An Updating Method for Finite Element Models of Flexible-Link Mechanisms Based on an Equivalent Rigid-Link System

This paper proposes a comprehensive methodology to update dynamic models of flexible-link mechanisms (FLMs) modeled through ordinary differential equations. The aim is to correct mass, stiffness, and damping matrices of dynamic models, usually based on nominal and uncertain parameters, to accurately represent the main vibrational modes within the bandwidth of interest. Indeed, the availability of accurate models is a fundamental step for the synthesis of effective controllers, state observers, and optimized motion profiles, as those employed in modern control schemes. The method takes advantage of the system dynamic model formulated through finite elements and through the representation of the total motion as the sum of a large rigid-body motion and the elastic deformation. Model updating is not straightforward since the resulting model is nonlinear and its coordinates cannot be directly measured. Hence, the nonlinear model is linearized about an equilibrium point to compute the eigenstructure and to compare it with the results of experimental modal analysis. Once consistency between the model coordinates and the experimental data is obtained through a suitable transformation, model updating has been performed solving a constrained convex optimization problem. Constraints also include results from static tests. Some tools to improve the problem conditioning are also proposed in the formulation adopted, to handle large dimensional models and achieve reliable results. The method has been experimentally applied to a challenging system: a planar six-bar linkage manipulator. The results prove their capability to improve the model accuracy in terms of eigenfrequencies and mode shapes

digital surveys and 3d reconstructions for augmented accessibility of archaeological heritage

Abstract. This paper presents part of the results of a larger research project that focused on the surveying and documenting of Roman theatres and amphitheatres in the Campania region as well as the testing of a virtual fruition system for the digital reconstruction of a case study: the Roman theatre of Benevento. The work was carried out by the research group at the Interdepartmental Urban/Eco Research Centre of the University of Naples Federico II in collaboration with Spinvector, a company specialized in ICT – Information and Communication Technology – which lead to the defining of a fruition system of Cultural Heritage applied to archaeological heritage.The project included 3D digital surveys of the study samples carried out using reality-based techniques, which allowed for the acquisition of metric, morphological, geometric and colorimetric data. This made it possible to elaborate three-dimensional models, based on the current configuration of the places as well as of the possible original reconfigurations.</p

The effects of physical activity on balance and postural control in people with down syndrome

People with Down Syndrome (DS) often have impaired balance and postural control and result as less active than their peers, that can lead to reduced quality of life and movement skills. Effects of physical activity may be important in preventing falling risk and health consequences in people with DS. In this context, we conducted a literature search of original articles, published between January 2010 and January 2020, on the effects of physical activity on balance and postural control in people with DS. We found 16 articles from almost all continents, investigating the effects of different types of physical activity on static and dynamic balance and postural control. The included studies reported improvements in both static and dynamic balance with exercise programmes lasting at least 6 weeks and containing strength, aerobic and sensorimotor training. However, the most suitable type of physical activity for people with DS is not clear. In conclusion, physical activity is highly recommendable in people with DS, to improve their balance and prevent falling risk

Frontal alpha asymmetry neurofeedback for the reduction of negative affect and anxiety

Frontal alpha asymmetry has been proposed to underlie the balance between approach and withdrawal motivation associated to each individual's affective style. Neurofeedback of EEG frontal alpha asymmetry represents a promising tool to reduce negative affect, although its specific effects on left/right frontal activity and approach/withdrawal motivation are still unclear. The present study employed a neurofeedback training to increase frontal alpha asymmetry (right - left), in order to evaluate discrete changes in alpha power at left and right sites, as well as in positive and negative affect, anxiety and depression. Thirty-two right-handed females were randomly assigned to receive either the neurofeedback on frontal alpha asymmetry, or an active control training (N = 16 in each group). The asymmetry group showed an increase in alpha asymmetry driven by higher alpha at the right site (p < 0.001), as well as a coherent reduction in both negative affect and anxiety symptoms (ps < 0.05), from pre-to post-training. No training-specific modulation emerged for positive affect and depressive symptoms. These findings provide a strong rationale for the use of frontal alpha asymmetry neurofeedback for the reduction of negative affect and anxiety in clinical settings

Review on the effects of physical activity on body composition and shape in people with down syndrome

People with Down Syndrome (DS) are often characterized by overweight or obesity and result to be less active than their peers. Both overweight/obesity and physical inactivity are considered important risk factors for health, thus augmenting mortality risk. World Health Organization recommends different training programmes for health benefits in different age ranges of general population. Effects of physical activity may be even more important in preventing health consequences in people with DS. In this context, we conducted a literature search of original articles, published between May 2010 and May 2020, on the effects of physical activity on body shape, body composition and bone quality in people with DS. We found twelve articles from all the continents, investigating the effects of different types of physical activity on body fat and lean masses, bone composition and anthropometry. In sum, the included studies reported improvements in body composition (with augmented lean mass and reduced fat mass), body size (with lower weight, waist circumference and BMI) and bone quality (in terms of bone mineral content and/or bone mineral density). In particular, body composition improves after conditioning and plyometric jumps training program, 2-wheel bicycle training, whole body vibration and swimming. Body shape is significantly improved by bicycle training, interval training and swimming. Finally, bone quality shows positive results after conditioning and plyometric jumps training program, whole body vibration and weight bearing exercise. Although different types of physical activity are investigated in people with DS, however the best training programme for this population is not clear. So future studies may focus on the comparison or combination of different types of physical activity to assess which one could maximize benefits

Calculating Nonlocal Optical Properties of Structures with Arbitrary Shape

In a recent Letter [Phys. Rev. Lett. 103, 097403 (2009)], we outlined a computational method to calculate the optical properties of structures with a spatially nonlocal dielectric function. In this Article, we detail the full method, and verify it against analytical results for cylindrical nanowires. Then, as examples of our method, we calculate the optical properties of Au nanostructures in one, two, and three dimensions. We first calculate the transmission, reflection, and absorption spectra of thin films. Because of their simplicity, these systems demonstrate clearly the longitudinal (or volume) plasmons characteristic of nonlocal effects, which result in anomalous absorption and plasmon blueshifting. We then study the optical properties of spherical nanoparticles, which also exhibit such nonlocal effects. Finally, we compare the maximum and average electric field enhancements around nanowires of various shapes to local theory predictions. We demonstrate that when nonlocal effects are included, significant decreases in such properties can occur.Comment: 30 pages, 12 figures, 1 tabl

Discovering hidden architectures of ancient time: 3d data survey to reveal the myth of mithra in Santa Maria Capua Vetere

The research illustrated in this paper is part of a wider testing ground, aimed at identifying and developing processes of le arning and development taking place in archaeological contexts. These sites are investigated through the use of advanced technology, based on integrated methods of survey of new generation. The aim is to identify alternative languages of representation, able to read and to represent effectively the analyzed object and to propose alternative enjoyment systems. The case study is the Mithraeum in Santa Maria Capua Vetere, for which were carried out surveys with non-contact techniques, based on the use of instrumentations, for the acquisition of colorimetric and metric informations, that exploit a non-invasive approach. Data coming from laser scanner's sensors, combined with GPS receivers, are processed to define a three-dimensional centimetric space, in a single reference system of individual scans. Purpose of this research is to identify representation techniques able to communicate the sense of the multiple interrelations and of interferences among parties, providing the subsequent insertion of data into a wider project of cataloging, fruition and valuation of cultural heritage. The chance to diffuse Digital surveys is now a possible and implementable reality. The purpose is to spread awareness of World Heritage, in a participatory manner and based on the spiri t of knowledge, conveying all the strength of cultural content that heritage has

Uncertainty Quantification in Synthetic Controls with Staggered Treatment Adoption

We propose principled prediction intervals to quantify the uncertainty of a large class of synthetic control predictions (or estimators) in settings with staggered treatment adoption, offering precise non-asymptotic coverage probability guarantees. From a methodological perspective, we provide a detailed discussion of different causal quantities to be predicted, which we call `causal predictands', allowing for multiple treated units with treatment adoption at possibly different points in time. From a theoretical perspective, our uncertainty quantification methods improve on prior literature by (i) covering a large class of causal predictands in staggered adoption settings, (ii) allowing for synthetic control methods with possibly nonlinear constraints, (iii) proposing scalable robust conic optimization methods and principled data-driven tuning parameter selection, and (iv) offering valid uniform inference across post-treatment periods. We illustrate our methodology with an empirical application studying the effects of economic liberalization in the 1990s on GDP for emerging European countries. Companion general-purpose software packages are provided in Python, R and Stata

Early impairment of endothelial structure and function in young normal-weight women with polycystic ovary syndrome

The aim of this study was to evaluate the presence of early vascular damage in young normal-weight women with polycystic ovary syndrome (PCOS).Thirty young normal-weight women with PCOS, who had no additional metabolic or cardiovascular diseases, and 30 healthy women (controls) matched for age and body mass index were studied. A complete hormonal assay was performed in each subject. Serum insulin and glucose levels were measured at baseline and after the oral glucose tolerance test. Plasma endothelin-1 levels and serum lipid profile were also assessed. The endothelial function was studied by flow-mediated dilation on the brachial artery, and arterial structure was evaluated by intima-media thickness measurement using Doppler ultrasound of both common carotid arteries.A significant (P &lt; 0.05) difference in flow-mediated dilation (14.3 +/- 1.9% vs. 18.1 +/- 2.0% for PCOS patients and controls, respectively) and in intima-media thickness (0.53 +/- 0.09 mm vs. 0.39 +/- 0.08 mm for PCOS patients and controls, respectively) was found between PCOS and control subjects. Serum endothelin-1 levels were also significantly (P &lt; 0.05) higher in PCOS patients compared with controls (1.1 +/- 0.4 pmol/liter vs. 0.5 +/- 0.2 pmol/liter for PCOS patients and controls, respectively).In conclusion, our data show that young, normal-weight, nondyslipidemic, nonhypertensive women with PCOS have an early impairment of endothelial structure and function

MULTI-SENSOR SURVEYS FOR THE CHURCH OF SANT'AGNELLO ABATE. 3D MODELS AND VIRTUAL FRUITION

The proposed contribution outlines the study conducted on the Church of Sant’Agnello Abate, located in the ancient center of the city of Maddaloni. The church is characterized by severe decay conditions and has been inaccessible and unusable for decades. To recover the memory of a place that was habitually used until 1980, survey activities were performed on the building body. Specifically, multi-sensor surveys have been performed and allowed the complete 3D documentation of the building. Various goals were set: documenting the current condition and configuration of the church: creating virtual fruition systems, since the place is closed and characterized by poor safety conditions; establishing communication models, aligned with contemporary iconographic culture, for the appearance of the places before 1980. Both for survey technologies and fruition modalities, low-cost systems were employed and tested