on the exposure data collected in the Italian CARTIS database. It uses a bidimensional finite element model and static nonlinear analyses to obtain the structural behaviour. Monte Carlo simulations are performed to propagate the uncertainties. Both local and global scale structural behaviour are considered to define the damage grade. A case-study regarding the city centre of Cosenza, in southern Italy, validates the proposal
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